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Screening Assessment for the Challenge

Hydrazine

Chemical Abstracts Service Registry Number
302-01-2

Environment Canada
Health Canada

January 2011


(PDF version - 506 KB)

Table of Contents

Synopsis

The Ministers of the Environment and of Health have conducted a screening assessment of hydrazine, Chemical Abstracts Service Registry Number (CAS[*] RN) 302-01-2. The substance hydrazine was identified in the categorization of the Domestic Substances List as a high priority for action under the Chemicals Management Plan Challenge initiative. Hydrazine was identified as a high priority as it was considered to pose an intermediate potential for exposure of individuals in Canada and is classified by other agencies on the basis of carcinogenicity. The substance did not meet the ecological categorization criteria for persistence or bioaccumulation potential, but it did meet the criteria for inherent toxicity to aquatic organisms.

Most hydrazine is imported into Canada in aqueous solutions, the form of the product commonly found on the market. In aqueous solution, all the hydrazine is invariably present as the hydrate. This chemical species has a molecule of water loosely attached to an electronegative nitrogen atom by a weak hydrogen bond. The hydrated form is not considered to be chemically different from the anhydrous substance, and can be considered to represent a mixture of the substance with water. Therefore, this assessment considers that hydrazine and hydrazine hydrate are effectively the same substance. Only minor differences in physical-chemical properties are observed between these two forms due to the association of hydrazine with water in the hydrated form.

According to information submitted under section 71 of CEPA 1999, hydrazine was not manufactured by any company in Canada in the calendar year 2006 above the 100 kg reporting threshold. However, 10 000–100 000 kg of hydrazine was reported to have been imported in 2006. The major use of hydrazine is as a corrosion inhibitor in boiler water used at power generating plants. Releases of hydrazine to the environment from these sources do occur. However, exposure of the general population of Canada to hydrazine is expected to be low.

Based principally on the weight-of-evidence-based assessments of international or other national agencies, a critical effect for characterization of risk to human health for hydrazine is carcinogenicity. Increased incidences of bronchial tumours in male and female rats, thyroid tumours in male rats, and nasal tumours in hamsters were observed after inhalation exposure. Increased incidences of lung tumours were observed in mice of both sexes after oral exposure. Genotoxicity was observed in both in vivo and in vitro assays with hydrazine. Based on tumours observed in multiple sites in experimental rodents for which modes of induction have not been fully elucidated, it cannot be precluded that hydrazine induces tumours via a mode of action involving direct interaction with genetic materials.

Repeated-dose studies based on inhalation exposure showed effects on the respiratory systems and systemic effects in multiple sites of male rats. Except for increased mortality, no other effects were observed from repeated-dose studies based on oral exposure to hydrazine. Increased incidence of bile duct proliferations was observed in male rats exposed to hydrazine hydrate. Margins of exposure (MOE) were derived for inhalation and oral exposures and these margins were considered adequate to account for uncertainties in the exposure and health effects dataset for non-cancer effects. However, based on the observed genotoxicity and carcinogenicity, for which there may be a probability of harm at any level of exposure, it is concluded that hydrazine may be entering the environment in a quantity or concentration or under conditions that constitute or may constitute a danger in Canada to human life or health.

Hydrazine has high aquatic toxicity but does not meet the criteria defined for persistence or bioaccumulation potential set out in the Persistence and Bioaccumulation Regulations of CEPA 1999. Given its use particularly in power generating plants, this substance tends to be dispersed widely in the Canadian environment. The National Pollutant Release Inventory reported sustained relatively high quantities of hydrazine released to the environment over a six-year period. In some cases, concentrations in surface water near nuclear and fossil-fuel power generating plants across Canada, estimated based on measured and modelled concentrations in effluent outfalls, are higher than or close to the estimated no-effect levels. Based on this information, it is concluded that hydrazine is entering the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity.

It is therefore concluded that hydrazine meets one or more of the criteria under section 64 of CEPA 1999.

This substance will be considered for inclusion in the Domestic Substances List inventory update initiative. In addition and where relevant, research and monitoring will support verification of assumptions used during the screening assessment and, where appropriate, the performance of potential control measures identified during the risk management phase.

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Introduction

The Canadian Environmental Protection Act, 1999 (CEPA 1999) (Canada 1999) requires the Minister of the Environment and the Minister of Health to conduct screening assessments of substances that have met the categorization criteria set out in the Act to determine whether these substances present, or may present a risk, to the environment or to human health.

Based on the information obtained through the categorization process, the Ministers identified a number of substances as high priorities for action. These include substances that:

The Ministers therefore published a notice of intent in the Canada Gazette, Part I, on December 9, 2006 (Canada 2006), that challenged industry and other interested stakeholders to submit, within specified timelines, specific information that may be used to inform risk assessment and to develop and benchmark best practices for the risk management and product stewardship of those substances identified as high priorities.

The substance hydrazine was identified as a high priority for assessment of human health risk because it was considered to present an intermediate potential for exposure and had been classified by other agencies on the basis of carcinogenicity. The Challenge for this substance was published in the Canada Gazette on June 20, 2009 (Canada 2009a). A substance profile was released at the same time. The substance profile presented the technical information available prior to December 2005 that formed the basis for categorization of this substance. As a result of the Challenge, submissions of information pertaining to the substance were received.

Although hydrazine was determined to be a high priority for assessment with respect to human health, it did not meet the ecological categorization criteria for persistence or bioaccumulation in the Persistence and Bioaccumulation Regulations but it did meet the criteria for toxicity to aquatic organisms.

Screening assessments focus on information critical to determining whether a substance meets the criteria as set out in section 64 of CEPA 1999. Screening assessments examine scientific information and develop conclusions by incorporating a weight-of-evidence approach and precaution[2].

This screening assessment includes consideration of information on chemical properties, hazards, uses and exposure, including the additional information submitted under the Challenge. Data relevant to the screening assessment of this substance were identified in original literature, review and assessment documents, stakeholder research reports and from recent literature searches, up to October 2010 for the human and ecological sections of the document. Key studies were critically evaluated; modelling results may have been used to reach conclusions.

Evaluation of risk to human health involves the consideration of data relevant to estimation of exposure (non-occupational) of the general population, as well as information on health hazards (based principally on the weight-of-evidence assessments of other agencies that were used to prioritize the substance). Decisions for human health are based on the nature of the critical effect and/or margins between conservative effect levels and estimates of exposure, taking into account confidence in the completeness of the identified databases on both exposure and effects, within a screening context. The screening assessment does not represent an exhaustive or critical review of all available data. Rather, it presents a summary of the critical information upon which the conclusion is based.

This screening assessment was prepared by staff in the Existing Substances Programs at Health Canada and Environment Canada and incorporates input from other programs within these departments.

The ecological and human health portions of this assessment have undergone external written peer review and consultation. Comments on the technical portions relevant to human health were received from Dr. Chris Bevans (CJB Consulting), Dr. Bernard Gadagbui (Toxicology Excellence for Risk Assessment and Dr. Donna Vorhees (Science Collaborative). Additionally, the draft of this screening assessment was subject to a 60-day public comment period. While external comments were taken into consideration, the final content and outcome of the screening assessment remain the responsibility of Health Canada and Environment Canada. Approaches used in the screening assessments under the Challenge have been reviewed by an independent Challenge Advisory Panel.

The critical information and considerations upon which the assessment is based are summarized below.

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Substance Identity

For the purposes of this document, this substance will be referred to as hydrazine. The identity of this substance is presented in Table 1a. Most respondents to the section 71 notice (Environment Canada 2009) imported aqueous solutions in which hydrazine is present at ~ 35% by weight, the form of the product commonly found on the market. Mohr and Audrieth (1949) determined that hydrazine-water mixtures are composed of monohydrate of hydrazine (hydrazine hydrate). They also suggested the existence of two other chemical forms of hydrazine, but it is generally assumed that in commercial aqueous solutions of hydrazine, all the hydrazine is present as the hydrate (Arch Chemicals Inc. 2009). In the hydrate form, a molecule of water is loosely attached to an electronegative nitrogen atom by a weak hydrogen bond (Huheey 1978). The hydrated form is not considered to be chemically different from the anhydrous substance, but can be considered to represent a mixture of the substance with water. Therefore, this assessment considers that hydrazine and hydrazine hydrates (both CAS RN – see Table 1b) are effectively the same substance. It is nevertheless acknowledged that there are minor differences in their physical-chemical properties due to the association of hydrazine with water in the hydrated form, which results for example in a different melting point (Table 2). Both forms of hydrazine are described in the present section and in the section on physical and chemical properties. Throughout the balance of this report, when the term hydrazine is used it refers to both the anhydrous and hydrated forms. It should be noted that there are commercial hydrazine salts (e.g., hydrazine sulphate) however these do not fall within the scope of this assessment.

Hydrazine and hydrazine hydrate present conformations in which one NH2 group is rotated from the transposition (Tables 1a and 1b). The vacant tetrahedral positions are occupied by lone electron pairs that impart the basic and nucleophilic character to these molecules (Rothgery 2004). As mentioned above, hydrazine and the water molecule are linked by a hydrogen bond (Table 1b). With two active nucleophilic nitrogens and four reactive hydrogens, hydrazine is the starting material for the production of many chemical derivatives (Rothgery 2004).

Table 1a. Substance identity for Hydrazine

Chemical Abstracts Service Registry Number (CAS RN)302-01-2
DSL nameHydrazine
National Chemical Inventories(NCI) namesHydrazine (AICS, ASIA-PAC, ECL, EINECS, ENCS, SWISS, NZIoC, PICCS, TSCA)
Other namesDiamide
Diamine
Levoxine
Nitrogen hydride
Oxytreat 35
UN 2029
UN 2030
H70
Chemical group
(DSL Stream)
Discrete inorganics
Major chemical class or useAmmonia
Major chemical sub-classAmmonia-derived compound
Chemical formulaN2H4
Chemical structure

Chemical structure 302-01-2 (Hydrazinium ion)
Hydrazinium ion 

Chemical structure 302-01-2 (Hydrazine)
Hydrazine

SMILESNN
Molecular mass32.0 g/mol
Abbreviations: AICS, Australian Inventory of Chemical Substances; ASIA-PAC, Asia-Pacific Substances
Lists; CAS RN, Chemical Abstracts Service Registry Number; DSL, Domestic Substance List; ECL,
Korean Existing Chemicals List; EINECS, European Inventory of Existing Commercial Chemical
Substances; ENCS, Japanese Existing and New Chemical Substances; NCI, National Chemical Inventories;
NZIoC, New Zealand Inventory of Chemicals; PICCS, Philippine Inventory of Chemicals and Chemical
Substances; SMILES, simplified molecular input line entry system; SWISS, Swiss Giftliste 1 and Inventory
of Notified New Substances; TSCA, Toxic Substances Control Act Chemical Substance Inventory. Source:
NCI (2006).

 

Table 1b. Substance identity for hydrazine hydrate

Chemical Abstracts Service Registry Number (CAS RN)7803-57-8 / 10217-52-4
DSL nameNot on the DSL
National Chemical Inventories(NCI) namesCAS RN 7803-57-8:
Hydrazine monohydrate (AICS, ASIA-PAC, ENCS, NZIoC, PICCS, REACH, SWISS)
Hydrazine hydrate (ECL, PICCS)
CAS RN 10217-52-4:
Hydrazine hydrate (ASIA-PAC, NZIoC)
Other namesCAS RN 7803-57-8:
Hydrazine hydroxide
Hydrazine, hydrate
Hydrazinium hydroxide


CAS RN 10217-52-4:
None
Chemical group (DSL Stream)Not on the DSL
Major chemical class or useAmmonia
Major chemical sub-classAmmonia-derived compound
Chemical formulaN2H4·H2O (CAS RN 7803-57-8)
N2H4·xH2O (CAS RN 10217-52-4)
Chemical structure

Chemical structure 7803-57-8 (Hydrated hydrazinium ion)
Hydrated hydrazinium ion  

Chemical structure 10217-52-4 (Hydrazine hydrate)
Hydrazine hydrate

SMILESNN.O
Molecular mass50.0 g/mol (CAS RN 7803-57-8)
Abbreviations: AICS, Australian Inventory of Chemical Substances; ASIA-PAC, Asia-Pacific Substances
Lists; CAS RN, Chemical Abstracts Service Registry Number; DSL, Domestic Substance List; ECL,
Korean Existing Chemicals List; ENCS, Japanese Existing and New Chemical Substances; NCI, National
Chemical Inventories; NZIoC, New Zealand Inventory of Chemicals; PICCS, Philippine Inventory of
Chemicals and Chemical Substances; REACH, Registration, Evaluation, Authorisation and Restriction of
Chemicals; SMILES, simplified molecular input line entry system; SWISS, Swiss Giftliste 1 and Inventory
of Notified New Substances. Source: NCI (2006).

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Physical and Chemical Properties

Physical and chemical properties for hydrazine and hydrazine hydrate are reported in Table 2. Quantitative structure-activity relationships (QSAR) model results are not available for most inorganic compounds, including the present substances, because inorganic compounds fall outside of most QSAR application domains and their structures are not compatible with the estimation methods of these models. Therefore, Table 2 does not include any QSAR-based estimates. All of the numerical values of Table 2 have been obtained from internationally recognized and credible sources (i.e., chemistry handbooks, peer-reviewed databases). Only values determined at environmentally relevant temperatures are included in this table.

Table 2. Physical and chemical properties for hydrazine and hydrazine hydrate

PropertySubstanceTemperature (ºC)Reference
HydrazineHydrazine hydrate (CAS RN 7803-57-8)
Physical stateLiquidLiquid IPCS 1987
ColourColourlessColourless IPCS 1987
OdourAmmoniacal and pungentAmmoniacal and pungent IPCS 1987
Melting point
(ºC)
2.0–51.5 IUCLID 2000
2.0–51.7 IPCS 1987, Budavri 1996
2.0–51.6 Rothgery 2004
Boiling point
(ºC)
113.5120.1 IPCS 1987
113.5 a119.4 a Rothgery 2004
113 113.5 119–120120.1 IUCLID 2000
Density
(kg/m3)
1.0036 × 103 a
(1.0036 g/cm3)
1.03 × 103
(1.03 g/cm3 at 20ºC )
25IUCLID 2000
1.008 × 103
(1.008 g/mL)
1.032 × 103
(1.032 g/mL)
20IPCS 1987
1.004 × 103
(1.004 g/mL)
1.032 × 103 a
(1.032 g/mL)
25Rothgery 2004
Vapour pressure
(Pa)
2 100
(21 hPa)
2000
(20 hPa)
20IUCLID 2000
1.39 × 103
(1.39 kPa; 10.4 mm Hg)
1 × 103
(1 kPa; 7.5 mm Hg)
20IPCS 1987
1.92 × 103 a
(14.4 mm Hg)
 25HSDB 2010
1.92 × 103 (1.92 kPa)1.2 × 103 a (1.2 kPa)25Rothgery 2004
Henry’s Law constant
(Pa·m3/mol)
6.2 × 10–2 (6.1 × 10–7atm·m3/mole)6.2 × 10–2 (6.1 × 10–7atm·m3/mole)25HSDB 2010
5 × 10–2 to
6 × 10–2
5 × 10–2 to
6 × 10–2
 Calculatedb
Log Kow
(Octanol–water partition coefficient)
(dimensionless)
–1.37  IUCLID 2000
–3.08  IPCS 1987
–2.07 a  HSDB 2010
Water solubility
(mg/L)
Miscible 25IUCLID 2000
MiscibleMiscible IPCS 1987 Rothgery 2004
pKa
(Log acid dissociation constant)
7.96  HSDB 2010
pKa1: 7.94 c
(Kb = 8.4 × 10–7)
 25Rothgery 2004
pKa2: –1.05 c
(Kb = 8.9 × 10–16)
 25Rothgery 2004
Abbreviations: Kow, octanol–water partition coefficient.
Values and units in parentheses represent those originally reported by the authors or estimated by the models.
a Value used for fate modelling.
b Constant derived for this assessment using values of vapour pressures (see footnote a) and solubilities reported in the table; miscible is equivalent to 106 mg/L.
c pKa derived for this assessment from Kbs provided by Rothgery (2004), and the expression pKa = pKW – pKb where pKW, the pK of water, is 14 (Schwarzenbach et al. 2003).

Based on its pKa, hydrazine is a strong base, although slightly weaker than ammonia (Equation 1). The second ionization constant pKa2 (Equation 2) is so small that the N2H62+ cation will exist at only extremely low pHs (Rothgery 2004). Because of strong resemblances with hydrazine, hydrazine hydrate is also considered a strong base (Isaacson and Hayes 1984). In principle, aqueous solubilities of substances with acid–base properties vary with pH but this information is not available for solubilities reported here. However, it is expected that solubilities in water of anhydrous and hydrated hydrazine will be large regardless of the pH of the test solution.

N2H4 + H2O ® N2H5+ + OH [1]
N2H5+ + H2O ® N2H62+ + OH [2]

Hydrazine is reported to be a powerful reducing agent in basic solutions; Equation 3 represents the half-reaction of the molecule as a reductant. It is much less of a reducer in an acidic medium with an E0 (redox potential) decreasing by nearly one volt (Equation 4) (Rothgery 2004).

N2H4 + 4 OH ® N2+ 4 H2O + 4 e E0 = +1.16 V [3]
N2H5+ ® N2 + 5 H+ + 4 e E0 = +0.23 V [4]

The very similar physico-chemical properties of hydrazine and hydrazine hydrate reflect the equivalence of both forms of hydrazine. Nevertheless the low melting point of hydrazine hydrate (Table 2) is consistent with a solid crystal structure that is somewhat different from that of anhydrous hydrazine. Specifically, the low melting point of the hydrate indicates that its crystal is held together by relatively weak chemical forces including hydrogen bonds (Huheey 1978).

Regarding the decomposition of hydrazine, Rothgery (2004) indicates that elevated temperatures, over 200°C, are required for appreciable decomposition to occur. In the absence of decomposition catalysts, the author mentions that liquid anhydrous hydrazine can be heated to >200°C without appreciable decomposition. Similarly, Singer (1991) indicates that hydrazine reacts with oxygen very slowly at temperatures <350°F (177°C). Above 450 °F (232°C), hydrazine is decomposed rapidly to nitrogen, hydrogen and ammonia. Hence, depending on the temperatures reached in boiler systems in thermal power plants, the hydrazine used will decompose to a certain degree.

The principal benefit of hydrazine is its ability to reduce the oxidized forms of copper and iron (Singer 1991). Copper oxide is reduced with hydrazine at temperatures as low as 150°F (66°C). Iron oxide (Fe3O3) can be reduced at a temperature of 250°F (121°C). Reactions of hydrazine in the feedwater cycle and boiler are:

6 Fe2O3 + N2H4® 4 Fe3O4 + N2 + 2 H2O [5]

4 CuO + N2H4 ® 2 Cu2O + N2 + 2 H2O [6]

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Sources

Hydrazine is thought to occur as a natural product, although the major source of hydrazine in the environment is attributed to anthropogenic activities (ATSDR 1997, Choudhary and Hansen 1998; CERI 2007).

In response to a notice issued under section 71 of CEPA 1999, hydrazine was reported not to be manufactured in Canada in the 2006 calendar year above the reporting threshold of 100 kg (Environment Canada 2009). The quantity of hydrazine imported into Canada in 2006 was in the range of 10 000–100 000 kg. Most of these imports were as aqueous solutions of hydrazine, the form of the product commonly found on the market (Environment Canada 2009).

In 1981, global production of hydrazine was estimated in excess of 35 000 tonnes with major manufacturing capacities identified in the United States, Germany, France, Japan and the United Kingdom (IPCS 1991). More recent estimates indicate that annual global production of hydrazine in 2004 was approximately 47 350 tonnes (Rothgery 2004).

Hydrazine has been reported to occur naturally in the algae, Azotbacter agile, as a result of nitrogen fixation (ATSDR 1997) and in tobacco plants (Liu et al. 1974; IPCS 1991; Choudhary and Hansen 1998). Hydrazine is present in tobacco smoke at levels that indicate it is also a combustion product of tobacco (Liu et al. 1974; Dockery and Trichopoulos 1997).

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Uses

According to submissions received under section 71 of CEPA 1999 and information from other sources, hydrazine is used for industrial purposes only (ATSDR 1997; Choudhary and Hansen 1998; CERI 2007; Environment Canada 2009; HSDB 2010). No consumer products containing hydrazine as an ingredient were identified. When used as a raw material or an intermediate in the formulation of consumer products, hydrazine may be found in final products as a residual.

Based on responses to a notice issued under section 71 of CEPA 1999, in 2006, 10 000–100 000 kg of hydrazine were used for industrial purposes in Canada and the general population of Canada would not be exposed to hydrazine as a result of these uses (Environment Canada 2009). The major use of hydrazine in Canada in 2006 was as an oxygen scavenger/corrosion inhibitor in the boiler water used mainly at power generating plants, which accounted for 87% of reported uses (Environment Canada 2009).

In Canada and elsewhere, hydrazine may be used as a raw material or an intermediate in the production of pesticides and other agricultural chemicals (Liu et al. 1974; Newsome 1980; ATSDR 1997), pharmaceuticals (Lovering et al. 1982, 1985; Matsui et al. 1983; ATSDR 1997; Choudhary and Hansen 1998), and in the manufacture of chemical blowing agents (ATSDR 1997; Choudhary and Hansen 1998; CERI 2007). Hydrazine has also been used as a liquid propellant for space craft and as fuel for emergency power units in military aircraft (ATSDR 1997; Choudhary and Hansen 1998; CERI 2007; Apr 2009 personal communication from National Defence Headquarters, Department of National Defence to Risk Management Bureau, Health Canada; unreferenced).

Hydrazine is not listed in the Health Canada Drug Product Database (DPD), the Therapeutic Products Directorate’s (TPD’s) internal non-medicinal ingredient database, the Natural Health Products Ingredients Database (NHPID) nor the Licensed Natural Health Products Database (LNHPD) as a medicinal or non-medicinal ingredient, or as present in final pharmaceutical products, natural health products or veterinary drugs marketed in Canada (DPD 2010; LNHPD 2010; NHPID 2010; Feb 2010 personal communication from Risk Management Bureau, Health Canada to Existing Substances Risk Assessment Bureau, Health Canada; unreferenced). However, hydrazine may be present in pharmaceuticals as a residual because it is used as a catalyst or an intermediate in the formulation of pharmaceuticals (Matsui et al. 1983; ATSDR 1997; Choudhary and Hansen 1998; CERI 2007).

Hydrazine is also a residual in the polymer polyvinyl pyrrolidone (PVP) and the vinyl pyrrolidone/vinyl acetate copolymer copovidone (Colonnese and Ianniello 1989; CIR 1998; ISP 2007). Information on hydrazine levels in other PVP-derived polymers was not found.

In Canada, PVP and copovidone are used as formulants for personal care products, pharmaceuticals, natural health products and veterinary drugs (NHPID 2009; DPD 2010; Aug 2009 personal communication from Risk Management Bureau, Health Canada, to Risk Assessment Bureau, Health Canada; unreferenced; Mar 2010 personal communication from Veterinary Drugs Directorate, Health Canada to Risk Management Bureau, Health Canada; unreferenced). PVP and copovidone are listed in the NHPID as acceptable non-medicinal ingredients in natural health products (NHPID 2010). PVP has an acceptable daily intake of 50.0 mg/kg of body weight (bw)/day (NHPID 2010). When PVP and copovidone are used as non-medicinal ingredients, the polymers function as an adhesive binder, disintegrate, film former, antioxidant or stabilizer (NHPID 2010). Both PVP and copovidone are listed in the LNHPD, thus are used in current licensed natural health products available in Canada (LNHPD 2010). Therefore, hydrazine may be present in personal care products, pharmaceuticals, natural health products and veterinary drugs at residual levels.

PVP has permitted uses as a food additive in Canada, as per Division 16 of the Food and Drug Regulations (Canada 2009b). Therefore, trace amounts of hydrazine may be present in food as a result of the use of PVP as a food additive (Canada 2009b; Mar 2010 personal communication from Food Directorate, Health Canada, to Existing Substances Risk Assessment Bureau, Health Canada; unreferenced).

Hydrazine was also identified as a residual in the manufacture of one laminated film used in food packaging applications (Dec 2009 personal communication from Food Directorate, Health Canada, to Risk Management Bureau, Health Canada; unreferenced) and formulant impurity in six registered pest control products with food uses at trace levels (parts per billion) and lower (Feb 2010 personal communication from Pest Management Regulatory Agency, Health Canada, to Risk Management Bureau, Health Canada; unreferenced). Pest control products are regulated by the Pest management Regulatory Agency (PMRA) under the Pest Control Products Act.

Hydrazine is listed on the Cosmetic Ingredient Hotlist, and as such, is not permitted to be intentionally added to cosmetic products available in Canada (Health Canada 2009b).

Historically, the primary use of hydrazine was as a rocket propellant. In the United States, 73% of hydrazine consumed in 1964 was used for this purpose. By 1982, the use profile for hydrazine had diversified: 40% of hydrazine was used in the manufacture of agricultural chemicals, 33% for chemical blowing agents, 15% in boiler water treatment as a corrosion inhibitor, 5% as rocket propellant and 7% for other purposes (ATSDR 1997).

A Japanese assessment on hydrazine reported that all anhydrous hydrazine produced in Japan was used as rocket propellant, whereas hydrazine hydrate was used mainly as a raw material for industrial purposes. The primary use of hydrazine hydrate in Japan was in the production of chemical blowing agents (41%), as a corrosion inhibitor in boiler water treatment (28%), as a raw material for the synthesis of industrial chemicals (21%), in the manufacturing of agricultural chemicals and pharmaceuticals (3% and 1%, respectively), and 6% for other purposes (CERI 2007).

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Releases to the Environment

In response to a notice issued under section 71 of CEPA 1999, during 2006, 123 kg and 1865 kg of hydrazine were reported to have been released to the atmosphere and hydrosphere, respectively. In addition to environmental releases of hydrazine, 1076 kg were transferred to hazardous waste facilities for disposal in 2006 (Environment Canada 2009).

Releases of hydrazine and its salts in Canada were reported to the National Pollutant Release Inventory (NPRI) by four to five facilities per year from 2004 to 2008: three nuclear power generating plants, one producer of specialty chemicals and one manufacturer of chemical products (NPRI 2008; Table 3). Nearly all the emissions to air, water and soil were associated with the operation of nuclear power generating plants, which are known to release hydrazine (not as a salt) to the environment (Environment Canada 2009). More than 90% of these emissions were to water. Quantities disposed of were mainly sent off-site for incineration or physical or chemical treatment.

These NPRI data are consistent with the fact that cooling water circuits of boilers of nuclear reactor plants generate a liquid effluent containing hydrazine, which is released to the environment (Hirzel 1998). Indeed, there is partial removal of water from the steam-generating systems with replacement by fresh, demineralized water to maintain dissolved solids concentrations at constant low levels. This water removal, called ‘blowdown,’ becomes part of the final effluent from plants and contains hydrazine because this substance is used in stochiometric excess to ensure removal of dissolved oxygen from the make-up water used to compensate the blown down steam (Collins 2000, Environment Canada 2009, James 1989). The frequency of these blowdown events varies from one facility to the other. This blowdown process also occurs in those fossil-fuelled power generating plants in Canada that use hydrazine in their boiler feed water systems. This constitutes the major use of hydrazine in both nuclear and fossil-fuelled power plants, but smaller quantities of hydrazine are also used by these plants for corrosion and pH control in a variety of systems, including auxiliary boiler water, recirculating cooling water, emergency coolant injection and boiler layup. In principle, these other systems can also generate and release liquid effluents to the receiving environment (Environment Canada 2009). Nuclear power is produced in New Brunswick, Quebec and Ontario. Fossil-fuelled power generating plants are present in every province, with the largest production being in the Atlantic provinces, Ontario, Saskatchewan and Alberta (CEA 2006).

Table 3. National Pollutant Release Inventory (NPRI) release and disposal data (kg) for hydrazine and its salts, 2004–2008

YearReleases to airReleases to waterReleases to landTotal releasesTotal disposals
20041523 40003 552836
20051862 20002 386655
20061191 90002 019248
20071452 70062 851225
20081076 4002906 797243
Source: NPRI (2008).

Hydrazine fuel that is used in aircraft can be released into air and water as a result of accidental discharges on airfields (MacNaughton et al. 1981). During international training exercises, allied countries flying F-16 aircraft may use and store small quantities of hydrazine fuel at Canadian Forces bases. These countries are responsible for the management of the fuel and, in the event of an accidental discharge, for spill response.

Hydrazine which may be present in human pharmaceuticals may reach aquatic environments via wastewater collection/treatment systems, the incorrect disposal of unused drugs, and to a lesser extent via waste and spills during production (Jones et al. 2004).

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Environmental Fate

The acid dissociation constant (pKa) of 7.96 for the acidic functional group indicates that about half of hydrazine will be in neutral form at pH 8, with the remainder present as the hydrazinium cation (N2H5+). With a Henry’s Law constant of 6.2×10-2Pa·m3/mol, the neutral form of this base will have a low volatility in waters of high pH. Conversely, the ionized form (hydrazinium ion) will be essentially not volatile (Schwarzenbach et al. 2003) and will dominate in slightly acidic waters of pH 6 and below. It follows that the environmental partitioning of hydrazine will vary notably as a function of the pH of surface waters. Simulations for environmental partitioning were performed using Level III (steady-state, non-equilibrium) of the Equilibrium Criterion (EQC) model for Type 1 chemicals (Mackay et al. 1996; EQC 2003). Two types of waters were considered for Canada. Modelling was performed for alkaline hardwaters of pH 9 and above, which are typical of hard and productive waters (rich in phytoplankton and/or rooted macrophytes) in many parts of the Laurentian Great Lakes (e.g., Dobson 1984); more than 92% of hydrazine would be in neutral form at pH 9. Modelling was also performed for slightly acidic softwaters of pH 6 and less, characteristic of many regions of Canada (e.g., Precambrian Shield: FPRMC 1990; Nova Scotia: Farmer et al. 1988; MacPhail et al. 1987); more than 99% of hydrazine would be protonated at pH 6. Input parameters for running the EQC model and the results are presented in footnotes to Tables 4a and 4b.

If released to air, most of the substance is expected to reside in air in the scenario for alkaline hardwater (Table 4a). In contrast, the scenario for slightly acid softwater will see all the hydrazine leaving air to partition chiefly to water (Table 4b), a consequence of the negligible volatility of the hydrazinium ion prevailing in this type of water.

If hydrazine is released to surface water, the model predicts that hydrazine will remain almost entirely in that compartment whatever the type of water is (Tables 4a and 4b). This result is obtained despite the fact that the chemical’s volatility and degradation half-life vary considerably in the two water types considered (Table 4a and 4b).

If released to soil, hydrazine is predicted to remain mainly in this medium in the alkaline hardwater scenario (Table 4a). Volatilization from moist soil surfaces seems to be an unimportant fate process based upon its estimated Henry's Law constant. This chemical may volatilize from dry soil surfaces based upon its vapour pressure. In the slightly acidic softwater scenario, hydrazine will partition significantly to water although a significant proportion will remain in soil (Table 4b).

The above predictions of environmental fate have to be considered with caution because the environmental partitioning of this substance is not exclusively a function of its hydrophilicity, which is the only process considered in the EQC model.

Table 4a. Results of the Level III fugacity modelling (EQC 2003) for typical alkaline hardwaters of Canada.

Substance released to:Percentage of substance partitioning into each compartment
AirWaterSoilSediment
Air (100%)909.60.510.01
Water (100%)0.0099.90.000.02
Soil (100%)0.109.0910.01

Modelling performed for the non-ionized form at a temperature of 25ºC. Input parameters: molecular mass, 32.0 g/mol; aqueous solubility, miscible (106 mg/L); vapour pressure, 1.92×103 Pa; log Kow, -2.07; melting point, 2ºC. Details on selected half-lives (water, 93.6 h; sediments, 38.4 h; air, 5.2 h; soil, 1 h) are given in the section on Persistence and Bioaccumulation Potential.

Table 4b. Results of the Level III fugacity modelling (EQC 2003) for typical slightly acid softwaters of Canada.

Substance released to:Percentage of substance partitioning into each compartment
AirWaterSoilSediment
Air (100%)0.00981.80.02
Water (100%)0.001000.000.00
Soil (100%)0.0036640.00

Modelling performed for the fully ionized form at a temperature of 25ºC. Input parameters: molecular mass, 32.0 g/mol; aqueous solubility, miscible (106 mg/L); vapour pressure, ~ 0 Pa; log Kow, -2.07; melting point, 2ºC. Details on selected half-lives (water, 1526 h; sediments, 38.4 h; air, 5.2 h; soil, 1 h) are given in the section on Persistence and Bioaccumulation Potential.

Interactions between hydrazine and natural soils may result in chemical decomposition or chemical adsorption depending on pH and cation exchange capacity (Hayes et al. 1984, Heck et al. 1963; see section on Environmental Persistence). Chemical interactions identified include cation exchange involving particulate phases, chemisorption (i.e., strong binding) to various ligands and non-specific sorption (Isaacson and Hayes 1984, Mansell et al. 2001). The EQC model does not account for these interactions and therefore the partitioning results in Table 4b only reflect hydrophobic/hydrophilic interactions.

In principle, the hydrazinium cation may form complexes with anions in surface waters. It is well established that this cation may form salts with Br-, Cl-, NO3-, and SO4-2 anions. In turn, these salts will readily dissolve, dissociate and release the hydrazinium cation in solution (Rothgery 2004). It follows that this cation will likely not form strong complexes with typical anions in natural waters.

The ammonium anion can be oxidized anaerobically by obligately anaerobic bacteria. The chemical reaction is named ‘anommox’ (anaerobic ammonium oxidation) and proceeds as follows (Strous and Jetten 2004):

NH4+ + NO2- ® N2 + 2 H2O [5]

15N-labelling experiments using waste waters have demonstrated that hydrazine was an important intermediate in the conversion of ammonium to dinitrogen gas (Schmid et al. 2003, van de Graaf et al. 1997). Anommox has been detected in many wastewater treatment plants and in estuarine sediments (Strous and Jetten 2004, Trimmer et al. 2003). It is not known how important these processes are in freshwater ecosystems (Strous and Jetten 2004). These findings suggest the possibility that hydrazine can form naturally in anoxic waters and sediments.

To summarize, the fate of hydrazine in the aqueous environment is dependent on the relative rates of chemical and biological degradation (see section on Environmental persistence below), volatilization, sedimentation, dilution and/or dispersion (Kuch 1996). Inorganic speciation is expected to remain simple with an absence of strong complexes with major dissolved anions. Hydrazine may occur naturally in anaerobic aquatic environments.

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Persistence and Bioaccumulation Potential

Environmental Persistence

Available empirical data indicate that there exist many processes for the degradation of hydrazine in the natural environment.

Air

The likely pathways for the degradation of hydrazine in the atmosphere are reaction with ozone (O3) and attack by hydroxyl radicals (OH·). Both chemical species are present in the unpolluted troposphere and stratosphere, and are also generated during photochemical air pollution events, reducing further the half-life of the amine-based compound in polluted air (Atkinson and Carter 1984, Tuazon et al. 1981, Warneck et al. 1973). The products of these reactions are generally not known with certainty. Tuazon et al. (1981) determined in a laboratory setting that the main degradation product resulting from the reaction of ozone and hydrazine was H2O2 with lesser contributions from N2O and NH3. On the other hand, laboratory tests performed by MacNaughton et al. (1981) identified N2 and water as the main products of hydrazine oxidation. Ammonia production was also detected but attributed to the specifics of the experimental set-up. Vaghjani et al. (1996) showed in the laboratory that atomic oxygen (O(3P)) can react with hydrazine, contributing to its consumption in the stratosphere where the O monomer is abundant. Photolysis likely does not play any role in hydrazine degradation in this medium (Tuazon et al. 1981). Table 5 presents degradation half-lives for photooxidation by OH radicals and ozone.

Water

The main mechanisms of hydrazine degradation in the hydrosphere are biodegradation and auto-oxidation. Bacterial abundance in the water column is one of the main drivers for aqueous biodegradation (Ou and Street 1987a, Appendix 3). Auto-oxidation is a four-electron oxidation producing nitrogen gas (Moliner and Street 1989) for which redox Equation No. 3 is an approximate representation. Determinants of the effectiveness of auto-oxidation identified at this time include aqueous concentration of copper ion, water hardness and ionic strength, oxygen content, organic matter content, pH and water temperature (James 1989, Jingqiu et al. 1994, Moliner and Street 1989, Ou and Street 1987a, Slonim and Gisclard 1976). Hydrazine exhibits a remarkable resistance to oxidation in the absence of an appropriate catalyst; for example, it is very stable in distilled water (MacNaughton et al. 1981, Ou and Street 1987a). The copper ion may fulfill this role of catalyst (Moliner and Street 1989, Ou and Street 1987a) but to exert this potency it is required in much higher levels than copper concentrations found in freshwaters of most streams and lakes, which are typically less than 3×10-3 mg/L (Reimann and de Caritat 1998; see Appendix 3). The ionic strength of the solution increases the rate constant for hydrazine degradation probably via some reaction between ionic intermediates of the same charge (Moliner and Street 1989). The influence of water hardness could be interpreted in a similar manner. A number of studies have found that auto-oxidation is inhibited at pH values below 4 and above 12 (Jingqiu et al. 1994, Moliner and Street 1989).

Regarding the influence of water temperature, Jingqiu et al. (1994) determined with sterilized water samples that the degradation rate constant of hydrazine obtained at 10ºC, was 67% of the rate measured at 20ºC. James (1989) added a concentration of 10-4 M hydrazine to a seawater sample collected at a coastal site in California, and monitored the concentration of the amine compound over time for four different water temperatures. The persistence of hydrazine increased with the decrease of water temperature. James (1989) estimated chemical half-lives from initial decay rates and obtained t½ values exceeding 116 days for temperatures less than 10ºC (Table 5). James (1989) also found that a sample of this seawater filtered on a membrane of a porosity of 0.22 µm exhibited one tenth the degradation rate of an unfiltered sample at 20ºC. A similar albeit less important decrease was observed at a temperature of 9ºC. The author attributed the enhanced degradation in unfiltered samples to either biological (bacteria, plankton) or abiotic (colloidal matter, fulvic and humic acids with complexed metal ions) factors.

Table 5. Empirical degradation half-lives of hydrazine in environmental media.

Fate processHalf-life (days)Temperature (ºC)NotesReference
Air
Photooxidation by OH·0.2525Rate constant k= 6.5×10-11 cm3molecule-1 second-1aHarris et al. 1979
Photooxidation by O30.0821-24--Tuazon et al. 1981
Photooxidation by O30.5425Rate constant k = 3×10-17 cm3molecule-1 second-1bAtkinson and Carter 1984
Oxidation0.2125--MacNaughton et al. 1981
Water
Biodegradation1.70
1.31
1.31
0.60
0.31
0.20
15pH 10 c
pH 10
pH 8
pH 8
pH 6
pH 6
Jingqiu et al. 1994
Biodegradation & autooxidation2.5
9.4
7.4
8.8
> 14
> 14
> 14
> 14
25Unsterile surface water A d
Sterile surface water A
Unsterile surface water B
Sterile surface water B
Unsterile surface water C
Sterile surface water C
Unsterile surface water D
Sterile surface water D
Ou and Street 1987a
Biodegradation & abiotic degradation3.7
3.9
22.7
63.6
0.5
0.7
Ambient laboratory temperatu-reSurface waters with various hardnesses:e
420 mg/L as CaCO3
216 mg/L as CaCO3
108 mg/L as CaCO3
24 mg/L as CaCO3
‘Dirty’ river water
Pond water
Slonim and Gisclard 1976
Biotic & abiotic degradation~ 24
~ 6
25Pond water of pH 8
Seawater
MacNaughton et al. 1981
Biotic & abiotic degradation0.83
2.4
125
117
35
20
10
0
Hydrazine (10-4 M) added to natural seawater
Initial decay rate
-0.57%/hour
-0.25%/hour
-0.02%/hour
-0.02%/hour
James 1989
Soil
Biodegradation & autooxidation< 4×10-2
~ 0.5
~ 3
25Fine sand with a pH of 5.7 and organic carbon content of 1.7%.
10 mg hydrazine/g soil
100 mg hydrazine/g soil
500 mg hydrazine/g soil
Ou and Street 1987b
a Half-life derived for this assessment using the following equations: tOH=(kOH [OH])-1 and t½= tOH×ln(2); tOH is the atmospheric residence time attributable to OH· oxidation and [OH] is the hydroxyl radical concentration of 1×106 molecules cm-3 (Schwarzenbach et al. 2003). A daytime of 12 hours, the period of active production of OH·, is considered in these calculations.
b Half-life derived for this assessment using the following equations: tO3=(kO3[O3])-1 and t½= tO3×ln(2); tO3 is the atmospheric residence time attributable to ozone oxidation and [O3] is the ozone concentration of 1×1012 molecules cm-3 (Atkinson and Carter 1984). A daytime of 12 hours, the period of active production of O3, is considered in these calculations.
c The authors determined that the degradation of hydrazine was a first order reaction. They calculated rate constants k (h-1) from experimental data. The assessor derived a biodegradation half-life using the expression ln(2)/k.
d Half-lives derived numerically for this assessment from diagrams of % hydrazine degradation versus time. Tests performed by Ou and Street (1987a) with bacteria amendment were not presented or considered because of lack of environmental realism.
e Half-lives derived numerically for this assessment from diagrams of hydrazine concentrations versus time.

Research conducted since the 1970s has demonstrated that bacteria are able to degrade hydrazine (Ou 1987) but efficiency of degradation depends on bacterial species and ambient conditions (Farmwald and MacNaughton 1981, Kane and Williamson 1983). For example, using a basal medium supplemented with glucose, Ou (1987) found that Achromobacter sp. efficiently degraded hydrazine and hydrazine sulfate. Degradation was nearly complete with cell suspensions maintained for 2 hours in hydrazine concentrations as high as 90 mg/L. However, the bacterium was incapable of growing on hydrazine as a sole source of nitrogen, designating a co-metabolic process for this substance. The role of auto-oxidation was determined to be negligible in the experimental settings used in Ou’s study.

Ready biodegradability tests suggest that efficiency of degradation decreases with increase in hydrazine loading, a trend consistent with the high toxicity of the substance towards bacteria. Jingqiu et al. (1994) investigated the degradation of hydrazine in urban and industrial wastewaters. Their approach was similar to OECD tests (OECD 2006a) in that a reasonably high concentration of the test substance, ≤ 5 mg/L, was used and the source of the bacterial inoculum was urban sewage sludge. The authors determined first-order rate constants from test results, and the assessor derived half-lives from these constants (Table 5). Degree of biodegradation depended on water temperature, with the rate for 10ºC predicted to be 46% of that estimated for 20 ºC. Unfortunately, this study could not be critically evaluated because of missing information with regard to experimental and analytical methods. An OECD 301D test performed on domestic sewage resulted in 9% degradation of hydrazine after 5 days of exposure to 80 mg/L hydrazine. The same test produced 28% degradation after 20 days of exposure to 24 mg/L of the test substance (IUCLID 2000). An OECD 301C test using activated sludge showed almost no degradation after 4 weeks of exposure to 100 mg/L hydrazine (NITE 2002).

The important variability in numerical values for degradation half-lives in water presented in Table 5 reflects the fact that hydrazine degradation is governed by a multiplicity of factors in this compartment. The studies of Ou and Street (1987a), Slonim and Gisclard (1976) and NITE (2002) were critically reviewed using Robust Study Summaries (RSS) and found to be of satisfactory confidence for this risk assessment – their RSS are provided in Appendix 4.

Soil and sediment

Tests were performed with soil columns charged with hydrazine solutions (Hayes et al. 1984, Heck et al. 1963). Soil types were characterized for sand, silt and clay content, as well as pH, organic content and cation exchange capacity (CEC). The main determinants of hydrazine loss were the pH of the solution and the CEC of the clay.

Bacteria are able to degrade hydrazine in soil (Kuch 1996, Ou and Street 1987a,b). Ou and Street (1987b) amended a Arrerondo fine sand with hydrazine sulphate to give hydrazine levels ranging from 10 to 500 µg/g. Sterile and non-sterile treatments were prepared and hydrazine concentration was monitored over time in them. The diamine compound was efficiently degraded at all treatment levels. Auto-oxidation appeared to be the principal factor contributing to the disappearance of the chemical from the soil. For example, 8% of applied hydrazine at a concentration of 100 µg/g soil was recovered from sterile soil after one day of incubation, whereas hydrazine at this applied concentration in nonsterile soil was completely degraded within one day of incubation. By comparing the hydrazine loss from sterile and nonsterile soils, it appeared that biological degradation was responsible for about 20% of the degradation. Ou (1987) reported that three soil bacteria degraded 15N2H4 to 15N2. There was no evidence that hydrazine was converted to ammonia. Results from this study are summarized in Table 5 and its RSS is provided in Appendix 4; it has been determined to be of satisfactory confidence for this assessment.

No studies could be found on the degradability of hydrazine in sediments of natural water bodies. Therefore, the approach of Boethling et al. (1995) was used to estimate a biodegradation half-life based on the extrapolation ratio of 1:4 from soil to sediment proposed by these authors. Only the study of Ou and Street (1987a) was used for extrapolating because of its reliability and greater relevance to sediments, even if it did not fully discriminate between biotic and abiotic degradation processes. This study used a soil suspension made of 0.5 g Arredondo fine sand and 5 mL of distilled water. The geometric mean of the three half-lives reported in this study (Table 5) is 0.39 day. The half-life value extrapolated for aerobic sediments is thus 1.6 days.

Conclusion

There are several lines of evidence to suggest that the persistence of hydrazine in natural ecosystems is low to moderate: all four half-lives in air are less than 1 day; the 26 half-lives in water range from 0.2 to 125 days; the three half-lives in soil are less than or equal to 3 days; the one estimated biodegradation half-life in aerobic sediment is 1.6 day. Ready biodegradability tests indicate that the degree of degradation depends on hydrazine loading. Tests on natural water samples indicate that biodegradability is also a function of bacterial abundance and species present. Decrease of water temperature can decrease degradation half-lives in this compartment but this effect is not established with certainty given the low level of detail provided by James (1989) and Jingqiu et al. (1994) for their experiments. Hydrazine does not meet the persistence criteria in air, water, soil or sediment (half-life in air ≥ 2 days, half-lives in soil and water ≥ 182 days and half-life in sediment ≥ 365 days), as set out in the Persistence and Bioaccumulation Regulations (Canada 2000).

Potential for Bioaccumulation

Research conducted with microorganisms suggests that hydrazine (including anhydrous and hydrated forms) can be degraded co-metabolically provided that there is a carbon source other than hydrazine-based (Ou 1987 and references cited herein). Literature reviews performed by IUCLID (2000), IPCS (1987) and HSDB (2010) report that these amine products are readily metabolized, and the metabolites are excreted from body tissues of higher mammals such as dogs and rats.

One study evaluated the bioaccumulation potential of hydrazine in fish. Slonim and Gisclard (1976) exposed guppies to hydrazine dissolved in hard (420 mg/L as CaCO3) or in soft (24 mg/L as CaCO3) water. Laboratory tests lasted 4 days and used concentrations of 0.5 mg/L and 0.25 mg/L for hard and soft waters, respectively. No bio-uptake was observed in softwater exposures because of analytical limitations, whereas bioconcentration occurred in hardwater. The assessor derived a bioconcentration factor (BCF) from the hydrazine concentration measured in guppies after 4 days in contaminated hardwater, 144 mg/kg, and aqueous concentration of hydrazine, 0.5 mg/L. The resulting BCF of 288 L/kg may somewhat underestimate bioconcentration because the hydrazine level of 0.5 mg/L is high enough to generate ecotoxicity (see section of ecological effects assessment). In addition, it is not known if steady-state was reached between fish and the surrounding medium. In the absence of information in the paper, it is assumed that the hydrazine concentration in fish was expressed on a wet weight basis.

Considering the low empirical BCF obtained for guppy, experimental evidence for metabolic transformation, high miscibility in water and low log Kow, hydrazine does not meet the bioaccumulation criterion (log Kow≥ 5, BCF ≥ 5000, or BAF ≥ 5000) as set out in the Persistence and Bioaccumulation Regulations (Canada 2000).

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Potential to Cause Ecological Harm

Ecological Effects Assessment

A - In the Aquatic Compartment

Freshwater environment

There is significant empirical evidence to suggest that hydrazine is harmful to aquatic organisms at low concentrations. Information on hydrazine toxicity in the aquatic compartment was gathered in order to generate a Species Sensitivity Distribution (SSD), and using that to define a Critical Toxicity Value (CTV) for freshwater environments.

The hazard assessment of hydrazine recently conducted by Japan (CERI 2007) recorded more than 30 studies published in peer-reviewed science journals and in the grey literature between the early 1960s and the late 1980s. Acute and chronic toxicity values were obtained from hydrazine exposures to micro-organisms, micro-algae, invertebrates, fish and amphibians. Many of these tests used static systems without renewal of test medium. This constitutes a problem for an unstable substance like hydrazine which decomposes rapidly in many test solutions and results were difficult to interpret. Competing factors that may influence test results include the effect of the non-degraded parent compound, the effect of diatomic nitrogen produced by biodegradation which notably was stimulatory for algae (Scherfig et al. 1978), and the effect of oxygen depletion caused by hydrazine auto-oxidation. Furthermore, hydrazine appeared less toxic in static systems with aeration than in experimental set-ups with frequent or constant renewal of test substance (Heck et al. 1963).

Scherfig et al. (1977) evaluated the relative stability of hydrazine in systems without renewal of test compound. Rate of degradation was concentration-dependent and increased with decrease of initial hydrazine concentration at time 0. They determined that in aerated 10% Standard Algal Assay Medium (SAAM: US EPA 1971), hydrazine decomposition was relatively modest after 4 days with a 14% loss starting with an initial concentration of 0.7 µL/L. In aerated 33% SAAM, hydrazine decomposition reached a 22% loss after 3 days starting with an initial concentration of 0.09 µL/L. In this regard, OECD guidelines for the testing of chemicals prescribe that if the concentration of the substance being tested has been satisfactorily maintained within ± 20 % of the nominal or measured initial concentration throughout the test, analysis of the results can be based on nominal or measured initial values (OECD 2006b, 2004).

Hence, for those tests conducted without renewal of hydrazine, this effects characterization has considered only results of toxicity tests lasting less than, or equal to, 96 hours. It was assumed that nominal or measured concentrations of the test compound at time 0 remained relatively constant during the exposure, unless there was evidence of the contrary. Tests with micro-algae lasting 72 or 96 hours and for which the endpoint measured was an EC50 were considered short-term, although there is no consensus among regulatory regimes on this point (CCME 2009, ECHA 2008). Flow-through tests were considered, whatever their durations; however chronic studies using this methodology were not found.

Information regarding hydrazine toxicity on freshwater organisms was gathered from sixteen toxicity papers ranging in date of publication from 1976 to 1984; no data published after that date were found. Of the sixteen papers only one, a study on the effects of hydrazine to two different species of algae (Scherfig et al. 1977), reported data from a chronic (long-term) test. Six of the papers reporting acute (short-term) data did so for fish, three for amphibians, two reported data on fish and invertebrates, and one for bacterium and protozoa. These papers in total yielded data on fourteen different species, six fish, three invertebrates, two amphibians, one algal species, one bacterium, and one protozoa.

Toxicity results for hydrazine on freshwater fish are given in Table 6; all data are short-term (24h to 96h). Values ranged from a 96h LC50 of 0.61 mg/L to a 96h LC50 of 5.98 mg/L, the lowest value being for the common guppy (Lebistes rericulatus) (Slonim 1977), and the highest for the fathead minnow (Pimephales promelas) (Velte 1984). Hardness of the water appears to have a significant effect on the toxicity of hydrazine upon fish, as demonstrated by Slonim (1977), a study in which a six fold increase in LC50 was achieved via assaying fathead minnows in water of differing hardness (20 versus 500 mg/L CaCO3). Only one other study (Slonim 1986) assayed the test species at differing hardness, making it unfeasible to generate effect estimates for differing hardnesses. Temperature also seems to have some effect on hydrazine toxicity (Hunt et al. 1981) although there are not enough data to draw conclusions.

Toxicity values for invertebrates (Table 6) are all short-term. Of the three reported values, the amphipod Hyalella aztecawas the most sensitive having a 48h LC50 of 0.04 mg/L. The least sensitive invertebrate was an isopod (Asillidae), which had a 72h LC50 of 1.30 mg/L.

Amphibian toxicity data are given in Table 6. Only two species of amphibians were subject to hydrazine toxicity tests. One of these, the South African clawed toad embryos, were exposed for less time and required twice the concentration of the LC50for the most resistant fish species to produce an EC50for teratogenic effects (Greenhouse 1976). This suggests a particularly high resistance to hydrazine. Whether this result applies exclusively to the South African clawed toad, or toads in general, or is due to some unknown factor in the tests cannot be speculated on due to the paucity of data. Larvae of two species of salamander (Ambystoma maculatum and A. opacum) were assayed under conditions of differing hardness (Slonim 1986), and similar to the fathead minnow study, hardness appears to have a significant effect.

Bacterium, protozoa, and micro-algae data are given in Table 6. The test with the bacterium Pseudomonas putida which lasted 16 hours can be considered an acute exposure because pseudomonads can have generation times as long as 8.5 days (Obayori et al. 2009). The bacteria data provide the lowest of all freshwater effect values, while the micro-algae data provides the lowest value suitable for use in the SSD.

Table 6. Acute hydrazine toxicity data for freshwater organisms

OrganismHardness (CaCO3 in mg/L)pHTemp. (ºC)Diss. O2(mg/L)Conc. measu-
red?
Test typeEnd-
point
Hydra-
zine (mg/L)
In SSD?Reference
Bacteria (Pseudomonas putida)NRNR25NRNoStaticEC3 1
(16 h)
0.010NoBringmann and Kühn 1980
Protozoa (Entosyphon sulcatum)NR6.925NRNoStaticLOEC 1
(72 h)
0.48No
Micro-algae (Pseudo-
kirchneriella subcapitata)
Hard- waterNR25NRNoStaticEC50
(72 h)
0.012YesScherfig et al. 1977
Daphnid
(Daphnia pulex)
36.3 - 34.87.1-7.2208.2YesStatic renewalEC50
(48 h)
0.16YesVelte 1984
Amphipod
(Hyalella azteca)
967.9-8.7217.2YesStaticLC50
(48 h)
0.04YesFisher et al. 1980a
Isopod
(Asillidae)
966.5-7.8237.3YesStaticLC50
(72 h)
1.3YesFisher et al. 1980a
Fathead Minnow (Pimephales promelas)NR6.95207.9- 8.3YesFlow-throughLC50
(96 h)
5.98YesVelte 1984
1507.0-7.5219.0- 9.8NoLOEC 2
(24 h)
0.1NoHenderson et al.1981
EC1002
(24 h)
1
Channel Catfish
(Ictalurus punctatus)
106- 1136.9-8.622- 22.57.0- 7.2YesStaticLC50
(96 h)
1.0YesFisher et al 1980a
Golden Shiner (Notemigonus crysoleucas)140- 1736.8-7.621- 22.56.6-7.4YesStaticLC50
(96 h)
1.12Yes
Bluegill
(Lepomis macrochirus)
160- 1906.7-8.010,15.5, 215.8- 11.4YesFlow- throughLC50
(96 h)
1.2; 1; 1.63YesHunt et al. 1981
240- 292NRNR7.1-7.8NoStaticLC50
(96 h)
1.083Fisher et al 1978
240- 2927.2-8.423- 245.9- 8.3NoStaticLC50
(96 h)
1.083Fisher et al 1980b
1647.8-7.923- 245.9- 8.3YesFlow- throughNOEC
(lethality) (96 h)
0.43NoFisher et al 1980b
Common Guppy
(Lebistes rericulatus)
400- 5007.8-8.222- 24.56.9- 7.8NoStaticLC50
(96 h)
3.85NoSlonim 1977
20-256.3-6.922- 24.56.9- 7.8NoLC50
(96 h)
0.61Yes
Rainbow Trout (Oncorhynchus mykiss)
Embryos
1507.0-7.511.5- 12.09.0- 9.8YesFlow- throughLOEC 4
(48 h)
1NoHenderson et al 1983
NOEC 4
(48 h)
0.1No
Spotted and marbled salamander larvae (Ambystoma maculatum and A. opacum)400- 5007.8-8.2236.9- 7.8NoStaticLC50
(96 h)
4.11NoSlonim 1986
20- 256.3-6.9236.9- 7.8NoLC50
(96 h)
2.12Yes
African Clawed Frog embryos
(Xenopus laevis)
NRNRNRNRNoStaticED505
(66 h)
11.5NoGreenhouse 1977
NRNRNRNRNoStaticED505
(67 h)
12.4NoGreenhouse 1976
Abbreviations: NR: not reported; ECXX: concentration of a substance that is estimated to cause some effect on XX% of the test organisms; ED50: Effect dose for 50% of test organisms; LC50: Concentration of a substance that is estimated to be lethal to 50% of the test organisms; NOEC: The No Observed Effect Concentration is the highest concentration in a toxicity test not causing a statistically significant effect in comparison to the controls; LOEC: The Low Observed Effect Concentration is the lowest concentration in a toxicity test that caused a statistically significant effect in comparison to the controls; SSD: Species Sensitivity Distribution.
As mentioned in the body of the text, only acute LC50s (or equivalent, e.g., EC50 for immobilization in Daphnia) were used to generate the SSD.
1 The effect value reported for hydrazine hydroxide was converted to an effect value for hydrazine from value in the paper × fraction product purity × (MW hydrazine / MW hydrazine hydroxide).
2 Teratogenic effects are the endpoint for the LOEC; aneurulae-microcephalic condition is the endpoint for the EC100.
3 Geometric mean of five values (1.2, 1.00, 1.6, 1.08, 1.08); assays performed at different temperatures.
4 Physical deformities are the endpoints for these LOEC and NOEC.
5 Teratogenic effects are the endpoints for these ED50s.

The acute toxicity data met the criteria for a Type A Guideline of the Canadian Council of the Ministers of the Environment (CCME 2009). Robust study summaries were completed for all studies, and only those meeting the CCME reliability standards were included in the assessment. The data set used to generate the SSD is identified in Table 6. As the Gompertz distribution fits the data set best, the acute CTV was chosen based on that model (Figure 1). This CTV was the hazard concentration corresponding to the 5thpercentile of the SSD (HC5). At a value of 0.026 mg/L, the Gompertz distribution provided not only the most conservative CTV compared to those derived from other types of distributions, but one of the narrowest confidence intervals as well (0.0101-0.674 mg/L). The Anderson-Darling goodness-of-fit test statistic (A2) also suggested the Gompertz model as the best choice.

Figure 1. Species Sensitivity Distribution for the acute toxicity of hydrazine to freshwater species. The Hazardous Concentration corresponding to the 5th percentile of the SSD, i.e., the HC5, is equal to 0.026 mg/L.

Figure 1. Species Sensitivity Distribution for the acute toxicity of hydrazine to freshwater species. The Hazardous Concentration corresponding to the 5th percentile of the SSD, i.e., the HC5, is equal to 0.026 mg/L.

Marine environment

Most of the acute and chronic effect values found for marine organisms were obtained with exposures of early life stages of phaeophytes (brown algae) to hydrazine (Table 7). Brown algae are ecologically important as a variety of species since they can form canopy structures providing larval settlement substrates and serving as refuges for invertebrates and fish (James 1989). James et al. (1987) measured the growth rates of gametophytes (microscopic life stage of a 10 to 100 µm size) of phaeophytes in the presence of hydrazine in natural seawater. Minimum hydrazine concentrations leading to significant inhibition of growth, 24-h LOECs, were calculated for seven algal species. A SSD developed with these LOECs gave inconclusive results because all the distributions used resulted in poor fit to data and wide confidence intervals around HC5 values (results not shown). Therefore, the lowest effect concentration obtained with this group of algae, a 96-h LOEC of 2×10-3 mg/L, was selected as the CTV for marine environments (Table 7).

All the brown algae tested by James and collaborators were from the Californian coast but they are also found in Pacific waters along the Canadian coast. In addition, these toxicity test results should be relevant to species of the Atlantic coast of Canada because many of the genera tested (e.g., Laminaria) are part of the indigenous seaweeds found in the Maritimes (South 1981). The studies presented in Tables 6 and 7 were critically reviewed using RSS and found to be of satisfactory confidence for this risk assessment.

Table 7. Short-term hydrazine toxicity data for marine organisms

OrganismSalinity (‰)Temp. (ºC)Test typeEndpointHydrazine (mg/L)Reference
Bacteria (Photobacterium phosphoreum)3015StaticEC50 (20 min)0.02Yates 1985
Early life stages of Brown Algae (gametophytes)
Eisenia arborea35 110-14StaticLOEC 2
(24 h)
0.25James et al. 1987
Laminaria dentigera0.025
Laminaria ephemera0.025
Laminaria farlowii0.25
Macrocystis pyrifera0.13
Nereocystis luetkeana0.025
Pterygophora californica0.025
Macrocystis pyrifera35 110-14StaticEC502
(96 h)
0.005James 1989
Pelagophycus porraLOEC 2
(96 h)
0.002
Abbreviations: EC50: concentration of a substance that is estimated to cause some effect on 50% of the test organisms; LOEC: The Low Observed Effect Concentration is the lowest concentration in a toxicity test that caused a statistically significant effect in comparison to the controls.
1 Offshore seawater.
2 Growth rate of gametophyte is the endpoint for these effect values.

 

B - In Other Environmental Compartments

Although data regarding hydrazine in other compartments are available, they were not the focus of this assessment (see section on Ecological exposure assessment below). CERI (2007) and Hirzel (1998) reported results of toxicity tests performed on 14 species of terrestrial plants exposed to hydroponic solutions containing hydrazine. CERI (2007) briefly describes results of exposures of 7 species of plants to hydrazine in air. One species of nematode was exposed for 6 days to a culture medium amended with hydrazine (CERI 2007, Hirzel 1998). Three papers looked at toxicity in the soil compartment, each of them dealing with bacteria (London 1983, Mantel and London 1980, Ou and Street 1987b).

Ecological Exposure Assessment

A- Measured concentrations

Measured concentrations of hydrazine in effluents from power plants located in Ontario have been identified (Table 8a). Hydrazine concentrations were measured in the main effluent (i.e. cooling water discharge) of the nuclear power plants (Environment Canada 2009). From these values, Predicted Exposure Concentrations (PECs) were calculated using either the average or the maximum effluent concentration (Table 8a). Raw data were not available for Pickering A and B but the data distribution deduced from the comparison of the yearly average with the yearly range indicates that the yearly average is representative of the majority of the data (i.e. unimodal, narrow distribution). The average concentration was used for Darlington since the raw data (weekly sampling) show that no other values close to the maximum concentration of 0.02 mg/L were detected over the year. As a narrow distribution is also seen for Darlington, selection of the annual average is suitable. Neither the raw data nor the yearly range were available for Bruce power plant, hence it was not possible to make an assumption about data distribution. Thus the maximum value was chosen, to be conservative. A dilution factor of 10 was applied to the concentrations chosen to derive the PECs to account for effluent dilution when discharged to receiving water bodies, i.e., large lakes in the case of these power generation plants. Certain studies have shown that a dilution factor of 10 is not overly conservative even for large water bodies (e.g., Gagné et al. 2001, Jiang et al. 2003).

Elsewhere in the world, the Ministry of the Environment of Japan conducted environmental surveys for the monitoring of hydrazine at many sampling sites (NITE 2002). Table 8b indicates that this substance was detected in bottom sediments, shellfish and dietary items. These results support the evaluations above to the effect that the environmental persistence of hydrazine is not negligible and that it can accumulate in biota even if at low levels. In addition, these measured concentrations suggest a natural occurrence of hydrazine in sediment which might be formed by the anaerobic oxidation of ammonium in this compartment (Strous and Jetten 2004).

Table 8a. Measured concentrations of hydrazine in the effluents of nuclear power plants in Ontario, and resultant predicted environmental concentrations (PECs) in receiving waters.

FacilityYearEffluent concentration (mg/L)PEC (mg/L)1Reference for effluent data
Yearly averageYearly range
Pickering A20060.010.003-0.031×10-3Environment Canada 2009
Pickering B20060.0050.003-0.025×10-4
Darlington20060.0040.004-0.024×10-4
Bruce1995-20040.0020.028 (max)2.8×10-3Golder Associates Ltd. 2005
1 PEC, Predicted Environmental Concentration, is taken as the yearly average or maximum concentration in the effluent (see text) divided by a limiting dilution factor of 10.

 

Table 8b. Measured concentrations of hydrazine in the Japanese environment (NITE 2002).

MediumYearLimit of detectionNumber of detections/num-ber of samplesConcentration
Surface water20051.3×10-6 mg/L0/9ND
19862×10-3 mg/L0/30ND
Bottom sediments20056.5×10-4 mg/kg dry wt14/173.8×10-4 to 6.6×10-2 mg/kg dry wt
19862×10-1 mg/kg dry0/30ND
Shellfish20061.2×10-3 mg/kg wet wt24/301.3×10-3 to 9.5×10-2 mg/kg wet wt
Others (diet)20066.6×10-6 to 9.5×10-6 mg/kg wet wt146/1789.5×10-6 to 8×10-4 mg/kg wet wt
ND: Not detectable

 

B – Modelling of industrial releases

Site-specific exposure scenarios were developed based on the expectation that certain amounts of hydrazine are released into the cooling water discharge when water used for steam generation is blown down from the steam-generating systems of nuclear and fossil-fuel power plants, and that these releases occur daily (Environment Canada 2009, Collins 2000). Site-specific exposure modelling was conducted for hydrazine releases from the three nuclear plants for which measured concentrations in effluents are available (Table 8a), as well as for seventeen other power generating plants located in British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Québec, New Brunswick, Nova Scotia and Prince Edward Island. Those seventeen plants were chosen because data obtained through the Section 71 survey could be used for the modelling. The number of plants included in this assessment represents a modest proportion (21%) of the total number of power generating plants using or potentially using hydrazine in Canada; however, the plants included in this assessment may be considered as representative of all Canadian facilities.

The following equation was used to derive estimates of the concentration of hydrazine in receiving waters:

Cwater-ind = [1000 × Q × L × (1 - R)] / [N × F × D] [7]

where

Cwater-ind: aquatic concentration resulting from industrial releases, mg/L
Q: total substance quantity used annually at an industrial site, kg/yr
L: loss to wastewater, fraction
R: wastewater treatment plant removal rate, fraction
N: number of annual release days, d/yr
F: final plant effluent flow (blowdown water + raw water from other processes such as cooling), m3/d
D: receiving water dilution factor, dimensionless

Hydrazine quantities (Q) used annually by these plants were provided by surveys conducted under section 71 of CEPA 1999 for this substance which collected data for 2006. The nuclear plants of Ontario provided masses of hydrazine released in their liquid effluents in terms of kg/yr (instead of quantities used; Environment Canada 2009). These quantities were used as input values for Q.

The effluent flows (F) of Point Lepreau, Brandon, Battle River and Burrard power generating stations were obtained from NB Power (2008-2010), Badiou et al. (2006; p. 33), Atco Power (Environment Canada 2010), and BC Hydro (Environment Canada 2010), respectively. For the other power generating plants, effluent flows were estimated based on energy produced by these plants (Maritime Electric 2010, NB Power Group 2007/2008, Nova Scotia Power 2009, OPG 2008, SaskPower 2010, Statistics Canada 2000). Conditions of operation of steam-generating systems in nuclear power plants are different from those of fossil-fuel power plants (Collins 2000). Therefore, estimations of effluent flows made for nuclear power plants were based on factual information obtained for specific nuclear power plants, and a similar approach was taken for fossil-fuel power plants. The Darlington and Pickering A+B nuclear power plants are reported to have average cooling water discharge (i.e. effluent) of 11.20 and 13.42 million m3/day, for power generating capacities of 3,524 and 3,100 MW, respectively (Environment Canada 2010). The mean ratio for these two plants of (average cooling water discharge/generating capacity) 3,754 m3/day/MW, was used to estimate the daily effluent flow of a nuclear power plant based on its reported power generating capacity. In a similar approach, the Lambton, Lennox and Nanticoke fossil-fuel power plants are reported to have average cooling water discharges of 2.79, 0.52, and 8.79 million m3/day, for power generating capacities of 1920, 2100 and 3640 MW respectively (Environment Canada 2010). The mean ratio for these three plants of (average cooling water discharge/generating capacity), 1,372 m3/day/MW, was used to estimate the daily effluent flow of a fossil-fuel power plant based on its reported power generating capacity. The assumption is made that discharge rates are very similar to intake rates of water, which appears to be reasonable for water purposely used for thermal-electric power generation (Statistics Canada 2007).

For nuclear plants, the value for loss of hydrazine to wastewater (L) was estimated to be 7.59%, based on quantities of hydrazine used (13,500 kg) and released to water (1024 kg) in 2006, and reported by Bruce Power to the S.71 survey of this assessment. This value was applied to Gentilly II and Pointe Lepreau since these power plants only reported the quantity of hydrazine used and not the quantity released. Hence, it was assumed that the L value is similar among nuclear power plants. The L values were set at 100% for the effluents of Bruce, Darlington and Pickering nuclear plants since the Q values used for these plants corresponded to hydrazine levels measured in effluents (see above). Some of the values for L that were submitted by stakeholders for some fossil-fuel power plants were equal or close to 0% of the quantity used. Given that hydrazine is used in stochiometric excess to ensure removal of dissolved oxygen in boiler water and that monitoring data do indicate that hydrazine is present in blow down water from these boilers – at least for nuclear power plants (Environment Canada 2009, James 1989) – a value of 0% for L was not deemed realistic. Instead, loss of hydrazine to wastewater for fossil-fuel power plants was attributed a default value of 10%, based on the numbers provided by Bruce Power and assuming that losses of hydrazine in fossil-fuel and nuclear power plants are similar.

For all of the above scenarios, except Battle River, Boundary Dam, Burrard and Charlottetown, values of R, N and D were set at 0%, 365 days/year and 10, respectively. A dilution factor of 10 is not overly conservative even for large aquatic systems (e.g., Gagné et al. 2001). More specifically, a study conducted in Port Moody Arm using dye tracing showed that the dilution factors of the cooling water discharged by Burrard power generating station vary from 5 to 100, 1 kilometre away from the outlet (Jiang et al. 2003). The 10-fold dilution plume was estimated to extend up to 1200-1400 m from the discharge point with a width of 200-400 m, depending on tide conditions. As a result, the value of 10 was chosen to calculate the PEC for Burrard, as a reasonable worst-case scenario. Similarly, dispersion modelling of a substance contained in the effluent of Charlottetown waste water treatment plant (WWTP) indicated a five-fold dilution, 500 metres away from the WWTP (Canada 2001). Since the power plant in Charlottetown is located only a few kilometres away from the WWTP and since its effluent is discharged into the same water body (Hillsborough River Estuary), this suggests that using a dilution factor of 10 for this scenario is, again, suitable. For the Battle River scenario, the selected value for D was 2.4 corresponding to complete effluent dilution in Battle River at 10th percentile flow rate (Environment Canada 2008). For Boundary Dam, the value for D was set at 1 based on the 10th percentile flow rate of the receiving water course (Environment Canada 2008). For all sites included in this assessment, the dilution factor is applied at the point of discharge of the effluent (outfall) into the receiving water body.

For the Burrard scenario, the selected value for N was 215 days based on quarterly reports for 2008 and 2009 provided by BC Hydro on its website (BC Hydro 2010). For the Charlottetown scenario, the estimate for N was 200 days based on the fact that the boilers of this plant are idle during the summer months (Environment Canada 2010).

The value of 365 for the number of annual release days that is used for all other plants is likely overestimated since blow down events are often intermittent and not continuous in time.

Table 8c provides modelled PECs (modelled Cwater-ind) based on annual quantities of hydrazine used or discharged in effluents, power generation capacities, and estimated daily effluent flows for the nuclear and fossil-fuelled power plants considered for this exposure characterization. It is noted that modelled PECs are one to two orders of magnitude lower than measured PECs for Pickering, Darlington and Bruce power plants (Tables 8a and 8c). This could be due to an overestimation of the effluent flow and/or the number of annual release days and/or to an underestimation of the loss of hydrazine to wastewater.

In addition to the above, a site-specific scenario was developed to estimate a conservative concentration of hydrazine resulting from an industrial effluent discharged to the Montréal Wastewater Treatment Plant (WWTP). Numerical values of the model’s parameters were as follows: L of 5%; R of 0%; N equal to 250 days; F was the effluent flow of the Montréal WWTP; D of 10. The hydrazine quantity (Q) used at this site is confidential and can not be reported in this document. This yielded a PEC of 1 × 10-4 mg/L.

Table 9 lists a number of fossil-fuelled power generating plants and other possible anthropogenic sources of hydrazine to the environment in Canada for which exposure scenarios were not developed (justifications are provided).

Table 8c. Modelled concentrations of hydrazine in the receiving waters of nuclear and fossil-fuelled power plants located in Canada. See text for additional explanations.

FacilityTypeQuantity of hydrazine used (u), or released in effluent (r) (kg/yr)Power installed (MW)Effluent flow reported by sources (r)or estimated (e) 1
(m3/d)
PEC
(mg/L)
(estimated yearly average)
Pickering, ONNuclear570 (r)3,1001.34×107 (r)1.2×10-5
Darlington, ON271 (r)3,5241.12×107 (r)6.6×10-6
Bruce, ON1024 (r)4,0001.34×107 (e)1.9×10-5
Gentilly II, QC408 (u)6752.53×106 (e)3.3×10-6
Point Lepreau, NB1664 (u)6355.01×105 (r)6.9×10-5
Lingan, NSFossil-fuelled1507 (u)6208.50×106 (e)4.9×10-5
Point Aconi, NS1004 (u)1712.35×105 (e)1.2×10-4
Point Tupper, NS1080 (u)1542.11×105 (e)1.4×10-4
Trenton, NS209 (u)3074.21×105 (e)1.4×10-5
Tuft's Cove, NS240 (u)4155.69×105 (e)1.2×10-5
Charlottetown, PEI624 (u)628.50×104 (e)3.7×10-4
Lambton, ON 23230 (u)19202.79×106 (r)3.2×10-5
Lennox, ON 2170 (u)21005.20×105 (r)9.0×10-6
Nanticoke, ON 27650 (u)36408.79×106 (r)2.4×10-5
Brandon, Man 3265 (u)958.74×103 (r)8.3×10-4
Boundary Dam, SK 2440 (u)8131.12×106 (e)1.1×10-4
Poplar River, SK 2330 (u)5827.99×105 (e)1.1×10-5
Queen Elisabeth, SK 2220 (u)3865.30×105 (e)1.1×10-5
Battle River, AB1120 (u)6705.60×103 (r)2.3×10-2
Burrard, BC125 (u)9503.26×103 (r)1.8x10-3
1 Flow rates were estimated using factors previously derived (3754 and 1372 m3/d/MW for nuclear and fossil-fuel power plants, respectively). See text for additional explanations.
2 The mass of hydrazine used by each of the three plants is assumed to be proportional to the amount of power generated by that power plant
3 Most information in this report is based on use data reported for 2006. Recent information however indicates that Brandon Generating Station has discontinued its use of hydrazine in 2008 (Environment Canada 2010). In addition, the modelled PEC reported here does not take into account the fact that the effluent of the Brandon generating station goes to a lagoon (Environment Canada 2010). Therefore the hydrazine concentration expected in the receiving Assiniboine River will likely be much lower than reported here based on an estimated water residence time of ~ 10 days in the lagoon where the chemical will degrade (i.e., 94,000 m3/8741 m3/day).

 

Table 9. Fossil-fuel power plants and other possible anthropogenic sources of hydrazine to the environment for which exposure scenarios were not developed.

Use or source typeLocationJustificationReference
Fossil-fuelled power generating plantsHolyrood, NFLDUse of another chemical, diethylhydroxyamine (not hydrazine), for oxygen scavengingEnvironment Canada 2009
Grand Lake, NBScheduled to be decommissioned
Coleson Cove, NBUse of hydrazine discontinued in 2007
Dalhousie, Belledune, Courtenay Bay, NBNo reported use of hydrazine
Atikokan & Thunder Bay, ONThese plants do not use hydrazine anymore.
Selkirk, ManUse of another chemical, carbohydrazide (not hydrazine), for oxygen scavenging
Shand Power, SKA closed-loop, zero-discharge water management system is used.Estevan CAP 2008
TransAlta plants in ON & AB: Mississauga, Ottawa, Sarnia, Windsor, Grande Prairie, Keephills, Sundance, Wabamun, Fort Saskatchewan, Meridian, Poplar CreekTransAlta discontinued the use of hydrazine in 2004. It is not used at any plant owned and operated by the company.Environment Canada 2009
Sheerness, ABNo corrosion inhibitor is used and instead a process approach is taken, utilizing monitoring and management control.
City of Medicine Hat power plant, ABThe corrosion inhibitor currently used does not contain hydrazine.
Howe Sound Pulp and Paper plant, BCHydrazine was not used in 2006.
Releases to airVarious industrial facilities reporting to the NPRIReleases are small, typically less than 100 kg/yr for a given source. In addition, hydrazine has a short half-life in air.NPRI 2008, Table 5
Releases to soilsReleases are small, typically less than 300 kg/yr for a given source. In addition, hydrazine is rapidly degraded in soils.NPRI 2008, Table 5
Industrial facilities using hydrazineVarious sitesQuantities used are small, typically less than 20 kg/yr for a given industrial facility. Environmental releases are expected to be very low.Environment Canada 2009
Waste treatment and disposal facilityMississauga, ON643 kg of hydrazine were treated as hazardous wastes. No releases to the environment are expected from this activity.Environment Canada 2009
Use of hydrazine fuel in aircraftCanadian Air Force BasesQuantities stored on site are expected to be low based on the fact that each aircraft requiring hydrazine will carry about one litre of 70% hydrazine fuel.Apr 2009, personal communication from National Defence Headquarters, Department of National Defence to Risk Management Bureau, Health Canada; unreferenced
Hydrazine as an ingredient in drugsDown-the-drain releasesThe drugs are low production volume chemicals. Quantities released in wastewaters would typically be small.See section on Releases to the environment.
Hydrazine in the pesticide maleic hydrazideDispersive use in the field

Hydrazine is an impurity present in low amounts in the pesticide; hence it is unlikely to produce ecotoxicity in the field.

Pesticides are regulated under the Pest Control Products Act.

See section on Releases to the environment

 

Characterization of Ecological Risk

The approach taken in this ecological screening assessment was to examine the available scientific information and develop conclusions based on a weight-of-evidence approach and using precaution as required under CEPA 1999. Lines of evidence considered include results from conservative risk quotient calculations, as well as information on persistence, bioaccumulation, toxicity, sources, distribution and fate of the substance.

Hydrazine does not meet the criteria for persistence or bioaccumulation as set out in the Persistence and Bioaccumulation Regulations. However, the frequent presence of this substance in aquatic ecosystems is expected to result in chronic exposure to aquatic organisms, particularly in cases where blow down events are close in time. Degree of water hardness is an important determinant of the persistence and toxicity of this amine-based compound in surface waters (Tables 5 and 6). However, not enough testing has been done on these factors to be able to adjust CTVs for the hardness of receiving waters. The high importation volumes of aqueous solutions of hydrazine into Canada, along with information on their uses and evidence for environmental releases given by NPRI data, indicate the potential for widespread release into the Canadian environment. Once released into the environment, hydrazine may be found in air, water or soil, depending on medium of release and the hardness of receiving waters. Hydrazine has been demonstrated to have an elevated potential for toxicity to aquatic organisms.

In order to determine whether there is potential for ecological harm in Canada, a risk quotient analysis, integrating estimates of exposure with toxicity information, was performed for aquatic ecosystems, which is the main environmental medium receiving releases of hydrazine. Site-specific industrial exposure estimates based on monitoring data were available for three nuclear plants located in Ontario (Table 8a). Site-specific exposure was estimated for nuclear and fossil-fuel electric power plants located elsewhere in Canada (Table 8c).

Table 10. Risk quotients (RQs) for hydrazine calculated for various exposure scenarios.

FacilityTypePECPNECRQs
(mg/L)Based on(mg/L)
Scenarios for freshwater ecosystems
Pickering A, ONNuclear power generating plants1×10-3Measured concentrations2.6×10-30.38
Pickering B, ON5×10-40.19
Darlington, ON4×10-40.15
Bruce, ON2.8×10-31.1
Pickering, ON1.2×10-5Modelled concentrations0.0045
Darlington, ON6.6×10-60.0025
Bruce, ON1.9×10-50.0072
Gentilly II, QC3.3×10-60.0013
Trenton, NSFossil-fuel power generating plants1.4×10-5Modelled
concentrations
0.0052
Lambton, ON3.2×10-50.012
Lennox, ON9.0×10-60.0034
Nanticoke, ON2.4×10-50.0092
Brandon, Man 18.3×10-4< 0.32
Boundary Dam, SK1.1×10-40.042
Poplar River , SK1.1×10-50.0044
Queen Elisabeth, SK1.1×10-50.0044
Battle River , AB2.3×10-28.8
Scenarios for marine ecosystems
Point Lepreau, NBNuclear plant6.9×10-5Modelled
concentrations
2×10-40.35
Lingan, NSFossil-fuel power generating plants4.9×10-50.24
Point Aconi, NS1.2×10-40.59
Point Tupper , NS1.4×10-40.70
Tuft's Cove, NS1.2×10-50.056
Charlottetown, PEI3.7×10-41.8
Burrard, BC1.8x10-38.9
1 Most information in this report is based on use data reported for 2006. Recent information however indicates that Brandon Generating Station has discontinued its use of hydrazine in 2008 (Environment Canada 2010). In addition, the modelled PEC reported here does not take into account the fact that the effluent of this station goes to a lagoon (Environment Canada 2010). Therefore the hydrazine concentration expected in the receiving Assiniboine River would have likely been much lower than reported here based on an estimated water residence time of ~ 10 days in the lagoon where the chemical will degrade.

Predicted No Effect Concentrations (PNEC) were derived for freshwater and marine organisms based on the empirical toxicity data available. Since the CTV for freshwater organisms was based on the HC5 of the SSD for acute toxicity (0.026 mg/L: Figure 1), an assessment factor of 10 was applied to this value to estimate a long-term no-effects concentration from short-term acute endpoints, yielding a chronic PNEC of 0.0026 mg/L. For marine organisms, the CTV was the chronic endpoint of 96-h LOEC (0.002 mg/L) for the gametophyte of a brown algae exposed to hydrazine. An assessment factor of 10 was applied to this value given the limited data available (i.e. brown algae only), yielding a chronic PNEC of 0.0002 mg/L.

The resulting risk quotients (PEC/PNEC) shown in Table 10 range from 1.3x10-3 to 8.9. Four sites have risk quotients (RQs) that exceed one, and a few sites have RQs that are close to this level (between 0.1 and 1). Even if these latter sites are below the level, they are considered as being of concern mainly due to the uncertainties associated with the PEC estimates. Indeed, a comparison between the modelled and the measured PECs for those power plants for which measured effluent concentrations are available showed that modelled PECs were underestimated by a factor of 61 to 147. Since most of the sites assessed rely only on modelled PECs, this means that RQs for these sites may have been underestimated by similar factors. RQs for those sites for which monitoring data are available for effluents were based on average concentrations, except for one site. While data distributions are narrow, maximum concentrations were 3 to 5 times higher than the averages.

In addition, the number of plants included in this assessment represents about one fifth of the total number of power generating plants using or potentially using hydrazine in Canada. Therefore, a number of other sites could be of concern in addition to the ones identified in this assessment.

The site-specific scenario modelling an industrial release to the Montréal WWTP provided a highly conservative risk quotient (PEC/PNEC) of 2.7×10-2, indicating that exposure concentrations generated by this industrial operation are unlikely to be high enough to cause harm to aquatic organisms.

The above information indicates that hydrazine has the potential to cause ecological harm in Canada.

Uncertainties in Evaluation of Ecological Risk

This section summarizes the key uncertainties associated with the risk assessment of hydrazine.

The number of plants included in this assessment represents a modest proportion (21%) of the total number of power generating plants using or potentially using hydrazine in Canada. Exposure scenarios were developed for 20 power generating plants and information was obtained for an additional 24 exposure scenarios (Table 9). There were 112 power plants using steam operating in Canada in 2000 (Statistics Canada 2000). Information received through Section 71 survey indicates that 22 of these 112 plants do not use hydrazine in their boilers (Environment Canada 2009). The number of 112 power plants includes fossil-fuel generating plants using Canadian bituminous coal, subbituminous coal, lignite, heavy fuel oil, natural gas and biomass; however, this number excludes nuclear power generating plants as well as steam-based power plants operated by the pulp and paper industry. The reasons for these exclusions are: 1) all nuclear power plants in Canada (n = 5) are already included in this assessment, and 2) hydrazine has not been used in the pulp and paper industry for many years (April 2010 personal communication between Ashland Canada Corporation to Ecological Assessment Division, Environment Canada; unreferenced). This assessment probably provides a representative sample of the power generating stations operating in 2006. Since 2000, many of these installations have stopped using hydrazine and/or have since relied on chemicals other than hydrazine for inhibiting corrosion in water cooling systems (Table 9). Also, smaller operations such as independent co-generation plants are more likely to use hydrazine alternatives and most of these would have an installed capacity of less than 200 MW (April 2010 personal communication between Ashland Canada Corporation to Ecological Assessment Division, Environment Canada; unreferenced ).

Estimates of daily effluent flows would be more exact if based on power generated during the year rather than on installed capacity. However, the former estimates are often not available for specific plants while estimates of capacity installed are obtained more easily, for example from the websites of power utility companies.

The modelled PECs for those power plants for which measured effluent concentrations were available were one to two orders of magnitude lower than the measured values. This could mean that the effluent flow and/or the number of annual release days was overestimated, and/or that loss of hydrazine to wastewater was underestimated. The number of release days may have been overestimated since blow down events, which are the source of hydrazine to the plant effluent, are usually intermittent and not continuous. In other words, peaks of hydrazine concentration are expected in the effluent following the schedule of blow down events. In addition, in case of a blow down event for one of the boilers in a plant, it is expected that the volume of cooling water for the entire plant would be reduced due to the temporary shut down of the boiler and associated lower requirement for cooling. In such a case, the volume of blow down water would make up for a major portion of the plant effluent, in comparison with the cooling water. As a result, the PECs and risk quotients could be underestimated. This would be especially likely if the available monitoring data were measured soon after a blow down event; however, this information is not available.

The value chosen for loss of hydrazine to wastewater (L) for those fossil-fuel power plants for which no data were available was estimated to be 10%. This value is likely conservative. Given that hydrazine is used as an oxygen scavenger, it is recognized that an important proportion of it will be consumed in chemical reactions. However, because this substance is likely used in excess to avoid limitation of chemical reactions, it is expected that some fraction will not transform and will be lost to wastewater.

Even if the values for some of the parameters used to model the PECs were conservative, modelled PECs were still likely underestimated compared to PECs that were based on measured concentrations, as explained above.

Potential environmental releases of hydrazine can occur from the auxiliary feed water systems from fossil-fuelled power generating plants, or from industrial plants making use of hydrazine in their boiler systems (Environment Canada 2009). No characterizations of exposure were designed for these releases because of a lack of information concerning these potential applications for hydrazine. In principle, one would expect these systems use much less hydrazine than that used to counter oxidation in steam-generating systems of electric power plants (Environment Canada 2009).

The fact that hydrazine is a reaction intermediate of anaerobic ammonium oxidation makes it plausible to expect natural occurrence of this substance in anaerobic environments. Natural background concentrations have not been taken into account in the exposure scenarios of this assessment because of an absence of data in the present context, but any natural background concentrations would be expected to be negligible.

There is uncertainty regarding the persistence of hydrazine in aquatic ecosystems. Its half-life could exceed 64 days and 125 days (Table 5) for Canadian fresh and marine waters, respectively, under reasonable worst case conditions such as those presenting physico-chemical characteristics favouring its persistence: slightly acidic pH, low water hardness and/or mineralization, low bacterial abundance, relatively low dissolved copper concentrations, and relatively low water temperatures. However, given the thermal plume created by the discharge of power plants, accelerated biotic and abiotic degradation of hydrazine in the receiving aquatic environment may occur.

The paucity of chronic toxicity data renders uncertain the determination of PNECs for chronic exposures to hydrazine such as in the present cases with liquid effluents of electric power plants.

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Potential to Cause Harm to Human Health

In aqueous solutions of hydrazine, all hydrazine is present as the hydrate. In this context, the anhydrous and hydrated forms of hydrazine are considered to be chemically equivalent to hydrazine in the present assessment. While the human health assessment focuses predominantly on the anhydrous form of hydrazine, toxicological data on the hydrated form is included where appropriate. While slight differences in toxicity were noted in animal studies using anhydrous or hydrated hydrazine, both forms are considered to be toxicologically equivalent in the present assessment.

Exposure Assessment

Environmental Media and Food

Upper-bounding estimates of hydrazine intake from environmental media for each age group in the general population of Canada are presented in Appendix 1. These upper-bounding estimates of intake range from 0.35 µg/kg body weight (bw)/day (60+ years old) to 1.1 µg/kg bw/day (0.5–4 years old). For all age groups, indoor air was estimated to be the major contributor to hydrazine exposure (intake estimates from indoor air were based on a detection limit of 0.002 mg/m3). When intake estimates from indoor air were based on atmospheric release data (Environment Canada 2009) using exposure modelling software (ChemCAN 2003), upper-bounding estimates of hydrazine intake decreased for all age groups, ranging from 1.5 × 10–4 µg/kg bw/day (60+ years old) to 3.8 × 10–4 µg/kg bw/day (0.5–4 years old).

Hydrazine reacts rapidly in the atmosphere by reacting with ozone, hydroxyl radicals and nitrogen dioxide (Tuazon et al. 1981; IPCS 1987). The half-life of hydrazine in the atmosphere is estimated to range between 10 minutes to 6 hours (Tuazon et al. 1981). Owing to the reactive nature of hydrazine, its atmospheric half-life is inversely related to air pollution levels from ozone and nitrogen dioxide.

Due to its reactive nature, detectable levels of hydrazine in ambient air are associated with locations near industrial emissions, where aircraft are using hydrazine as fuel, where emergency power units are assembled or refuelled, or near accidental spills or at contaminated sites (IPCS 1987; ATSDR 1997; Choudhary and Hansen 1998).

In Canada, releases of hydrazine and hydrazine salts into the air were less than 200 kg/year from 2004–2008 (Table 3; NPRI 2008). Although NPRI data are not exhaustive, as only certain types of facilities are required to report, atmospheric release quantities identified in NPRI and from a notice issued under section 71 of CEPA 1999 for the 2006 calendar year are in agreement. In 2006, 123 kg of hydrazine were released to the atmosphere, based on industry responses to the notice issued under section 71 of CEPA 1999 (Environment Canada 2009).

No reports of detectable levels of hydrazine in Canadian ambient air were identified in a review of the literature. Small release quantities and the short half-life of hydrazine in the atmosphere are two factors that may account for the absence of detectable levels of hydrazine in ambient air. In the United States, where hydrazine is manufactured, the situation is similar.

Estimated hydrazine releases to air in the United States were 13 000 kg/year (1988–1991) then declined to 4500 kg/year from 1992 to 1999 (TRI 2010). A review of 188 hazardous air pollutants in the United States, which included hydrazine, examined ambient air quality data collected between 1964 and 1992, but did not identify detectable levels of hydrazine in urban air (Spicer et al. 2002).

In the absence of Canadian empirical data, a hydrazine concentration in outdoor air of 4.42 × 10–4µg/m3 was estimated based on an atmospheric release of 123 kg of hydrazine in 2006 (Environment Canada 2009) and by using exposure modelling software (ChemCAN 2003). This modelled estimate was used to determine the upper-bounding exposure estimate from ambient air (Appendix 1).

Hydrazine has been detected in the indoor air of facilities that produce or process hydrazine at levels ranging from <0.01 to 1.98 ppm (ATSDR 1997; IUCLID 2000; CERI 2007) and up to 0.23 ppm for short-term exposure to hydrazine when it is used in boiler feed water (ATSDR 1997). Occasionally, levels may be higher, but typical occupational hydrazine concentrations in indoor air for derivative manufacturing and hydrazine production are <0.13 and <0.35 mg/m3, respectively (IPCS 1987). Hydrazine present in non-occupational indoor air has not been reported at concentrations above detection limits of 0.002–0.02 mg/m3 (ATSDR 1997).

The hydrazine detection limit of 0.002 mg/m3 was used as a conservative value for calculating the upper-bounding estimate of exposure to hydrazine in indoor air in the absence of non-occupational empirical data. Since hydrazine degrades rapidly in the environment, measurable levels are not normally encountered (ATSDR 1997; IPCS 1987). Therefore, an indoor air concentration for hydrazine of 4.42 × 10–4 µg/m3, based on estimated levels in ambient air (see above) was used to calculate estimated hydrazine intakes presented in Appendix 1.

In Canada, releases of hydrazine and hydrazine salts to water reported to NPRI from 2004 to 2008 are shown in Table 3. Reported releases to water range from 1900 to 6400 kg/year (NPRI 2008). Similar quantities have been reported to be released to water under NPRI and in response to the CEPA S.71 notice (NPRI 2008; Environment Canada 2009).

Limited information was found on hydrazine levels in drinking water in the United States and no monitoring data on detectable levels of hydrazine in drinking water in Canada or the United States was found. Analysis of hydrazine in drinking water was reported in a water quality data summary for 2002 for the city of Edmonton, Alberta. However, no further information was provided regarding the number of samples analysed, results or detection limits (EPCOR 2002).

Researchers reported developing a 15N2-hydrazine radio-labelled approach to hydrazine analysis in drinking water that was used to confirm detectable levels of hydrazine in California drinking water. Using radio-labelled hydrazine and tandem mass spectrometry, hydrazine was detected in 7 of 13 chloraminated drinking water samples (0.5–2.6 ng/L, 0.5 ng/L detection limit). One chlorinated drinking water sample was also analysed but did not contain detectable levels of hydrazine. The study did not provide details of the source water for the six water treatment plants investigated (Davis and Li 2008).

In another report, a very limited sampling (actual number of samples unreported) from one full-scale chloraminating water treatment plant, located in the southeastern United States, was performed for field verification purposes of a newly developed method. All samples did not contain detectable levels of hydrazine (detection limit of 3.7 ng/L) (AwwaRF 2006).

Elsewhere, no detectable levels of hydrazine (30 samples, 2 µg/L detection limit and 9 samples, 1.3 ng/L detection limit) were reported in Japanese surface water collected in 1986 and 2005, respectively (CERI 2007).

These findings are not unexpected as hydrazine is not expected to be present in drinking water, except near contaminated sites (ATSDR 1997; Choudhary and Hansen 1998). Contamination of drinking water by hydrazine may originate from military and industrial wastes and wastewater treatment plant effluents where it is used for the removal of halogens (Choudhary and Hansen 1998).

Davis and Li (2008) did not mention whether selection of the California water treatment plants was influenced by any of these factors. The authors of the AwwaRF (2006) report indicate the selection of the water treatment facility investigated was based, in part, on the relatively high dose of chloramine used at the facility. Under certain conditions, the use of monochloramine as a disinfectant in drinking water may lead to inorganic by-products that include hydrazine (Choudhary and Hansen 1998; AwwaRF 2006).

A study of the potential formation of hydrazine under chloramination conditions used to produce drinking water (monochloramine concentration of 3 mg/L, free ammonia concentration of 0.2 mg/L measured as N, 24-hour contact time) found no detectable concentration of hydrazine (detection limit of 3.7 ng/L) (AwwaRF 2006). A stability study of hydrazine in chloraminated drinking water reported hydrazine in water decreased from 60 ng/L (initial fortification concentration) to less than 2 ng/L in 4 hours (water spiked with 60 ng/L with hydrazine, pH 8.5, temperature 22°C, 1.3 mg/L monochloramine as Cl2) (AwwaRF 2006), thus indicating that hydrazine is unstable and rapidly degrades in the presence of monochloramine or free chorine under conditions typically used for treated and distributed drinking water (Atkinson and Carter 1984; Moliner and Street 1989).

Hydrazine is degraded in water mainly by oxidation, although biodegradation is also a removal mechanism (ATSDR 1997; Choudhary and Hansen 1998). The half-life of hydrazine is dependent on aquatic conditions and the degradation process is favoured by alkaline solutions and the presence of metal ions. Water temperature, water hardness, levels of naturally occurring organic matter and dissolved oxygen concentration are variables that affect the rate of degradation (Atkinson and Carter 1984). This is evident in the reporting of hydrazine degradation rates in waters of varying characteristics. Hydrazine concentrations in a polluted water source degraded more than 66% in 2 hours (Slonim and Gisclard 1976), while in chlorinated potable waters, hydrazine degradation ranged from >90% (1 day) to almost no reduction after 4 days (Moliner and Street 1989). The slower decay process in the potable water is attributed to lower levels of organic matter and water hardness in the water (Choudhary and Hansen 1998; HSDB 2010). Elsewhere, the half-life of hydrazine in pond water was reported as 8.3 days (HSDB 2010).

There are no Canadian guidelines established for hydrazine levels in drinking water; however, in the United States, the US EPA has estimated hydrazine poses a 1 × 10–6 cancer risk level at hydrazine drinking water concentrations of 10 ng/L (US EPA 1991). However, the US EPA has not developed a maximum contaminant level for hydrazine in drinking water. In the absence of Canadian drinking water data, the maximum hydrazine level in U.S. drinking water (2.6 ng/L), as reported by Davis and Li (2008), was used to calculate upper-bounding estimates of exposure to hydrazine from drinking water (Appendix 1).

Hydrazine appears to degrade faster in soil than in water, although the removal processes, oxidation and biodegradation, are the same. One soil study reported hydrazine levels of 10–500 µg/g to be entirely degraded in 1.5 hours to 8 days, depending on initial hydrazine concentration (Ou and Street 1987a). When hydrazine was added into a continuous sewage treatment system at a rate of 1 mg/L or lower, the hydrazine was completely degraded and was not detected in the treated effluent water. When added at concentrations of 10 mg/L and higher, hydrazine was not degraded (CERI 2007).

No information was found on hydrazine concentrations in soil or sediments in Canada. Therefore, a hydrazine level in soil of 6.68 × 10–7 µg/kg was estimated based on 2008 NPRI release data to land (NPRI 2008) and by using exposure modelling software (ChemCAN 2003). This modelled estimate was based on the most recent Canadian release data (NPRI 2008) and used to determine the upper-bounding exposure estimate from soil (Appendix 1).

Although hydrazine is not known to occur naturally in food, it may become concentrated in some fish living in contaminated water. Most animals quickly digest and excrete hydrazine, so high levels of the substance are not expected to remain in their flesh (ATSDR 1997). The presence of hydrazine covalently bound to an amino acid in some species of mushroom has been reported (Shubik 1979). However, a relationship between this substance, agaritine (2-[4-(hydroxymethyl)phenyl]-L-glutamohydrazide), and environmental hydrazine levels has not been established.

While hydrazine is not a permitted food additive, PVP[3] has permitted uses as a food additive. As per Division 16 of the Food and Drug Regulations, PVP may be used as a fining agent in various alcoholic beverages at a maximum level of 2 ppm in the finished product, as a tablet binder in table-top sweetener tablets containing aspartame at a maximum level of use of 0.3%, and as a viscosity reduction agent and stabilizer in colour lake dispersions at a maximum level of use consistent with Good Manufacturing Practice (residues of PVP are not to exceed 100 ppm in the finished foods) (Canada 2009b). PVP must meet the specifications of the Food Chemicals Codex (FCC) when used in these food additive applications (Canada 2009b). The FCC monograph for PVP requires that residual hydrazine levels in PVP be not more than 1 ppm (FCC 2008). Given that the presence of hydrazine in PVP is limited by the FCC specifications, that the Food and Drug Regulations permit PVP in only a very few foods and limits the level of PVP in those foods, and that PVP is not necessarily added to all food products for which a provision exists, exposure to hydrazine from the use of PVP as a food additive is expected to be negligible. Similarly, polyvinyl polypyrrolidone (PVPP) could be used as a fining agent in manufacturing some alcoholic beverages that are sold in Canada. However, the FCC does not have a criterion for residual hydrazine in PVPP as it does for PVP. PVPP is insoluble in water so it is expected that filtering of the beverage would remove PVPP. Consequently, negligible consumer exposure to hydrazine is expected to occur as a result of the use of PVPP as a fining agent in manufacturing alcoholic beverages.

In Canada, hydrazine has been identified as a residual impurity in one component of a coating for one laminated film used to package a variety of foods. Since hydrazine is used as a starting ingredient and due to its reactive nature, it is not expected that it would be in the final product at a significant level (Mar 2010 personal communication from Food Directorate, Health Canada, to Risk Management Bureau, Health Canada; unreferenced).

Based on the absence of detectable levels in, and limited releases to, the Canadian environment (Environment Canada 2009), as well as the reactive nature of hydrazine, it is unlikely that Canadians are exposed to significant concentrations of hydrazine from the environment. This finding is supported by an estimated upper-bounding daily intake based on recent Canadian hydrazine emissions data (NPRI 2008; Environment Canada 2009), the lack of detectable hydrazine levels in indoor air (ATSDR 1997) and low hydrazine levels measured in US drinking water (Davis and Li 2008).

Estimated hydrazine exposure from drinking water is based on the presence of hydrazine in chloraminated drinking water as an unintended by-product of disinfection; although many Canadian drinking water supplies are not disinfected with monochloramine. Hydrazine is only produced as a disinfection by-product under certain conditions. Conditions typically observed for treated and distributed drinking water have been shown to destabilize hydrazine, causing it to degrade rapidly. Therefore, the upper-bounding estimate of hydrazine in drinking water is considered to be highly conservative, as exposure is based on foreign data of targeted samples rather than Canadian monitoring data.

Despite the uncertainty of hydrazine levels in environmental media and food, confidence in the assessment of environmental exposure is moderate, based on the mostly industrial use of hydrazine, its reactive nature in the environment and small quantities of environmental releases reported in Canada.

Consumer Products

Hydrazine is an industrial chemical not intended to be present in consumer products. However, hydrazine has been identified as a residual in the polymer PVP and copolymer copovidone (Colonnese and Ianniello 1989; CIR 1998; ISP 2007). The United States Pharmacopeia specifies a limit of 1 ppm hydrazine in pharmaceutical grade PVP (USP 2009). International Specialty Products (ISP) state that typical PVP preparations (specific grade unspecified) have hydrazine contaminations of 200 ppb, although most sales specifications continue to report commercial grades of hydrazine levels that are <1 ppm (CIR 1998). Therefore, hydrazine may be present at residual levels in consumer products formulated from PVP and copovidone.

Although hydrazine is listed on the Cosmetic Ingredient Hotlist and as such, is not permitted to be intentionally added to cosmetic products available in Canada, at any concentration, hydrazine may be present in cosmetics as a residual. Typical PVP concentrations in cosmetics range from 0.3% to 10% by weight (Oct 2009 personal communication from Risk Management Bureau, Health Canada, to Existing Substances Risk Assessment Bureau, Health Canada; unreferenced). Copovidone is not used in cosmetics available in Canada (Mar 2010 personal communication from Risk Management Bureau, Health Canada, to Existing Substances Risk Assessment Bureau, Health Canada; unreferenced). Assuming a 1 ppm hydrazine residual in PVP, the estimated hydrazine residual in cosmetic products would range from 3 to 100 ng/g or from 0.6 to 20 ng/g assuming a 200 ppb polymer residual.

In Canada, PVP and copovidone are listed in the NHPID as acceptable non-medicinal ingredients in natural health products (NHPID 2010). For PVP, the NHPID specifies an acceptable daily intake of 50.0 mg/kg bw/day (NHPID 2009). When used as non-medicinal ingredients, PVP and copovidone may function as an adhesive, binder, disintegrate, film former, antioxidant or stabilizer in licensed natural health products (NHPID 2009). Both PVP and copovidone are listed in the LNHPD; thus, both are used in current licensed natural health products available in Canada (LNHPD 2010). Therefore, hydrazine may be present in licensed natural health products at residual levels.

Similarly, PVP and copovidone are listed in the TPD’s internal non-medicinal ingredients database as non-medicinal ingredients present in final pharmaceutical products and veterinary drugs (DPD 2010; Nov 2009 and Feb 2010 personal communications from Risk Management Bureau, Health Canada, to Risk Assessment Bureau, Health Canada; unreferenced). Therefore, hydrazine may be present in pharmaceutical products at residual levels (Sep 2009 personal communication from Veterinary Drugs Directorate, Health Canada, to Risk Management Bureau, Health Canada; unreferenced; Nov 2009 and Jan 2010 personal communications from Risk Management Bureau, Health Canada, to Risk Assessment Bureau, Health Canada; unreferenced).

Although hydrazine is not listed in the DPD or TPD’s internal non-medicinal ingredients database as a medicinal ingredient or non-medicinal ingredient in final pharmaceutical products or veterinary drugs, hydrazine may be present as a residue in specific drugs because it is used as a catalyst or intermediate in the formulation of pharmaceuticals (Choudhary and Hansen 1998; CERI 2007; DPD 2010; Feb 2010 personal communications from Risk Management Bureau, Health Canada, to Risk Assessment Bureau, Health Canada; unreferenced).

Medications containing hydrazine-derived active ingredients may contain residual hydrazine (Lovering et al. 1982, 1985; Matsui et al. 1983) or degradation products of the active ingredients (Lovering et al. 1982; Matsui et al. 1983). Furthermore, hydrazine is a metabolite of isoniazid (Blair et al. 1985) and hydrazaline (Timbrell and Harland 1979). Both, isoniazid and hydrazaline contain hydrazine derivatives as active ingredients (Matsui et al. 1983; ATSDR 1997; DPD 2010).

Researchers in Health Canada reported residual hydrazine present in hydrazaline pharmaceutical products (ca. 0.15 µg/tablet), with hydrazine levels increasing to 0.9 µg/tablet when the medications are stressed under elevated temperature and increased relative humidity for 221 days (Matsui et al 1983). Previous work had shown hydrazine levels in hydrazaline tablets to be stable over a 2-year period under ambient conditions, but that hydrazine was a degradation product in injectable formulations (Lovering et al. 1982).

Hydrazine is a raw material or intermediate in the formulation process of hydrazine-derivative active ingredients of specific medications (isoniazids and hydrazalines), which have therapeutic value.

In Canada, the presence of hydrazine in products is not expected, except as a residual at very low residual levels (as is the case for cosmetics) or in products that have therapeutic value.

Confidence in the assessment of hydrazine exposure from consumer products is moderate to low, based on the limited amount of Canadian exposure and use data available. Technology to reliably measure hydrazine at ppb levels is not available.

Health Effects Assessment

An overview of key toxicological studies on hydrazine and other hydrazine compounds is presented in Appendix 2. Toxicological studies conducted with various hydrazine salts were provided as supportive information only and were not used as part of the risk characterization for hydrazine (and its hydrate) in this screening assessment.

IARC has classified hydrazine as a Group 2B carcinogen (i.e., possibly carcinogenic to humans) (IARC 1999). The European Commission has classified hydrazine as Category 2 for carcinogenicity (i.e., should be regarded as if it is carcinogenic to man) (ESIS 2006). The US EPA conducted a weight–of-evidence assessment of the carcinogenicity of hydrazine and classified it as a Group 2B carcinogen (i.e., probable human carcinogen) (US EPA 1991). The US NTP (2005) considered hydrazine to be “reasonably anticipated to be a human carcinogen”. The classifications were based on inadequate evidence for carcinogenicity in humans but sufficient evidence in experimental animals. This evidence included induction of tumours in mice, rats and hamsters after oral or inhalation administration of hydrazine, and mutagenicity in numerous assays.

In 1-year chronic inhalation studies on hydrazine at concentrations of 0, 0.06, 0.3, 1.3, or 6.5 mg/m3, there were significantly increased incidences of nasal and bronchial tumours (adenomas, adenocarcinomas and carcinomas) in rats of both sexes, thyroid tumours in male rats, and nasal tumours in hamsters at 1.3 and/or 6.5 mg/m3. There was an increased incidence of lung adenomas in female mice at 1.3 mg/m3(MacEwen et al. 1981; Vernot et al. 1985). In chronic oral studies, there was an increased incidence of lung tumours in mice of both sexes treated with hydrazine at a dose of 1.87 mg/kg bw/day (Roe et al. 1967; Toth 1969; Toth 1972). There were no oral carcinogenicity studies identified in rats. However, in a drinking water carcinogenicity study the hydrated form of hydrazine was noted to induce liver tumours in both male and female rats (Steinhoff and Mohr 1988).

There was insufficient evidence to assess the potential of hydrazine to cause carcinogenicity in humans. In a cohort study of 423 men engaged in hydrazine manufacture, five cancers were reported (three stomach, one prostate and one neural) in the group with intermediate exposure to hydrazine, while no tumours were observed in the highest exposure group (Wald et al. 1984). In the follow-up study, mortality from all causes was not elevated (49 observed, 61.5 expected) and the only incidents of excess tumour rate were two lung cancer cases within the highest-exposure category (3 observed versus 2.43 expected). Due to the small sample size, this study was too limited to exclude lower relative risks (Morris et al. 1995).

Non-neoplastic effects observed in chronic studies included significantly increased inflammation in the trachea of male rats exposed to hydrazine via inhalation at a lowest observed adverse effect concentration (LOAEC) of 0.06 mg/m3, and significantly increased lesions in multiple sites (liver, lymph nodes, kidney, thyroid and adrenal) in male hamsters at 0.3 mg/m3 (MacEwen et al. 1981; Vernot et al. 1985). There was no information on non-neoplastic effects from chronic inhalation exposure to hydrazine in mice, or from chronic oral exposure to hydrazine in rodents. Dose-dependent reductions in water consumption in male and female rats and mice, and increased incidence of bile duct proliferations in male rats were observed at 0.3 mg hydrazine/kg bw/day, in 2-year chronic studies in which rodents were exposed to hydrazine hydrate (Steinhoff and Mohr 1988; Steinhoff et al. 1990).

Hydrazine was found to be genotoxic in a number of in vivo assays in experimental animals and Drosophila; and in in vitro assays in bacteria, yeast and in mammalian cells. In in vivo bioassays, significant increases in the frequency of DNA damage in different tissues (liver, lung, kidney, brain, bone marrow and mucosa of stomach, colon and bladder) were observed in male mice exposed to single doses of hydrazine orally by gastric intubation or by intraperitoneal injection (Sasaki et al. 1998; Robbiano et al. 2006). There was formation of N7-methylguanine and O6-methylguanine in liver DNA of Wistar, Sprague-Dawley and Fischer 344 rats exposed to hydrazine orally by gavage (Becker et al. 1981; van Delft et al. 1997). Gene mutation was also positive in Drosophilaexposed orally to hydrazine (Jain and Shukla 1972).

In in vitro assays, hydrazine was mutagenic in Salmonella typhimurium (with metabolic activation), Escherichia coli (with or without metabolic activation) and in yeast (without metabolic activation) (Herbold and Buselmaier 1976; Herbold 1978; McMahon et al. 1979; Noda et al. 1986). In mammalian cell bioassays, consistent positive results were observed in mouse lymphoma L5178Y cell mutation assays, micronucleus induction assay in Chinese hamster V79 cells, DNA damage assay in isolated rat hepatocytes and cell transformation in human neonatal fibroblast cells (Milo et al. 1981; Sina et al. 1983; Onfelt 1987; Kumari et al. 1992).

Fully elucidated modes of action for induction of the observed tumours that have been accepted by other regulatory agencies have not been identified, but the data suggested multiple modes of actions. One proposed mode of action involves direct binding of hydrazine with a free amino group to key cellular molecules; the generation of reactive species such as free radical intermediates or methyldiazonium ions as a result of metabolism has also been proposed (ATSDR 1997). Hydrazine reacts with alpha-keto acids and forms hydrazones. This process inhibits oxygen consumption with mitochondrial substrates in vitro, which maybe the cause for the hyperlactemic and hypoglactemic effects of hydrazine observed in humans (O’Leary and Oikemus 1956; Fortney 1967; Ochoa et al. 1975). Hydrazine can bind to natural and active form of vitamin B6 and produce hydrazone (Cornish 1969). By binding to vitamin B6 derivatives, hydrazine was able to inhibit reactions that require vitamin B6 as a cofactor (such as transamination reactions, decarboxylation and other transformations of amino acids, the metabolism of lipids and nucleic acids, and glycogen phosphorylation). The formation of hydrazone derivatives of vitamin B6 can produce convulsions and anaemia (Cornish 1969). Convulsions were noted in rats after intraperitoneal injection of 100 mg/kg hydrazine (Cornish 1969; NRC 1989). Hydrazone may also be produced from the reaction of hydrazine with endogenous formaldehyde, and it may be involved in the DNA methylation mechanism, which is proposed to be responsible for gene mutations (ATSDR 1997; IARC 1999). Above all, genotoxicity resulting from direct interaction with genetic material cannot be discounted as a possible mode of action contributing to the development of tumours observed in rodents.

The lowest LOAEC for subchronic inhalation was 0.26 mg/m3 based on lipidosis in the liver of ICR female mice exposed to hydrazine for 6 months (Haun and Kinkead 1973). Short-term exposures (up to 6 weeks) to rats and mice at high concentrations(26 mg/m3 and above) of hydrazine caused liver toxicity (fatty metamorphosis of liver) along with pulmonary edema and localized damage to the bronchial mucosa (Comstock et al. 1954). The lowest LOAEC of 0.06 mg/m3 based on increased inflammation in trachea was determined after chronic exposure (MacEwen et al. 1981; Vernot et al. 1985).

The lowest observed adverse effect level (LOAEL) for subchronic toxicity based on an oral study was 12 mg/kg bw/day based on an increase in mortality in albino rats exposed to hydrazine in drinking water for 14 weeks (Weatherby and Yard 1955). Mortality was also increased in female Swiss mice treated with hydrazine for 7 days at a substantially higher dose of 133 mg/kg bw/day and above (Roe et al. 1967).

The lowest dermal LD50 was 93 mg/kg bw in rabbits exposed to hydrazine on clipped skin. Indications of skin penetration were noted rapidly, as a bluish-black discolouration of the skin at the site of application was noted within 15 minutes of hydrazine administration. The discolouration was observed to penetrate deeply into the dermis, which correlated with the onset of acute local inflammation and moderate edema (Rothberg and Cope 1956).

Hydrazine was classified as a Group 2 skin-sensitizing substance by the Japan Society for Occupational Health (CERI 2007). Positive results from a sensitization test was reported for all 23 volunteers tested with 5% hydrazine solution applied to the upper arm and with the application site occluded for 48 hours (Kligman 1966). Skin irritation was also reported in animal patch testing with hydrazine (Hathaway 1984; Mobay Chemical 1984).

Neurological effects of hydrazine exposure were observed in several human and animal studies. Long-term impairment of verbal and visual learning and memory was observed in a water technician exposed to unspecified levels of hydrazine mixtures (Richter et al. 1992). Clinical signs that may represent neurological toxicity have been noted in humans with one or more exposures to hydrazine mixtures. These clinical signs include fatigue, trembling, conjunctivitis, nausea, confusion and vomiting (Reid 1965; Sotaniemi et al. 1971; Harati and Niakan 1986). In animal experiments, tonic convulsions were noted in one of eight dogs exposed continuously to 1.33 mg/m3 hydrazine for 6 months, and in rats administered hydrazine at 100 mg/kg via intraperitoneal injection (Cornish 1969; Haun and Kinkead 1973). These data suggest that the central nervous system may be a target for the toxicity of hydrazine, although these effects have not been noted at the LOAELs in the animal database.

For reproductive effects, atrophy of the ovaries and inflammation of the endometrium and oviducts were noted in female rats exposed to high doses (6.5 mg/m3) of hydrazine in a carcinogenicity study (MacEwen et al. 1981; Vernot et al. 1985). In an oral reproductive study, lesions of the testicular epithelial cells were observed in male rats exposed to the hydrated form of hydrazine at 0.0014 mg/kg bw/day and above and a reduction in surviving embryo, and an increase in resorptions and pre-implantation loss were noted at 0.016 mg/kg bw/day (Duamin et al. 1984). However, testicular toxicity was absent in the hydrazine database in studies using higher dose levels, e.g., 2-year chronic oral studies at 0.3 mg/kg bw/day (Steinhoff and Mohr 1988; Steinhoff et al. 1990).

For developmental toxicity, a significant dose-related increase in the number of resorptions per litter was noted in an embryotoxicity study in rats exposed to hydrazine by intraperitoneal injection at 5 mg/kg bw/day through gestation days 6 to 15, or by a single dermal application at 50 mg/kg bw (Keller et al. 1982). Maternal toxicity was observed at the same or lower dose levels where developmental effects were observed. Suppression of body weight gain and epidermal necrolysis in the application site was observed at 5 mg/kg bw by a single dermal application; dose-related reduction in body weight gain was observed at 5 mg/kg bw/day and higher via intraperitoneal injection (Keller et al. 1982). No inhalation or oral study was identified to assess developmental effects of hydrazine via these routes.

Hydrazine was found to be rapidly absorbed and widely distributed in tissues. Hydrazine was detected in plasma and liver in male Sprague-Dawley rats that were dosed orally by stomach tube with the hydrated form of hydrazine in distilled water (Preece et al. 1992b). Between 18% and 35% of the original dose was eliminated as hydrazine, and between 1% and 6% as cetylhydrazine (Preece et al. 1992a, Preece et al. 1992b). At least 19–46% of the administered dose was absorbed, based on the levels of hydrazine and its metabolites excreted in the urine within 24 hours. However, since certain metabolites of hydrazine could not be detected by the analytical method employed in the study, and the 24-hour sample period was of inadequate duration to fully identify urinary metabolites, the absorption of hydrazine in the gastrointestinal tract is most likely higher than 19–46% (Preece et al. 1992a). After nose-only exposure to the rats, hydrazine and its metabolites (monoacetylhydrazine and diacetylhydrazine) were excreted in the urine, and the absorption of hydrazine was estimated to be at least 8.4–29.5%. However, since metabolites were only examined in urine, absorption after inhalation exposure may be significantly higher than 8.4–29.5% (Llewellyn et al. 1986).

The confidence in the toxicity database for hydrazine is considered to be moderate to high, as adequate information is available to identify critical endpoints based on repeated-dose exposure, both orally and by inhalation of acute to long-term duration, with the exception of reproductive and developmental toxicity studies. However, there were limited data for the effects induced by dermal routes of exposure. There was sufficient information on carcinogenicity with genotoxicity found in both in vivo and in vitro animal studies. But there is insufficient evidence of hydrazine carcinogenicity in humans.

Characterization of risk to human health

Based principally on the weight of evidence assessments of international or other national agencies (IARC 1987, 1999; US EPA 1991; ATSDR 1997; US NTP 2005; European Commission 2008), a critical effect for characterization of risk to human health for hydrazine is carcinogenicity. As shown in the “Health Effect Assessment” section, tumours in the respiratory tracts were observed in rats, mice and hamsters after inhalation and/or oral exposure to hydrazine, while liver tumours were noted in rats exposed to the hydrated form of hydrazine. Genotoxicity was observed in both in vivo and in vitro assays with hydrazine. Although the modes of action for the induction of tumours in rodents has not been fully elucidated, based on the weight of evidence of carcinogenicity and the genotoxicity of hydrazine, it cannot be precluded that the tumours observed may have resulted from direct interaction of hydrazine with genetic material.

The US EPA (1991) quantified the risk of cancer from inhalation exposure to hydrazine, using a linear multistage procedure. An inhalation unit risk of 4.9 × 10-3 per (µg/m3) was calculated based on a carcinogenicity study in rats exposed to hydrazine conducted by MacEwen et al. (1981) (US EPA 1991).

As a comparison, the inhalation unit risk derived by the US EPA was used to calculate a cancer risk level, given the expected Canadian use pattern. Multiplying the upper bound estimate of inhalation exposure to hydrazine (4.42 × 10-4µg/m3) in ambient air by the inhalation unit risk of 4.9 × 10-3 per (µg/m3), a risk level of 2.17 × 10-6 is derived. Based on the basis of the genotoxicity and carcinogenicity, for which there may be a probability of harm at any level of exposure, it is concluded that hydrazine (and its hydrate) is a substance that may be entering the environment in a quantity or concentration or under conditions that constitute or may constitute a danger in Canada to human life or health.

With respect to non-cancer effects after inhalation exposure, at the lowest LOAEC of 0.06 mg/m3, inflammation significantly increased in trachea of male rats exposed to hydrazine. At a higher concentration of 0.3 mg/m3, a significant increase in the number of lesions in multiple sites (liver, lymph nodes, kidney, thyroid and adrenal) in male hamsters were observed. No non-neoplastic effects were reported after chronic oral exposure to hydrazine. Since the toxicity of hydrazine hydrate and hydrazine was considered to be comparable, the lowest LOEL of 0.3 mg hydrazine /kg bw/day based on increased incidence of bile duct proliferations in male rats exposed to the hydrated form of hydrazine in 2-year chronic studies, was determined to be the critical effect level. Hydrazine was not considered to be a developmental or reproductive toxicant, as effects specific to reproductive or developmental function occurred at higher dose levels (5 mg/kg bw/day via intraperitoneal injection or 6.5 mg/m3 via inhalation) than the critical dose levels identified above.

A comparison of the critical non-neoplastic effect level for inhalation exposure in rats (0.06 mg/m3), using the upper-bounding hydrazine concentration in ambient air (4.42×10-4 µg/m3), results in a margin of exposure (MOE) of 135 746. This margin of exposure is considered adequate to address non-cancer effects.

The critical non-neoplastic effect level for oral exposure in rats was 0.3 mg hydrazine/kg bw/day based on evidence of bile duct proliferations in male rats exposed to the hydrated form of hydrazine. Comparison of the critical non-neoplastic effect level for oral exposure (0.3 mg/kg bw per day) with the upper-bounding total intake estimate of hydrazine for the most sensitive sub-population (4.0×10-4 µg/kg bw/day derived for formula fed infants), results in a MOE of 7.5×105. This margin of exposure is considered adequate to address non-cancer effects.

Uncertainties in Evaluation of Risk to Human Health

This screening assessment does not include a full analysis of the modes of action of hydrazine for the induction of effects, including carcinogenicity, neurotoxicity, and reproductive and developmental toxicity, nor does it take into account possible differences between humans and experimental species in sensitivity. Standard reproductive toxicity studies were not available. Also, only limited information was available concerning the potential toxicity of hydrazine after dermal routes of exposure. However, the database is considered adequately characterized to assess hydrazine on the basis of carcinogenicity.

The lack of recent Canadian data regarding levels of hydrazine in environmental media, food and consumer products is a source of uncertainty in the upper-bounding exposure estimates for the general population of Canada. However, concern about this uncertainty is reduced considering that the lack of recent data can be attributed to the very low levels of hydrazine expected in the Canadian environment, food and consumer products available in Canada. Confidence is moderate to low that the derived multimedia and consumer product exposure estimates are adequately protective of the general population of Canada, as conservative estimates and upper-bounding scenarios were used when recent Canadian data were unavailable.

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Conclusions

Based on the information presented in this screening assessment, it is concluded that hydrazine is entering or may enter the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity.

On the basis of the carcinogenicity, for which there may be a probability of harm at any level of exposure, it is concluded that hydrazine is a substance that may be entering the environment in a quantity or concentration or under conditions that constitute or may constitute a danger in Canada to human life or health.

It is therefore concluded that hydrazine meets one or more of the criteria under section 64 of CEPA 1999. Hydrazine does not meet the criteria for persistence or bioaccumulation potential as set out in the Persistence and Bioaccumulation Regulations(Canada 2000).

This substance will be considered for inclusion in the Domestic Substances List inventory update initiative. In addition and where relevant, research and monitoring will support verification of assumptions used during the screening assessment and, where appropriate, the performance of potential control measures identified during the risk management phase.

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Wakabayashi T, Horiuchi M, Sakaguchi M, Onda H, Misawa K. 1983. Induction of megamitochondria in the mouse and rat livers by hydrazine. Exp Mol Pathol 39:139–153.

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Appendix 1: Upper-bounding estimates of daily intake of hydrazine by the general population in Canada

Route of exposureEstimated intake (µg/kg bw per day) of hydrazine by various age groups
0–6 months10.5–4 years45–11 years512–19 years620–59 years760+ years8
Breast fed2Formula fed3Not formula fed
Ambient air91.6×10-53.3×10-52.6×10-51.5×10-51.3×10-51.1×10-5
Indoor air100.49
(1.1×10-4)
1.1
(2.3×10-4)
0.82
(1.8×10-4)
0.47
(1.0×10-4)
0.40
(8.8×10-5)
0.35
(7.7×10-5)
Drinking water11N/A2.8×10-41.0×10-41.2×10-49.2×10-55.3×10-55.5×10-55.8×10-5
Food and beverages12N/AN/AN/AN/AN/AN/AN/AN/A
Soil132.71×10-124.3×10-121.4×10-122.4×10-132.8×10-132.8×10-13
Total intake14N/A4.0×10-4 to 0.492.3×10-4 to 0.493.8×10-4 to 1.13.0×10-4 to 0.821.7×10-4 to 0.471.6×10-4 to 0.401.5×10-4 to 0.35
Abbreviation: N/A, not applicable.
1 Assumed to weigh 7.5 kg, to breathe 2.1 m3of air per day, to drink 0.8 L of water per day (formula fed) or 0.3 L/day (not formula fed) and to ingest 30 mg of soil per day (Health Canada 1998).
2 No data on detectable levels of hydrazine in breast milk were located.
3 For exclusively formula-fed infants, intake from water is that amount required to reconstitute formula. No data on hydrazine levels in formula were found; however, concentrations of hydrazine in drinking water were used in this model (see footnote 11). Approximately 50% of non-formula-fed infants are introduced to solid foods by 4 months of age and 90% by 6 months of age (NHW 1990).
4 Assumed to weigh 15.5 kg, to breathe 9.3 m3of air per day, to drink 0.7 L of water per day and to ingest 100 mg of soil per day (Health Canada 1998).
5 Assumed to weigh 31.0 kg, to breathe 14.5 m3 of air per day, to drink 1.1 L of water per day and to ingest 65 mg of soil per day (Health Canada 1998).
6 Assumed to weigh 59.4 kg, to breathe 15.8 m3 of air per day, to drink 1.2 L of water per day and to ingest 30 mg of soil per day (Health Canada 1998).
7 Assumed to weigh 70.9 kg, to breathe 16.2 m3 of air per day, to drink 1.5 L of water per day and to ingest 30 mg of soil per day (Health Canada 1998).
8 Assumed to weigh 72.0 kg, to breathe 14.3 m3 of air per day, to drink 1.6 L of water per day and to ingest 30 mg of soil per day (Health Canada 1998).
9 Hydrazine was not detected in outdoor air in Canada. A modelled estimate of a hydrazine concentration of 4.42 × 10–4 µg/m3was used to calculate the upper-bounding estimates for ambient air exposure (ChemCAN 2003). Canadians are assumed to spend 3 hours per day outside (Health Canada 1998).
10 Hydrazine was not detected in residential indoor air in Canada. In the absence of experimental data from Canada, two upper-bounding estimates of daily exposure to hydrazine from indoor air were estimated with the modelled estimate of 4.42 × 10–4 µg/m3 of hydrazine in ambient air (see footnote 9) and a more conservative estimate based on the detection limit of 0.002 mg/m3 reported in studies of occupational hydrazine exposure from indoor air (ATSDR 1997). Intake estimates based on the modelled estimate of 4.42 × 10–4 µg/m3 are shown in parentheses. Canadians are assumed to spend 21 hours indoors each day (Health Canada 1998).
11 Hydrazine was not detected in Canadian drinking water. A report on hydrazine levels in drinking water identified hydrazine concentrations ranging from 0.5 to 2.6 ng/L in 7 of 13 drinking water samples collected in California (Davis and Li 2008). The upper-bounding concentration of 2.6 ng/L was used to calculate upper-bounding daily exposure to hydrazine from drinking water.
12 No data were identified for the concentration of hydrazine in foods in Canada or elsewhere.
13 Hydrazine was not detected in Canadian soil or sediment. In the absence of experimental data from Canada, a modelled estimate of a hydrazine concentration of 6.68 × 10–7 µg/kg was used to calculate the upper-bounding estimates for soil exposure (ChemCAN 2003).
14 Total intake estimate is reported as a range for each age group, taking into account the two intake estimates calculated for indoor air (see footnote 10).

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Appendix 2: Summary of health effects information for hydrazine*

EndpointsLowest effect levels/Results

Acute toxicity

(Hydrazine)

Lowest inhalation LC50 (mouse) = 330 mg/m3 (Jacobson et al. 1955 cited in IUCLID 2000).

Other inhalationstudies: LC50 (rat) = 750 mg/m3(Jacobson et al. 1955 cited in IUCLID 2000);

LOAEL (rat) = 106 mg/m3 based on mortality observed, this was the lowest dose tested, no data for LC50 available (Comstock et al. 1954).

[No additional inhalation studies identified]

Lowest oral LD50(rat) = 60 mg/kg bw (Witkin 1956)

Other oral study: LD50(rat) = 90 mg/kg bw (Becker et al. 1981)

[No additional oral studies identified]

Lowest dermal LD50 (rabbit) = 93 mg/kg bw (Rothberg and Cope 1956).

[No additional dermal studies identified]

Acute toxicity

(other hydrazine compounds)

Hydrazine hydrate

Lowest inhalation LC50= 3400 mg/m3 (HRC Report 1989 cited in IUCLID 2000)

[Additional inhalation studies are cited in CERI 2007]

Lowest oral LD50 (rabbit) = 55 mg/kg bw (Ekshtat 1965).

[ Additional oral studies are cited in CERI 2007]

Short-term repeated-dose toxicity (Hydrazine)

Lowest inhalation LOAEC= 26 mg/m3based on fatty metamorphosis of liver, pulmonary edema and localized damage to the bronchial mucosa observed under autopsy examination of rats and mice (strains unknown) (10 animals per group) exposed to 0 or 26 mg/m3; 6 hours/day, 5 days/week for up to 6 weeks (Comstock et al. 1954).

Other inhalation LOAECs = 70 or 980 mg/m3 in rats and mice (Comstock et al. 1954; Latendresse et al. 1995).

[No additional inhalation studies identified]

Lowest oral LOAEL= 133 mg/kg bw/day based on mortality of all female Swiss mice treated with hydrazine observed within 7 days, dosed by gavage (5 females per dose) at 0, 33.3, 133, 533, 2133 mg/kg bw per day, five times a week (Roe et al. 1967)

Other oral LOAEL = 1333 mg/kg bw/day based on hepatic megamitochondria (reversible after 72 h normal diet) with fragmented and distorted crystal membranes and proliferation of smooth endoplasmic reticulum in males rats and mice dosed orally (10 or 20 animals per dose) at 0, 0.5, 1 or 2% hydrazine in diet (equivalent of 0, 617, 1333, 2666 mg/kg bw per day) for 3 days (Wakabayashi et al. 1983).

[No additional oral studies identified]

No dermal studies identified.

Short-term repeated-dose toxicity

(other hydrazine compounds)

Hydrazine hydrate

Lowest oral LOAEL= 10 mg/kg bw/day based on fatty change in the hepatocytes in male and dirty nasal discharge in female Crj rats (5 per sex per group) exposed orally (gavage) to 0, 1, 3, 10 or 30 mg/kg bw/day for 28 days (MHLW 2005).

No additional studies identified.

Subchronic toxicity

(Hydrazine)

Lowest inhalation LOAEC = 0.26 mg/m3based on lipidosis in the liver of ICR female mice (40 per group), exposed to 0, 0.26 or 1.33 mg/m3 (0, 0.2 or 1 ppm) , along with 4 female rhesus monkeys, 50 male Sprague-Dawley rats and 8 male beagle dogs. Neurological effects i.e., tonic convulsions, were observed in one of eight dogs exposed continuously to 1.33 mg/ m3, but were not observed in any dogs exposed to 0.26 mg/m3 (Haun and Kinkead 1973).

[No additional inhalation studies identified]

Lowest oral LOAEL = 12 mg/kg bw/day based on increase in mortality in albino rats (10 per groups) exposed via drinking water to 0, 12, 24, 60, 120, 240 mg /kg bw/day for 14 weeks (Weatherby and Yard 1955).

[No additional oral studies identified]

No dermal studies identified.

Subchronic toxicity

(other hydrazine compound)

Hydrazine sulphate

Lowest oral LOEL = 1.1 mg/kg bw/day based on adrenal degeneration in female CBA mouse (40-51 per group) exposed via drinking water to 0, 1.1, 2.3, 4.9 mg /kg bw/day for 15 to 25 weeks (Biancifiori 1970a).

Other oral LOEL= 5.0 mg/kg bw/day based on reticuloendothelial cell proliferation and hepatic cirrhosis in Golden hamsters (23-56 per group) exposed to hydrazine sulphate orally by stomach tube at 3.0 mg/animal/day for 60 doses, at 2.8 mg/animal/day for 100 doses, respectively (equivalent to 5.4 and 5 mg hydrazine/kg bw per day, respectively), for 15 and 20 weeks, respectively. (Unit conversion: divided by mice body weight =0.14 kg (Health Canada 1998), nd multiply the molecular weight ratio of hydrazine and hydrazine sulphate =32.05/130.12) (Biancifiori 1970a).

No additional studies identified.

Chronic toxicity/ carcinogenicity (Hydrazine)

Inhalation carcinogenicity in mice: Groups of 400 C5 7BL/6 female mice were exposed to hydrazine by inhalation (whole body) 0, 0.06, 0.3, 1.3 mg/m3 (equivalent to 0, 0.0798, 0.399 or 1.69 mg/kg bw per day, using a dose conversion method by Health Canada 1998) 6 hours per day, 5 days per week for 1 year, without exposures on weekends and holidays. There was a borderline statistical significance of increase in incidence of lung adenomas at the highest concentration tested (4/378, 12/379, in concurrent control, and 1.3 mg/ m3 respectively) (MacEwen et al. 1981; Vernot et al.1985).

Inhalation carcinogenicity in rats: Groups of 100 F-344 rats/sex were exposed to hydrazine by inhalation (whole body) at 0, 0.06, 0.3, 1.3, or 6.5 mg/m3 (equivalent to 0, 0.0798, 0.399, 1.69 or 8.65 mg/kg bw per day, using a dose conversion method by Health Canada 1998)  6 hours per day, 5 days per week for 1 year, without exposures on weekends and holidays. There was a significantly increased incidence of nasal adenomatous polyp in males at the 2 highest doses (0/146, 2/96, 1/94, 9/97*, 58/98* at 0, 0.06, 0.3, 1.3, or 6.5 mg/m3, respectively, *p ≤0.01). There was an increased incidence of nasal, bronchial and thyroid tumours in males at the highest dose (nasal villous polyp 0/146, 0/96, 0/94, 1/97, 12/98*; nasal squamous cell carcinoma 0/146, 0/96, 0/94, 1/97, 2/98; bronchial adenoma 0/146, 0/96, 0/94, 0/97, 3/98; thyroid carcinoma 7/146, 6/96, 5/94, 9/97, 13/98**, respectively; *p ≤0.01, ** 0.01≤p ≤0.05). There was a significantly increased incidence of nasal adenomatous polyp in females at the highest dose (0/145, 2/97, 0/98, 2/94, 28/95* *p ≤0.01). Although not statistically significant, there was an increased incidence of nasal and bronchial tumours in females at the highest dose (nasal villous polyp 0/145, 0/97, 0/98, 2/94,2/95; nasal adenocarcinoma 0/145, 1/97, 0/98, 0/94, 3/95; nasal squamous cell papilloma 0/145, 0/97, 0/98, 0/94, 3/95; nasal squamous cell carcinoma 0/145, 0/97, 0/98, 0/94, 2/95; bronchial adenoma 0/145, 0/97, 0/98, 0/94, 1/95, respectively) (MacEwen et al. 1981; Vernot et al. 1985).

Other inhalation carcinogenicity study:

Groups of 200 golden Syrian male hamsters were exposed to hydrazine by inhalation at 0, 0.3, 1.3 or 6.5 mg/m3(equivalent to 0, 0.3, 1.3, or 6.5mg/kg bw per day, using a dose conversion method by Health Canada 1994) 6 hours per day, 5 days per week for 1 year. There was a significant increase in nasal adenomatous polyp in the highest dose (1/181, 0/154, 1/148, 16/160*, at 0, 0.3, 1.3 or 6.5 mg/m3*, *p ≤0.01) (MacEwen et al. 1981; Vernot et al. 1985).

Inhalation non-neoplastic LOAEC = 0.06 mg/m3 based on significantly increased inflammation in trachea of male rats. Other non-neoplastic effects included a significant increase in inflammation in trachea and hepatic focal cellular change in female rats at 1.3 mg/m3 and higher; significantly increased lesions in multiple sites (liver, lymph nodes, kidney, thyroid and adrenal) in male hamsters at 0.3 mg/m3. Reproductive effects including atrophy of the ovaries and inflammation of the endometrium and oviducts in female rats, and exposed intermittently to 6.5 mg/m3 hydrazine for 1 year. No non-neoplastic effects of exposure were recorded in mice (MacEwen et al. 1981; Vernot et al. 1985).

[Additional inhalation carcinogenicity studies: Latendresse et al. 1995]

Oral carcinogenicity in mice: Groups of 50 Swiss mice per sex were exposed to hydrazine orally in drinking water at 0.056 mg/animal for females and 0.069 mg/animal for males (equivalent to 1.87 mg/kg bw/day for females and 2.3 mg/kg bw/day for males, using a dose conversion by Health Canada 1998), daily for life span (110-120 weeks). There was an increase (statistical significance unknown) in incidence of lung tumours in both sexes treated with hydrazine (males: adenoma 10/110, 21/50 at 0, 2.3 mg/kg bw/day, respectively; adenocarcinoma 1/110, 9/50; adenoma and adenocarcinoma combined 11/110, 24/50. Females: adenoma 12/110, 25/50; adenocarcinoma 2/110, 9/50; adenoma and adenocarcinoma combined 14/110, 27/50 in 0, 1.87 mg/kg bw/day, respectively). The appearance of liver tumour in hydrazine treated group was difficult to relate to treatment (male: 2/110, 2/50 in 0, 2.3 mg/kg bw/day, respectively; female: 3/110, 1/50 in 0, 1.87 mg/kg bw/day, respectively) (Toth 1969, Toth 1972).

Group of 25 virgin female Swiss mice administered hydrazine in water orally by gavage at 0.25 mg/animal/day (equivalent to 16.67 mg/kg bw/day, female mouse body weight=15 g), 5 days per week for 40 weeks. There was a significant increase (p<0.001) in incidence of lung tumours (6/42, 4/4 survivors, in control and hydrazine treated group, respectively at 50-60 weeks) (Roe et al. 1967).

Oral non-neoplastic effects were not provided in the available two carcinogenicity studies.

[No additional oral chronic toxicity / carcinogenicity studies identified]

No dermal studies identified.

Chronic toxicity/ carcinogenicity (Other hydrazine compounds)

Hydrazine hydrate

No inhalation studies identified

Oral carcinogenicity in rats: Group of 50 Wistar rats per sex exposed to hydrazine hydrate orally in drinking water at 0, 2, 10 or 50 ppm (equivalent of 0, 0.3, 1.4 or 7.1 mg/kg bw per day, using a dose conversion method by Health Canada 1998) for 2 years. There was an increase in tumour incidence in the liver (male: benign 0/50, 1/50, 1/50, 4/50; malignant 0/50, 0/50, 1/50, 0/50; benign and malignant combined 0/50, 1/50, 2/50, 4/50. Female: benign 0/50, 0/50, 0/50, 4/50; malignant 0/50, 0/50, 0/50, 3/50; benign and malignant combined 0/50, 0/50, 0/50, 7/50. Female and male combined 0/100, 2/100, 3/100, 14/100, at 0, 0.25, 1.2 or 6.0 mg/kg bw/day respectively). The tumour incidence in hydrazine hydrate treated groups exceeded the historical control with the incidence of liver-cell tumours of 9/652 (1.4%) (Steinhoff and Mohr 1988; IARC 1999).

Oral carcinogenicity in mice: Group of 50 NMPI mice per sex exposed to hydrazine hydrate orally in drinking water at 0, 2, 10, 50 ppm (equivalent to 0, 0.3, 1.1 and 3.7 mg of hydrazine/kg bw/day in males and 0, 0.3, 0.7 and 3.1 mg of hydrazine /kg bw/day in females). There was no increase in the incidence of tumours at any site or at any dose observed (Steinhoff et al. 1990).

Oral non-neoplastic effects LOAEL= 0.3 mg/kg bw per day, based on dose-dependent reduction in water consumption in male and female rats and mice, and increased incidence of bile duct proliferations in male rats (Steinhoff and Mohr 1988; Steinhoff et al. 1990).

No dermal studies identified

[No additional carcinogenicity/chronic toxicity studies identified]

Hydrazine sulphate

No inhalation studies identified

Oral carcinogenicity in rats: Groups of 13-18 Cb/Se male and female rats were exposed to hydrazine sulphate orally by stomach tube at 18 and 12 mg (600 mg/kg bw/day and 400 mg/kg bw/day for males and females), respectively, daily for 68 weeks. Various numbers of control animals was also included. There was significant increase in liver tumours in males and increase in lung tumours in both males and females (male: liver 0/19, 4/13 in control and hydrazine sulphate treated group, respectively; lung 0/28, 3/14, respectively. Female: liver 0/14, 0/18, respectively; lung 0/22, 5/18, respectively) (Severi and Biancifiori 1968).

Oral carcinogenicity in mice: Groups of 50 Swiss mice per sex were treated with hydrazine sulphate orally in drinking water at 0.65 mg/female/day and 0.74 mg/male/day (equivalent to 5.4 and 6.1 mg hydrazine /kg bw/day for female and male hamsters, respectively) daily for life. Groups of 40 AKR mice per sex were treated with hydrazine sulphate orally in drinking water at 0.63 mg (equivalent of 5.2 mg/kg bw/day). (Unit conversion: divided by mice body weight =0.03 kg (Health Canada 1998), and multiply the molecular weight ratio of hydrazine and hydrazine sulphate =32.05/130.12). 110 Swiss mice per sex, and 30 AKR mice per sex were kept untreated as control. There was an increase in lung tumour incidence in Swiss mice (male 11/110, 25/50; female 14/110, 24/50, in control and hydrazine sulphate treated group, respectively). Malignant lymphomas were observe in both control and hydrazine treated AKR mice (male 23/30, 30/40; female 29/30, 33/40, in control and hydrazine sulphate treated group, respectively) (Toth 1969).

Groups of 40-59 CBA/Cb/Se mice of both sexes were exposed to hydrazine sulphate orally by stomach tube at 0, 0.14, 0.28, 0.56 and 1.13 mg/animal/day (equivalent to 0, 1.1, 2.3, 4.7, 8.3 mg hydrazine/kg bw/day) for 25 weeks. (Unit conversion: divided by mice body weight =0.03 kg (Health Canada 1998), and multiply the molecular weight ratio of hydrazine and hydrazine sulphate =32.05/130.12). There was increased in incidences of liver tumours (male 3/30, 1/26, 7/25, 12/25, 15/25; female1/29, 0/25, 2/25, 16/24, 15/24, at 0, 1.1, 2.3, 4.7, 8.3 mg hydrazine/kg bw per day, respectively) (Biancifiori 1970a).

[Additional carcinogenicity studies in mice: Biancifiori and Rtbacchi 1962; Biancifiori et al. 1964; Milia et al. 1965; Milia 1965; Severi and Biancifiori 1967 cited in IARC 1974; Biancifiori 1970b; Biancifiori, 1970c; Biancifiori 1971 cited in IARC 1974]

Oral carcinogenicity in hamster: Groups of 31-34 male Syrian hamsters were exposed to hydrazine sulphate orally in drinking water at 0, 170, 340, or 510 mg hydrazine sulphate/L (equivalent of 0, 4.6, 8.3, or 10 mg hydrazine/kg bw /day, used conversion in IARC 1999) daily for 2 years. There was increase in hepatocellular carcinomas in the mid- and high-dose animals (0/31, 0/31, 4/34 and 11/34 in the control, low-, mid- and high-dose groups respectively) (Bosan et al. 1987).

Lowest oral non-neoplastic effect LOAEL= 1.1 mg/kg bw/day based on adrenal degeneration in female mice (Biancifiori 1970a).

Other non-neoplastic effects: LOAEL=4.6 mg/kg bw/day in hamsters based on nodular hyperplasia, hypertrophy and necrosis in hepatocytes (Bosan et al. 1987), LOAEL=5.0 mg/kg bw/day in hamsters based on liver lesions (Biancifiori 1970a). No non-neoplastic effects were reported in rats (Severi and Biancifiori 1968).

No dermal studies identified

[No additional carcinogenicity/chronic toxicity studies identified]

Reproductive toxicity

(Hydrazine)

No studies were identified.

Reproductive toxicity

(other hydrazine compound)

Hydrazine hydrate

Lowest inhalation LOAEL for reproductive toxicity: 0.13 mg hydrazine/m3 based onincreases in resorption and fetal death in albino rats (group size unknown) exposed to 0, 0.01, 0.13, 0.85 mg/m3through inhalation (details on exposure: whole-body or nose-only not available), 5 hours per day, 5 days per week for 4 months. There were increases in resorption and fetal death observed at 0.13 and above. No effects were observed on 315 fetuses or on the gonad of male parents (Duamin et al.1984 cited in IPCS 1987 and CERI 2007).

Lowest oral LOEL for reproductive toxicity:0.0014 mg hydrazine/kg bw/day based on lesion in the gonadal epithelial cells of male parent albino rats (10 per hydrazine treated groups, 20 in control group) exposed to 0, 0.002, 0.018, 0.82 mg/L (corresponding to 0, 0.00016, 0.0014, 0.016 mg/kg bw/day, based on conversion in IPCS 1987) orally via drinking water for 6 month. There was a reduction in surviving embryo, an increase in resorptions and death before implantation at the highest dose tested. No developmental anomaly was found in all of 293 fetuses of the treated groups (Duamin et al.1984 cited in IPCS 1987 and CERI 2007).

Other oral LOAEL = 18 mg/kg bw/day based on fail in maintaining pregnancy in female Crj:CD(SD)IGS rats (12 per sex per group) exposed orally to 0, 2, 6 or 18 mg/kg bw/day of hydrazine hydrate by gavage (in water) for 2 weeks before mating , throughout gestation and up to day 3 of lactation (39 days), for males for 48 days. Parental toxicity was observed at 6 mg/kg bw/day and above. No adverse reproductive effects in the treated males (MHLW 2005).

[No additional oral studies identified]

No dermal studies identified.

Hydrazine nitrate

NOEL = 13 mg/kg bw/day, based on no changes in female fertility, the number of

newborns and resorptions and in the development of the surviving litters in rats (strain and group size not specified) exposed to hydrazine nitrate orally (gavage) at 0 or 13 mg hydrazine/kg bw/day daily for 30 days (Savchenkov and Samoilova 1984).

[No additional oral studies identified]

No inhalation or dermal studies identified.

Developmental toxicity

(Hydrazine)

No inhalation or oral studies identified.

Lowest dermal LOAEL= 50 mg/kg bw based on complete fetal resorption (10/12 of maternal animals), suppression of body weight gain and epidermal necrolysis in pregnant F344 rats (11-13 per group) exposed to hydrazine at 0, 5, 50 mg/kg by a single dermal application on gestation day 9 (caesarian section on gestation day 20). Suppression of body weight gain and epidermal necrolysis in the application site 24 hours after treatment was observed at 5 mg/kg bw, but no abnormal findings in implantation, fetal body weight and external, visceral or skeletal anomalies in Caesarian section on gestation day 20 at 5 mg/kg and above (Keller et al.1982).

A significant dose-related increase in the number of resorptions/litter occurred in fetuses of female Fischer rats exposed to hydrazine by intraperitoneal injections at 5.0 mg/kg/day or greater on days 6 through 15 of gestation. Dose-related reduction in weight gains was observed at 5.0 mg/kg/day and above (Keller et al. 1982).

[Additional developmental toxicity study (intraperitioneal): Keller et al. 1980; Lyng et al. 1980.]

Developmental toxicity

(other hydrazine compounds)

Hydrazine hydrate

Lowest oral LOAEL = 6 mg/kg bw/day based on a reduction in weights and viability index on day 4 lactation in pups of Crj:CD(SD)IGS rats (12 per sex per group) dosed orally by gavage (in water) with hydrazine hydrate at 0, 2, 6 or 18 mg/kg bw/day for 2 weeks prior to mating, throughout gestation and up to day 3 of lactation (39 days). There was salivation observed in both sexes given 6 mg/kg bw/day and above. Histological effects on the liver and the spleen in males at 6 mg/kg bw/day and in both sexes of the top dose group were observed (MHLW 2005).

Other oral LOAEL = 260 mg/kg bw based on postnatal effects on the enzyme activity in the brush border of fetal intestinal ciliated border in pups of Syrian golden hamsters (24 per group) exposed to hydrazine hydrate orally at 0 or 260 mg/kg single dose on gestation day 12. No incidence of cleft palate. Other items were not examined (Schiller et al. 1979).

[No additional oral studies identified]

No inhalation or dermal studies identified

Hydrazine hydrochloride

LOEL (subcutaneous) = 8 mg/kg bw/day based on decrease in survival, reduction in body weight, pale appearance of fetuses, and reduction in body weight and mortality of parent Wistar rats (26 per group) dosed by subcutaneous injection during days 11-20 of gestation 0, or 8 mg hydrazine /kg bw/day. LOAEL for maternal toxicity = 8 mg/kg bw/day based on reduced maternal body weight gain (Lee and Aleyassine 1970).

No inhalation, oral or dermal studies identified

Genotoxicity and related endpoints: in vivo(Hydrazine)

DNA damage (Comet assay)

Positive: liver, lung and kidney; CD-1 male mice (4 per group); oral by gastric intubation (30 mg/kg bw, single dose) (Robbiano et al. 2006).

Positive: liver, kidney, lung, brain, bone marrow, and mucosa of stomach, colon and bladder; CD-1 male mice; intraperitoneal (100 mg/kg bw, single injection) and oral (100 and 150 mg/kg bw, single dose) (Sasaki et al. 1998).

DNA adduct

Positive: liver; Wistar rats (3-6 per group sex not specified); oral by gavage in 0.1 M HCl (0.01-10 mg/kg bw, single dose). There was formation of N7-methylguanine and O6-methylguanine in the liver DNA (van Delft et al. 1997).

Positive: liver; male Sprague-Dawley and Fischer 344 rats (2 per group); orally by gavage (0, 45, 60, 75, 90 mg/kg, single dose) (Beker et al. 1981).

Gene mutation in Drosophila

Positive: Gene mutation; Oregon-K Drosophila melanogaster (group size unspecified); oral (food, 10 or 20 mmol) (Jain and Shukla 1972).

Genotoxicity and related endpoints: in vivo (other hydrazine compounds)

Hydrazine hydrate

DNA damage

Positive: liver and lung; Swiss albino mice (8 for liver, 9 for lung); intraperitoneal injection (33 mg/kg bw for 5 doses) (Parodi et al.1981).

Gene mutation

Positive: spot mutation; C57BL-6J female mice (group size not specified); intraperitoneal injection (40 mg/kg, single dose) on gestation day 9 (Fraunhofer-Institute 1989 Cited in CERI 2007).

Hydrazine hydrochloride

Micronucleus test

Positive: bone marrow; male Sprague Dawley rat (4 per group); intraperitoneal injection (75 mg/kg bw/day) for 2 days (Wakata et al. 1998).

Inconclusive: peripheral blood; male Sprague Dawley rat (4 per group); intraperitoneal injection (75 mg/kg bw/day) for 2 days (Wakata et al. 1998).

Hydrazine dihydrochloride

Micronucleus test

Positive: peripheral blood; male ICR mouse (5 per group); intraperitoneal injection (0, 12.5, 25, 50 or 100 mg/kg bw) for 4 days (Morita et al. 1997).

Marginal positive: peripheral blood; male ICR mouse (5 per group); intraperitoneal injection (0, 25, 50 or 100 mg/kg bw, single dose) (Morita et al. 1997).

Hydrazine sulphate

DNA adduct

Positive: liver; male Syrian golden hamster (3 per group); oral in drinking water (1.12 mg/kg bw/day, for 2 years). There was formation of N7-methylguanine and O6-methylguanine in the liver DNA (Bosan et al. 1987).

Micronucleus test

Positive: bone marrow; B6C3F1 mouse (sex and number not specified); intraperitoneal injection (70 mg/kg bw, 2 doses) (Salamone et al 1981).

Transgenic assay

Negative: male MutaTM mice (5 per group); oral by intubation (0, 135, 270, 350 and 400 mg/kg, single dose) (Douglas et al. 1995)

Genotoxicity and related endpoints: in vitro(Hydrazine)

Mutagenicity in bacteria

Positive: S. typhimurium, strains TA1535, TA100 and G46 with metabolic activation; no data available without metabolic activation (Herbold and Buselmaier 1976; McMahon et al. 1979; Herbold 1978 cited in CERI 2007).

Negative: S. typhimurium, strains TA98, TA1535, TA1536, TA1537 and TA1538 with metabolic activation; no data available without metabolic activation (Herbold and Buselmaier 1976; McMahon et al. 1979; Herbold 1978 cited in CERI 2007).

Positive: E. coli, strains WP2 and WP2uvrA- without metabolic activation (McMahon et al. 1979).

Negative: E. coli, strains WP2 and WP2uvrA- with metabolic activation (McMahon et al. 1979).

Positive: E. coli, strains B/r / WP2uvrA with rat liver microsomes activation (Noda et al. 1986).

Mutagenicity in yeast

Positive: Saccharomycescerevisiae Strains 7854-8A(RAD), XY726-7C(RAD), XY726-7D(RAD), XY726-7A(rad6-1), XY726-7B( rad6-1), 7a(rad6-1), without metabolic activation; no data available with metabolic activation (Lemontt and Lair 1982)

Gene mutation in mammalian cells

Positive: mouse lymphoma L5178Y cells, without metabolic activation; no data available with metabolic activation (Rogers and Back 1981).

Positive: rat neonatal hepatocyte cells (Kumari et al. 1992)

Micronucleus induction

Positive: Chinese hamster V79 cells in absence of metabolic activation (Onfelt 1987).

DNA strand break (Alkaline elution)

Positive: isolated rat hepatocytes (Sina et al. 1983).

Cell transformation

Positive: Human neonatal fibroblast cells (Milo et al. 1981).

Genotoxicity and related endpoints: in vitro (other hydrazine compounds)

Hydrazine hydrate

Mutagenicity in bacteria

Positive: S. typhimurium, strains TA1535 with or without metabolic activation (De Flora 1981; Parodi et al. 1981; Bayer 1989; Fraunhofer Institute 1990a cited in CERI 2007; MLHW 2005).

Negative: S. typhimurium, strains TA98, TA 1537, TA 1538, TA100 with or without metabolic activation (De Flora 1981; Parodi et al. 1981; Bayer 1989; Fraunhofer Institute 1990a cited in CERI 2007; MLHW 2005).

Positive: E. coli, strains WP2, WP67, CM871, without metabolic activation (De Flora 1984).

Negative: E. coli, strains WP2, WP67, CM871, with metabolic activation (De Flora 1984).

Chromosome aberration

Negative: human peripheral lymphocytes (Fraunhofer Institute 1990b cited in CERI 2007).

Unscheduled DNA synthesis

Positive: isolated hepatocytes from C3H/HeN mice (Mori et al. 1988)

Negative: isolated hepatocytes from ACI/N rats (Mori et al. 1988)

Chromosomal aberration

Positive: Chinese hamster CHL/IU cells, with or without metabolic activation (MHLW 2005).

Hydrazine sulphate (All data are as cited in CERI 2007)

Mutagenicity in bacteria

Positive: S. typhimurium, strains TA1950, TA1.35, 5G46, with or without metabolic activation (with or without metabolic activation not clear) (Braun et al. 1976; Rohrborn et al. 1972; Simmon et al. 1979; all cited in CERI 2007), strain TM677 with metabolic activation, no data available without metabolic activation (Skopek et al. 1981).

Positive: E. coli, strains 343/113/uvrB with metabolic activation; no data available without metabolic activation (Mohn et al. 1981).

Positive: E. coli, strain WP2, WP67, CM871 with or without metabolic activation (Mohn et al. 1981; Green 1981).

Positive: E. coli, strain 343/636, -/591/, with metabolic activation (Hellmer and Bolcsfoldi 1992).

Negative: E. coli, strain 343/636, -/591/, without metabolic activation (Hellmer and Bolcsfoldi 1992)

Mutagenicity in yeast

Positive: S. cerevisiae XV185-14C (polyploid), without metabolic activation (Mehta and von Borstel 1981).

Negative: S. cerevisiae XV185-14C (polyploid), with metabolic activation (Mehta and von Borstel 1981).

Positive: Schizosaccharomyces pombe,with or without metabolic activation (Loprieno 1981).

Positive: S. cerevisiae D7 (diploid), without metabolic activation (Zimmermann and Scheel 1981).

Negative: S. cerevisiae D7 (diploid), with metabolic activation (Zimmermann and Scheel 1981).

Negative: S. cerevisiae D3 (diploid), with or without metabolic activation (Simmon 1979).

Positive: S. cerevisiae D4 (diploid), with metabolic activation (Jagannath et al. 1981).

Negative: S. cerevisiae D4 (diploid), without metabolic activation (Jagannath et al. 1981).

Gene mutation in mammalian cells

Positive: human lung fibroblast HSC172 cells, with metabolic activation (Gupta and Goldstein 1981).

Negative: human lung fibroblast HSC172 cells, without metabolic activation (Gupta and Goldstein 1981).

Weakly Positive: mouse lymphoma L5178 cells, without metabolic activation (Amacher et al. 1980).

Negative: CHO AT3-2 cells (with or without metabolic activation not clear (Carver et al. 1981).

Unscheduled DNA synthesis

Positive: isolated hepatocytes from C3H/HeN mice (Mori et al. 1988).

Negative: isolated hepatocytes from ACI/N rats (Mori et al. 1988).

Positive: human cancer cells HeLa, without metabolic activation (Martin and McDermid 1981).

Negative: human cancer cells HeLa, with metabolic activation (Martin and McDermid 1981).

Negative: human embryos fibroblast WI-38 cells, (with or without metabolic activation not clear) (Robinson and Mitchell 1981).

DNA damage

Negative: mouse lymphoma L5178Y TK+/-cells, DNA strand breaks with metabolic activation (Garberg et al. 1988).

Sister chromatid exchange

Positive: DON cells (with or without metabolic activation not clear) (Baker et al. 1983).

Negative: CHO cells (with or without metabolic activation not clear) (Natarajan and van Kesteren-van Leuwen 1981).

Weakly positive: CHO cells (with or without metabolic activation not clear) (Perry and Thomson 1981)

Cell transformation

Positive: Syrian golden hamster embryo cells, with metabolic activation; no data available without metabolic activation (Pienta et al. 1978; Pienta 1980).

Hydrazine hydrochloride

Mutation in bacteria

Positive: Haemophilus influenzaewithout metabolic activation; no data available with metabolic activation (Kimball and Hirsch 1975).

Sister chromatid exchange

Positive: CHO cells and Chinese hamster V79 cells, without metabolic activation; no data available without metabolic activation (MacRae and Sitch 1979; Speit et al. 1984)

Hydrazine dihydrochloride

Mutation in bacteria

Positive: Salmonella typhimurium, strain TA100, without metabolic activation; no data available with metabolic activation (Hakura et al. 2005).

Mutation in yeast

Positive: S. cerevisiae, strains XY505-18C,XY-222-1A, XY491-4B, without metabolic activation; no data available with metabolic activation (Lemontt 1977).

Human studies (Hydrazine)

Cohort

Case control

Observational studies

Accidental ingestion

The most pertinent epidemiology studies are described below.

423 workers (gender unknown) in a hydrazine production plant, exposure period between 1945 and 1970, were divided into 3 exposure groups: “most exposed”: 64 had been employed directly in the manufacture of hydrazine or on other plants in the same building; “intermediately expose”: 189 consisted of men either employed for only a proportion of their time in the hydrazine manufacturing area (e.g. fitters) or in other buildings where hydrazine was handled (mainly liquid form, in the course of the manufacture of hydrazine derivatives”; “lease exposed”: not involved either in the manufacture or use of hydrazine (no data on concentration). It was concluded based on this study that hydrazine did not enhance cancer risk (Roe 1978).

427 workers of the almost same population in the above study (workers engaging in production for 6 months and above) were studied, 78 of them were exposed to 1-10 ppm hydrazine (sometimes 100 ppm), the others (n=375) were exposed to 1 ppm and below, between 1945 and 1971. The number of observed deaths exceeded expected deaths (but not significantly) only for lung cancer (3 observed versus 2.43 expected). A relative risk of lung cancer of about 3.5 or more can be excluded, however, the power of study is too limited (small sample size), to exclude lower relative risks (Wald et al. 1984; Morris et al. 1995).

A case control study was conducted in 284 children with autistic spectrum disorders born in 1994 to mothers resident in one of six San Francisco Bay area counties. Controls were 657 randomly selected children from mothers in same districts, matched to cases by sex and month of birth. Presumed exposure of the mothers to 19 potential neurotoxins was obtained from the Hazardous Air Pollutant Database compiled by the US EPA. Exposure information on the census tract of birth residence was extracted. There was no significant difference between the hydrazine exposures of the mothers of the children with autism and the mothers producing an unaffected child (1.29 +/- 2.96 ug/m3 in cases, 1.16 +/- 2.39 ug/m3 in controls) [mean +/- SD in 10-7µg/m3] (Windham et al. 2006).

A 59 years old machine operator were exposed to hydrazine hydrate once a week for 6 months at 0.071 mg/m3(hydrazine concentration of the air was measured after accident). Fatigue, trembling and conjunctivitis were observed on the operation day and the following day. He was admitted to the hospital due to fever, vomiting, diarrhea, abdominal pain, black stool and jaundice and died 15 days after admission. Autopsy revealed pneumonia, severe nephritis, tubulonecrosis, glomerulonephritis and focal hepatocellular necrosis (Sotaniemi et al. 1971).

Two case studies on two men, who accidentally ingested unknown dose level of hydrazine, reported signs of neurological toxicity such as afebrile, unconscious, continent, vomiting. dilated pupils, ataxia, loss of vibration sense, paraesthesia of all four limbs at the extremities, unable to reproduce with one hand movements imposed upon the other, severe hypoaesthesia of the hands, confusion, lethargic and restlessness (Reid 1965; Harati and Niakan 1986).

Human studies (Other hydrazine compounds)

Controlled human exposure

Observational studies

Cohort

Occupational inhalation exposure

Hydrazine sulphate

The most pertinent epidemiology studies are described below.

102 male and female cancer patients were exposed to hydrazine sulphate orally at 0.6 to 2.0 mg hydrazine /kg bw/day for 1.0 to 1.5 month, and in some cases up to 6 months. Dizziness, general excitement, insomnia occurred in 11% of the patients and polyneuritic syndrome occurred in 2.9% of the patients after a 2-5 months of prolonged treatments, and completely disappeared after 1.5 months of therapy. Other local irritative effects such as nausea and vomiting occurred in 14% of the patients, and disappeared without any specific treatment upon removal of the drug or reduction of the daily dose by one third. LOAEL=0.6 mg/kg bw/day based on neurological effects (Gershanovich et al. 1976).

233 male and female cancer patients were exposed to hydrazine sulphate orally at 0.6 to 2.0 mg hydrazine /kg bw/day for 1.0 to 1.5 month, and in some cases up to 6 months Nausea / or vomiting (9.8%), other signs of dyspepsia (0.9%), dizziness (5.8), insomnia (0.4%) and polyneuritic syndrome (1.8%), general excitement (1.3%), loss of appetite (1.3%), chill (0.4%) were observed among these patients. LOAEL=0.6 mg/kg bw/day based on neurological effects (Gershanovich et al. 1981)

25 male and female cancer patients were exposed to hydrazine sulphate orally at 0.6 to 2.5 mg hydrazine/kg bw/day for up to 47 days. Neurological effects were reported in one patient with breast cancer, who experienced dizziness while on hydrazine sulphate. Dizziness was cleared after stopped hydrazine sulphate treatment for 3 days, but recurred when hydrazine sulphate treatment resumed (Spremulli et al. 1979).

32 male and female cancer patients were exposed to hydrazine sulphate orally at 0.3 mg hydrazine/kg bw/day in gelatine capsules for up to 57 days. Neurological effects such as paresthesia, lethargy/somnolence, pain, confusion, depression, dysgeusia, headache, blurred speech, singultus, pruitis, vertigo, nausea, vomiting, anorexia, pyrosis, diarrhea, -constipation, hunger were observed. LOAEL = 0.3 mg hydrazine/kg bw/day based on neurological effects (Ochoa et al. 1975).

511 workers engaged in some aspect of aircraft manufacture, who were referred to a dermatologist because of their skin problems, were exposed to standard allergens and additional materials (e.g. hydrazine sulphate) as suggested by history and work exposure, using patch testing to identify the materials responsible. A 21-year-old “metal assembler” with dermatitis of the hands and forearms, reacted in patch tests with hydrazine sulphate [patch test concentration not reported]. His workplace exposure to hydrazine sulphate was thought to be from cutting fluids [no quantitative information provided] (Hackett 1999).

281 patients with possible allergic contact dermatitis were seen in two clinics between January 1999 and June 2000, 104 of these patients were patch tested with hydrazine sulphate [patch test concentration was not reported]. Two positive reactions to hydrazine sulphate was observed [no information was provided on the exposures that induced the sensitized state] (Francalanci et al. 2001).

A patient with maxillary nasal cancer self medicated with hydrazine sulphate orally at 180 mg/day (about 1.5 mg/kg bw per day). Hepatic encephalopathy, renal failure, and profound coagulopathy; death (after severe gastrointestinal haemorrhage developed) were reported. Autopsy revealed autolysis of the kidneys and submassive bridging necrosis of the liver (Hainer et al. 2000).

Hydrazine hydrate

A cross-sectional study was done in 172 male workers (18-60 year-old) from five plants producing hydrazine hydrate were matched with for age. The mean hydrazine concentration in the breathing zone was 0.012 mg/m3. Mean hydrazine concentration in urine was 0.866 µmol/g creatinine. Exposure period is 0.50-34.17 years, with the mean duration of exposure to hydrazine hydrate of 13.4 years. The exposed workers showed a significantly greater prevalence of viral hepatitis (rate ratio 1.99, 95% CI 1.15, 3.43), liver cirrhosis (2.48, 95% CI 1.51, 4.08), thyroid disorders (2.48, 95% CI 1.51, 4.08) and cerebrovascular disease other than infarction (2.29, 95% CI 1.35, 3.78) (Nomiyama et al. 1998).

Hydrazines mixture

8372 Rocketdyne workers employed for a minimum of 6 months on or after 1 January 1948 at the Santa Susana Field Laboratory followed up from 1 July 1948 to 31 December 1999. Standardized mortality ratios (SMRs) were calculated based on State and National rates. Potential qualitative chemical exposures estimated on the basis of job titles. Most of the workers who would have been exposed to hydrazines (“predominantly monomethyl-hydrazines”) would have been employed at particular test areas. Four categories of potential hydrazines exposure were used in the analysis; test stand mechanics who did not work at a test stand with potential hydrazine exposure (920), test stand mechanics with “possible but not likely exposure” (205), test stand mechanics with “likely” exposure to hydrazines for less than 1.5 year (156), and test stand mechanics with “likely” exposure to hydrazines for greater than 1.5 years (159). For whole cohort, SMR for all deaths was 0.83 (95% CI 0.80, 0.86) based on 2251 deaths, and for all cancers 0.89 (0.82, 0.96), based on 655 cancer deaths. For the 315 workers “likely exposed to hydrazine” the SMR for all deaths was 0.89 (0.72, 1.08), and for all cancers was 1.09 (0.75, 1.52), the latter based on 33 cancer deaths. There was a weak association between risk of dying from lung cancer and likely hydrazines exposure (SMR 1.45, 95% CI 0.81, 2.39, based on 15 lung cancer deaths), but the magnitude of this increase did not achieve statistical significance. There was no increase in lung cancer in the 159 workers with more than 1.5 years of likely hydrazine exposure (Boice et al. 2006).

Male workers employed before 1980 at the Santa Susana Field Laboratory, who had worked for at least 2 years in any Rockwell division were studied. Rate Ratios (RRs) were estimated based on State and National cancer and death rates. Follow-up period for cancer mortality was from start of employment or 1 January 1950 (whichever was later) until the end of 2001. The cohort size from the perspective of cancer mortality was 6044 men, and from the perspective of cancer incidence was 5049 men. Exposure assessments by an industrial hygienist “familiar with facility operations and records”. Job titles assigned to one of four categories of presumptive exposure (high, medium, low or unexposed) for each chemical, including “hydrazine”, reflecting the exposure of each of three periods; the 1950-1960s, the 1970s, and the 1980-1990s. The term “hydrazine” in the context of exposure was in fact exposure to hydrazine, 1-methyhydrazine and 1,1-dimethylhydrazine. In the mortality cohort of 6044 men, 1050 workers were assigned to the high exposure category. In the 5049 incidence cohort, 850 men were assigned to the high exposure category. “Little association” observed between smoking status and chemical exposure in a subset of 200 workers for whom smoking status was known in the 1960s. In the “mortality” cohort of 6044 there were 600 cancer deaths out of 2117 deaths in total, whilst in the “incidence” cohort of 5049 there were 691 registered cancers. For lung cancer mortality with a 20-year exposure lag, the RR values for low, medium and high hydrazine exposure were 1.00, 1.24 (95% CI 0.78, 1.96) and 1.67 (0.99, 2.83) respectively (P for trend 0.031). The RR for the high exposure group was based on 36 lung cancer deaths. The equivalent values for lung cancer incidence were 1.00, 1.18 (0.62, 2.24) and 2.49 (1.28, 4.89) (P for trend 0.003). With zero exposure lag, the P for trend for lung cancer mortality was 0.065 (based on 48 lung cancer deaths in the high exposure group), and the P for trend for lung cancer incidence was 0.007. It was concluded that exposure to hydrazine increases the risk of incident lung cancers (Ritz et al. 2006). (See also earlier report on the mortality of the cohort: Ritz et al. 1999).

A 36-year-old man was checking for leaks and discovered high concentration of Aerozine-50 (AZ50, a 50/50 mix of hydrazine and unsymmetrical dimethylhydrazine), and obtained an acid suit and a gas mask and returned to the area to check for other leaks. Complains of headache, nausea and a shaky feeling were reported. There was also complains of burning skin of the face, a sore throat and tightness in the chest. Examination revealed twitching of the extremities and clonic movements, reflexes were all hyperactive (Frierson 1965).

A 44-year-old man was fabricating vent piping in a test cell when he received evacuation notice. As he was putting on his acid suit, he noted strong odour or AZ50. As he evacuated the cell, he noted even stronger odour of AZ50 and received a strong inhalation. Severe dyspnea was reported. Examination revealed hyperactive reflexes, bilateral pulmonary edema, dyspnea, increase in respiration rates and chest pain (Frierson 1965).

A 38-year-old man being a water technician for about 6 years, whose job was to examine water quality, add hydrazine mixtures when necessary, and oversee the workings of the pumping system in a large hospital, was reported. The hydrazine was stored in a 200-l drum with an unsealed opening from which an ammonia-like odour was nearly always emitted. There were complaints of sore throat and “colds”. Long-term neurobehavioral impairment of short and long memory, for both verbal and visual showed in neuropsychological testing; impaired learning were reported (Richter 1992).

Irritation

(Hydrazine)

Skin irritation

Irritating: in 6 New Zealand White rabbits, 0.5 ml 35% aqueous solution per patch applied to shaved skin on the back, for 4 hours, closed application, using draize method, irritating response reported in 2/6 animals (Hathaway 1984, cited in CERI 2007).

Unclear: in 6 New Zealand White rabbits, 0.5 ml 35% aqueous solution per patch (corresponding to 60 mg/kg bw) applied to shaved skin on the back, for 4 hours, closed application, using draize method, 4 rabbits died 24 hours after application (Mobay Chemical 1984, cited in CERI 2007).

Irritation and corrosion

(Other hydrazine compound)

Hydrazine hydrate

Skin irritation and corrosion

Corrosive: in 11 Japanese albino male rabbits, 0.5 ml 55% aqueous solution per patch applied to shaved skin on the back, for 4 hours, closed application, draize method; corrosive response found in 7/11 animals (Otsuka Chemical 1978, cited in CERI 2007).

NotIrritating: in 6 New Zealand White rabbits, 5% aqueous solution per patch (amount applied unknown) applied to shaved skin on the back, for 4 hours, semi-closed application, OECD TG 404 method (Bayer 1988, cited in CERI 2007).

Eye irritation

Not irritating: in New Zealand White rabbits (number of animal used unknown), 5% aqueous solution (amount applied unknown) dropping in the conjunctival sac, washing eyes 24 hours after dropping (OECD TG 405 method) (Bayer 1988, cited in CERI 2007).

Hydrazine sulphate

Not irritating: in 6 humans (volunteers), 25% hydrazine sulphate or its concentrated solution applied to skin for 24 hours (Bayer 1954, cited in CERI 2007).

Sensitization

(Hydrazine)

Sensitizing: in 23 humans (volunteers), 5% hydrazine solution was applied to the upper arm and the application site was occluded for 48 hours; positive results in all volunteers (Kligman 1966, cited in CERI 2007)

Sensitization

(Other hydrazine compounds)

Hydrazine sulphate

Sensitizing: in 2 gold-plating workers, 1% aqueous solution of hydrazine sulphate or 0.1%-10% gold-plating stabilizing solution (contains hydrazine), using patch testing (Wrangsjo and Martensson 1986 ).

Sensitizing: in 3 male workers, 1% aqueous solution of hydrazine sulphate, using patch testing (Hovding 1967).

Sensitizing: in 1 man, 0.05%-5% hydrazine sulphate, using patch testing, for 48 and 96 hours (Suzuki and Ohkido 1979)

Sensitizing: in 1 woman, 1% hydrazine sulphate in water, using patch testing (van Ketel 1964).

Hydrazine hydrate:

Sensitizing: in 1 man, 0.005%-5% hydrazine hydrate, using patch testing, for 48 and 96 hours (Suzuki and Ohkido 1979)

LD50 = median lethal dose;
LOEL/LOEC = lowest-observed-effect level/concentration;
LOAEL/LOAEC = lowest-observed-adverse-effect level/concentration;
NOAEL/NOAEC = no-observed-adverse-effect level/concentration.
* Toxicological studies conducted with various hydrazine salts were provided as supportive information only and were not used as part of the risk characterization for hydrazine in this screening assessment.

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Appendix 3: Study of Ou and Street (1987a)

Ou, L.T., Street J.J. 1987a. Microbial enhancement of hydrazine degradation in soil and water. Bull. Environ. Contam. Toxicol. 39: 541-548.

The authors studied the degradability of hydrazine (supplied as hydrazine sulphate) in six water types of various physico-chemical characteristics. Four natural riverine and lacustrine waters were included in their work. For each type of water, a sterilized and unsterile water sample was prepared. The authors performed also tests with bacterial amendment but they were not considered for this assessment because of lack of environmental realism. Interpretation of results led the authors to conclude that no relationship existed between copper content in water and rate of hydrazine degradation. Re-analysis of the dataset (Table A.1) indicates on the contrary that such a relationship exists; an approach based on measures of partial correlation has been used to demonstrate this.

The assessor derived numerically half-lives (days, (d)) for natural water samples from diagrams of % hydrazine degradation vs time. Values in days used for correlational analyses are (N=8): unsterile Santa Fe: 2.5 d; sterile Santa Fe: 9.4 d; unsterile Lake Alice: 7.4 d; sterile Lake Alice: 8.8 d, unsterile & sterile Newmans Lake, unsterile & sterile Prairie Creek: 14.1 d.

Covariance of aqueous Cu and bacterial abundance obscured individual relationships between each of these variables and rate of hydrazine degradation in natural water samples. Figure A.1a shows the significant relationship between bacterial activity in cfu/mL and hydrazine degradation half-life, a positive influence acknowledged by Ou and Street (1987a). Figure A.1b indicates that this relationship is improved when aqueous Cu is held constant (the principle of the partial correlation). Figure A.1c demonstrates that hydrazine half-life in water decreases with increases in Cu concentrations, when bacterial abundance is held constant. The other variables measured by the authors (Table A.1) were not found to have any effect on hydrazine half-life in this exercise.

Table A.1 Physico-characteristics of the six water types used in Ou and Street (1987a).*

WaterCu (mg/mL)Fe (mg/mL)Bacteria (cfu/mL) (×10-3)Fungi (cfu/mL)pHSuspended solid (mg/mL)
Santa Fe River4×10-54×10-520647.73
Prairie Creek1×10-52.4×10-4136.63
Lake Alice2×10-4025227.43
Newmans Lake02.8×10-4997.73
Tap water00008.53
Distilled water00006.40
* Cfu/mL: Number of colony-forming units/mL.

 

Figure A.1. (a) Total correlation between hydrazine degradation half-life and bacterial abundance in cfu/mL, for the natural water samples (N=8) tested by Ou and Street (1987a). (b) Partial correlation between hydrazine degradation half-life and bacterial abundance, holding Cu in water constant. (c) Partial correlation between hydrazine degradation half-life and Cu in water, holding bacterial abundance constant. X1= bacterial abundance, X2= Cu in water; X3=hydrazine degradation half-life.

Figure A.1. (a) Total correlation between hydrazine degradation half-life and bacterial abundance in cfu/mL, for the natural water samples (N=8) tested by Ou and Street (1987a). (b) Partial correlation between hydrazine degradation half-life and bacterial abundance, holding Cu in water constant. (c) Partial correlation between hydrazine degradation half-life and Cu in water, holding bacterial abundance constant. X1= bacterial abundance, X2= Cu in water; X3=hydrazine degradation half-life.

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Appendix 4: Robust Study Summary

Robust Study Summary for Persistence

NoItemWeightYes/NoSpecify
1Reference: Ou, L.T., Street J.J. 1987a. Microbial enhancement of hydrazine degradation in soil and water. Bull. Environ. Contam. Toxicol. 39: 541-548.
2Substance identity: CAS RNn/aN 
3Substance identity: chemical name(s)n/aYHydrazine sulfate
4Chemical composition of the substance2 N/A
5Chemical purity1N 
Method
6Reference1YOu and Street. 1987. Bull. Environ. Contam. Toxicol. 38: 179-183.
7OECD, EU, national, or other standard method?3N 
8Justification of the method/protocol if not a standard method was used2YExperiments destined to increase hydrazine degradation by inoculating with bacteria.
9GLP (Good Laboratory Practice)3 N/A Study performed before 1997.
Test design / conditions
10Test type (i.e. hydrolysis, biodegradation, etc.)n/aYBiodegradation and auto-oxidation
11Test conditions type (aerobic or anaerobic)n/aYAerobic
12Test medium (water, sediment, or soil)n/aYWater
13Test durationn/aY14 days (d)
14Negative or positive controls?1YPartly, distilled water as negative control for biodegradation
15Number of replicates (including controls)1N 
16Measured concentrations reported?3Y 
17Analytical method / instrument1YColorimetric method
Details on Biodegradation
18Type of biodegradation (ready or inherent) reported?2N 
19When type of biodegradation (ready or inherent) is not reported, if there is indirect information allowing to identify biodegradation type?1YEvidence to the effect that both biological degradation and abiotic degradation have a role in hydrazine loss from water.
20Inoculum source1YNatural water samples
21Inoculum concentration or number of microorganisms1Ycolony-forming units/mL (cfu)
22Were inoculum pre-conditioning and pre-adaptation reported?1N 
23Were inoculum pre-conditioning and pre-adaptation appropriate for the method used?n/a  
24Temperature1Y25 C
25Has percentage degradation of the reference compound reached the pass levels by day 14?n/a N/A
26Soil: soil moisture reported?1  
27Soil and sediments: background SOM (Soil Organic Matter) content reported?1  
28Soil and sediments: clay content reported?1  
29Soil and sediments: CEC (Cation Exchange Capacity) reported?1  
Results
30Endpoint and valuen/an/aEndpoint: degradation t1/2; unsterile Santa Fe: 2.5 d; sterile Santa Fe: 9.4 d; unsterile Lake Alice: 7.4 d; sterile Lake Alice: 8.8 d; unsterile Newmans Lake: >> 14 d; sterile Newmans Lake: >> 14 d; unsterile Prairie Creek: >> 14 d; sterile Prairie Creek: >> 14 d.
31Breakdown productsn/a  
32Score: ... %60.0
33EC Reliability code:2
34Reliability category (high, satisfactory, low):Satisfactory Confidence
35CommentsOnly the experiments on hydrazine stability in water without bacteria amendment were considered for the present evaluation. Six water types were considered: 2 rivers, 2 lakes, tap water, distilled water. These water types were characterized for pH, Cu and Fe concentrations, suspended solids and bacteria and fungi abundances. Each water type received an autoclave treatment (sterile) or not (nonsterile). Tests lasted 14 days with an initial hydrazine concentration of 25 mg/L.

 

Robust Study Summary for Persistence

NoItemWeightYes/NoSpecify
1Reference: Slonim, A.R., Gisclard J.B. 1976. Hydrazine degradation in aquatic systems. Bull. Environ. Contam. Toxicol. 16(3): 301-309.
2Substance identity: CAS RNn/aY302-01-2
3Substance identity: chemical name(s)n/aYAnhydrous hydrazine
4Chemical composition of the substance2 N/A
5Chemical purity1Y97% pure
Method
6Reference1YSlonim 1975
7OECD, EU, national, or other standard method?3N 
8Justification of the method/protocol if not a standard method was used2YDetermination of the effect on hydrazine of various properties of water (pH, DO, hardness, etc.)
9GLP (Good Laboratory Practice)3 N/A Chemical analyses carefully made with good QA/QC
Test design / conditions
10Test type (i.e. hydrolysis, biodegradation, etc.)n/aYAbiotic & biotic degradation
11Test conditions type (aerobic or anaerobic)n/aYAerobic
12Test medium (water, sediment, or soil)n/aYWater
13Test durationn/aY96 hours
14Negative or positive controls?1N 
15Number of replicates (including controls)1YTwo
16Measured concentrations reported?3Y 
17Analytical method / instrument1YPolarographic method
Details on Biodegradation
18Type of biodegradation (ready or inherent) reported?2N 
19When type of biodegradation (ready or inherent) is not reported, if there is indirect information allowing to identify biodegradation type?1YIt is an integration of abiotic and biotic degradation pathways
20Inoculum source1YWater types
21Inoculum concentration or number of microorganisms1N 
22Were inoculum pre-conditioning and pre-adaptation reported?1N 
23Were inoculum pre-conditioning and pre-adaptation appropriate for the method used?n/a  
24Temperature1YRoom Temperature
25Has percentage degradation of the reference compound reached the pass levels by day 14?n/a N/A
26Soil: soil moisture reported?1 N/A
27Soil and sediments: background SOM (Soil Organic Matter) content reported?1 N/A
28Soil and sediments: clay content reported?1 N/A
29Soil and sediments: CEC (Cation Exchange Capacity) reported?1 N/A
Results
30Endpoint and valuen/an/aEndpoint t1/2 for degradation: t1/2 hardwater: 3.7 days; t1/2 moderately hardwater: 3.9 d; t1/2 lightly hard water: 22.7 d; t1/2 soft water: 63.6 d; t1/2 'dirty' river water: 0.5 d; t1/2 pond water: 0.7 d;
31Breakdown productsn/a  
32Score: ... %60.0
33EC Reliability code:2
34Reliability category (high, satisfactory, low):Satisfactory Confidence
35CommentsTwo experiments of the paper were considered: (i) a degradation experiment in which various water types were equalized in terms of temperature and oxygen; (ii) a test which water of four different hardnesses, using hardwater from undiluted to 1:20 dilution with distilled water. An initial concentration of hydrazine of 5 mg/L was followed for four days.

 

Robust Study Summary for Persistence

NoItemWeightYes/NoSpecify
1Reference: Ou, L.T., Street J.J. 1987b. Hydrazine degradation and its effect on microbial activity in soil. Bull. Environ. Contam. Toxicol. 38: 179-183
2 n/a  
3Substance identity: chemical name(s)n/aYHydrazine sulfate
4Chemical composition of the substance2 N/A
5Chemical purity1N 
Method
6Reference1YOu et al. 1978. J. Environ. Qual. 7: 241-246
7OECD, EU, national, or other standard method?3N 
8Justification of the method/protocol if not a standard method was used2YEffect of hydrazine on microbial activity not known. Therefore, degradation rates and effects on microorganisms determined.
9GLP (Good Laboratory Practice)3 N/A Study performed before 1997
Test design / conditions
10Test type (i.e. hydrolysis, biodegradation, etc.)n/aYBiodegradation and autooxidation
11Test conditions type (aerobic or anaerobic)n/aYAerobic
12Test medium (water, sediment, or soil)n/aYSoil
13Test durationn/aY8 d
14Negative or positive controls?1YNegative control
15Number of replicates (including controls)1YTwo
16Measured concentrations reported?3Y 
17Analytical method / instrument1YColorimetric method for determination of hydrazine in soil
Details on Biodegradation
18Type of biodegradation (ready or inherent) reported?2N 
19When type of biodegradation (ready or inherent) is not reported, if there is indirect information allowing to identify biodegradation type?1YEvidence that biological degradation is less important than autoxidation contributing for only 20% of hydrazine disappearance.
20Inoculum source1YNon-sterile Arredondo fine sand
21Inoculum concentration or number of microorganisms1YCfu/g soil
22Were inoculum pre-conditioning and pre-adaptation reported?1N 
23Were inoculum pre-conditioning and pre-adaptation appropriate for the method used?n/a  
24Temperature1Y25 C
25Has percentage degradation of the reference compound reached the pass levels by day 14?n/a N/A
26Soil: soil moisture reported?1N 
27Soil and sediments: background SOM (Soil Organic Matter) content reported?1Y1.7% organic carbon
28Soil and sediments: clay content reported?1YAssumed to be very low, it is fine sand primarily
29Soil and sediments: CEC (Cation Exchange Capacity) reported?1N 
Results
30Endpoint and valuen/an/aEndpoint: Auto-oxidation; t1/2 at 10 µg hydrazine/g soil: < 1 hour; t1/2 at 100 µg hydrazine/g soil: 0.5 day; t1/2 at 500 µg hydrazine/g soil: 3 days
31Breakdown productsn/a No evidence of ammonia produced via degradation.
32Score: ... %62.5
33EC Reliability code:2
34Reliability category (high, satisfactory, low):Satisfactory Confidence
35CommentsHydrazine concentrations were monitored in sterile and non-sterile Arredondo fine sand. Autooxidation appeared to be the principal factor contributing to the disappearance of the chemical from the soil, as less than 3% of applied hydrazine at a concentration of 10 µg/g soil was recovered from sterile soil. By comparing the hydrazine loss from sterile and non-sterile soils, it appeared that biological degradation was responsible for about 20% of the degradation.

 

Robust Study Summary for Persistence

NoItemWeightYes/NoSpecify
1Reference: [NITE] National Institute of Technology and Evaluation [database on the Internet]. 2002. Comprehensive Information for CAS RN 302-01-2. Tokyo [JP]: NITE. [cited 2010 01]. Available from: http://www.safe.nite.go.jp/english/Haz_start.htmlReference:
2Substance identity: CAS RNn/a 302-01-2
3Substance identity: chemical name(s)n/a Hydrazine
4Chemical composition of the substance2 N/A Pure substance
5Chemical purity1N 
Method
6Reference1Y 
7OECD, EU, national, or other standard method?3YMITI-I(OECD TG 301C)
8Justification of the method/protocol if not a standard method was used2 N/A
9GLP (Good Laboratory Practice)3 N/A Study performed prior to 1997
Test design / conditions
10Test type (i.e. hydrolysis, biodegradation, etc.)n/a Biodegradation
11Test conditions type (aerobic or anaerobic)n/a Aerobic
12Test medium (water, sediment, or soil)n/a Activated sludge mixed with water
13Test durationn/a 4 weeks
14Negative or positive controls?1YBoth
15Number of replicates (including controls)1N 
16Measured concentrations reported?3Y100 mg/L
17Analytical method / instrument1YIon chromatography and BOD
Details on Biodegradation
18Type of biodegradation (ready or inherent) reported?2YReady
19When type of biodegradation (ready or inherent) is not reported, if there is indirect information allowing to identify biodegradation type?1 N/A
20Inoculum source1YActivated sludge
21Inoculum concentration or number of microorganisms1Y30 ppm
22Were inoculum pre-conditioning and pre-adaptation reported?1N 
23Were inoculum pre-conditioning and pre-adaptation appropriate for the method used?n/a  
24Temperature1Y25
25Has percentage degradation of the reference compound reached the pass levels by day 14?n/a No. Did not pass
26Soil: soil moisture reported?1 N/A
27Soil and sediments: background SOM (Soil Organic Matter) content reported?1 N/A
28Soil and sediments: clay content reported?1 N/A
29Soil and sediments: CEC (Cation Exchange Capacity) reported?1 N/A
Results
30Endpoint and valuen/an/aBOD 2% after 4 wks; 0% by hydrazine measurement by Ion Chromatography
31Breakdown productsn/a N/A
32Score: ... %82.4
33EC Reliability code:1
34Reliability category (high, satisfactory, low):High Confidence
35Comments 

Footnotes

[*] CAS RN= Chemical Abstracts Service Registry Number. The Chemical Abstracts Service (CAS) information is the property of the American Chemical Society and any use or redistribution, except as required in supporting regulatory requirements and/or for reports to the Government of Canada when the information and the reports are required by law or administrative policy, is not permitted without the prior written permission of the American Chemical Society.
[2] A determination of whether one or more of the criteria of section 64 are met is based upon an assessment of potential risks to the environment and/or to human health associated with exposures in the general environment. For humans, this includes, but is not limited to, exposures from ambient and indoor air, drinking water, foodstuffs, and the use of consumer products. A conclusion under CEPA 1999 on the substances in the Chemicals Management Plan (CMP) Challenge Batches 1-12 is not relevant to, nor does it preclude, an assessment against the hazard criteria specified in the Controlled Products Regulations, which is part of regulatory framework for the Workplace Hazardous Materials Information System [WHMIS] for products intended for workplace use. Similarly, a conclusion based on the criteria contained in section 64 of CEPA 1999 does not preclude actions being taken under other sections of CEPA or other Acts.
[3] Hydrazine reported as a residual in PVP at a concentration <1 ='____' ppm (Colonnese and Ianniello 1989; CIR 1998; ISP 2008).

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