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Proposed Risk Management Strategy for N-nitrosodimethylamine (NDMA)
Chemicals Sector Division
Environmental Stewardship Branch
1.0 ISSUE AND BACKGROUND
- In December 1995, the second Priority Substances List (PSL) of the Canadian Environmental Protection Act was published. This list included N-nitrosodimethylamine (NDMA).
- On April 13, 2002, the Ministers of the Environment and Health published the final assessment report on NDMA [subsection 77(6) of the Canadian Environmental Protection Act, 1999 (CEPA 1999)]. This assessment report indicates that NDMA is considered "toxic" for human life or health as defined in paragraph 64(c) of the CEPA 1999. The report also indicates that NDMA is not considered toxic for the environment as defined under paragraphs 64(a) and 64(b) of CEPA 1999.
- On May 15, 2003, NDMA was added to the List of Toxic Substances (Schedule 1 of CEPA 1999).
- It is considered highly likely that NDMA is carcinogenic to humans, potentially at relatively low levels of exposure.
- There are no industrial or commercial uses of NDMA in Canada. In the past, NDMA was used in Canada and other countries in rubber formulations as a fire retardant and in the organic chemical industry as an intermediate, catalyst, antioxidant, additive for lubricants and softener of copolymers. 1
- NDMA is released to the Canadian environment as a by-product and contaminant from various industries and from municipal wastewater treatment plants. Major releases of NDMA have been from the manufacture of pesticides, rubber tires, alkylamines and dyes. NDMA has been detected in drinking water and in emissions from diesel vehicles.
- NDMA may also form under natural conditions in air, water and soil as a result of chemical, photochemical and biological processes.
2.0 NEED FOR ACTION ON NDMA
- NDMA is considered toxic because it is 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 (paragraph 64(c) of CEPA 1999).
- Based on the assessment report, human exposure to NDMA would likely be through food, water and air. In addition, with food consumption contributing to most of the daily intake, the principal route of exposure to NDMA would be ingestion.
- CEPA 1999 requires that the Minister of the Environment develop a proposed preventive or control instrument within two years of the publication of the final decision under subsection 77(6) of the CEPA 1999. In this case, the proposed Total, Partial or Conditional Prohibition of Certain Toxic Substances Regulations were published in the Canada Gazette, Part I on April 3, 2004. The final regulations (Prohibition of Certain Toxic Substances Regulations, 2005) were published in the Canada Gazette, Part II on March 9, 2005. NDMA is included in Schedule 1 of the Regulations, which lists prohibited toxic substances subject to total prohibition, with the exception of incidental presence.
- As NDMA is not persistent in the environment, it requires management throughout its entire life-cycle to prevent or minimize release into the environment, as it is a Track 2 substance under the federal Toxic Substances Management Policy(TSMP).
3.0 PRESENCE OF NDMA IN THE ENVIRONMENT AND NDMA EXPOSURE SOURCES
- There are no industrial or commercial uses of NDMA in Canada.
- NDMA is not manufactured in or imported into Canada.
- NDMA is produced as a by-product of industrial processes that use amines and nitrites under a range of pH conditions. 2
- Possible sources of NDMA releases and exposure include tobacco products, food products (for example, food preserved by the addition of nitrate and/or nitrite, such as cured meat products and cheeses), dimethylamine production, rubber processing operations, consumer products (such as rubber containing products and personal care and cosmetics products), municipal waste water effluents and sludge, and pesticides.
- NDMA has been detected in drinking water and in emissions from diesel vehicles.
- Rubber-containing products that come in contact with human skin are another potential source of exposure to NDMA. 3
- Almost all releases of NDMA to the Canadian environment are to water and nearly all of the NDMA remains and reacts in the water phase. NDMA has not been detected in ambient air, except in the vicinity of industrial sites, as reported in small surveys of several cities in southern Ontario.
4.0 CONSIDERATIONS AND DISCUSSION
- NDMA is not on the Domestic Substances List and is on the Non-Domestic Substances List.
- According to the Accelerated Reduction / Elimination of Toxics (ARET) data, releases of NDMA to water were reduced from 6 089 grams in 1993 to 131 grams in 2000, based on reports from 3 companies.
- In its 2002 emissions inventory, the Canadian Chemical Producers' Association (CCPA) reports that releases of NDMA, including projected emissions to the year 2007, are less than 10 grams.
- Based on ARET and CCPA information, NDMA releases as by-products from industrial point sources have been reduced by an order of magnitude and previous industrial operations that had significant releases have either closed or changed their processes. Consequently, trends will continue to be followed and if necessary appropriate actions will be taken should the trends show an increase for these sources. Further investigation is recommended to determine the level of NDMA in the dimethylamine produced.
- The United States Environmental Protection Agency's Toxics Release Inventory (TRI) program reported NDMA releases of 5 pounds (2270 grams) in 1999.
- While the PSL assessment report identifies that NDMA has been detected in crankcase emissions of diesel vehicles (limited data from 1980), there is no evidence that vehicles contribute significantly to ambient air concentrations of the substance. As noted in the Priority Substances List assessment report, NDMA was not detected in a single survey of ambient air not impacted by point sources.
- Some pesticide formulations may contain NDMA as a micro-contaminant. Typically, NDMA, if present, is in a concentration of less than 1 mg/kg. Toxicology studies done with these pesticide formulations do not exhibit any of the toxicological characteristics of NDMA and, therefore, are unlikely to pose a health risk to humans.
5.0 EXISTING ENVIRONMENTAL AND HEALTH CONTROLS
5.1 Federal Government
- NDMA is presently governed under the following four federal statutes: the Food and Drugs Act, the Hazardous Products Act, the Pest Control Products Act and theCanadian Environmental Protection Act, 1999.
- The Food and Drugs Act states that no person shall sell any cosmetic that has in or on it any substance that may cause injury to the health of the user when the cosmetic is used according to its customary method. As a result, all nitrosamines, including NDMA, are listed on the List of Prohibited and Restricted Cosmetic Ingredients, and cannot be added to cosmetics. Furthermore, nitrosamine formation within a cosmetic must not exceed 10 µg/kg.
- Pacifiers (and other similar products included in item 27 of Part II of Schedule 1 to the Hazardous Products Act) may not contain more than 10 µg/kg of total volatileN‑nitrosamines.
- Infant feeding bottle nipples (and other similar products included in item 37 of Part II of Schedule 1 to the Hazardous Products Act) may not contain more than 10 µg/kg of total volatile N-nitrosamines.
- There are no specific limits for NDMA in food; however in the 1975 amendments to the Canadian Food and Drug Regulations, Health Canada set permissible levels of nitrites in preserved foods such as bacon. This limits the formation of nitrosamines during high heat frying.
- Pesticides are regulated under the Pest Control Products Act which is administrated by the Pest Management Regulatory Agency (PMRA).
- NDMA was added to the List of Toxic Substances in Schedule 1 of the Canadian Environmental Protection Act, 1999, in May 2003 and is included in Schedule 1 of the Total, Partial or Conditional Prohibition of Certain Toxic Substances Regulations, 2005.
5.2 Provinces and territories
- Ontario Drinking Water Quality Standards(Ontario Regulation 268/03) is a supporting regulation made under the Ontario Safe Drinking Water Act, 2002 and includes a maximum concentration of 0.000009 mg/L (9x10-6 mg/L) for NDMA.
- The province of Ontario has an interim Provincial Water Quality Objective for the protection of surface water of 15 µg/L (0.015 mg/L) for NDMA.
- The province of Quebec in its Critères de qualité de l'eau de surface au Québec (Surface water quality criteria) has a criterion of 6.9x10 -7 mg/L for the prevention of contamination of water and aquatic organisms.
- The Regional Municipality of Waterloo has a sewage discharge limit of 400 ppt (0.0004 mg/kg) of NDMA in its sanitary system by-law (By-law Number 50-92).
- The City of Ottawa has a revised Sewer Use By-law (By-law Number 2003-514) which came into effect on January 1, 2004 and includes a maximum discharge limit of 0.4 mg/L of NDMA into the sanitary and combined sewers.
5.4 United States of America
- NDMA is classified as a probable human carcinogen (classification B2) under the Integrated Risk Information System (IRIS) of the US Environmental Protection Agency. NDMA is found in Group 2A - probably carcinogenic to humans under theInternational Agency for Research on Cancer(IARC).
- In the US, NDMA is among the chemicals for which releases must be reported as part of the US Toxic Release Inventory(TRI) program.
- NDMA is also listed in the following Acts as:
- a hazardous air pollutant (HAP) under Section 112 (b)(1) of theU.S. Clean Air Act;
- a hazardous constituent under the Resource Conservation and Recovery Act (RCRA);
- a substance on the Priority List of Hazardous Substances under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, also known as Superfund.) This list includes substances most commonly found at facilities in the US that have been deemed to pose the greatest threat to human health.
- In California, NDMA is listed under the Safe Drinking Water and Toxic Enforcement Act of 1986 (better known by its original name of Proposition 65). This Act is intended to protect California citizens and the State's drinking water sources from chemicals known to cause cancer, birth defects or other reproductive harm, and to inform citizens about exposures to such chemicals (No Significant Risk Level of 0.04 µg/day for NDMA). This Act also prohibits California businesses from knowingly discharging significant amounts of NDMA into sources of drinking water.
- NDMA in drinking water is regulated under the Water Quality Standards; Establishment of Numeric Criteria for Priority Toxic Pollutants for the State of California (generally known as theCalifornia Toxics Rule) at a limit of 0.00069 µg/L (6.9 x10-7 mg/L).
5.5 European Union
- On October 29, 2003, the European Commission adopted a proposal for a "Directive of the European Parliament and of the Council" amending Council Directive 67/548/EEC in order to adapt it to Regulation of the European Parliament and of the Council concerning the registration, evaluation, authorization and restriction of chemicals in which NDMA, dimethylnitrosamine is listed. The proposal is now being considered by the European Parliament and the Council of the European Union for adoption under the so-called co-decision procedure.
6.0 PROPOSED OBJECTIVES
6.1 Proposed environmental objective
- The environmental objective is to reduce to the lowest feasible level the concentration of NDMA in the environment.
6.2 Proposed risk management objective
- The proposed risk management objective for all sources is to encourage reduction of the formation and releases of NDMA to the extent possible.
7.0 PROPOSED RISK MANAGEMENT APPROACH
In order to accomplish the objective of reducing the concentration of NDMA in the environment, certain risk management actions have been taken. It is believed that these actions will adequately address the risks posed by anthropogenic sources of NDMA. In addition, monitoring activities are being undertaken. These activities will help to identify progress and will assist in determining whether additional actions need to be taken to meet the stated objective.
7.1 Prohibition of Certain Toxic Substances Regulations, 2005
- The risk management instrument will prevent the manufacture, use, sale or offer for sale of NDMA in Canada and the importation of NDMA into Canada. The substance was added to the Prohibition of Certain Toxic Substances Regulations, 2005, in March 2005, incorporating an exemption for the incidental presence of NDMA.
7.2 National Pollutant Release Inventory (NPRI)
- NDMA is not listed under the NPRI and Environment Canada does not currently intend to add it, for the moment.
7.3 Emissions from diesel vehicles
- The new On-Road Vehicle and Engine Emission Regulations require that crankcase emissions from new on-road turbocharged diesel engines be controlled beginning in 2007. Similarly, the draft off-road diesel engine emissions regulations (currently under development) will prohibit the direct discharge of crankcase emissions from naturally aspirated engines. Accordingly, no specific action is warranted at this time with respect to NDMA emissions from diesel vehicles or engines. Environment Canada is conducting a literature review on the chemical characterization of diesel emissions. If any new scientific information comes to light which suggests that vehicle emissions may contribute significantly to human exposure to NDMA, Environment Canada will reconsider the need to take further action.
7.4 Releases from pesticides
- NDMA occurs as a micro-contaminant in certain pest control products. The Pest Management Regulatory Agency (PMRA) will continue to monitor NDMA concentrations in pesticides and will manage NDMA contamination in pest control products according to its Regulatory Directive The Pest Management Regulatory Agency's Strategy for Implementing the Toxic Substances Management Policy (DIR99-03).
- Under Directive 99-03, levels of micro-contaminants of concern in pest control products are reviewed to ensure that products, and the uses for which they are registered, do not pose unacceptable risks to people or the environment. The PMRA works in partnership with registrants to reduce/eliminate micro-contaminants of concern in line with the best available technology from a manufacturing perspective and encourages the development of new technology.
7.5 Food products, consumer and personal care products
- Health Canada will pursue monitoring of NDMA in products, such as foods, baby bottle nipples, latex rubber gloves and condoms, orthodontic elastics and children's balloons all of which fall under the authority of various Health Canada administered acts and regulations. In addition, Health Canada's Federal Tobacco Control Strategy, the objective of which is to decrease tobacco use in Canada, should result in a decrease in NDMA exposure due to cigarette smoke.
7.6 Drinking water and waste water effluent
- Health Canada through their Water Quality and Health Bureau will discuss the need to develop a drinking water guideline at a future meeting of the Federal-Provincial-Territorial Committee on Drinking Water. NDMA in municipal waste water effluent will be addressed as part of the overall municipal wastewater effluent strategy.
8.0 PROPOSED CONSULTATION APPROACH
- The risk management strategy for NDMA will be posted on Environment Canada's National Office of Pollution Prevention Web site for comments and mailed to stakeholders.
9.0 NEXT STEPS / TIMELINE
1 Priority Substances List Assessment Report, N-Nitrosodimethylamine (NDMA), 2001
2 This is due to its inadvertent formation in industrial situations when alkylamines, mainly dimethylamine (DMA) and trimethylamine, come in contact and react with nitrogen oxides, nitrous acid or nitrite salts, or when trans-nitrosation via nitro or nitroso compounds occurs.
3 Dialkylamines used in rubber vulcanization can react with nitrosating agents during processing to form nitrosamines.
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