Comment

          Response

Environmental assessment

One commenter noted that: “In the analysis, it is implied that exposure is proportional to releases and that Total Releases (last column, Table 2) are the sum of Total Disposal, Total Recycled and Untreated Releases. It is inappropriate to include Total Recycled and Total Disposal in Total Releases, as total releases then characterizes exposure to include recycled and disposal.”

The last column in Table 2 is in fact the sum of the other three columns (Total Disposal, Total Recycled and Untreated Releases), i.e. the sum of both treated and untreated streams. In Section 2.2.2, the total releases referred to in the first paragraph are an indirect measure of ethylene glycol usage at reporting facilities. While this usage has tended to rise over the period covered, the amount of untreated released ethylene glycol reported to the National Pollutant Release Inventory (NPRI) has in fact gone down, both numerically and proportionally. In the case of airports, this is further quantified at the end of the section on releases to land (page 6).  The Total Releases value referred to above was not used to characterize exposure. Risk quotients were calculated using the predicted environmental concentrations (PECs) derived from a distribution of actual measured ethylene glycol concentrations in airport effluents.

One commenter stated that: “Proper disposal is not a release to the environment and will not cause exposure. Proper disposal will ensure the substance does not reach the environment, as the substance is destroyed, encapsulated, etc. and therefore the substance is not available to cause exposure.”

We agree and in no way state or imply otherwise.

One commenter noted that: “Analogously, proper recycling is not a release to the environment and does not allow the substance into the environment.”

We agree and in no way state or imply otherwise.

One commenter stated that: “In the first paragraph of Section 2.2.2, Sources and releases, the following assertion is made: total releases generally increased and untreated releases dropped. While we agree that “untreated” releases have decreased (Table 3), given that disposal and recycle are not releases, Environment Canada should recharacterize the statement above to recognize that increased waste disposal and recycling are positive (and in fact meet government policy objectives to encourage recycling for resource recovery, etc.).”

Refer to the first comment above.

One commenter noted that: “Further identifying all releases as untreated is a misnomer. While some releases are not treated, numerous facilities do practice pollution prevention to mitigate any release. As such, various emissions are treated, prevented, etc. before a release occurs. To state all releases are untreated does not recognize the efforts expended by various facilities in Canada. As such, it is suggested that “release” be characterized as “release” without the “untreated” modifier.”

Refer to the first comment above.

There were several comments from members of the Canadian Airports Council stating that they “would like to participate in the discussion of any further measures dealing with the usage and management of ethylene glycol.”

Based on new information submitted during the public comment period, ethylene glycol is no longer considered to meet any of the criteria under section 64 of the Canadian Environmental Protection Act, 1999 (CEPA 1999), and no further action is proposed under the Act at this time.

One commenter noted that: “…We would thus strongly recommend that ethylene glycol not be added to Schedule 1 to CEPA 1999the. If this recommendation is not followed, ATAC would strongly suggest than no regulation be imposed as regards the use of ethylene glycol for aircraft de-icing and anti-icing operations.”

Based on new information submitted during the public comment period, ethylene glycol is no longer considered to meet the criteria under section 64 of CEPA 1999, and no further action is proposed under CEPA 1999 at this time.  

One commenter stated that: “…The present airport controls have been proven to work and would suggest that no further regulatory requirements are required for our airport and our industry. The GTAA would be happy to participate in any further development of any further measures dealing with the usage and management of ethylene glycol.”

Based on new information submitted during the public comment period, ethylene glycol is no longer considered to meet the criteria under section 64 of CEPA 1999, and no further action is proposed under CEPA 1999 at this time.  

A commenter stated that: “Since the notice concludes that ethylene glycol is not dangerous to the environment as per paragraph 64(a) and (b) and, since we feel that Canadian airports and airlines are successfully managing the substance, we would not like to see any further regulatory controls placed on ethylene glycol.”

Based on new information submitted during the public comment period, ethylene glycol is no longer considered to meet the criteria under section 64 of CEPA 1999, and no further action is proposed under CEPA 1999 at this time.

Human health

Comments were made that the entry of ethylene glycol onto Schedule 1 of CEPA 1999 should be clearly marked as “Ethylene glycol in latex paint only” and not simply “Ethylene glycol”, which would create unnecessary confusion and possible fear in consumers.

Based on new information submitted during the public comment period, ethylene glycol is no longer considered to meet the criteria under section 64 of CEPA 1999, and no further action is proposed under CEPA 1999 at this time.

An opinion was expressed that ethylene glycol should not be considered toxic under paragraph 64(c) of CEPA 1999, based on the comparison of a latex paint exposure scenario and the results of a short-term inhalation study.

Based on new information submitted during the public comment period, ethylene glycol is no longer considered to meet the criteria under section 64 of CEPA 1999, and no further action is proposed under CEPA 1999 at this time.  The new information included data regarding levels of ethylene glycol in latex paint, and comments pertaining to use of ethylene glycol-specific defaults in the exposure model used.

One commenter stated that Health Canada’s conclusion regarding the toxic potential of short-term exposures to ethylene glycol is in conflict with the findings from the US NTP Center for the Evaluation of Risks to Human Reproduction (CERHR), American Conference of Governmental Industrial Hygienists (ACGIH) and Carstens et al. (2003).

Based on new information submitted during the public comment period, ethylene glycol is no longer considered to meet the criteria under section 64 of CEPA 1999, and no further action is proposed under CEPA 1999 at this time. Results from the CERHR and Carstens et al. (2003) are included in the report. As the ACGIH focuses on workplace exposures and the focus of assessments under CEPA 1999 are on the general population, findings from the ACGIH are not included in the report. 

Another comment made was that the results of the short-term inhalation study (Tyl et al. 1995b) should not be used to calculate tolerable concentration due to the confounding effects of the study.

The Government of Canada acknowledges the limitations in the Tyl et al. (1995b) study and has elaborated on these limitations in the report. The approach for characterizing risk to human health following short-term inhalation exposure has been modified accordingly. 

The same commenter also pointed out that if Health Canada is using the Wills et al. study (1974) as an alternative for a short-term inhalation study, then 67 mg/m3 should be used as the no-observed-adverse-effects level
(NOAEL). The uncertainty factor should be 1 for intraspecies variation, since ethylene glycol is a direct-acting irritant that does not need any biotransformation.

The Wills et al. study (1974) is used to characterize risk to human health following short-term inhalation exposure. The achieved margins between upper-bounding conservative estimates of exposure and the NOAEL from this study (67 mg/m3) are considered adequate.  

Further, it was proposed that Health Canada should use all available scientific evidence, including ethylene glycol’s robust database on the mode of action for renal toxicity, pharmacokinetics and pharmacodynamics, in deriving tolerable intake (TI). 

Health Canada has considered the available scientific information. Additional analysis of pharmacokinetics and pharmacodynamics beyond what is presented in the report was not required, as general population exposures are well below the TI  and short-term inhalation exposures were not considered to be harmful to human health.

One commenter pointed out that Health Canada should use physiologically based pharmacokinetics models (PBPKs) to reduce the uncertainty factors in assessing chronic TI and short-term tolerable concentration.

The Government of Canada has considered the available scientific information.  Additional analysis of pharmacokinetics and pharmacodynamics beyond what is presented in the report was not required, as general population exposures are well below the TI and short-term inhalation exposures were not considered to be harmful to human health.   

It was suggested that the dermal penetration of ethylene glycol should be lowered to 10% (as opposed to 100% used in the assessment) based on the available data.

Available information on dermal absorption has been summarized in the report. It is acknowledged that use of a default dermal absorption value of 100% is conservative, and this is taken into consideration when characterizing risk to human health in the report. 

A commenter pointed out that, although Health Canada assumed a 5% level of ethylene glycol in consumer paints, a survey revealed that approximately 80% of consumer paints contain ≤ 2% ethylene glycol. Therefore, a lower concentration of ethylene glycol should be used in the wall paint exposure model (WPEM), along with a 2-day application scenario: 1 day to apply the primer and the next day to apply the top coat. The same commenter also pointed out that it would be very difficult to apply 3 coats of paint in 1 day. Further, it was pointed out that Health Canada should use ethylene glycol‑specific values for the recovery percent (i.e. 9% recovery instead of the default 25%), and for the emission decay rate constant for desorption (i.e. K1 = 3.0 instead of 11.7) for the WPEM exposure estimates.

Estimates of exposure from use of latex paints containing ethylene glycol were revised based on information submitted during the public comment period. Ethylene glycol-specific values for percent recovery and for the emission decay rate constant were used. A range of levels of ethylene glycol in consumer paints submitted by industry was modelled (average at 1.9%, 3% and 5%). In addition, the text describes the percentage of paint in Canada that contains the various levels to illustrate, for example, that only 0.4% of paint sold in Canada is above 5%. The number of coats applied in 1 day was also changed from 3 to 2 because this was determined to be a more typical scenario, based on the time required for the paint to dry before applying the next coat of paint.

A commenter recommended using US EPA default scenarios for the WPEM, which are

• one coat of paint for the do-it-yourself painter-exposure scenario, and
• two coats of paint for the professional painter-resident child exposure scenario.

The default scenario for the professional painter-resident child was used in the final report. Two coats of paint for the do-it-yourself painter-exposure scenario was retained, as it was considered to be realistic.

It was suggested that a higher ventilation rate be used in the WPEM as paint label warnings state “Use only under well-ventilated conditions,” and do-it yourself painters are unlikely to paint when there is insufficient ventilation.

The default ventilation rate provided by the WPEM was retained; however, text was added to indicate that product labels specify use only under well-ventilated conditions and that concentrations of ethylene glycol in indoor air may therefore be lower than those presented in the report.