Ethylene glycol final content: synopsis


Synopsis

Ethylene glycol was included on the Priority Substances List (PSL) under the Canadian Environmental Protection Act (CEPA) to assess the potential environmental and human health risks posed by exposure to ethylene glycol in consumer products and the environment.

In December 2000, the Priority Substances List (PSL) assessment of ethylene glycol was formally suspended due to limitations in the available data for assessing health effects. At the same time, a state of the science report (Environment Canada and Health Canada 2000) on ethylene glycol was released, providing an in-depth review of the toxicity and exposure information related to human health and the environment. The essential information needed to complete the assessment was identified and acquired during the subsequent seven years.

During the suspension period, more data were obtained. This led to the proposed conclusion, published in 2007, that the substance met one or more of the criteria under section 64 of CEPA 1999. During the comment period that followed that publication, additional data were received on levels of ethylene glycol in latex paints as well as ethylene glycol-specific model parameters which supported a refinement of exposure estimates from use of latex paints. The revised exposure estimates were not considered to be of concern and resulted in the final conclusion that the substance does not meet any of the criteria under section 64 of CEPA 1999.

Ethylene glycol is primarily used as a component of deicer and anti-icer/anti-freeze fluid used in aircraft deicing and anti-icing operations, and as an anti-freeze component in motor vehicles. It is also used in manufacturing polyester products. Ethylene glycol is present as a slow-evaporating solvent and/or freeze-thaw stabilizer in latex paints.  Ethylene glycol can also be used in a variety of other products such as floor and wall adhesives, brake fluid, automotive wax/polish and floor wax/polish. In 2006, approximately 1540 kilotonnes (kt) of ethylene glycol were manufactured in Canadaby three companies in Alberta. Most Canadian glycol production is destined for export.

With regard to the environment, the highest reported releases of ethylene glycol to the environment are to land resulting from aircraft deicing/anti-icing operations, with subsequent release to the aquatic environment. However, in recent years, management practices at Canada’s major airports have improved with the installation of new ethylene glycol application and mitigation facilities or improvements to existing ones.

The direct comparison of exposure concentrations measured in the aquatic environment with the estimated no-effect values (ENEVs) suggests that adverse effects are unlikely when consideration is given to the seasonal nature of releases, ambient temperatures, metabolic rates and duration of exposure. Furthermore, examination of potential indirect effects through oxygen depletion caused by biodegradation of ethylene glycol suggests a low potential for concentrations of dissolved oxygen (DO) to drop to levels of concern. As such, it is proposed that ethylene glycol is not 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, or that constitutes or may constitute a danger to the environment on which life depends.

With regard to human health, upper-bounding estimates of daily intake of ethylene glycol by the general population of Canada, and by a highly exposed population in the immediate vicinity of an industrial point source, are well below tolerable intake (TI), derived based on a Benchmark Dose calculated for non-neoplastic renal effects in animals and an uncertainty factor.  “Tolerable intake” is the level of intake to which it is believed a person may be exposed daily over a lifetime without deleterious effect. Estimates of short-term indoor air concentrations from use of consumer products containing this substance, such as latex paint, are not considered to be of concern based on a comparison of upper-bounding exposure estimates and the no-observed-adverse--effect level in an inhalation study conducted with humans. Ethylene glycol is, therefore, not entering the environment in a quantity or concentration or under conditions that may constitute a danger to human life or health.

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.

Based on the information available for human health and the environment, it is thus concluded that ethylene glycol does not meet any of the criteria set out in section 64 of the Canadian Environmental Protection Act, 1999 (CEPA 1999).

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