1. Introduction
Ethylene glycol was added in 1995 to the second Priority Substances List (PSL2) under the Canadian Environmental Protection Act (CEPA) to assess the potential environmental and human health risk posed by the exposure to ethylene glycol in the environment and consumer products.
The PSL2 assessment of ethylene glycol was formally suspended in December 2000 due to the uncertainties associated with the human effect and exposure data set. At the same time, a state of the science report (SoS report) (Environment Canada and Health Canada 2000) on ethylene glycol was released, providing an in-depth review of the available toxicity and exposure information related to human health and the environment. A large number of uncertainties were identified in the SoS Report and Health Canada was unable to determine whether EG was toxic or capable of becoming toxic to the general population in Canada. The SoS Report stated that information on concentrations of ethylene glycol present in consumer products in Canada, dose-response results for renal effects of ethylene glycol based on a chronic animal study, and information on the intake of ethylene glycol by individuals living in the vicinity of industrial point sources were essential for the completion of the human health assessment. Furthermore, the SoS Report concluded that harmful environmental effects were unlikely to result from exposure to ethylene glycol in Canada.
However, effects related to the depletion of dissolved oxygen (DO) levels in receiving waters were possible near some Canadian airports a very small percentage of the time under conditions of maximum loading. It was therefore recommended that efforts to reduce releases of ethylene glycol during aircraft deicing/anti-icing operations continue to be strengthened with the aim of reducing further the instances when ethylene glycol concentrations in stormwaters exceed the CEPA Part IV guideline of 100 mg total glycol/L.
The essential information needed to complete the PSL2 health assessment was identified and acquired during the ensuing seven years, and is included in this report.
External peer-review of a draft of the human health component of this document was coordinated by Toxicology Excellence in Risk Assessment (TERA). In addition, Dr. Douglas C. Wolf, U.S. Environmental Protection Agency provided expert advice on endpoint selection for key dietary toxicity studies. Mike Walker, Health Canada,provided biostatistical expertise. External peer-review of a draft of the ecological component of this document was undertaken by Saleem Sattar, Manager, Environmental Protection, Environmental Programs, Transport Canada and by Jonathan Farley, Manager, Environmental Protection, Client and Internal Services, Transport Canada.