Canadian water quality guidelines for glycols-An ecotoxicological review of glycols and associated aircraft anti-icing and deicing fluids

Abstract

This paper reviews the environmental fate, chemistry and toxicology of ethylene, propylene, and diethylene glycol, and their associated aircraft deicing/anti-icing fluids. Ethylene glycol is currently the most prevalent glycol in Canada with high volume production and primary uses in deicing fluid and antifreeze mixtures and minor uses in polyester manufacturing. Propylene glycol use in Canada is concentrated in resin and polyester production whereas diethylene glycol is primarily used as a dehydrator in the natural gas industry. Glycols are miscible in water, and have very low log Kow, and log Koc values, which make these substances highly mobile. Aerobic biodegradation is the most important environmental fate process affecting glycols in waters and soils with available information demonstrating low persistence. Canadian monitoring data is limited to ethylene glycol where it has been routinely detected in stormwater runoff at airports. Glycols have relatively low aquatic toxicity, with algae being more sensitive than vertebrates or invertebrates. The most sensitive response recorded for ethylene glycol exposure was a 96-h LOEC of 1923.4 mg L−1 for the green alga Selenastrum capricornutum. Aircraft deicing/anti-icing fluids were more toxic than pure glycols. The most sensitive recorded response was a 96-h LC50 of 18 mg L−1 for the fathead minnow Pimephales promelas, following exposure to a propylene glycol based anti-icing fluid. The review details the development and derivation of the Canadian Water Quality Guidelines for glycols, including numerical concentrations for the protection of aquatic life. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 481–522, 1999