Canadian Water Quality Guidelines for glycols - An ecotoxicological reviewof glycols and associated aircraft anti-icing and deicing fluids

This paper reviews the environmental fate, chemistry and toxicology of ethy lene, propylene, and diethylene glycol, and their associated aircraft deici ng/anti-icing fluids. Ethylene glycol is currently the most prevalent glyco l in Canada with high volume production and primary uses in deicing fluid a nd antifreeze mixtures and minor uses in polyester manufacturing. Propylene glycol use in Canada is concentrated in resin and polyester production whe reas diethylene glycol is primarily used as a dehydrator in the natural gas industry. Glycols are miscible in water, and have very low log K-ow, and l ogK(oc) values, which make these substances highly mobile. Aerobic biodegra dation is the most important environmental fate process affecting glycols i n 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 relativel y low aquatic toxicity, with algae being more sensitive than vertebrates or invertebrates. The most sensitive response recorded for ethylene glycol ex posure was a 96-h LOEC of 1923.4 mg L-1 for the green alga Selenastrum capr icornutum. Aircraft deicing/anti-icing fluids were more toxic than pure gly cols. 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 deriv ation of the Canadian Water Quality Guidelines for glycols, including numer ical concentrations for the protection of aquatic life. (C) 1999 by John Wi ley & Sons, Inc.