A concise assessment of the risks to the environment posed by ethylene glycol. The chemical is produced in large quantities for use as a chemical intermediate, as an antifreeze in engine coolants, and as a de-icer on airport runways and airplanes. Most release to the environment is to the hydrosphere, with use for the de-icing of runways and airplanes accounting for the largest local release to surface waters. Concerning behavior in the environment, studies show little or no capacity to bind to particulates and no mobility in soil. Evidence likewise indicates a low likelihood of bioaccumulation. Rapid biodegradation has been observed under both aerobic and anaerobic conditions in sludge, surface waters, groundwater, and soil. Although data are limited, levels detected in surface water are generally low with the exception of very high concentrations in runoff water from airports. Studies of toxic effects indicate generally low toxicity to aquatic organisms when the pure compound was tested but higher toxicity when tests used a de-icer containing ethylene glycol. Laboratory exposure of aquatic organisms to stream water receiving runoff from airports resulted in toxic effects and death. Terrestrial organisms, which are much less likely to be exposed, generally show low sensitivity to the compound. The report concludes that the risk to aquatic organisms from the production of ethylene glycol is very low and is probably negligible. Substantially higher concentrations in runoff water at particular airport sites are of much greater concern. The report further concludes that risk assessment and field monitoring of overt effects should be applied on a case-by-case basis to determine the need to apply measures for pollution control.