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DRINKING WATER ISSUES
Citation:
Speth*, T F., R J. Miltner*, AND E W. Rice. DRINKING WATER ISSUES. Presented at MTBE Biodegradation Workshop, Cincinnati, OH, February 01 - 03, 2000.
Impact/Purpose:
information
Description:
According to recent reports by the California Department of Health Services, the State of Maine, and the United State Geological Survey (USGS); the fuel oxygenate methyl teri-butyl ether (MTBE) is present in 5 to 20 percent of the drinking water sources in California and the northeastern United States. This presence is of great concern to water uitilities and consumers. The concentrations determined in the surveys were typically low (less than 20 ug/L), with only 0.8 percent above 20 ug/L. Because MTBE is used as a gasoline additive, MTBE would be expected to co-occur with BTEX compounds; however, such co-occurrence only happened in 0.3 percent of the USGS/NAWQA surveyed cases. MTBE does co-occur with other volatile compounds. Other volatile compounds are present in 44 percent of the USGS/NAWQA sites that also have MTBE. This can be explained by MTBE's ability to travel through subsurfaces without retardation. MTBE essentially travels as fast as the water in an aquifer, whereas BTEX compounds are retarded by the aquifer material. Apparently, the other volatiles that co-occur with MTBE also do not retard onto aquifer material. According to the USEPA, there is a lack of consistent health effects data to accurately determine what MTBE levels are safe for human consumption. However, because MTBE has a very unpleasand odor, the USEPA has issued an Advisory on MTBE in drinking water of 20 to 40 ug/L. The advisory serves only as guidance for aesthetic effects in drinking water. However, the USEPA Fact Sheet reports that concentrtions in the 20 to 40 ug/L range are roughly 20,000 to 100,000 times lower than the exposure levels in which cancers or non-cancer effects were determined in animal studies. Therefore, based on animal extrapolation, reducing MTBE levels to the 20 to 40 ug/L range will also protect consumer health.