Volatile organic compounds (VOCs) are produced in large volumes and are associated with amyriad of products, such as plastics, adhesives, paints, gasoline, fumigants, refrigerants, and dry cleaningfluids. Widespread and long-term use of VOCs and their ability to persist and migratein groundwater raise questions about possible adverse effects on the environment, includingdrinking water quality. A long-term survey by the National Water-Quality Assessment Programof the United States Geological Survey provides the most comprehensive national analysis todate of the occurrence of VOCs in groundwater, based on results from sampling between 1985and 2002. Among the major findings are that VOCs were detected in most aquifers throughoutthe Nation, and were not limited to a few specific aquifers or regions. VOCs were not detected,however, in many of the nearly 3,500 sampled wells; for example, about 80 percent had nodetections above a threshold of 0.2 part per billion. The most frequently detected VOCs werechloroform, the solvents perchloroethene and trichloroethene, and the gasoline oxygenate methyltert-butyl ether; 13 of the 55 compounds included in the assessment were not detected at all. Aseparate analysis of untreated groundwater samples from drinking water supply wells showedthat VOCs were detected in domestic well samples (14 percent) and public well samples (26percent). Less than 3 percent of samples of groundwater from domestic and public wells hadconcentrations greater than Federal drinking water standards. Includes 3 references, table.
