High Quality Content by WIKIPEDIA articles! VOCs (volatile organic compounds) are a dangerous contaminant of groundwater. They are generally introduced to the environment through careless industrial practices.VOCs are responsible for a number of adverse health effects especially for nursing and pregnant mothers. Many of these compounds were not known to be harmful until the late 1960s and it was some time before regular testing of groundwater identified these substances in drinking water sources.Tetrachloroethylene is used in metal degreasing and dry cleaning. It is a suspected to cause cancer, and a host of other health problems.