Organic chemicals commonly used by industry with known or suspected human health impacts that are often encountered in groundwaters include, for example, aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylene (collectively known as “BTEX”) as well as volatile chlorinated hydrocarbons such as tetrachloroethene and trichloroethene. A diverse range of pesticides is also found in groundwaters that is primarily, but not exclusively, ascribed to agricultural activities. Typically pesticide concentrations encountered are low, but have in some cases exceeded regulatory limits for drinking water supplies or ecoystem protection. .
