By Philip L. Comella and Craig B. Simonsen

The U.S. Environmental Protection Agency (EPA or Agency) just released its Toxicological Review of Trichloroethylene (EPA/635/R-09/011F, September 28, 2011) (Toxicological Review). This publication represents the first time that EPA has classified trichloroethylene (TCE) (CASRN 79-01-6) as a human carcinogen regardless of the route of exposure. TCE had previously been classified as a “possible human carcinogen.”

According to the Agency, the purpose of the Toxicological Review is to provide scientific support and rationale for the hazard and dose-response assessments given in its Integrated Risk Information System (IRIS) pertaining to chronic exposure to TCE. TCE is a volatile chemical widely used by industry as a chlorinated solvent; and unfortunately, it is also widely found at contaminated sites, including hundreds of Superfund facilities across the country.

The Toxicological Review concludes that based on the available human epidemiologic data and experimental and mechanistic studies, “TCE poses a potential human health hazard for noncancer toxicity to the central nervous system, kidney, liver, immune system, male reproductive system, and the developing fetus. The evidence is more limited for TCE toxicity to the respiratory tract and female reproductive system.”

The chief impact of this new hazard classification will likely be on the developing vapor intrusion standards and on groundwater remediation projects.