EPA Releases Final Health Assessment for Tetrachloroethylene (PERC)

On February 10, 2012, the U.S. Environmental Protection Agency (EPA) posted the agency’s final toxicological review of tetrachloroethylene. Tetrachloroethylene – also known as PERC, or PCE – is a solvent widely used in the dry cleaning industry. The review characterizes PERC as a “likely human carcinogen” and provides estimates for both cancer and non-cancer effects of exposure to the chemical. EPA's new calculated cancer risks for PCE are lower than the current values used by EPA, while non-cancer risks are higher by an order of magnitude or more.  Thus, risk-based screening levels based on EPA's newly-calculated cancer risks may increase, resulting in less stringent cleanup standards at PCE-contaminated sites. 

Many states, including California, already have stricter risk-based cleanup standards for PCE, and will not be immediately affected by the new federal standards.  The new standard will be used to develop a revised Maximum Contaminant Level (MCL, the federal drinking water standard) for PCE, but it is too early to predict whether that standard will be lower than the current MCL.

-Chris Jensen and Morgan Gilhuly