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

Ninth Circuit Invalidates State Implementation Plan

California's Central Valley is once again without an approved State Implementation Plan for ozone. On Friday, January 20, the Ninth Circuit held, in Sierra Club v. US EPA, that EPA had acted arbitrarily and capriciously in approving the 2004 plan.

The Valley is an extreme non-attainment area for ozone, and has been a non-attainment area since 1991. California proposed a SIP for the Valley in 2004, but amendments to the plan and EPA's review took so long that by the time EPA approved the plan, which was based on 2004 data, in 2010 there was more current data that EPA chose not to consider in approving the SIP. The Ninth Circuit held that the SIP was required to be based on "current" and "accurate" data, and although that standard doesn't require constant updating, EPA could not ignore data that was collected in 2007 and in EPA's possession when it approved the SIP.