Perc Assessment May Affect Regulations

A scientific assessment of perchloroethyl­ene (perc), released by EPA on Feb. 10, may lead to tighter regulation of the chemical. Perc, also known as tetrachloroethylene, is a solvent widely used for dry cleaning. The assessment sets a safe daily dose of 0.006 mg of perc per kg of body weight, based on studies that found neurotoxic effects in workers exposed to the chemical. This replaces a safe dose that EPA set in 1988 of 0.01 mg/kg/day, based on laboratory studies with rats. The assessment also categorizes perc as a likely human carcinogen, a conclusion affirmed by the National Research Council in a 2010 report. EPA says it will use the data in the assessment as it revises its maximum contaminant level for perc in drinking water. The agency will also use the toxicity values in the assessment as it evaluates whether to ratchet down allowable emissions of perc into air. Meanwhile, EPA will use the values to establish cleanup levels at hundreds of Superfund hazardous waste sites contaminated with perc.