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The Environmental Protection Agency formally concluded Feb. 10 that a widely used dry cleaning solvent is a likely human carcinogen, paving the way for the agency to reconsider drinking water and other standards for the chemical.

The agency released its final assessment of perchloroethylene, or perc (CAS No. 127-18-4). That assessment had not been updated since 1988.

The agency’s decision to classify perc as a likely human carcinogen is consistent with its finding in 2008, when it released a draft assessment of perchloroethylene (32 CRR 641, 6/30/08)

The National Academies also supported that classification in a 2010 report.

In EPA’s new assessment, the agency also concluded that laboratory animal testing and other data on perc show lifetime daily ingestion at far lower levels of the solvent than estimated in 1988 could cause neurological, kidney, immune, or other problems other than cancer.

Specifically, the final assessment provides a reference dose of 0.006 milligram per kilogram body weight per day compared to the RfD of 0.1 mg/kg/day set by the agency in 1988.

EPA’s assessment sets its first reference concentration, or RfC, for perchloroethylene. The RfC is an estimate of a lifelong concentration of perchloroethylene in air that people could breathe over their lifetimes without the expectation that solvent would cause neurological, kidney, immune, or other noncancer problems. Previously EPA did not have an RfC for perchloroethylene.