EPA Officially Characterizes Perchloroethylene as ‘Likely Human Carcinogen’

Written by John Bird, P.G., Vice President, EnviroForensics.

On Friday, February 10, the U.S. Environmental Protection Agency (EPA) published the final health assessment for perchloroethylene (Perc) to the EPA’s Integrated Risk Information System (IRIS) database.  EPA’s IRIS is a human health assessment program that evaluates risk information on effects that may result from exposure to environmental contaminants.   Perc is a chemical solvent widely used in the dry cleaning industry.  This health assessment appears to confirm longstanding scientific understanding and research, that Perc is a “likely human carcinogen.”  For the first time, the EPA provides estimates for both cancer and non-cancer effects associated with exposure to Perc over a lifetime.

It’s important to note that the EPA does not believe that wearing clothes dry cleaned with perc will result in exposures which pose a risk of concern.  EPA has already taken several significant actions to reduce exposure to Perc. EPA has clean air standards for dry cleaners that use Perc, including requirements that will phase-out the use of Perc by dry cleaners in residential buildings by December 21, 2020. EPA also set limits for the amount of Perc allowed in drinking water and levels for cleaning up Perc at Superfund sites throughout the country, which will be updated in light of the IRIS assessment.

“The Perc health assessment will provide valuable information to help protect people and communities from exposure to Perc in soil, water and air,” said Paul Anastas, assistant administrator for EPA’s Office of Research and Development. “This assessment emphasizes the value of the IRIS database in providing strong science to support government officials as they make decisions to protect the health of the American people.”

According to the EPA IRIS assessment, the assessment has undergone several levels of rigorous, independent peer review including: agency review, interagency review, public comment, and external peer review by the National Research Council. All major review comments have been addressed.

The assessment replaces the 1988 IRIS assessment for Perc.  The most significant change from the 1988 IRIS assessment appears to be the reference dose (RfD) for Perc.  The RfD is an estimate of a daily oral exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime.  The RfD of 0.006 milligrams/kilograms per day (mg/kg-day) replaces the previous RfD of 0.01 mg/kg-day entered on the IRIS database on 03/01/1988. 

The EPA will use these revised toxicity values reported to establish cleanup levels at the hundreds of Superfund sites where Perc is a contaminant; to revise the EPA’s Maximum Contaminant Level for Perc as part of the carcinogenic volatile organic compounds group in drinking water, as described in the agency’s drinking water strategy; and to Evaluate whether to propose additional limits on the emissions of Perc into the atmosphere.

In addition, Occupation Safety and Health Administration (OSHA) may be prompted by the new lower toxicity values and the change in carcinogenic levels to re-evaluate the current permissible exposure levels for Perc in the work place.   EnviroForensics will be carefully tracking this issue and will keep you informed in our future communications.