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2012 EPA Research Progress Report

EPA's IRIS Program Releases Final Health Assessment for "Perc"

In February 2012, EPA released the final health assessment for the chemical tetrachloroethylene, also known as perchloroethylene, or more commonly as “perc.”

Perc is a chemical solvent widely used in the dry cleaning industry and to manufacture some consumer products and other chemicals; it is also a common environmental contaminant.

Confirming longstanding scientific understanding and research, the final assessment characterizes perc as a “likely human carcinogen.” The assessment, which underwent rigorous, independent peer review, includes toxicity values for both cancer and non-cancer effects associated with exposure to perc over a lifetime. 

EPA has already taken several significant actions to reduce exposure to perc. For example, the Agency established clean air standards for dry cleaners that use perc, including requirements that dry cleaners operating in residential buildings phase out its use by late 2020. EPA also set limits for the amount of perc allowed in drinking water.

The toxicity values reported in the perc IRIS assessment will be considered in future actions to protect public health, such as:

  • Informing new Superfund cleanup sites where vapor intrusion leads to indoor air contamination from perc;
  • Revising 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
  • Evaluating the need for additional limits on the perc emissions into the atmosphere; (perc is listed as a hazardous air pollutant under the Clean Air Act).

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