Expert Report

Each report is produced by a committee of experts selected by the Academy to address a particular statement of task and is subject to a rigorous, independent peer review; while the reports represent views of the committee, they also are endorsed by the Academy. Learn more on our expert consensus reports.

Tetrachloroethylene (also known as perchloroethylene, PCE, or PERC) is a chemical used for dry cleaning, metal degreasing, and other applications -- and is also an environmental contaminant linked to a range of health effects in humans, including cancer. This report provides an independent scientific review of a U.S. Environmental Protection Agency (EPA) draft assessment of the health effects of tetrachloroethylene. EPA's assessments will be used to guide air- and water-quality standards and cleanup procedures to protect public health. The report finds that EPA's classification of tetrachloroethylene as "likely to be a human carcinogen" and toxic to the nervous system is supported in the draft assessment. However, the report suggests using better designed studies than those EPA chose in calculating the risks of tetrachloroethylene. It also proposed ways to strengthen the scientific basis for estimating safe inhalation and oral exposures to tetrachloroethylene and cancer risk estimates.

Key Messages

  • EPA should develop one model that incorporates the three computer models, called physiologically based pharmokinetic models, which are currently used to describe the way tetrachloroethylene works in an organism.
  • EPA's assessment of tetrachloroethylene as "likely to be a human carcinogen" is supported by data that meet the relevant requirements in EPA's 2005 Guidelines for Carcinogen Risk
  • EPA's draft would be improved with greater consideration of the modes of action of cancer to support the conclusions drawn, with particular attention to outlining the proposed tetrachloroethylene-associated key events leading to cancer
  • The study that EPA used to characterize the noncancer health effects of tetrachloroethylene had methodological deficiencies -- EPA should reconsider its choice of study