In February, 2012, the EPA issued a revised risk assessment for tetrachloroethylene, more commonly known as PERCHLOROETHYLENE or PCE. As a result of this revised assessment, it is likely that cleanup standards for PCE will become more stringent. PCE is the predominant chemical solvent used in dry cleaning, and it is also used in the cleaning of metal machinery and in the manufacture of some consumer products and other chemicals. PCE can be released into the air, water, and ground during the cleaning, purification, and waste disposal phases of dry cleaning. Because of the large number of dry cleaners, PCE is present at many Superfund sites and is also commonly found in other locations, including shopping centers and residential areas.
The EPA's February, 2012 revised risk assessment for PCE was the result of an in-depth assessment conducted through the Integrated Risk Information System (IRIS) Program, which evaluates the human health effects that may result from exposure to environmental contaminants. Through the IRIS program, the EPA provides science-based human health assessments to support federal, state, local and other policy making activities. EPA's final IRIS assessment characterizes PCE as a "likely human carcinogen." The new risk assessment will not result in any immediate changes to Maximum Contaminant Levels (MCLs) for PCE, Superfund cleanup levels, or to the National Emission Standard for Hazardous Air Pollutants (NESHAP) for PCE. However, it is important to note that EPA intends to review its PCE NESHAP in 2014, and EPA is also reviewing its MCL for PCE. The new IRIS toxicity values will be taken into account in these reviews. Moreover, the new IRIS toxicity values for PCE are important because site-specific risk assessments utilize the IRIS toxicity values, and will now most likely result in more stringent cleanup standards for PCE-contaminated sites. Because the EPA's IRIS assessment was pending for some time before the final assessment was issued, some states have already made risk assessment standards for PCE more stringent, and have lowered permissible indoor air concentration limits. In sum, when evaluating sites that were formerly used as dry cleaners, or sites that are located close to dry cleaners, EPA's revised risk assessment for PCE will be an important consideration, especially in connection with indoor air or vapor intrusion issues.