WASHINGTON — When the U.S. Environmental Protection Agency (EPA) posted the final health assessment for tetrachloroethylene—also known as perchloroethylene, or perc—to its Integrated Risk Information System (IRIS) database in February, it deemed the chemical to be a “likely human carcinogen.”
The assessment replaces the 1988 IRIS assessment for perc and for the first time includes a hazard characterization for cancer effects. The assessment underwent several levels of rigorous, independent peer review including: agency review, interagency review, public comment, and external peer review by the National Research Council, according to the EPA, and all major review comments were addressed.
The Halogenated Solvents Industry Alliance says 70% of U.S. commercial dry cleaners use perc; EPA estimates the total number to be 27,000. So what does this development mean for the future of the industry’s preferred solvent?
WHAT IS THE INTEGRATED RISK INFORMATION SYSTEM?
IRIS evaluates the human health effects that may result from exposure to environmental contaminants. Through this program, EPA provides science-based human health assessments to support federal, state, local and other policy-making activities. It has an online database that contains information for more than 550 chemical substances containing information on human health effects that may result from exposure to various substances in the environment.
The IRIS process consists of the development of a draft Toxicological Review for a chemical; internal and external scientific reviews of the draft document; EPA responses to review comments; and development and posting of an IRIS Summary and final Toxicological Review to EPA’s website.
EPA continues to strengthen IRIS as part of an ongoing effort to ensure the best possible science is used to protect human health and the environment, the Agency says.
In May 2009, EPA streamlined the IRIS process to increase transparency, ensure the timely publication of assessments, and reinforce independent review. In July 2011, the Agency announced further changes in response to recommendations from the National Academy of Sciences. EPA’s peer review process is designed to elicit the strongest possible critique to ensure that each final IRIS assessment reflects sound, rigorous science.
WHAT DOES THE NEW ASSESSMENT MEAN?
While EPA has determined that perc is a “likely human carcinogen,” the Agency does not believe that wearing clothes cleaned with perc pose a risk of concern.
The cancer-causing potential of perc has been extensively investigated, the EPA says. In laboratory studies, perc has been shown to cause cancer in rats and mice when they ingest or inhale it. There is also suggestive evidence, the Agency says, from several studies of workers in the laundry and drycleaning industry that perc exposure is associated with elevated risks of certain types of cancer (including bladder, non-Hodgkin lymphoma, and multiple myeloma, a cancer of the blood).
The potential for an increased risk of cancer depends on several factors, including how much perc exposure there is, how often the exposure occurs, and how long it lasts.
The toxicity values reported in the perc IRIS assessment will be considered in:
• Establishing cleanup levels at hundreds of perc-contaminated Superfund sites
The new IRIS toxicity values will be used to derive cleanup levels for indoor air contaminated by vapor intrusion, EPA says. Previously, the Superfund program derived cleanup levels for indoor air based on the California EPA toxicity values. Because the cleanup levels based on the new IRIS values will be less stringent than the ones based on the California EPA values, no additional cleanup will need to be done at any previously cleaned Superfund sites.
The Office of Solid Waste and Emergency Response (OSWER) will continue to use the Maximum Contaminant Level (MCL) of 5 ppb for perc, established by the EPA Office of Water, as the remediation goal for ground water that may be used as a drinking water supply. At Superfund sites where a state, such as California, has a more stringent standard for perc, that standard will be considered as the cleanup goal.
• Revising EPA’s MCL for perc as part of the carcinogenic volatile organic compounds group in drinking water as described in the agency’s drinking water strategy
EPA decided to revise the federal MCL for perc in 2010 and regulatory efforts for addressing carcinogenic VOCs began in March 2011. Typically, it takes about 2 to 2.5 years to develop a proposed rule and about 2 years to promulgate a final rule.
• Evaluating whether to propose additional limits on the emissions of perc into the atmosphere, since perc is considered a hazardous air pollutant under the Clean Air Act
The National Emission Standard for Hazardous Air Pollutants (NESHAP) was issued in 2006 and is in effect. EPA updated its air toxics rule that requires operators to control perc emissions at individual dry cleaners. The rule includes a phase-out of perc use at dry cleaners located in residential buildings by Dec. 21, 2020, along with requirements that already have reduced perc emissions at other dry cleaners.
The final IRIS assessment will be considered when EPA next reviews the standard in 2014.
Law firms that handle environmental protection cases alerted their clients and potential clients to the possible impact the new assessment could have, such as requiring the deactivation and/or treatment of perc-impacted water supplies that the providers may have tolerated previously, or requiring dry cleaners and perc handlers to install new equipment to comply with higher perc emissions standards.
Wednesday: Reactions from industry and others…