Reprinted with permission from The National Clothesline:
The Environmental Protection Agency has posted its final assessment of the human health effects that may result from exposure to perchloroethylene. The document becomes part of EPA’s Integrated Risk Information System (IRIS) database that is used by the agency and other government regulators for setting standards for exposure to chemicals. In its final assessment, perc is designated as a “likely human carcinogen,” just as it was in a draft assessment that EPA released in 2008. Since then, the draft underwent an extensive peer review by panel of independent scientists who concurred on the carcinogen designation, which places perc in the second highest of five categories under EPA’s cancer assessment guidelines and represents an elevation of EPA’s official evaluation of perc’s cancer risk. Previously, EPA considered perc in a category between a “possible” and “probable” cancer risk. On one topic of concern to the dry-cleaning industry, EPA had positive words. The agency said it “does not believe that wearing clothes cleaned with perc pose a risk of concern.” That is contrary to warnings by some consumer and environmental groups over the years that wearing dry-cleaned clothes could cause a cancer risk.
EPA also addressed whether is safe to work around perc in a dry-cleaning plant. Occupational Safety and Health Administration regulations have set limits for permissible workplace exposures to perc, the agency pointed out, adding that its clean-air regulations require control of perc emissions, which has reduced the amount of perc released from dry-cleaning plants.“The use of newer dry-cleaning machines (dry-to-dry, closed looped) greatly reduce the amount of perc released into the air inside the shop as well as outdoors, resulting in cost savings since more perc is recovered for reuse, as well as safer working conditions and a cleaner environment,” EPA said. Still, the agency noted, “there may be an increased potential risk for some dry cleaning workers because people who work in dry-cleaning shops are expected to have the highest exposures to perc.”“As with all health effects,” EPA said, “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.”Regarding non-cancer health effects, EPA said “at certain levels over a sustained period, exposure to perc can cause adverse non-cancer effects on the human nervous system. Long-term exposure to perc can also pose a potential human health hazard to reproduction and development, and to the kidney, liver, immune and hematologic systems.“The risk of any non-cancer health effects from perc exposure depends on the amount of perc a person is exposed to and how long the exposure lasts. People exposed to high levels of perc, even for brief periods, may experience symptoms such as dizziness, fatigue, headaches, confusion, nausea, and skin, lung, eye and mucous membrane irritation.”The impact of the assessment remains to be seen but it could be felt in several ways. EPA explained those impacts in a Fact Sheet released in conjunction with the IRIS assessment.
EPA will consider the assessment when it next reviews the National Emission Standards for Hazardous Air Pollutants in 2014.EPA’s Office of Solid Waste and Emergency Response will continue to use the maximum contaminant level of 5 parts per billion as the remediation goal for groundwater that may be used as a drinking water supply at Superfund sites. The new IRIS toxicity values will be used to derive cleanup levels for indoor air contaminated by vapor intrusion. Previously the Superfund program used more stringent cleanup levels based on California’s state 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,” EPA said.EPA decided to revise the federal Maximum Contaminant Level for perc in 2010 and intends to address the perc MCL as part of a category of carcinogenic volatile organic compounds (VOCs). EPA expects to initiate regulatory efforts to begin addressing carcinogenic VOCs soon, but it will take four to five years to issue new rules. The Halogenated Solvents Industry Alliance, which represents manufacturers and suppliers of perc and other halogenated solvents, said it “welcomes the completion of the IRIS process.”“We are pleased that EPA has completed the review and removed some of the uncertainties related to evaluating human health exposures to the solvent, and also appreciate EPA’s reassurance that wearing clothes dry-cleaned with perchloroethylene is not a human health concern,” HSIA said
John Bell, HSIA Director of Scientific Programs, said that while EPA “took into account the comments it received from the National Research Council during its 2008 review of the document, the agency’s report reveals inconsistencies with the approach used to assess the cancer risks from trichloroethylene.”He noted that “while EPA has indicated it is considering a new Maximum Contaminant Level as low as 0.05 parts per billion (ppb), this IRIS review establishes a negligible human health risk at 20 ppb or higher.”HSIA reiterated its long-held position that perc “represents no harm to the environment or risks to human health when used and handled appropriately.”