HSIA Statement on Draft IRIS Assessment for PERC
The Halogenated Solvents Industry Alliance, Inc. (HSIA) looks forward to participating in the public discussion of the newly released draft of the health assessment for perchloroethylene (“perc”) for the US Environmental Protection Agency’s (EPA) Integrated Risk Information System (IRIS).  HSIA represents the manufacturers of perc and has sponsored a number of studies on the solvent, including an epidemiology study of drycleaning workers in the Nordic countries (Lynge et al, 2006) that found no evidence of an increased cancer risk related to perc exposure.

Perc is a common cleaning solvent with a 50-year history of use by a wide variety of industries.  It currently is used by an estimated 70 percent of the nation’s drycleaners.  EPA’s draft assessment was released for public comment in late June and will be reviewed by a special panel of the National Academy of Sciences starting in the fall.  It is the first such IRIS assessment to incorporate a comprehensive analysis of associated uncertainties.

Although a number of studies of workers exposed to perc have been conducted, the HSIA-sponsored study by Lynge et al is the first to compare cancer incidence among exposed workers with those in a similar socioeconomic group (i.e., laundry workers).  The Lynge study also included all drycleaning workers in the four Nordic countries and represents the largest group of drycleaning workers ever studied.  In addition, HSIA has sponsored several toxicology studies as part of voluntary agreements with EPA and the Agency for Toxic Substances and Disease Registry, including studies of the potential developmental, neurotoxic, and immunotoxic effects of perc.

Demand for perc by drycleaners has declined by 50 percent since 2000 (90 percent since 1990) as cleaners have installed more efficient equipment and work practices in response to federal and state requirements.  Perc also is used in precision cleaning and automotive aerosols, but its primary use (~70 percent of total demand) is as a chemical intermediate in the production of hydrofluorocarbons (HFCs) that have replaced ozone-depleting compounds previously used in air conditioning and refrigeration systems.

National emission standards have been in place for drycleaning and degreasing operations using perc since the mid 1990s.  Both standards were recently amended to include additional requirements.  A drinking water standard of 5 parts per billion (ppb) was established for perc in 1991.  EPA’s review of the standard in 2002-03 determined that it was “not appropriate for revision” at the time.

Although concerns about ambient and occupational exposures to perc have been largely addressed, questions remain about the potential for exposure from drinking water and from vapor intrusion caused by contaminated soil and groundwater.  This contamination results primarily from historic disposal practices that have long since been discontinued.  Potential exposures due to historical contamination are many times lower than levels experienced in the workplace.