EPA draft puts cloud over perc
A draft toxicological review of perchloroethylene by the Environmental Protection Agency casts a shadow over the long-range future
of the drycleaning solvent.
The draft is one step in a review process to update information on perc for the
Integrated Risk Assessment System (IRIS), a database of human health effects
that that could be caused by exposure to various substances. The information is
used in risk assessments, decision-making and regulatory activities.
Addressed in the new draft are potential cancer and non-cancer human health
effects that may result from perc exposure.
On cancer risk, the draft suggests that perc should be considered a likely human
carcinogen, which would place it in the second highest of five categories under
EPA’s cancer assessment guidelines, between the highest risk category “carcinogenic to humans,” and the third highest “suggestive evidence of carcinogenic approval.”
This would represent an elevation of EPA’s official evaluation of perc’s cancer risk. Previously under old guidelines, perc was considered in between a
“possible” and “probable” cancer risk.
In an e-mail to its members last month, the Drycleaning and Laundry Institute
warned that the new classification could have a devastating impact on the
industry.
“This would effectively raise the EPA’s risk assessment of the chemical leading to tougher clean-up standards, and
possibly stricter worker exposure standards,” said Mary Scalco, senior vice president of DLI.
While the draft notes that a causal association between perc exposure and cancer
has not been definitively established, a number of studies have shown a
positive association between perc exposure and various cancers. Thus, the draft
does not rule out the possibility of no cancer risk, but considers that
possibility unlikely.
The draft also addresses concerns for non-cancer health effects of perc
exposure, including effects on liver, kidneys, the developing fetus and
neurobehavorial consequences.
Release of the draft on June 28 started a 90-day public comment period which
ends Sept. 24.
Those comments, along with the draft itself, will be submitted to an external
review panel which could hold its first meeting this fall.
The peer review is expected to take 15 months. EPA then will complete its
assessment based on the expert peer review and public comments and include it
on IRIS. The earliest this could occur in that scenario would be in 2010.
The Halogenated Solvents Industry Alliance, which represents perc producers, said in a statement that it “looks forward to participating in the public discussion of the newly released
draft of the health assessment.”
HSIA has sponsored a number of studies on perc, including an epidemiology study
of drycleaning workers in the Nordic countries that found no evidence of an
increased cancer risk related to perc exposure.
Of all the studies of workers exposed to perc, HSIA said the Nordic study was “the first to compare cancer incidence among exposed workers with those in a
similar socioeconomic group (i.e. laundry workers)” and represented the largest group of drycleaning workers ever studied.
HSIA noted that it also 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.
“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,” HSIA said, noting that “this contamination results primarily from historic disposal practices that have
long since been discontinued.”
