Dry Cleaning Solvent Is Likely Carcinogen, EPA Concludes in First Update Since 1988

The Halogenated Solvents Industry Alliance thanks EPA for not trashing it too badly.

Bloomberg BNA reports:

The Environmental Protection Agency formally concluded Feb. 10 that a widely used dry cleaning solvent is a likely human carcinogen, paving the way for the agency to reconsider drinking water and other standards for the chemical.

The agency released its final assessment of perchloroethylene, or perc (CAS No. 127-18-4). That assessment had not been updated since 1988.

The agency’s decision to classify perc as a likely human carcinogen is consistent with its finding in 2008, when it released a draft assessment of perchloroethylene (32 CRR 641, 6/30/08)

The National Academies also supported that classification in a 2010 report…

The Halogenated Solvents Industry Alliance Inc., which represents companies that make perchloroethylene and other chlorinated solvents, said it is “pleased that EPA has completed the review and removed some of the uncertainties related to evaluating human health exposures to the solvent, and [we] also appreciate EPA’s reassurance that wearing clothes dry cleaned with perchloroethylene is not a human health concern”…

For More Information

EPA’s assessment of perchloroethylene is available at http://www.epa.gov/iris/toxreviews/0106tr.pdf.

EPA’s summary of that document is available at http://www.epa.gov/iris/subst/0106.htm.

2 thoughts on “Dry Cleaning Solvent Is Likely Carcinogen, EPA Concludes in First Update Since 1988”

  1. EPA asked the National Academy of Sciences to review its draft assessment, which they did–and found significant problems and disagreements which they reported to EPA…but no changes were made by EPA before releasing the IRIS report. Comments from the NSA Summary Review:


    The committee appreciates the extensive work that EPA has invested in
    the development of its draft assessment of tetrachloroethylene. However, the
    committee has identified concerns about so me of the approaches that EPA used
    to evaluate the data on tetrachloroethylene and subjects about which inadequate
    information or rationales are used to support its risk assessment—factors that
    call into question the soundness and reliability of EPA’s proposed reference
    values and cancer risk estimates for tetrachloroethylene. One of the overarching
    weaknesses of the draft assessment was a la ck of critical analys is of the data on
    which EPA relied in evaluating methodologic strengths and weaknesses. That
    lack was particularly evident in the assessment of the epidemiologic data: study
    selection and conclusions appeared to be based heavily on results that showed
    positive associations, and other data and the strengths and weaknesses of the
    selected studies were not adequately taken into consideration. The committee
    observed similar problems in its review of EPA’s evaluation of the genotoxicity
    evidence, in which preference appeared to be given to studies that reported posi-
    tive results. Specifically, EPA did not analyze studies critically with respect to
    their methodologic strengths and weaknesses, nor did it organize its discussion
    clearly to provide an integrated consideration of the weight of evidence on the
    genotoxicity of tetrachloroethylene. Other mode of action evaluations were also
    hampered in this way.
    In the sections below, the committ ee evaluates EPA’s noncancer and can-
    cer assessments of tetrachloroethylen e. The committee’s recommendations focus
    on improvements that should be made by EPA in producing its final assessment
    and on improvements that EPA should pursue in the future when tetrachloro-
    ethylene is due for another update.
    EPA provides descriptions of the relevant neurotoxicity studies, but its
    evaluation of the epidemiologic literature could be improved by providing a
    critical evaluation of the validity of study designs and evaluation of the methods
    used for data collection and analysis, which the committee judges to be most
    important in selecting key studies. EPA chose the 1995 study by Altmann et al.
    as the critical one for determining the RfC and RfD because it involved an envi-
    ronmental exposure and used a standardized computer-assisted testing battery.
    Those are reasonable bases for the choice, but they do not outweigh method-
    ologic deficiencies that seriously compromised the results of the study. Most
    important, the referent group was not appropriate. The group had more educa-
    tion than the exposed group and appeared to have pre-existing differences in
    cognitive abilities, which could account for its better test results. Evidence of
    residual confounding by education can be seen in the variability in reported re-
    sults. For example, there was no associ ation between tetrachloroethylene and
    visual evoked potentials; this is important because changes in the visual system
    and abnormalities in visual evoked potentials have been associated with tetra-
    chloroethylene and other related solvents , and they are essentially unrelated to
    education. Other limitations of the study included the lack of a rationale for ini-
    tial selection of study subjects, inadequacy of exposure ch aracterization, and
    lack of a dose-response relationship. Finally, even though the test battery was
    performed properly, some of the tests have not been well validated with regard
    to what they reveal about brain damage.
    Thus, the committee disagrees with EPA’s selection of the 1995 Altmann
    et al. study as the basis of its risk calculations. In reviewing the database, the
    committee gave greater weight to studies that had the strongest methods; it nei-
    ther chose nor excluded studies on the basi s of their results. The set of studies
    that the committee ju dged to be more appropriate for supporting the RfC and
    RfD include those of Altmann et al. (1990), Cavalleri et al. (1994), Gobba et al.
    (1998), Echeverria et al. (1995), and Boyes et al. (2009).

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