EPA’s draft risk evaluation of trichloroethylene contains major scientific flaws that understate the chemical’s risk and demand robust review

Richard Denison, Ph.D., is a Lead Senior Scientist.

Yesterday Environmental Defense Fund (EDF) filed comments on the Environmental Protection Agency’s draft risk evaluation for the highly toxic chemical trichloroethylene, or TCE.

This draft, readers will recall, is the document that the Trump White House forced EPA to dramatically weaken just prior to public release, as reported in detail by Elizabeth Shogren of Reveal News.

It is also the document that EPA seems intent on subjecting to a rushed peer review next week in a 4-day virtual meeting of the Scientific Advisory Committee on Chemicals (SACC) – despite numerous reasons why, in the midst of the current COVID-19 public health crisis, such a meeting simply will not provide the robust scientific review that this draft warrants.  EDF has urged EPA to postpone the SACC review so that it can be done under circumstances that are conducive to a proper review and fair to SACC members and stakeholders who would like to participate.

EDF submitted comments yesterday in order to meet the very tight deadline EPA set for comments if they are to be considered by the SACC.  Our comments raise numerous scientific deficiencies in EPA’s draft.  These flaws arise from a host of unwarranted and unsupported assumptions and methodological approaches that systematically lead EPA to understate the risks posed by this chemical to pregnant women, infants and children; to workers; to consumers; to the public; and to the environment.

Exposure to TCE is ubiquitous, coming from ambient and indoor air, vapor intrusion from contaminated sites, groundwater and drinking water wells, and food – yet EPA’s draft ignores or downplays each of these exposure sources and pathways.

It is vital that the current public health crisis caused by COVID-19 not be allowed to compromise the quality and integrity of scientific assessments of other critical public health risks we face.

Below I summarize some of the major concerns in EPA’s draft that we address in detail in our comments

Exclusion of known uses and exposures:  Once again, EPA has abdicated its responsibility under TSCA to identify and evaluate the risks the chemical presents to the general population, by excluding from its risk evaluation conditions of use and exposures that are known or reasonably foreseen, including exposures from releases of TCE to air, water, and land.  EPA has also failed to consider exposure to background levels of TCE.  See section 2 of our comments.

Insufficient consideration of vulnerable subpopulations: EPA has not met its mandatory duty under TSCA to thoroughly identify and evaluate the risks to vulnerable subpopulations.  These include, in addition to workers: subpopulations that are more susceptible to TCE exposure, including pregnant women and the developing fetus and diseased subpopulations including those managing kidney and liver disease; as well as consumers and others who may be at risk of cancer from acute exposures.  See sections 1.A. and 4.A. of our comments.

Failure to protect against the most sensitive endpoint, fetal cardiac malformations:  EPA’s reliance on immune-related endpoints instead of fetal cardiac malformations for its determinations of acute and chronic risk deviates from scientific best practices, defies requirements under the law, ignores longstanding agency policy, and is not sufficiently protective of public health.  See sections 4.C., D. and E. of our comments.

Underestimation of occupational risks:  Of particular concern is the extent to which EPA has underestimated occupational risks.  EDF has analyzed each of the individual risk estimates EPA has made in this draft risk evaluation, which is presented in sections 5.A. and 7.A. of these comments.  EDF’s analyses identify and quantify several major ways in which EPA has underestimated occupational risks, including through: EPA’s unsupported assumptions regarding worker use of personal protective equipment in many scenarios; its use of a cancer risk level for workers that fails to protect them as a vulnerable subpopulation as required by TSCA; its failure to consider combined exposures of workers from multiple sources; and its failure to identify unreasonable risks for the most highly exposed (and hence especially vulnerable) occupational non-users (ONUs).  EPA’s exposure assessment has underestimated occupational exposures.  See sections 5.A, 5.B., and 7.A. of our comments.

Dismissal of risk by invoking uncertainty:  EPA invokes uncertainty as an unwarranted basis for ignoring risks it has identified to the environment and to ONUs, and for not accounting for combined exposures to TCE.  See sections 5.B.i., 5.E.i., 7.A.iii., and 7.B. of our comments.

Failure to adequately evaluate environmental risks of TCE release and exposure:  EPA has over-relied on predictions from physical-chemical properties and unwarranted assumptions to ignore or underestimate environmental risks, including to aquatic, sediment, and terrestrial organisms,  EPA has also ignored available data on environmental releases.  See section 6 of our comments.

Use of a flawed systematic review approach:  EPA has continued to use its flawed TSCA systematic review approach that inappropriately downgrades epidemiological evidence, fails to provide and utilize a pre-established methodology for evidence integration, and selectively includes or excludes studies in a manner that reveals inconsistency and bias. See section 8 of our comments.


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