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WASHINGTON (June 3, 2020) – The American Chemistry Council (ACC) supports the consensus conclusion reached by the Science Advisory Committee on Chemicals (SACC) that controversial research suggesting fetal cardiac defects (FCDs) should not be included in EPA’s risk characterization of trichloroethylene (TCE). The SACC released its final report on June 2.

From the start, ACC agreed with numerous members of the SACC that the Johnson et al. (2003) study is an outlier, is not scientifically sound, and should not be included in the final TSCA risk evaluation. Central to this issue is the fact that the only evidence linking FCDs to TCE exposure comes from one laboratory, which reported results that numerous other efforts have been unable to replicate – including a study with Dr. Johnson herself brought in to advise and replicate the precise methodology used in 2003. But despite the attempts, the 2003 Johnson findings were not replicated, and there were no adverse effects seen at even higher doses of TCE.

The SACC, composed of independent scientists from academia, government, and industry, made it clear that it felt the same way: “The cardiac effects reported by Johnson et al., seen at trichloroethylene exposure levels that are orders of magnitude lower than no-effects levels of other studies, have not been seen even at much higher doses in other investigations of trichloroethylene where heart effects were also examined.”

In addition to the lack of validation of the results from the Johnson study, there are a number of legitimate questions about how the study itself was conducted that caused the SACC members to consider it “unacceptable for risk assessment” under EPA’s data quality guidelines. The inclusion of data from this study creates confusion about TCE exposure levels and should not be used to develop risk values.

While some epidemiological data suggest some evidence of cardiac effects, “several Committee members suggested down-weighting these results due to study design weaknesses that detract from the studies’ reliability and relevance (e.g., exposures to multiple solvents, uncertainty of where pregnant women were residing during critical time period for fetal cardiac development),” according to the committee.

Beyond the fact that no other organization has been able to reproduce the Johnson study’s conclusions, multiple SACC members made legitimate and credible arguments critical of its study protocol, procedures, and controls, and EPA heard these criticisms from the committee at a meeting on March 27.

In its TSCA risk evaluation, EPA should focus on inhalation studies, as the route of exposure is of greater relevance to the conditions of use being evaluated. The SACC agreed, saying in its report that TCE inhalation studies, “notably that of Carney et al.,” which underwent a rigorous peer review process by several federal agencies, should receive greater attention.

In the March 2020 meeting between EPA and the SACC, committee members expressed concerns that EPA was relying exclusively on a study that came to conclusions not found in numerous scientific reviews of TCE, including those conducted by the National Academy of Sciences and California’s Office of Environmental Health Hazard Assessment, as well as industry scientists.

Committee member James Bruckner, PhD, University of Georgia, told EPA that the study has multiple problems. He argued that the way in which it was conducted was faulty, specifically describing it as an unreliable combination of experiments conducted years apart and then combined to reach the fetal cardiac risk conclusion.

Bruckner also cited a follow-up study exposing lab rats to significant doses of TCE that attempted to replicate the Johnson findings.

Another SACC member, Charles Vorhees, PhD, University of Cincinnati College of Medicine, called the Johnson study “the strangest experimental design I’ve ever seen. If someone brought me that … I’d say it’s an improper design.” He continued by noting that “the Johnson data are outlier data. … They haven‘t been replicated. I just think carrying them forward into the latter parts of the [draft risk evaluation] is really, sort of, pushing the boundaries, based on the problematic aspects of those data.”

Similar statements skeptical of the Johnson study were made by other SACC members.

While ACC is generally satisfied with the SACC’s conclusions regarding Johnson et al., the use of FCDs as an endpoint should also have been recommended to be stricken entirely. The SACC made very clear that it has numerous problems with the draft risk evaluation, with some of the members seeing signs of bias within EPA in favor of emphasizing the Johnson study over other efforts that came to different conclusions. The SACC’s many legitimate complaints about the Johnson study should lead EPA to eliminate the FCD conclusions from any TCE risk evaluation calculations.

EPA’s efforts to develop a risk evaluation for TCE should be methodical, thorough, transparent, and unbiased. There are credible and critical questions with regard to the risk of FCDs related to TCE exposure, and the agency should take heed of the advice and guidance provided by the SACC.

As EPA continues its work on evaluating TCE exposure risks, ACC urges a common sense and comprehensive approach that will result in a conclusion that protects the health, environmental, and economic well-being of the United States.


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