Response to the comments of Runyan et al. on “Trichloroethylene in drinking water throughout gestation did not produce congenital heart defects in Sprague Dawley rats”
Abstract
To the Editor: As stated in our Introduction, DeSesso et al. (2019) attempted to replicate the Johnson, Goldberg, Mays, and Dawson (2003) trichloroethylene (TCE) drinking water study in pregnant rats, which reported “abnormal hearts” among offspring of treated dams. The Johnson et al. study has been heavily criticized (e.g., Hardin, Kelman, & Brent, 2005; Watson, Jacobson, Williams, Howard, & DeSesso, 2006) for design flaws (e.g., noncontemporary controls; data collected unevenly over several years; nonstandard microdissections of fetal hearts) as detailed in our article. Fetal cardiac defects were not observed in two high quality, robust studies (Carney, Thorsrud, Dugard, & Zablotny, 2006; Fisher et al., 2001) conducted according to contemporary guidance for developmental toxicity. Nevertheless, U.S. EPA has used the fetal “abnormal hearts” of Johnson et al., in part, as the basis for the TCE reference concentration (RfC)/reference dose (RfD). Thus, our study was designed to approximate Johnson et al. but enhanced to correct deficiencies and meet current EPA test guidance and data quality standards. The fetal cardiac findings did not repeat in our apical study, consistent with negative findings in oral gavage (Fisher et al., 2001) and inhalation (Carney et al., 2006) studies. These data suggest that the Johnson et al. results are spurious and not reproducible. Concerning Runyan et al.'s speculations (with no supporting data) regarding the irreproducibility of the Johnson et…
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