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Ruthann Rudel, Laura Perovich, Accurate Risk-Based Chemical Screening Relies on Robust Exposure Estimates, Toxicological Sciences, Volume 128, Issue 1, July 2012, Pages 295–296, https://doi.org/10.1093/toxsci/kfs143
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The massive undertaking reported in Wetmore et al. (2012) represents an important step forward as we integrate innovative in vitro chemical screening efforts such as ToxCast into risk assessment approaches. However, the authors overstate the degree to which their exposure estimates represent the “highest estimated U.S. population exposures” and consequently underestimate the number of chemicals for which current exposures exceed levels associated with biological activity.
In this study, the researchers estimated human oral doses expected to produce steady-state blood concentrations at which ToxCast chemicals were active in vitro. They then compared these “active” doses with estimates of human exposure that they characterized as the “highest estimated U.S. population exposures” and the “estimated upper limit of human exposure.” These estimates came primarily not only from pesticide registration documents but also from exposure surveillance data in National Health and Nutrition Examination Survey (NHANES). The authors attempted to capture higher exposures of susceptible subpopulations by selecting the 95th percentile estimates from subgroups presented in the Centers for Disease Control (CDC) exposure report (2009) and characterized these exposures as representing “most highly exposed subpopulations” in Figure 4B and the study abstract.
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