Bias in the US Environmental Protection Agency’s Baseline Health Risk Assessment Supporting the Decision to Require Dredging of PCB-Bearing Sediments from the Hudson River
Robert A. Michaels, Uriel M. Oko
CONTINUED FROM PREVIOUS POST
Purpose, Scope, and Overview
Administrative procedure under Superfund involves interested parties (‘stakeholders’), by design introducing politics into EPA administrative procedure. The present study addresses the question of whether, despite political inﬂuence, dredging is justiﬁable by the science of health risk assessment (HRA). The EPA apparently justiﬁed its decision to require dredging based upon a baseline assessment of PCB risks, not an assessment quantifying PCB risks potentially posed under dredging scenarios ~US Environmental Protection Agency, 1999, 2000a, 2000b!. An HRA should compare potential risks under speciﬁc dredging scenarios with baseline risks following completion of the demonstration dredging project. For this comparison process to be valid, baseline risks potentially posed by all relevant exposure routes, including PCB inhalation, should have been estimated in a valid and unbiased manner. The present study addresses this issue.
Selection of Parameters
The issue of bias must be addressed via evaluation of a fair, rather than a biased, selection of EPA’s parameters. A random selection of parameters is neither required nor appropriate; we focus narrowly upon mis-estimated parameters. Accordingly, our procedure was to evaluate EPA’s analysis and systematically ignore all parameters whose use by EPA was technically justiﬁed. Parameters of interest to us are not those of greatest a priori concern ~quantitatively most important in determining risk!. In our investigation, parameters that were accurately estimated were dropped from concern, no matter how important they might have been quantitatively in determining risk. We identiﬁed nine parameters whose evaluation by EPA was found to be technically deﬁcient. In short, we did not“cherry-pick”parameters to bias our analysis in a particular direction. Our analysis, of course, is veriﬁable against cited EPA documents.
TO BE CONTINUED
Michaels, RA.; and UM Oko. Bias in the US EPA baseline health risk assessment supporting the decision to require dredging of PCB-bearing sediments from the Hudson River. Environmental Practice (Cambridge University Press), 9(2):96-111, June 2007.