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Commentary
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The NAS Perchlorate Review: Questions Remain about the Perchlorate RfD Gary Ginsberg1 and Deborah Rice2 1Connecticut Department of Public Health, Hartford, Connecticut, USA; 2Maine Bureau of Health, Augusta, Maine, USA Abstract Human exposure to perchlorate is commonplace because it is a contaminant of drinking water, certain foods, and breast milk. The U.S. Environmental Protection Agency (EPA) conducted a perchlorate risk assessment in 2002 that yielded a reference dose (RfD) based on both the animal and human toxicology data. This assessment has been superceded by a recent National Academy of Science (NAS) review that derived a perchlorate RfD that is 20-fold greater (less stringent) than that derived by the U.S. EPA in 2002. The NAS-derived RfD was put on the U.S. EPA's Integrated Risk Information System (IRIS) database very quickly and with no further public review. In this commentary we raise concerns about the NAS approach to RfD development in three areas of toxicity assessment: the dose that the NAS described as a no observable adverse-effect level is actually associated with perchlorate-induced effects ; consideration of uncertainties was insufficient ; and the NAS considered the inhibition of iodine uptake to be a nonadverse effect. We conclude that risk assessors should carefully evaluate whether the IRIS RfD is the most appropriate value for assessing perchlorate risk. Key words: NAS, neurodevelopmental, perchlorate, RfD, thyroid hormone. Environ Health Perspect 113:1117-1119 (2005) . doi:10.1289/ehp.8254 available via http://dx.doi.org/ [Online 25 May 2005] Address correspondence to G. Ginsberg, 410 Capitol St., Mail Stop 11CHA, Hartford, CT 06134 USA. Telephone: (860) 509-7750. Fax: (860) 509-7785. E-mail: gary.ginsberg@po.state.ct.us The authors declare they have no competing financial interests. Received 28 April 2005 ; accepted 24 May 2005. An erratum was published in Environ Health Perspect 113:A732 (2005) . The full version of this article is available for free in HTML or PDF formats. |
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