| Intersubject Variability of Risk from Perchlorate in Community Water Supplies Doug Crawford-Brown,1 Bob Raucher,2 and Megan Harrod2 1Department of Environmental Sciences and Engineering and Carolina
Environmental Program, University of North Carolina at Chapel Hill, Chapel
Hill, North Carolina, USA; 2Stratus Consulting Inc., Boulder, Colorado,
USA Abstract
This article is a brief review and summary of the estimated incremental risks (increases in hazard quotient or decreases in thyroid uptake of iodine) to pregnant women (and hence their fetuses) associated with perchlorate exposure in community water supplies (CWSs) . The analysis draws on the recent health effects review published in 2005 by the National Research Council (NRC) . We focus on the potential level of risk borne by the NRC-identified most sensitive subpopulation (pregnant women and hence their fetuses) . Other members of the population should be at a level of risk below that calculated here, and so protection of the sensitive subpopulation would protect the general public health. The analysis examines the intersubject distribution of risks to this sensitive subpopulation at various potential drinking water concentrations of perchlorate and also draws on estimates of the national occurrence of perchlorate in U.S. CWSs to estimate the variability of risks under defined regulatory scenarios. Results suggest that maximum contaminant levels (MCLs) of up to 24.5 µg/L should pose little or no incremental risk to the large majority of individuals in the most sensitive subpopulations exposed in the United States at current levels of perchlorate in water. The protectiveness of an MCL of 24.5 µg/L depends, however, on whether the study subjects in the health effects data used here may be assumed to have been exposed to background (non-drinking water) contributions of perchlorate. Key words: Monte Carlo analysis, perchlorate, risk, sensitive subpopulations, water. Environ Health Perspect 114:975–979 (2006) . doi:10.1289/ehp.8459 available via http://dx.doi.org/ [Online 16 March 2006]
Address correspondence to D. Crawford-Brown, CB #1105, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-1105 USA. Telephone: (919) 966-6026. Fax: (919) 966-9920. E-mail: douglas_crawford-brown@unc.edu Funding for this project was provided by the Water Industry Technical Action Fund (WITAF) . WITAF is administered by American Water Works Association and is funded through member dues. WITAF funds information collection and analysis and other activities in support of sound and effective legislation, regulation, and drinking water policies and programs. All authors have performed contract consulting work on the risks of perchlorate in national drinking water regulatory deliberations. This consulting was funded by the American Water Works Association. Received 1 July 2005 ; accepted 16 March 2006. The full version of this article is available for free in HTML or PDF formats. |
