Intersubject Variability of Risk from Perchlorate in Community Water Supplies

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.

A review of perchlorate occurrence in public drinking water systems

“…RfDs are traditionally based on the no‐observed‐adverse‐effect level (NOAEL) and not the NOEL. By definition a NOAEL is an adverse effect equal to or higher than a NOEL when the effect used to establish the NOEL is a precursor to the adverse effect of interest in establishing a NOAEL (Crawford‐Brown et al, 2006). Even though the NOEL is considered a more conservative threshold for establishing an RfD, this approach has been criticized in the case of perchlorate as not being sufficiently protective of human health (Ginsberg et al, 2005).…”

On the Distributional Implications of Safe Drinking Water Standards

“…These questions address a household’s ability to meet essential expenses such as rent, utility, and medical bills; the ability to see a doctor or dentist as needed; and the adequacy of food availability. Based on the Bauman (1998) SIPP analysis, and similar hardship or financial distress studies, a hierarchy of household necessities can be constructed as shown in Figure 1 (Crawford-Brown et al., 2009).…”

Review on Fate, Toxicity, and Remediation of Perchlorate

“…Perchlorate was detected in natural waters (rain water), raw and treated drinking water, groundwater, bottled water, open well and surface water in the United States, India, England, and Wales, China, South Korea, Japan, and Canada (Srinivasan and Viraraghavan, 2009;Tikkanen, 2006;Stetson et al, 2006;Kannan et al, 2009;McLaughlin et al, 2011;Anupama et al, 2012, Snyder et al, 2005Crawford-Brown et al, 2006;Rajagopalan et al, 2006;Stetson et al, 2006;Kimbrough and Parekh, 2007;Kosaka et al, 2007;Quinones et al, 2007;Wagner et al, 2007). In the United States, perchlorate detection in 26 states, including Puerto Rico, Mariana Islands, and in the public water systems resulted in the discontinuation of the use of most of the perchlorate-contaminated sources (Brandhuber et al, 2009).…”