2007 CPEO Military List Archive

From: Lenny Siegel <lsiegel@cpeo.org>
Date: 9 Jan 2007 06:41:06 -0000
Reply: cpeo-military
Subject: [CPEO-MEF] Perchlorate and Nursing infants
Evaluation of the U.S. EPA/OSWER Preliminary Remediation Goal (PRG) for Perchlorate in Groundwater:
Focus on Exposure to Nursing Infants

Gary L. Ginsberg, Dale B. Hattis, R. Thomas Zoeller and Deborah C. Rice
Environmental Health Perspectives
doi:10.1289/ehp.9533 (available at http://dx.doi.org/)
Online 11 December 2006


Background: Perchlorate is a common contaminant of drinking water and food. It competes with iodide for uptake into the thyroid, thus interfering with thyroid hormone production. U.S. EPA's Office of Solid Waste and Emergency Response set a groundwater preliminary remediation goal (PRG) of 24.5 ug/L to prevent exposure to pregnant women that would affect the fetus. This doesn't account for greater exposure that is possible in nursing infants, and for the relative source contribution (RSC), a factor normally used to lower the PRG due to non-water exposures.

Objectives: To assess whether the OSWER PRG is protective of exposures to infants from breastfeeding, and to evaluate the perchlorate RSC.

Methods: Monte Carlo analysis was used to simulate nursing infant exposures associated with the OSWER PRG when combined with background perchlorate.

Results: The PRG can lead to a 7 fold increase in breast milk concentration, causing 90% of nursing infants to exceed the RfD (average exceedance 2.8 fold). Drinking water perchlorate must be below 6.9 ug/L to keep the median, and below 1.3 ug/L to keep the 90th % nursing infant exposure below the RfD. This is 3.6-19 fold below the PRG. Analysis of biomonitoring data suggests an RSC of 0.7 for pregnant women, and 0.2 for nursing infants. Recent data from CDC suggest that the RfD itself needs to be reevaluated because of hormonal effects in the general population.

Conclusions: The OSWER PRG for perchlorate can be improved by considering infant exposures, by incorporating an RSC, and by being responsive to any changes in the RfD resulting from the new CDC data.

[Note: "ug" stands for micrograms.]

To link to this article, go to


Lenny Siegel
Director, Center for Public Environmental Oversight
c/o PSC, 278-A Hope St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/961-8918

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