2010 CPEO Military List Archive

From: Lenny Siegel <lennysiegel@gmail.com>
Date: Wed, 21 Apr 2010 20:22:05 -0700 (PDT)
Reply: cpeo-military
Subject: [CPEO-MEF] PERCHLORATE: EPA Inspector General's office reports
EPA Office of Inspector
General Scientific Analysis of Perchlorate

Report No. 10-P-0101
April 19, 2010

What We Found

EPA should conduct a cumulative risk assessment to reduce the uncertainty in characterizing the public health risk posed by perchlorate. A cumulative risk assessment is the current state-of-the-art technique for evaluating the public health risk from multiple stressors. Over the last two decades, EPA has received numerous recommendations to improve environmental risk assessments. In 1997, EPA Administrator Carol Browner issued guidance directing EPA to embrace the cumulative risk assessment approach on all future major risk assessments. Although directed to improve the environmental risk assessment process, EPA continues to rely on the outdated single chemical risk assessment approach, originally developed in 1954, to characterize the risk posed by perchlorate. The single chemical risk assessment approach fails to address known sources of scientific uncertainty, which lowers the confidence in the perchlorate RfD.

Against established EPA risk assessment procedures, EPA derived the perchlorate RfD from a nonadverse biological effect instead of an adverse effect. The perchlorate RfD protects against all human biological effects from exposure, which is a stricter public health criterion than limiting environmental exposure to protect against adverse effects in humans. This shift in risk management constitutes a significant change in environmental policy.

Based on our scientific analysis, perchlorate is only one of several chemicals that stress the thyroid's ability to uptake iodide. The other sodium iodide symporter (NIS) stressors include thiocyanate, nitrate, and the lack of iodide. All four of these NIS stressors meet EPA's risk assessment guidance for conducting a cumulative risk assessment using the dose-addition method. Our analysis implemented a cumulative risk assessment that found the following: 1) the risk from each of the four NIS stressors is not equal; 2) EPA's perchlorate RfD is conservative and protective of human health, and further reducing the perchlorate exposure below the RfD does not effectively lower risk; 3) increasing maternal total iodide intake to healthy levels will reduce the frequency and severity of permanent mental deficits in children; and 4) correcting moderate and mild iodide deficiency occurring in about 29 percent of the U.S. pregnant and nursing population is the most effective approach for reducing risk.

To download the entire report, see


Lenny Siegel
Executive Director, Center for Public Environmental Oversight
a project of the Pacific Studies Center
278-A Hope St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/961-8918

Military mailing list

  Prev by Date: [CPEO-MEF] CHEMWEAPONS, FUDS: Spring Valley (DC) Explosive Destruction System
Next by Date: [CPEO-MEF] REUSE: Cita Systems at the Pueblo Chemical Depot (CO)
  Prev by Thread: [CPEO-MEF] CHEMWEAPONS, FUDS: Spring Valley (DC) Explosive Destruction System
Next by Thread: [CPEO-MEF] REUSE: Cita Systems at the Pueblo Chemical Depot (CO)

CPEO Lists
Author Index
Date Index
Thread Index