[CPEO-MEF] PERCHLORATE: Massachusetts calls for protective standard

[Lenny Siegel <lsiegel@cpeo.org>]

Drinking Water Standard for Perchlorate

Tsedash Zewdie, Clifford M. Smith, Michael Hutcheson, and Carol Rowan-West
Environmental Health Perspectives Online
July 13, 2009

Abstract

Objective: Perchlorate inhibits the uptake of iodide in the thyroid. 
Iodide is required to synthesize hormones critical to fetal and neonatal 
development. Many water supplies and foods are contaminated with 
perchlorate. Exposure standards are needed but controversial. Here we 
summarize the basis of the Massachusetts (MA) perchlorate reference dose 
(RfD) and drinking water standard (DWS), which are considerably lower 
and more health protective than related values derived by several other 
agencies. We also review information regarding perchlorate risk 
assessment and policy.

Data Sources: MA Department of Environmental Protection (DEP) 
scientists, with input from a Scientific Advisory Committee (SAC), 
assessed a wide range of perchlorate risk and exposure information. 
Health outcomes associated with iodine insufficiency were considered as 
were data on perchlorate in drinking water disinfectants.

Data Synthesis: We used a weight-of-the-evidence approach to evaluate 
perchlorate risks, paying particular attention to sensitive life-stages. 
A health protective RfD (0.07 [micro]g/kg/day) was derived using an 
uncertainty factor approach with perchlorate-induced iodide uptake 
inhibition as the point of departure. The MA DWS (2 [micro]g/L) was 
based on risk management decisions weighing information on perchlorate 
health risks and its presence in certain disinfectant solutions used to 
treat drinking water for pathogens.

Conclusions: Current data indicates that perchlorate exposures to 
sensitive life-stages attributable to drinking water should be minimized 
and supports the MA DEP perchlorate RfD and DWS. Widespread exposure to 
perchlorate and other thyroid toxicants in drinking water and foods 
suggest that more comprehensive policies to reduce overall exposures and 
enhance iodine nutrition are needed.



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To download the original, complete abstract or the entire article, see
http://www.ehponline.org/docs/2009/0900635/abstract.html

--


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
<lsiegel@cpeo.org>
http://www.cpeo.org




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