Scientific Panel Decides Against Adding Perchlorate to Proposition 65 List of Toxic Chemicals
Release No. 05-04
Contact: Allan Hirsch
(916) 324-0995
SACRAMENTO – An independent scientific panel today decided against adding perchlorate to the Proposition 65 list of chemicals known to the State of California to cause birth defects or other reproductive harm.
The state's Developmental and Reproductive Toxicant (DART) Identification Committee, a panel of independent scientists administered by the California Environmental Protection Agency's Office of Environmental Health Hazard Assessment (OEHHA), concluded that available scientific information on perchlorate was not sufficient for placing the substance on the Proposition 65 list.
Perchlorate is primarily produced for use in rocket fuel, explosives, fireworks, road flares and air-bag inflation systems. The chemical has been found in a number of California drinking water sources. Studies have also detected perchlorate in samples of lettuce and other leafy vegetables, and samples of dairy milk and human breast milk.
The DART Identification Committee's evaluation of perchlorate was performed in accordance with Proposition 65, which California voters approved in 1986. The statute requires the state to publish and periodically update a list of chemicals that are known to cause cancer, birth defects or other reproductive harm. Businesses that knowingly cause exposures to listed chemicals must provide warnings. Proposition 65 warnings are common throughout California. The statute also bans the discharge of significant amounts of listed substances into drinking water sources. OEHHA is the lead agency for implementation of Proposition 65.
Even though evidence of a substance's adverse health effects may be considerable, Proposition 65 says the committee can list a substance only if it determines the substance has been “clearly shown” to cause reproductive toxicity. A decision that a substance falls short of the “clearly shown” standard does not mean that the committee believes the substance to be non-toxic. Substances that are not listed under Proposition 65 may still be subject to regulation under other state environmental programs.
The committee consists of scientists with expertise in disciplines such as toxicology, epidemiology and medicine. Committee members are appointed by the Governor.
The DART committee decided in 2002 to consider the listing of perchlorate following formal requests by several environmental groups. OEHHA provided the committee with its 2004 assessment of perchlorate as a drinking water contaminant, which contains an extensive compilation of the scientific literature on perchlorate's health effects. OEHHA also provided the committee with the comprehensive January 2005 review of perchlorate published by the National Academy of Sciences, and several original studies of perchlorate. OEHHA does not make recommendations or take positions on the listing of chemicals under consideration by the committee.
When ingested at significant levels, perchlorate can disrupt the proper functioning of the thyroid gland (a butterfly-shaped gland in the throat), which regulates the body's metabolism and physical growth. Certain populations, such as pregnant women and their fetuses, may be particularly susceptible to adverse health effects when thyroid disruption persists. There is evidence that impairment of thyroid function in pregnant women may result in delayed development and decreased learning capability of the fetus.
The committee's decision will have no effect on the state's regulation of perchlorate under the California Safe Drinking Water Act. Like many environmental laws, the drinking water act recognizes the need to regulate contaminants based on highly suggestive evidence of their health effects. The act requires OEHHA to set public health goals (PHGs) for perchlorate and other contaminants at a level that is “not anticipated” to cause adverse health effects, based on an assessment of available information. OEHHA's PHG for perchlorate, published in its 2004 assessment of the substance, is currently guiding the development of a state perchlorate drinking water standard by the Department of Health Services. California's water-quality regulators will continue to require cleanups of perchlorate contamination where needed.