Perchlorate Levels Affect Thyroid Function, Study Finds
Many California women who have been exposed to a rocket fuel chemical that has contaminated 450 wells and other water sources in the state have suppressed thyroid function, according to a CDC study published Wednesday in the journal Environmental Health Perspectives, the Los Angeles Times reports.
According to the Department of Health Services, contaminated water sources and wells are most prevalent in Los Angeles, Orange, Riverside, San Bernardino and Sacramento counties. In August, state officials proposed a drinking water standard of six parts perchlorate per billion. Officials will hold a hearing on the proposal on Oct. 30 in Sacramento.
The federal Environmental Protection Agency also is considering imposing national drinking water standards and has set an interim goal for industrial cleanups, the Times reports.
Prolonged reductions in thyroid hormones can lead to hypothyroidism in adults and abnormal brain development in fetuses and infants, the Times reports. The chemical also has been found in milk, cheese, lettuce and other foods, and in human breast milk and baby formula, according to the Times.
Benjamin Blount of CDC's National Center for Environmental Health and colleagues analyzed thyroid hormones and perchlorate levels of 1,111 women living in the state.
According to the study:
- On average, women were ingesting 2.9 parts per billion of perchlorate -- 10 times less than the amount EPA considers safe;
- Women who were exposed to moderate or high levels of perchlorate had 8% to 33% less thyroxine -- a thyroid-regulating hormone -- than the normal range;
- The most significant reductions in the level of thyroid hormones were seen in women with iodine levels of less than 100 micrograms per liter, the minimum level the World Health Organization recommends; and
- The levels of thyroid hormones in men were not affected.
The study is available online. Note: You must have Adobe Acrobat Reader to view the report.
KPCC's "KPCC News" on Wednesday reported on the CDC study. The segment includes comments from James Pirkle, study co-author, and Renee Sharp, senior analyst for the Environmental Working Group (Setziol, "KPCC News," KPCC, 10/4). The complete segment is available online in RealPlayer.This is part of the California Healthline Daily Edition, a summary of health policy coverage from major news organizations. Sign up for an email subscription.