Perchlorate Affects Thyroid Function in Women
Mitch Kennedy, ND
Perchlorate, an oxidizer in solid rocket fuel, is widely found in groundwater, drinking water, milk, vegetables, fruit, grain and forage crops. Large doses of perchlorate have been shown to inhibit iodide uptake and reduce thyroid hormone production, which can contribute to metabolic problems in adults and abnormal neurodevelopment during gestation and infancy. Now, researchers at the Centers for Disease Control show that U.S. women with low iodine intake may be at risk for reduced thyroid function due to perchlorate exposure.
The study reviewed data on 2,299 men and women ages 12 and older for relationships between urine perchlorate concentrations and blood levels of the thyroid hormones thyroxine (T4) and thyroid-stimulating hormone (TSH), which stimulates T4. Urinary perchlorate was a significant predictor of thyroid hormone levels in women, but not in men. Women were then categorized into “sufficient” and “low” iodine groups (using the World Health Organization recommended threshold of 100µg/L urinary iodine). Researchers found a strong relationship between perchlorate concentrations and both T4 and TSH in the low-iodine group. This relationship was consistent with what would be expected if perchlorate were inhibiting iodine uptake to such an extent that it interfered with thyroid hormone production.
In the U.S., 36% of women have urinary iodine levels below 100µg/L. In addition, the perchlorate doses seen to cause effects in this study are well below the 24.5ppb reference dose recommended in 2005 by a National Academy of Sciences panel.
Source: Environmental Health Perspectives, 114(12), December 2006.
Mitch Kennedy, ND has a family practice in Avon, CT, and is the first ND with clinical privileges at the University of Connecticut, a teaching hospital. Before graduation from Southwest College, Kennedy earned an international reputation as a leader in pollution prevention, showing industries around the world how preventing pollution saves money
