Perchlorate (technically, ammonium perchlorate) is a potent simple chemical compound of chlorine and oxygen that disrupts thyroid function by interfering with uptake of iodine. How does rocket fuel get into us? Through water (depending where you live) and produce, such as lettuce irrigated with water contaminated with perchlorate.
The major source of perchlorate contamination is a former manufacturing site in Nevada. According to one estimate, 21 million pounds of perchlorate salts seeped into surface and underground waters outside Las Vegas, and 880pounds per day flow into Lake Meade. Some of this perchlorate ends up in lettuce grown in the Imperial Valley, far to the south. Somehow, it also gets into municipal water supplies, probably from military bases. The FDA found perchlorate in milk and lettuce in 15 states across the U.S. It has also been found in drinking water in 35 states, at levels of at least 4 ppb. Perchlorate is not a naturally occurring chemical, except in saltpeter deposits in Chile.
We seldom hear about diseases of the thyroid gland, because the major problem – goiter – has been prevented by the addition of iodine to table salt. Even if the thyroid gland has to be removed, a person can function quite well by simply taking a supplement of thyroxin, the hormone secreted by the thyroid gland. Perchlorate in the body probably does not show itself by even a small goiter; its effect is more likely to be upon metabolism. Thyroxin is the ultimate regulator of metabolism: it influences carbohydrate metabolism, protein synthesis, and cardiovascular, kidney, and brain function. Inadequate levels of thyroxin in babies inhibit normal development, and low levels in adults result in mental slowness, weight gain, depression, and fatigue. Subtle effects of poor thyroid function in children due to the effect of ingested perchlorates could be easily missed. Developing fetuses and newborns are particularly vulnerable to its effects.
A 2006 Center for Disease Control survey of 1,100 women indicated that perchlorate exposure may have caused decreases in critical thyroid hormone levels, especially the 36 percent of U.S. women whose iodide intake is on the low side. Based on that data, the Environmental working Group estimated that as many as 44 million women who are pregnant, thyroid deficient or have low iodine levels, are at heightened risk from exposure to the chemical. A 2008 University of Texas research team study found that perchlorate inhibits the transport of iodine through human breast milk. Breast-fed infants are completely dependent on maternal iodine, the building block for thyroid hormones that control brain development. The Texas study suggests infants are actually being contaminated with perchlorate and denied iodine, a double-whammy that could lead to subtle IQ and developmental deficits.
As of April 2005 no enforceable federal standard had been set. In February 2011 the EPA announced that it intends to regulate the amount of perchlorate in drinking water. (It may take two years to enact a regulation.) The National Research Council estimated a safe dose as 0.7 micrograms per kilogram of body weight per day, and from this number the Environmental Working Group and the National Resources Defense Council recommended a drinking water standard between 1 and 4 ppb – disturbingly close to the measured levels in 35 states.
Common sense and the Precautionary Principle should tell us to check with our water provider about the possible presence of perchlorate.
The Precautionary Principle states, “Instead of asking ‘How much harm is acceptable?’ one should ask, ‘How little harm is possible?”