Rocket Fuel Contaminant Found In Women's Breast MilkFeb 23, 2005 | San Francisco Chronicle A team of Texas Tech University researchers has found a contaminant from rocket fuel in women's breast milk at five times the average level found in dairy milk.
This first study in breast milk of perchlorate, a chemical that interferes with the thyroid, indicates that the majority of breast-feeding infants would be exceeding the safe daily dose set by the National Academy of Sciences.
The peer-reviewed data published Tuesday in the journal Environmental Science & Technology reported perchlorate in 36 milk samples from women in 18 states and in all but one of 47 cow milk samples from 11 states.
The average level in breast milk was 10.5 parts per billion, with a high of 92 ppb, while the average in cow's milk was 2 ppb with a high of 11 ppb.
Other studies of cow's milk including by Texas Tech and by the Food and Drug Administration have found perchlorate in cow's milk from 5 to 6 ppb. The levels vary depending on the cow's diet at different times of the year.
Perchlorate, a salt, can impair a person's ability to take up iodide, a form of iodine and the building block of thyroid hormones that control brain development. High levels of perchlorate in the body also may reduce the amount of iodide in breast milk.
"Perchlorate is not a toxic metal like mercury or lead,'' said chemist Purnendu K. Dasgupta, an author. "Its only effect is to deprive the human body of iodide."
The need for iodide is particularly important for infants, Dasgupta said. "The infant has only a 24-hour store of iodide, compared to an adult, who has enough to make thyroid hormone for months. If you inhibit an infant's iodide in a significant manner for any significant length of time, you're going to cause problems.''
The nutritional importance of iodine for pregnant and nursing women is well documented. Physicians recommend certain levels in supplements and such foods as iodized salt, kelp, seaweed and crustaceans and other seafood.
Last week, the U.S. Environmental Protection Agency adopted a safety dose for perchlorate set by the National Academy of Sciences then approved a "drinking water equivalent level'' of 24 ppb.
That, however, is not an enforceable standard, and some environmental groups criticized the agency's number, saying it was geared to protect a 156 pound person drinking 2 liters of water a day and not to protect infants and children. Also, the number considers exposure to perchlorate only from drinking water and doesn't take into account exposure from food.
The EPA and the state of California have not set enforceable drinking water standards for perchlorate. California set a public health goal of 6 ppb last year, which the state Department of Health Services will consider when developing a drinking-water standard within the year.
Environmentalists immediately responded to the new study by saying it should force the federal EPA to adopt a drinking-water standard for perchlorate and one that is strict enough to protect infants. They want a standard of 1 ppb.
Renee Sharp, a biologist in Oakland with Environmental Working Group, which does research into contaminants in consumer products and food, called the study "highly significant because it shows that perchlorate is pervasive in women's breast milk, often at high levels.''
The federal and state regulators saw the study results for the first time Tuesday.
Rich Hood, director of the EPA's national press office in Washington, D.C. , said, "We're not going to be able to comment on the Texas Tech study. The EPA scientists and researchers are looking at the study. They want to determine what our appropriate response ought to be.''
In Sacramento, Allan Hirsch, a spokesman for the state EPA, said, "We need to sit down and look at it.''
The strictness of future standards could force cleanups at toxic sites nationwide. Sources of perchlorate include rocket fuel from military and industrial plants, some nitrate fertilizers and natural rock deposits.
Perchlorate has been found in the Colorado River and other water bodies, drinking-water supplies, cow's milk, bottled water, and lettuce and other vegetables nationwide by Texas Tech, the FDA and the Environmental Working Group. Women probably get perchlorate in their bodies from consuming contaminated food and water.
Cows have lower levels of perchlorate in their milk than women because they produce six times more milk for the food they eat. The amount of milk dilutes the contaminant, scientists say.