Scientists on Tuesday reported that perchlorate, a toxic component of rocket fuel, was contaminating virtually all samples of women's breast milk and its levels were found to be, on average, five times greater than in cow's milk.
The contaminant, which originates mostly at defense industry plants, previously had been detected in various food and water supplies around the country. But the study by Texas Tech University's Institute of Environmental and Human Health was the first to investigate breast milk.
For The Record
Los Angeles Times Thursday February 24, 2005 Home Edition Main News Part A Page 2 National Desk 1 inches; 59 words Type of Material: Correction
Perchlorate contamination -- An article in Wednesday's Section A about chemical contamination of breast milk said levels of perchlorate, a toxic component of rocket fuel, are particularly high in the lower Colorado River. The levels used to be high but are now low because a remediation system has been cleaning contaminated ground water at a now-defunct Kerr-McGee chemical plant.
The findings concern health experts because infants and fetuses are the most vulnerable to the thyroid-impairing effects of the chemical.
Breast milk from 36 women in 18 states, including California, was sampled, and all contained traces of perchlorate.
Perchlorate blocks the nutrient iodide and inhibits thyroid hormones, which are necessary for brain development and cellular growth of a fetus or infant. A baby with impaired thyroid development may have neurological defects that result in lower IQ or learning disabilities.
The researchers recommended that pregnant and nursing women block the effects of perchlorate by taking iodine supplements as a precaution.
At the levels they found in breast milk, the scientists reported that 1-month-old infants would take in enough perchlorate to exceed a safe level, called a reference dose, that was established last month by a panel of the National Academy of Sciences.
"It is obvious that the NAS safe dose ... will be exceeded for the majority of infants," the report published in the journal Environmental Science and Technology says. Some infants would ingest so much that they would exceed levels that altered the brain structure of animals in laboratory tests.
The findings come as the U.S. Environmental Protection Agency is developing an enforceable limit on the amount of perchlorate in drinking water based on the recommendations of the National Academy of Sciences panel. Currently there is no national standard.
"This is not just another study," said Renee Sharp, a senior analyst at the Environmental Working Group, which advocated a strict national standard. "It ends the questions about whether women are passing along perchlorate to their kids through breast milk, and the sky-high levels the scientists found put more than half the kids over the safe levels the NAS now recommends."
