News Coverage
Breast milk toxin studied
Perchlorate traces raise concerns
Published February 25, 2005
A small study that found a rocket fuel chemical in breast milk drew quick reaction from California's U.S. senators Wednesday, with one calling for environmental reform and the other questioning whether all breast-feeding women should take supplements or have their milk tested.
The chemical, perchlorate, is used to make rocket fuel and explosives. Locally, it has been found in wells around Morgan Hill, near the site of a former highway flare plant. It has been linked to thyroid disorders because it inhibits the body's ability to absorb iodine -- which is critical for infants' brain development.
The study released this week suggested that the government should consider increasing the recommended daily allowance of iodine to protect against any harmful effects of perchlorate.
Sen. Barbara Boxer asked federal and California health officials to look into whether they should advise women to have their breast milk tested or take iodine supplements. A spokeswoman for Sandra Shewry, the director of the California Department of Health Services, said the agency would examine the issue. Sen. Dianne Feinstein also issued a statement calling on the government to clean up perchlorate contamination.
The study tested the breast milk of 36 women in 18 states and found perchlorate in all of them. The authors said the study, while small, suggests that perchlorate contamination may be more widespread than previously thought.
Three-quarters of the women had low levels -- less than 6 parts per billion, the level California has said is safe in drinking water. Only six were above 20 parts per billion, the level recently recommended as safe by a National Academy of Sciences panel.
Local health experts warned that far more study is needed before anyone issues sweeping changes such as universal testing or iodine supplements for pregnant or nursing women.
"To jump to the conclusion that women should measure this one chemical in their breast milk is extreme," said Dr. Ruth Shaber, director of women's health services for Kaiser Permanente-Northern California. "On the other hand, there's more and more concern about environmental exposures to toxins, not just for pregnant women and nursing babies but women with breast cancer."
Dr. Wayneab Truneh, an obstetrician-gynecologist with the Camino Medical Group, pointed out that iodine, a naturally occurring element important in maintaining thyroid function, can actually be dangerous for pregnant women at high levels.
"It's definitely not something you'd recommend as a blanket policy for women in pregnancy or who are lactating," Truneh said.
Scientists still debate what level of perchlorate is safe for humans. Of about 1,600 wells tested from Morgan Hill to Gilroy, more than 80 percent had perchlorate levels below 6 parts per billion. About 250 other wells range from 7 parts per billion to above 100 parts.
The breast milk study was conducted by researchers at Texas Tech University in Lubbock and published in the American Chemical Society's online journal Environmental Science and Technology. The researchers found some of the samples were low in iodide, an iodine compound, causing them to worry that infant brain development could be affected. The small size of the study makes it important to conduct more research before changing recommendations for pregnant and breast-feeding women, Truneh said.