Boxer Raises Questions About Perchlorate Levels After Study on Its Presence in Breast Milk

Sen. Barbara Boxer (D-Calif.) on Wednesday asked state and federal health officials to address perchlorate contamination after a Texas Tech University study found that the chemical is present in high levels in some breast milk samples, the Orange County Register reports (Bunis, Orange County Register, 2/24).

In the study, published Tuesday in the journal Environmental Science & Technology, breast milk samples of 36 women in 18 states all contained perchlorate, at an average level of 10.5 parts per billion (Kay, San Francisco Chronicle, 2/24).

Perchlorate can impair an infant's ability to absorb iodide, which is critical in the development of thyroid hormones that affect brain development (Orange County Register, 2/24).

Researchers found that based on body weight, most infants who received milk from mothers in the study are consuming higher levels of perchlorate than the 24.5 parts per billion guideline issued by the Environmental Protection Agency based on a National Academy of Sciences formula. Last year, California set a public health goal of perchlorate levels in drinking water of six parts per billion (Danelski, Riverside Press-Enterprise, 2/23).

Boxer wrote to HHS Secretary Mike Leavitt and Department of Health Services Director Sandra Shewry, asking them to consider requiring mothers to have their breast milk tested before nursing to determine perchlorate levels and whether women who are breastfeeding or pregnant should take iodide supplements (Orange County Register, 2/24).

Andrea Kirk, a doctoral student at Texas Tech and leader of the study, said that woman should not stop breastfeeding based on the results of the study (Riverside Press-Enterprise, 2/23).

Ruth Shaber, director of women's health services for Kaiser Permanente-Northern California, said, "To jump to the conclusion that women should measure this one chemical in their breast milk is extreme. 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."

Wayneab Truneh, an OB/GYN with the Camino Medical Group, said, "It's really difficult to take one small study and just make clinical applications that are sweeping. You have to be very careful."

Local health experts say more research is needed before the government requires breast milk screening or iodide supplements for pregnant or nursing women (Feder Ostrov, San Jose Mercury News, 2/24).

Boxer introduced legislation to set a national standard on perchlorate in drinking water in the last Congress, but the bill was not passed. She is expected to introduce similar legislation this session.

Sen. Dianne Feinstein (D-Calif.) also is expected to introduce a bill for national standards this session (Orange County Register, 2/24). The study is available online.