Environmental Toxin Collects in Breast Milk

FRIDAY, Dec. 7 (HealthDay News) -- Scientists have discovered the mechanism by which a chemical known as perchlorate can collect in breast milk and cause cognitive and motor deficits in newborns.

Used since the 1940s to manufacture explosives and rocket fuel, the contaminant is still widely present in the water and food supply, experts say.

And high concentrations of perchlorate in breast milk can be passed to an infant and affect it's ability to manufacture essential thyroid hormone, the new study suggests. Perchlorate can also lessen the amount of iodide available to a mother to pass on to her infant, and a baby needs iodide to produce thyroid hormones.

"The deficit of thyroid hormone is particularly delicate if it's at the beginning of life because the central nervous system has not completely matured," said study author Dr. Nancy Carrasco, a professor of molecular pharmacology at Albert Einstein College of Medicine, in New York City.

Thyroid hormones are "absolutely critical" for the development and maturation of the central nervous system, skeletal muscles and lungs, she explained.

In laboratory and rat research, Carrasco's team found that perchlorate limited the amount of iodide transported to a mother's mammary glands. The only source of iodide a baby typically has is mother's milk, she explained.

Her team discovered that perchlorate accumulates in mother's milk, but before this study, "we didn't know it would be passed on as actively to the baby," she said.

Carrasco and her colleagues at Einstein and at Johns Hopkins University reached this conclusion after experimental studies on how sodium iodide carries perchlorate to, and concentrates it in, mammary glands.

The next steps in this research will include animal studies looking at the effects of perchlorate exposure during pregnancy, she said.

The debate continues on how much perchlorate is a high and harmful concentration, Carrasco said. But scientists have long known that iodide deficiency contributes to lowered IQ.

The new finding is relevant to the Environmental Protection Agency's standards for acceptable perchlorate levels, added R. Thomas Zoeller, a professor of biology at the University of Massachusetts-Amherst who has served on the EPA's peer review panels for the assessment of perchlorate.

At the time the current safety standards were established, the EPA was not thinking about how perchlorate is concentrated in breast milk, he said.