Perchlorate in breast milk found nationwide

LUBBOCK, Texas, February 24, 2005 (ENS): In a new study of breast milk and milk purchased in stores across the United States, scientists at Texas Tech University found perchlorate in every sample but one. The results suggest that the chemical may be more widespread than previously believed.

The chemical can interfere with iodide uptake in the thyroid gland, disrupting adult metabolism and childhood development.

Perchlorate is a waterborne contaminant left over from propellants and rocket fuels. There are about 12,000 Department of Defense sites in the United States that have been used for training with live explosives.

Led by Professor Purnendu Dasgupta, Ph.D. of the university's department of chemistry and biochemistry, the researchers analyzed 47 dairy milk samples purchased randomly from grocery stores in 11 states, and 36 breast milk samples from women recruited at random in 18 states.

Every sample of breast milk contained perchlorate, and only one sample of dairy milk contained no detectable levels, researchers found.

The average perchlorate concentration in breast milk was 10.5 micrograms per liter; the dairy milk average was 2.0 micrograms per liter.

No definitive national standard exists for permissible levels of the chemical in milk, although the U.S. Environmental Protection Agency has suggested a limit of 1.0 micrograms per liter in drinking water.

The researchers also found that high levels of perchlorate correlated with low levels of iodide in breast milk, which can inhibit thyroid function in nursing women, an essential component for proper neural development of the fetus.

Although the data are limited, the levels of iodide in this study are sufficiently low to be of concern, according to the researchers. They suggest that the recommended daily intake of iodine for pregnant and nursing women may need to be revised upwards.

In March 2003, the Texas Tech University Institute of Environmental and Human Health received a $2 million research award from the Department of Defense Strategic Environmental Research and Development Program to research the effects the residues from explosives have on the environment and how to clean up any contamination.

The program's principal investigator Ronald Kendall, Ph.D said, "This work will be implemented to assist the Department of Defense in developing risk assessments on explosives and breakdown products of these compounds, and to assist in the establishment of safe limits and in remediation," he said.

"The consequences of having explosives and their breakdown products in the environment are not well understood," Kendall said.

The report was published February 22 on the website of "Environmental Science & Technology," a peer-reviewed journal of the American Chemical Society, the world's largest scientific society.