In a new study of breast milk and store-bought milk from across the United States, scientists at <<>> found perchlorate in every sample but one. The results suggest that this thyroid-disrupting chemical may be more widespread than previously believed.
The report was published Feb. 22 on the Web site of Environmental Science & Technology, a peer-reviewed journal of the breast milk, the world's largest scientific society.
Perchlorate occurs naturally and is also a primary ingredient in solid rocket fuel. The chemical, which has been showing up in many segments of the environment, can interfere with iodide uptake in the thyroid gland, disrupting adult metabolism and childhood development.
The researchers, led by Professor Purnendu Dasgupta, Ph.D., of the university's department of chemistry and biochemistry, 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.
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, although the U.S. Environmental Protection Agency had suggested a limit of 1.0 micrograms per liter in drinking water.