A study published this week found the toxic rocket fuel chemical perchlorate in every one of 36 samples of breast milk from nursing mothers in 18 US states.
The study comes just days after the US Environmental Protection Agency (EPA) adopted a safety standard for perchlorate in drinking water recommended last month by the National Academy of Sciences. The findings of today’s breast milk study raise serious concerns for breast-feeding infants relative to the EPA/NAS safety standard.
Although breast-feeding infants drink little or no water, they could be exposed to dangerous amounts of perchlorate through breast milk. The study authors characterized the health risks from perchlorate in breast milk in unusually stark language: “it is obvious that the NAS safe dose of 0.7 µg/kg/d will be exceeded for the majority of infants and some will also exceed the 10 µg/kg/d dose at which brain morphology changes were observed in nursing rat pups.”
The study by Texas Tech University is the first ever to look for the rocket fuel contaminant in human breast milk. It confirms many scientists’ long-standing suspicion that significant levels of perchlorate could be passed on to nursing infants. The average level found – 10.5 parts per billion (ppb) – is five times higher than the average level of perchlorate found in 47 samples of cows’ milk collected by Texas Tech scientists from supermarkets in 11 states.
And the average level is also more than twice as high as the average concentration found in the total of 222 samples of cow’s milk from 21 states that have been tested for perchlorate in tests by the Food and Drug Administration, the state of California, Texas Tech University and the Environmental Working Group (EWG).
The main ingredient of solid rocket and missile fuel, perchlorate has been found in the drinking water supplies of 22 US states and additional types of contamination have been identified in another 13 states. Pregnant women, fetuses and young infants are among the most susceptible to perchlorate because of the chemical’s affect on the thyroid gland.
Perchlorate interferes with the thyroid’s ability to take up the essential nutrient iodide and make thyroid hormones. In adults, these hormones help regulate metabolism, but in fetuses, infants and children, thyroid hormones also play an important role in the development of the brain and other organs. Studies have shown small disruptions in thyroid hormones in utero or during early development can cause lowered IQ while larger disruptions can cause mental retardation, loss of hearing and speech, or deficits in motor skills.
Scientists have long recognized the possibility that perchlorate could wind up in – and perhaps even be concentrated by – breast milk. Although perchlorate does not build up in human tissues over time, the same molecule that selectively imports perchlorate into the thyroid is also present in the mammary gland.
The Texas Tech study, posted online by the journal Environmental Science and Technology, shows that the contamination is more pervasive and the levels higher than any one had expected: Five women had breast milk with perchlorate concentrations over 20 parts per billion, and one woman’s breast milk had a concentration of 92 ppb.
The highest levels were found in women from New Jersey, New Mexico, Missouri, Nebraska and California, in that order. All of the samples exceeded the 1 ppb drinking water standard proposed by Massachusetts last year, and one-fourth of the samples exceeded the 6 ppb standard currently being considered by California.