23 February 2005
LUBBOCK, Texas - A toxic chemical used to make rocket fuel was found in virtually every sample taken in a new study of nursing mothers' milk, but researchers said it's too early to know whether the perchlorate levels are dangerous.
The multistate study by Texas Tech University researchers, published this week, found that breast milk samples were on average five times those detected in dairy milk pulled from grocery stores.
The article's abstract says that perchlorate in 47 dairy milk samples from 11 states and in 36 human milk samples from 18 states were measured. Iodide was also measured in a number of the samples. Perchlorate was detectable in 81 of 82 samples.
Perchlorate is a toxic chemical from rocket fuel and weapons production, and is also formed naturally through lightning. It has been linked to thyroid damage, learning disabilities, decreased IQ and attention deficit disorder in children. It leaches into the ground and has been found in drinking water supplies in 35 states and has also been found in vegetables.
The abstract says that the presence of perchlorate in the milk lowers the iodide content and may impair thyroid development in infants. It concludes that, "on the basis of limited available data, iodide levels in breast milk may be significantly lower than it was two decades ago. Recommended iodine intake by pregnant and lactating women may need to be revised upward."
The milk study is a concern, but its seriousness is still unclear, said Dr. Ed Urbansky, a former EPA chemist not involved with the study, who has published several papers on perchlorate.
"It's very difficult to determine what the findings might be other than to know it might be in so many milk samples," he said. "It's important not to raise undue alarm over the significance of the finding. We shouldn't be running through the streets screaming and not drinking milk because of this."
For the study, conducted over a two-year period, researchers obtained milk from more than 20 women selected at random and from stores in 23 states. It was funded out of researchers' pockets and published online Tuesday in the journal Environmental Science and Technology.
The average reading in the study was 10.5 parts per billion, less than half of the EPA's newly established safe exposure level of 24.5 parts per billion in drinking water.
The highest reading among the mothers in the Tech study was 92 parts per billion. In dairy milk, all but one of 47 samples had detectable levels of the chemical. No samples were above 11 parts per billion.
Pernendu Dasgupta, a Tech chemistry professor who led the study, said it "raises more questions than answers" but hopes it helps people become more aware.
Previous studies have indicated that perchlorate inhibits the transport in the body of iodine, which in fetuses and children is necessary for brain development, Dasgupta said.
"I want people to be iodine active rather than crying wolf about perchlorate," he said. "The real issue is if you're getting enough iodine."
Perchlorate was detected in 10 West Texas counties in recent years and in California, which has extensive ties to the military, defense industry and the space program.
It has also been found in the Colorado River, the major source of drinking water and irrigation in Southern California and Arizona.
According to public health advocates, perchlorate has leaked into the drinking water supplies of more than 16 million Californians through unsafe disposal and storage methods practiced by the aerospace, defense, fireworks and road flare industries.
Sujatha Jahagirdar with Environment California called the finding
"We need rocket fuel out of our drinking water now," she said. "And unless federal regulators act quickly, we're going to see this stuff popping up everywhere."
In July, the Pentagon announced it had found perchlorate contamination in ground water and soil samples at 14 abandoned or likely to be closed military sites in 10 states. In August, a Texas hydrologist claimed that low levels of perchlorate from New Mexico's Los Alamos lab had reached the Rio Grande. The lab did not dispute that contaminants have entered the ground water beneath its 40-square-mile property but said the conclusion that there is a quick pathway to the Rio Grande was in dispute.