High levels also have been documented in human breast milk and serum, especially in North America.
“Studies of breast milk and serum have shown that the U.S. population has the highest levels of contaminants in the world, probably because PBDEs are found in so many of the products we use every day,” says Stapleton.
In a paper published last year in Environmental Science & Technology, she reported finding high concentrations of the chemicals in materials as seemingly innocuous as house dust and clothes dryer lint. Editors of the journal have selected the article as one of the seven top environmental papers published in 2005, based on its potential implications for environmental and human health.
“We found elevated levels in about 5 percent of the households we tested. Smaller houses or apartments tended to have the highest levels,” Stapleton notes.
By using the U.S. Environmental Protection Agency's estimates of how much dust a toddler between the ages of one and four can be expected to ingest, she and her colleagues determined that children in the homes with the highest levels could be ingesting as much 1,200 nanograms of PBDEs from dust each day.
“These are not lethal exposures,” she says, “but they are alarmingly close to the levels above which we see behavioral effects in laboratory animals. Over time, it's possible that these sublethal exposures may affect IQ and learning in some children, as well as endocrine activity.”
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