UCSF study finds lower levels of chemical linked to learning difficulties in children.
A class of flame retardants that has been linked to learning difficulties in children has rapidly declined in pregnant women’s blood since the chemicals were banned in California a decade ago, according to a study led by researchers at UC San Francisco.
Blood levels of polybrominated diphenyl ethers (PBDEs), tested in patients at the UCSF-affiliated San Francisco General Hospital and Trauma Center fell by two-thirds since they were last tested three years ago and found to be the highest levels reported among pregnant women anywhere in the world. The findings were published online today (Sept. 25) in Environmental Science & Technology.
Researchers said the dramatic decline was most likely the result of the statewide ban, as well as a voluntary national phase out. But they said the levels fell more quickly than expected, given how persistently these chemicals remain in the environment once they have been introduced.
“We were pleasantly surprised by the extent of the decline,” said Ami R. Zota, Sc.D., M.S., an assistant professor of environmental and occupational health at the George Washington University School of Public Health and Health Services, and the study’s lead author. Zota conducted the research while she was a postdoctoral fellow at UCSF’s Program on Reproductive Health. “Regulations can have an impact on people’s everyday lives.”
PBDEs were used in foam furniture starting in the 1970s to meet the state’s fire safety regulations, which are now being reviewed. Experiments in animals and also in human cells have shown that PBDEs damage the brain in utero.
Researchers have found a strong relationship between an expectant mother’s exposure to the chemicals – even at low levels – and subsequent learning difficulties in her child, including worsened concentration and attention and lower IQ. The chemicals also can disrupt thyroid hormones in adulthood and during development. While much of the data is correlational, the researchers said there is enough evidence to raise serious concern that the chemicals are harmful to people.