Flame Retardants Linked to Lower IQs, Hyperactivity in Children
Almost a decade after manufacturers stopped using certain chemical flame retardants in furniture foam and carpet padding, many of the compounds still lurk in homes. New work to be presented today reaffirms that the chemicals may also still be hurting young children who were exposed before they were born.
Researchers investigating the health impacts of prenatal exposure to flame retardants collected blood samples from 309 pregnant women early in their second trimester. Spikes in the levels of one class of flame retardant, polybrominated diphenyl ethers (PBDEs) correlated with behavior and cognition difficulties during early childhood.
The researchers tracked children through the first five years of their lives, looking at a battery of tests for IQ and behavior. They found that children of mothers who had high PBDE levels during their second trimester showed cognition deficits when the children were five years old as well as higher rates of hyperactivity at ages two to five. If the mother’s blood had a 10-fold increase in PBDEs, the average five-year-old had about a four-point IQ deficit. “A four-point IQ difference in an individual child may not be perceivable in…ordinary life. However, in a population, if many children are affected, the social and economic impact can be huge due to the shift of IQ distribution and productivity,” says lead author Aimin Chen, an assistant professor of environmental health at the University of Cincinnati College of Medicine. The findings, based on women and children from Cincinnati, will be presented May 6 at the annual meeting of the Pediatric Academic Societies in Washington, D.C. The unpublished results have been submitted to a peer-reviewed journal, but the paper has not yet been accepted.
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Scientists believe that in humans PBDEs can lodge themselves in bodily lipids when contaminated air is inhaled or tainted dust swallowed, although exactly how they may wreak havoc inside the body remains unknown. Tests on animals suggest that the chemicals disrupt the endocrine system. The chemical structure of PBDEs strongly resembles thyroid hormones, and they affect thyroid regulation and decrease the level of thyroid hormones in the blood of animals. These hormones drive growth and development—in particular, brain development. Animal studies have also found that exposure to PBDEs in the womb and via nursing may damage the thyroid system and alter newborns’ brains.
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Furniture-makers have continued to use flame retardants because of a state law—the California Technical Bulletin 117. It says the furniture sold within state borders must withstand a 12-second exposure to a small flame without igniting. That state regulation has become the de facto law of the land as manufacturers have sought to comply with it so they can sell their wares throughout the U.S. But California is revising its standard so that products will only have to pass a “smolder test” that would prevent fires but would not require flame retardant use in manufacturing. State legislators may finalize the revision later this summer or in the fall.
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