Exposure to flame-retardant chemicals in the womb is associated with
hyperactivity and lower intelligence in children, a new study indicates.
Researchers examined the effects of polybrominated diphenyl ethers (PBDEs),
which were used for decades as fire retardants in common products such as
carpeting, baby strollers and electronics.
"In animal studies, PBDEs can disrupt thyroid hormone and cause hyperactivity
and learning problems. Our study adds to several other human studies to
highlight the need to reduce exposure to PBDEs in pregnant women," study author
Dr Aimin Chen, an assistant professor in the department of environmental health
at the University of Cincinnati College of Medicine, said in an American Academy
of Pediatrics news release.
How the research was done
The researchers looked at PBDE levels in blood samples from 309 pregnant
women and then performed intelligence and behaviour tests on the women's
children each year until they were five.
They found that PBDE exposure in the womb was associated with hyperactivity
at ages two to five, and with lower intelligence at age 5. A tenfold increase in PBDE
exposure during pregnancy was related to about a four-point IQ deficit in
While the study tied PBDE exposure during pregnancy to later hyperactivity
and lower intelligence, it did not prove a cause-and-effect relationship.
The study was to be presented at the Pediatric Academic Societies annual
meeting in Washington, DC.
PBDEs were mostly withdrawn from the US market in 2004, but they are present
in many consumer products bought several years ago and still widely used by
Americans, according to the news release. In addition, PBDEs remain in human
tissue for a long time and a pregnant woman can transfer them to her foetus.
"Because PBDEs exist in the home and office environment as they are contained
in old furniture, carpet pads, foams and electronics, the study raises further
concern about their toxicity in developing children," Chen concluded.
Research presented at medical meetings should be viewed as preliminary until
published in a peer-reviewed journal.
The US Environmental Protection Agency has more about PBDEs and