The ubiquitous chemicals added to furniture, electronics, and other products to keep them from going up in flames may have unsettling side effects, according to two recent studies.
Environmental epidemiologists at Columbia University and the Centers for Disease Control and Prevention measured the concentrations of widely used flame retardants known as polybrominated diphenyl ethers (PBDEs) in the umbilical cord blood of American infants. Six years of follow-up studies revealed that, after adjusting for factors such as the mother’s age and IQ, higher levels of the chemicals were associated with lower scores on aptitude tests. At age 4 children with the highest prenatal PBDE exposures had an average IQ four to six points below those who had the lowest levels.
A second study, led by epidemiologist Kim Harley of U.C. Berkeley, examined the relationship between PBDEs and fertility in 223 California women. Harley and her colleagues found that, after controlling for other variables, each tenfold increase in a woman’s PBDE blood serum level corresponded to a 30 percent decrease in her chance of becoming pregnant in any given month.
Environmental chemist Heather Stapleton of Duke University, who was not involved in the research, notes that the findings are among the first of their kind in humans and so need to be confirmed. But the preliminary conclusions are worrisome, she says, because they show possible health effects at the levels of exposure found in the general population. In December the EPA added PBDEs to its list of chemicals of concern, so regulation may be on the way. Unfortunately, potential substitute flame retardants have not been thoroughly tested for safety. “The other bad news is that these chemicals stick around,” Harley says, so their effects could persist for years to come.