Flame retardants associated with neurobehavioral problems in children

November 30, 2012 — Flame retardants found in furniture, cars, carpet padding, and baby products are supposed to make these products safer. But according to neuropsychologist and epidemiologist Brenda Eskenazi, they may do more harm than good—particularly in children, who are more vulnerable to environmental hazards than adults.

Eskenazi, professor of maternal and child health and epidemiology at the University of California, Berkeley and director of CERCH—the Center for Environmental Research & Children’s Health—spoke at an Environmental Health Colloquium at Harvard School of Public Health on November 26, 2012. The talk was sponsored by the Department of Environmental Health at HSPH. She discussed the troubling health effects of flame retardants called PBDEs—polybrominated diphenyl ethers. Research by Eskenazi and colleagues suggests links between PBDEs and a host of neurobehavioral problems among children with high exposures to these chemicals—attention problems, behavior issues, lack of fine motor coordination, and impaired cognitive development.

Although PBDEs were phased out in 2004, “they will be around for a long time to come because of their half-life, and because you’ve got all of these household objects that will continue to off-gas,” Eskenazi said. PBDEs leach out of furniture and other products and become part of household dust, which can be either inhaled or ingested.

Eskenazi and her colleagues have produced a substantial body of research shedding light on the potential dangers of a number of different chemicals—including pesticides, chemicals in plastics, and flame retardants—through CERCH’s signature longitudinal study, called CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas). Begun in 1999, the CHAMACOS study enrolled 600 pregnant women—mostly Spanish-speaking, roughly half of them illegal, many poor—living in farmworker communities in Salinas Valley, California, a region about 100 miles south of San Francisco known as the nation’s “salad bowl.” Eskenazi’s team gathered information about the women and their children over the past 12 years.

PBDE levels highest in United States

The researchers found that women with the highest PBDE levels were those who’d lived longest in the United States, where exposure to these chemicals is highest in the world. For each year a woman lived in the United States, there was a 4% increase in the PBDE level in her blood. PBDE levels in the children were even higher than those of their mothers—which makes sense, Eskenazi said, because the children had lived their entire lives in the United States.

The researchers also found that people with more than three pieces of stuffed furniture in their homes had nearly 27% higher PBDE levels than others.

Children throughout California—not just those in the CHAMACOS study—have the highest levels of PBDEs of any children in the country. That’s because California law requires that the foam inside couches and other products be able to resist a small open flame for at least 12 seconds.

“We in California are famous for many things, but this is one of the things I’d rather not be famous for,” said Eskenazi.

In addition to uncovering neurobehavioral difficulties among the CHAMACOS children, Eskenazi and her colleagues also found negative health impacts among women and infants. Women with high levels of PBDEs had a 30% decrease in the probability of becoming pregnant in a given monthly cycle. High PBDE levels were also associated with lower birthweight in babies.

Questioning flame retardants’ efficacy

Not only do flame retardants pose health risks, they don’t do much—if any—good, Eskenazi said. “It’s true that flame retardants make it longer for material to ignite—by three seconds,” she said. “But they also cause an increase in smoke, carbon monoxide, and soot”—often more deadly than the fire itself.

And while it’s true that deaths from fires caused by small open flames have dropped in recent years, Eskenazi attributes the change not to the presence of flame retardants in furniture but to the fact that cigarettes are now required to be “fire-safe” (extinguishing themselves more quickly if ignored), and because fewer people are smoking.

Fortunately, “there is change ahead,” Eskenazi said. In June 2012, California Gov. Jerry Brown asked for a review of his state’s flammability standards. But epidemiologists still have work to do, Eskenazi said. In addition to continuing to monitor the health effects of PBDEs that will linger in the environment for years, experts should study the health effects of a newer flame retardant in use, Firemaster 550, a trademarked mixture of chemicals that scientists have not yet been able to study but which likely contains chemicals similar in structure to PBDEs.

“Epidemiologists need to catch up,” Eskenazi said.

–Karen Feldscher

photo: Ginaellen/www.fotosearch.com