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Cause for Alarm Over Chemicals

Levels of common fire retardants in humans are rising rapidly, especially in the U.S. Animal tests show effects on the brain.

April 20, 2003|Marla Cone | Times Staff Writer

Toxic chemicals used as flame retardants are rapidly building up in the bodies of people and wildlife around the world, approaching levels in American women and their babies that could harm developing brains, new research shows.

The chemicals, PBDEs, or polybrominated diphenyl ethers, are used to reduce the spread of fire in an array of plastic and foam products in homes and offices, including upholstered furniture, building materials, televisions, computers and other electronic equipment.

This year, the European Union banned the two PBDE compounds that have been shown to accumulate in human bodies. Some European industries had already begun to phase out the chemicals, and levels in the breast milk of European women have begun to decline.

But in the United States, no action to regulate the flame retardants has been taken, and their use continues to rise. About half of the 135 million pounds of PBDEs used worldwide in 2001 were applied to products in North America.

Scientists who specialize in toxic contaminants say they haven't seen a chemical build up in human bodies and the environment as quickly as that of PBDEs in almost half a century. The flame retardants are as potent and long-lasting as PCBs (polychlorinated biphenyls) and DDT-- chemicals that began to accumulate in the environment in the 1950s and were banned in the 1970s. Even if PBDEs were banned today, they would endure in the environment for decades, scientists say.

A single, small dose of PBDEs fed to newborn laboratory mice and rats disrupts their brain development, altering their learning ability, memory, behavior and hearing, according to three studies, two conducted in Europe and one at the U.S. Environmental Protection Agency. Mice fed less than 1 part per million of PBDEs performed poorly in maze tests and were hyperactive and slower to become habituated to new environments.

"These effects are persistent and worsen with age," said Per Eriksson, a neurotoxicologist at Uppsala University in Sweden who led the rodent studies.

Only a few hundred people in the U.S. have been tested so far. But studies completed in the last few months show that some American women and their babies are carrying levels of PBDEs that are beginning to approximate those that harm newborn rodents.

The brains of newborn mice are altered when their bodies contain concentrations that are 10 to 100 times higher than levels already seen in some people in the United States today.

"That is not a comfortable margin of exposure," said Linda Birnbaum, director of experimental toxicology at the EPA's National Health and Environmental Effects Research Laboratory. Because concentrations in Americans are doubling every few years, it won't take long to close the gap.

Scientists have not yet determined how the flame retardants are getting into human beings. Some suspect that dust in homes and offices containing foam from old furniture cushions is the primary source; others suspect it comes mainly from consumption of fish caught in contaminated waters. The uncertainty complicates the task of figuring out ways to tell people how they can reduce their exposure.

"We're adding them to consumer products, so they're in every home, every office, every car, every bus, every plane," said Tom McDonald, a toxicologist with the California Environmental Protection Agency's Office of Environmental Health Hazard Assessment.


Impact on Intelligence

Researchers say the effects on children are likely to be subtle -- not mental retardation or disability, but measurable changes in a child's intelligence, memory, hyperactivity and hearing. "We're concerned about learning and memory and some behavioral effects and hearing loss," Birnbaum said.

The flame retardants, which pass through the placenta and are readily absorbed by a fetus, are doubling in concentration every two to five years in people and wildlife throughout North America, several studies show.

By far, the highest human exposures are in the United States.

A pregnant Indiana woman had the largest individual concentration found so far -- 580 parts per billion -- and her baby carried nearly as much at birth, according to an Indiana University study published last month. A San Francisco Bay Area woman in her 30s had amounts measuring nearly as much in another new study conducted by the California Department of Toxic Substances Control.

"The levels are rising, and as the levels rise, so should our concern about health effects," McDonald said.

The federal EPA, which has jurisdiction over the chemicals, has made no move to regulate them. The agency has begun a risk assessment of the compounds, which is expected to be completed next year.

EPA Administrator Christine Todd Whitman said in an interview that she is concerned about the spread of PBDEs, but that "we just don't know enough yet" to take any action, especially because the compounds help protect the public from fires.

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