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You Are What You Eat, Including Your Sofa

Public Health study tracks chemicals entering food supply


Tom Webster is a School of Public Health associate professor of environmental health. Alicia Fraser (SPH'08,'10) (right) is the lead author of the PBDE study. Photos courtesy of the School of Public Health

Watching television, kicking back on the couch, you may be eating tiny bits of them along with the chips and dip. That’s because particulates from degrading electronics, foam furniture, mattresses, and other consumer products containing chemical flame retardants known as PBDEs (polybrominated diphenyl ethers) have an unfortunate ability to get into the air, and then get into you. And that could be hazardous to your health.

Researchers from Boston University’s School of Public Health have been investigating the hazards of PBDEs, which have been used in mattresses and electronics since the 1970s. They’ve linked the chemicals to neurological problems, damage to reproductive systems, and increased liver cancer in rodents. Other studies have shown a buildup of PBDEs in humans.

While studies of human health effects are incomplete, governments around the world have banned most PBDEs. Nevertheless, a few are still in use, and the toxins continue to be released from old furniture and electronics, polluting homes, offices, landfills, and eventually, our bodies.

According to the most recent SPH research, we can now add the food supply to that list of PBDE sources.

“Because PBDEs are fat-soluble and persist in the environment, they bioaccumulate up the food chain,” says Alicia Fraser (SPH’08, 10), a doctoral student in environmental health. In a paper published this summer in Environmental Health Perspectives, Fraser and Thomas Webster and Michael McClean, SPH associate professors of environmental health, report higher levels of these flame retardants in the blood of people who eat more meat, with stark differences in PBDE concentrations between meat eaters and vegetarians.

The study was part of the lab’s larger research agenda, funded by the National Institute of Environmental Health Sciences of the National Institutes of Health, to find out how humans are exposed to these chemicals. A 2004 study led by scientists at the Centers for Disease Control (CDC) found that between 1985 and 2002, PBDE levels in Americans increased. Indoor dust and food have been the prime suspects.

Fraser decided to look at food, hypothesizing that if flame retardants were making their way into the environment, the concentration would increase as they moved up the food chain from plants to animals that eat those plants. Those of us who eat the most meat would harbor the most PBDEs in our blood.

She examined data from the CDC’s annual National Health and Nutrition Examination Survey, which runs a toxicology screen on the blood of about 5,000 randomly chosen Americans and also asks them for details about their smoking, drinking, diet, and exercise habits.

Fraser split the study subjects into meat eaters and vegetarians, defining the latter as anyone who averaged less than one serving of meat per week. She divided the carnivores into three levels: low, medium, and high consumers of either poultry or red meat, and she looked for PBDE concentrations among different consumption levels of dairy and fish.

On average, vegetarians had 25 percent lower levels of PBDEs than meat eaters. Slightly smaller differences appeared within the carnivore group, with PBDE levels higher in those who ate the most poultry and red meat. Fraser detected no significant differences in PBDE contamination based on the amount of dairy or fish eaten.

“We were surprised that we found such clear results,” says Fraser, who admits that the CDC questionnaires made for “somewhat crude” measurements of exactly what people ate. For instance, what a person eats in a given 24-hour period may not be typical. Also, the amount of meat or dairy in any given meal — lasagna, for example — had to be estimated based on guidelines from the U.S. Department of Agriculture. “There were a lot of foods that I had to categorize as miscellaneous,” says Fraser.

The lack of accumulation due to fish and dairy consumption is a mystery Fraser would like to investigate. Another is the PBDE pathway from consumer products and household furniture to farm-raised meat.

“It might be something at the factories where this meat processed,” says Fraser. “But my guess would be that it’s in the feed the animals are eating, grown on farms that use sewage sludge as fertilizer.”

Fraser says that the lack of epidemiological studies on PBDEs prevents people from knowing the true health risks of our current levels of exposure. It also points to a dangerous lack of testing for all industrial chemicals; just because these toxins aren’t added to food or medicine doesn’t mean we won’t ingest them. “We should know the health effects of things that we’re putting in our environment,” she says.

The lab team will continue testing PBDE concentrations in houses, offices, and cars, says Webster, “trying to determine if, for the average person, diet is more or less important for contamination than dust in these indoor environments.”

Scientists have been seriously studying these chemicals for only about a decade, according to Webster. But the findings thus far have been alarming enough for the European Union to ban two of the three major types of PBDEs in 2004. Multinational corporations, including Philips, Sony, Intel, Apple, and Hewlett-Packard, then began a voluntary phaseout of PBDEs. Last spring, the United Nations Stockholm Convention on Persistent Organic Pollutants added those two categories of PBDEs to the list of chemicals that signatory nations agree should be banned.

“This is the Superfund problem of the future,” says Webster. “We have all this stuff lying around that’s eventually going to end up in landfills and contaminate the environment, and people haven’t figured out how to deal with that yet.”

Chris Berdik can be reached at cberdik@bu.edu.

Read more about the hazards of PBDEs in Bostonia magazine.

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