8 March 2007

Is Your Carpet Making You Fat?

by Kate Melville

Flame retardants, known as polybrominated diphenyl ethers (PBDEs), are found in consumer products like carpeting, upholstered furniture, computers and household appliances. In use since the 1960s, the chemicals supposedly make for safer households by retarding combustibility, but their ubiquity is now prompting questions about what other effects these additives might have.

PBDEs are so widespread that it is estimated that American consumers come into contact with up to 100 products containing PBDEs every day. Perhaps more worryingly, their persistence in the environment has been compared to the now-banned toxins PCB and DDT.

Now, researchers from the University of New Hampshire are investigating if PBDEs are in some way linked to the obesity epidemic plaguing America. "Environmental chemicals are a possible third component to the obesity epidemic, along with diet and exercise," says project leader Gale Carey. She and her co-researchers are exploring how PBDEs affect fat storage and production. "We know PBDEs are fat-soluble - they dissolve in fat tissue," says Carey. "What are they doing in the fat as they sit there? Nobody has asked that question yet."

The researchers plan to expose laboratory rats to PBDEs through pregnancy and lactation, stages Carey describes as critical windows for exposure. The team will be working at the molecular level, seeing what PBDEs do to stem cell populations and their effects on gene expression; as well as at a cellular level, exploring the insulin sensitivity of fat cells.

The preliminary data make interesting reading, suggesting that chronic exposure to PBDEs can cause fat cells to become less sensitive to insulin, which is a forerunner to developing Type II diabetes. The fat cells of growing male rats that were fed PBDEs daily for a month acted metabolically like the fat cells of obese rats, although the PBDE-fed rats weighed the same as a control group. Additionally, the researchers noted that PBDEs appear to interrupt thyroid hormone levels, which may impact caloric expenditure.

But with the research just getting underway, the scientists are duly cautious about predicting outcomes. If the findings do implicate PBDEs in obesity, Carey mused, the news would be good and bad. "From a scientific standpoint, it would be very interesting if these animals began to put on weight," she said. "But part of me hopes they don't, because these chemicals are all around."

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Source: University of New Hampshire