Common flame-retardant chemicals called polybrominated diphenyl ethers, or PBDEs, appear to be linked to reduced fertility in women, according to a study published Tuesday in the journal Environmental Health Perspectives, the Los Angeles Times reports. The chemicals, which have been used for more than four decades, are found in foam furniture, electronics, fabrics, carpets and plastics. Although use of PBDEs is being phased out in the U.S, the chemicals are still found in household products manufactured before 2004, according to the Times.

For the study, researchers at University of California-Berkley analyzed blood samples of 223 pregnant women for presence of PBDE. The women -- mainly Mexican immigrants who lived in an agricultural community -- were surveyed about the length of time that they had tried to become pregnant. The study found that for each tenfold increase in the blood concentration of PDBEs, there was a 30% drop in the likelihood of becoming pregnant each month.

Earlier studies suggest that 97% of U.S. residents have detectable levels of PBDEs in their blood. Although most previous research has been in animals, a 2008 study linked PBDEs with disrupted thyroid levels in men, and a study published this month linked exposure during pregnancy to neurodevelopmental delays in children. Hugh Taylor, an expert on endocrine-disrupting chemicals at Yale University, noted that the studies are association studies and do not prove cause and effect. "But we have cause-and-effect studies in animals, and we have association studies in humans," he said, adding, "I think that is fairly convincing."

Kim Harley, lead author of the new study and associate director of the Center for Children's Environmental Health Research at the UC-Berkeley School of Public Health, said more research is needed to determine how PBDEs relate to fertility. "One of the strongest associations of PBDEs is with thyroid hormone," which appears to play a role in fertility, she said, adding that "PBDEs also seem to mimic estrogen" (Roan, Los Angeles Times, 1/27).

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