Household Chemicals Linked to Reduced Fertility

From the LA Times:

Household chemicals linked to reduced fertility Flame-retardant chemicals found in many household consumer products mayreduce fertility in women, researchers reported today. Their study joinsseveral other papers published in the last two years suggesting that thechemicals, polybrominated diphenyl ethers, or PBDEs, affect human health. PBDEs have been used as flame retardants for four decades and are found infoam furniture, electronics, fabrics, carpets and plastics. The chemicalsare being phased out nationwide, and certain PBDEs have been banned for usein California. But they are still found in products made before 2004.Californians may have higher exposures compared with residents of otherstates because of the state's strict flammability laws, according to thestudy authors, from UC Berkeley. Most of the previous research on the chemicals has been in animals. But a2008 study linked the chemicals to disrupted thyroid levels in men, and astudy published this month tied PBDE exposure in pregnancy toneurodevelopmental delays in young children. "These are association studies. You can't show cause and effect," said Dr.Hugh Taylor, an expert on endocrine-disrupting chemicals at Yale Universitywho was not involved in the new study. "But we have cause-and-effectstudies in animals, and we have association studies in humans. I think thatis fairly convincing." In the study, published today in the journal Environmental HealthPerspectives, researchers measured PBDE levels in blood samples from 223pregnant women. The women, who were primarily Mexican immigrants living inan agricultural community, were asked to recall how long they had beentrying to become pregnant, which was defined as being sexually activewithout the use of birth control. Women with the highest concentrations of the chemicals experienced a longerdelay before pregnancy. Each 10-fold increase in blood concentration ofPBDEs was linked to a 30% decrease in the likelihood of becoming pregnanteach month. "It's a pretty strong effect," said Kim Harley, the lead author of thestudy and associate director of the Center for Children's EnvironmentalHealth Research at UC Berkeley's School of Public Health. "They can allbecome pregnant, but they all had very different amounts of time it tookthem to become pregnant." Previous studies suggest that 97% of Americans have detectable levels ofthe substances in their blood. PBDEs are also found in some foods,particularly dairy products and higher-fat meat and fish, but householdproducts are considered a major source of exposure. "PBDEs have the ability to just leach out of these products into ourenvironment," Harley said. "We're thinking the routes are probablyingestion or hand to mouth. But it seems that the larger route of exposureis house dust." How the chemicals might impair fertility is unclear, she said. "One of the strongest associations of PBDEs is with thyroid hormone,"Harley said. "Thyroid hormone does seem to play an important role infertility. Either too low or too high levels can impair fertility. PBDEsalso seem to mimic estrogen. It could be through a hormonal mechanism. Butwe need more research on that." Fertility may be one of the first biological processes affected by chemicalexposures, said Taylor, director of reproductive endocrinology andinfertility at Yale. "Fertility is easy to perturb," he said. "Miscarriage is another thing thatmay be related to environmental exposures. We also have to ask: What arethe effects on the next generation? We know these endocrine-disruptingchemicals can affect the next generation's fertility. Is it due to themother's exposure?" Last month, the Environmental Protection Agency and the two largestmanufacturers of one type of PBDE agreed to phase out the chemical.However, the substances will be in the environment a long time, Harleysaid. And understanding their effects is important. "The thing is, they are used in these durable goods that we have in homes,"she said. "Couches, chairs, TVs, carpet padding. These are things that willstay in our house for years to come."

shari.roan@latimes.com Copyright © 2010, The Los Angeles Times