Flame Retardants Linked to Delayed Pregnancy

Most people don't know what PBDE stands for, but they should. Polybrominated diphenyls (PBDEs) are a class of flame retardants found in furniture, carpet padding, cell phones and other electronics. PBDEs leach out of consumer products into our environment. Animal studies have confirmed their adverse effects, but now researchers from UC Berkeley are the first to show that PBDEs may disrupt fertility in women.

Kim Harley, UC Berkeley
School of Public Health

Participants in the study were part of a birth cohort investigation by the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS). "A couple of years ago we started measuring PBDEs in house dust and in the blood of our participants and found very high levels," said study author Kim Harley. "We went to Salinas to study the health effects of pesticides, but what we're learning is that PBDEs also seem to be an important exposure in the community."

Almost all Americans have detectable levels of PBDEs in their blood. Levels are 20 times higher in the United States than in Europe, with the highest levels in California, possibly due to the state's strict flammability standards.1

"It's something we're concerned about," reported Harley. "In study after study, levels of PBDEs in dust, breast milk and blood samples in Californians are higher than the rest of the country."

Kim Harley is associate director of the Center for Children's Environmental Health Research within the School of Public Health at UC Berkeley. The project was funded by the National Institute of Environmental Health Sciences and the US Environmental Protection Agency.

"Animal studies are showing us that PBDEs are endocrine disrupters. They affect thyroid hormone balance, they impact brain development, and they interfere with sex hormones and reproduction—three outcomes that we are interested in looking at in our human population," said Harley.

Researchers interviewed 223 pregnant women over age 18 from six prenatal care clinics in Salinas Valley, California, to determine how long it took for them to get pregnant. Residents of the area are predominantly low-income Mexican immigrants.

Blood samples were taken near the end of the second trimester to detect four PBDE substances found in greater than 75% of the general population (BDE-47, -99, -100, -153). All four were found in over 95% of participants. The strongest predictor of PBDE levels was years of residency in the United States. Increasing levels of BDE-47, -99, -100, -153, and the sum of the four substances, were associated with longer time to pregnancy.2

"What we are seeing is a 30% decrease in the odds of becoming pregnant each month," said Harley. "Women with higher levels of PBDEs took significantly longer to become pregnant."

Researchers took into account variables that might affect their results such as maternal age, a history of gynecologic medical conditions or breast feeding in the two months prior to conception. "We also controlled for working in agriculture and pesticide use in the home," confirmed Harley.

The good news is that PBDEs are being phased out, but their legacy remains in big ticket items like TVs and sofas that we don't replace very often. "It's hard for consumers to know which items contain PBDEs and which don't," added Harley.

She suggested that people can reduce their exposure to house dust that may contain PBDEs by using a wet mop or a HEPA (high efficiency particulate absorbing) filter vacuum. "Washing hands is important. We may be ingesting PBDEs by hand-to-mouth contact with remotes and cell phones." Consumers can also inquire about flame retardants when purchasing new furniture.

"Our next steps are to see if PBDEs are associated with other health outcomes," said Harley. "We've seen in animal studies that PBDEs affect learning and memory, and we're concerned they might be having the same effect in children."


1,2Harley KG, Marks AR, Chevrier J, Bradman A, Sjödin A, Eskenazi B. PBDE Concentrations in Women's Serum and Fecundability. Environ Health Perspect. 2010 Jan 26.

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