Flame retardant exposure may harm fertility

26th January 2010 — Women with higher blood levels of flame retardants known as PBDEs (polybromodiphenyl ethers), found in some household objects, took about twice as long to become pregnant as women with lower blood levels, according to a new study.

''For every tenfold increase in PBDEs in the blood, we saw a 30% to 50% decrease in the odds of becoming pregnant in any given month," says study researcher Professor Kim Harley of the University of California Berkeley School of Public Health in the US.

The study appears online in Environmental Health Perspectives.

Decabromodiphenyl ether (deca-BDE) is now the only commercially available PBDE for use as a flame retardant in the EU. Deca-BDE can be found in many household items. These include casings of televisions, computers, audio-visual equipment, sofas and curtains. The Health Protection Agency says these flame retardants may be released in small amounts from any material which contains them as particles or dust.

Flame retardants and fertility: Study details

Professor Harley and her colleagues interviewed 223 pregnant women living in northern California, asking them how many months it took them to become pregnant. They measured the PBDE levels from blood samples taken near the end of the second trimester.

PBDEs are typically measured from the blood in nanograms per gram of fat, Professor Harley tells us. The levels found in the women ranged from three to 1,200 nanograms per gram of fat.
''Women with a higher exposure to a commonly used [in the past] flame retardant took longer to become pregnant," she says. The higher the levels, the longer it took to get pregnant.

The median time to pregnancy was three months (half took longer, half less), but 15% took longer than 12 months to conceive. ''But some took 10 years or more," Professor Harley says.

Exactly how the chemicals may affect the length of time it takes to get pregnant isn't known, but experts say one way may be to disrupt thyroid functioning. Low and high thyroid levels can alter normal menstrual patterns and therefore affect fertility.

The women's levels, overall in the study, were actually a bit lower than the US national average, Professor Harley says. She notes that about 97% of Americans have detectable PBDE levels in their blood, citing a survey. Californians are likely to have the highest levels because of the state's strict flammability requirements for products.

The women in the study were living in a low-income, predominantly Mexican-immigrant community. Most were recent immigrants from Mexico, where PBDE use is lower, she says.

Flame retardants in the UK

The research concentrated on two types of PBDEs: penta and octa. Professor Harley says even though these have been phased out, they remain in older household furniture and can still leach out.

The Health Protection Agency says there is very little information regarding adverse health effects in humans following exposure to PBDEs. It says there is no evidence to suggest that exposure to PBDEs would cause cancer. The Agency says developing infants may be more susceptible to effects of PBDEs on the nervous system and thyroid than adults.

Professor Harley is now focusing on the effects of PBDE exposure on children.