Flame Retardant Exposure May Harm Fertility
Study Finds High PBDE Levels in Blood Double Time to Get Pregnant
Jan. 26, 2010 -- Women with higher blood levels of flame retardants known as
PBDEs, 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 Kim Harley, PhD, adjunct assistant professor of maternal and child
health and associate director of the Center for Children's Environmental Health
Research at the University of California Berkeley School of Public Health. The
study appears online in Environmental Health Perspectives.
But a spokesperson for the industry said that the study findings are limited
to PBDEs no longer used in new production and the environmental levels of those
PBDEs are expected to decline over time.
PBDEs became common after the 1970s, when new fire safety standards were
implemented in the United States; the compounds are found in furniture,
carpets, electronics, plastic, and other household items.
Flame Retardants and Fertility: Study Details
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
PBDEs are typically measured from the blood in nanograms per gram of fat,
Harley tells WebMD. The levels found in the women ranged from 3 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 the time to pregnancy.
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," Harley says.
The PBDEs found in the highest concentration were four types of penta-BDEs.
In the U.S., the manufacturer of penta and octa-BDEs stopped production in
2004, but the chemicals remain in older products. Because the compounds are not
chemically bound, they can leach out of products.
Exactly how the chemicals may affect time to pregnancy 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 thus affect fertility.
The women's levels, overall in the study, were actually a bit lower than the
national average, 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.