WebMD Medical News
Louise Chang, MD
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.
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.
The new study backs up some lab findings, says Sonya Lunder, a senior
analyst at the Environmental Working Group, which has also studied the
Of the results, she says: “A 50% decrease in the odds of becoming pregnant
The study is scientifically sound, says Ruthann Rudel, director of research
for Silent Spring Institute, a Boston-based organization that conducts research
on environmental factors affecting women's health.
The researchers controlled for other factors that may affect fertility, she
says, such as pesticide exposure, and still found an effect of the
A representative from the flame retardant industry took exception to the
findings. ''The study is limited to penta and octa-[PBDEs] and does not include
deca, the only PBDE currently in use," says John Kyte, a spokesman for the
Bromine Science and Environmental Forum, an industry group based in Washington,
As a result, he says, ''the study is not applicable to all PBDEs or to PBDEs
generally." Each of the PBDE forms is different, he says.
He says penta and octa-PBDEs are no longer in use in the U.S., so exposure
to them should decline over time.
In response, Harley says that deca (also known as BDE-209) was not measured
because the CDC lab didn't have the analytical capability to measure it at the
time of the study. ''So we have no idea what the deca levels are in these
women," she says.
Although it is true the PBDEs found to be associated with delayed time to
pregnancy in her study have been banned, she says many older products still
contain the penta chemicals ''and we expect that our exposure to penta will
continue over the next several years."
Even though penta and octa-PBDEs have been phased out, Harley says they
remain in older household furniture and can still leach out.
She can't specify a ''safe'' level of exposure based on her study, but she
and others suggest that women follow a few simple steps to reduce exposure.
Two main sources of the chemicals are found in food and in household
products. "Choose meat, fish, and dairy lower in fat," she says. The compounds
are fat-soluble, she says.
Don't reupholster foam-filled furniture yourself, Lunder says. The PBDEs are
in the foam and can leach out. Limit exposure to old carpet padding, which is
often recycled foam, she says.
''When you are replacing carpet, get women and children out of the house,"
she says. The exposure concern is not limited to its effect on fertility, but
also to children's development.
Harley is now focusing on the effects of PBDE exposure on the children.
SOURCES:Harley, K. Environmental Health Perspectives, online Jan. 26,
2010.Kim Harley, PhD, adjunct assistant professor of maternal and child health
and associate director, Center for Children's Environmental Health
Research, University of California Berkeley School of Public Health.Sonya Lunder, senior analyst, Environmental Working Group, Washington,
D.C.John Kyte, spokesman, Bromine Science and Environmental Forum, Washington,
D.C.Ruthann Rudel, director of research, Silent Spring Institute, Boston.
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