In a study published this week, a decreased likelihood of pregnancy is linked to flame-retardant chemicals in foam furniture, electronics, fabrics and more.
Flame-retardant chemicals found in
many household consumer products may reduce fertility in women, researchers reported.
Their study joins several other papers published in the last two years
suggesting that the chemicals, polybrominated diphenyl ethers, or PBDEs, affect
PBDEs have been used as flame
retardants for four decades and are found in foam furniture, electronics,
fabrics, carpets and plastics. The chemicals are being phased out nationwide, but
they are still found in products made before 2004.
Californians may have higher
exposures compared with residents of other states because of the state’s strict
flammability laws, according to the study authors, from UC Berkeley.
Most of the previous research on
the chemicals has been in animals. A 2008 study linked the chemicals to
disrupted thyroid levels in men, and a study published this month tied PBDE
exposure in pregnancy to neurodevelopmental 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 University who was not involved in the new study. “But we
have cause-and-effect studies in animals, and we have association studies in humans.
I think that is fairly convincing.”
In the study, published in the
journal Environmental Health Perspectives, researchers measured PBDE levels in
blood samples from 223 pregnant women. The women, who were primarily Mexican
immigrants living in an agricultural community, were asked to recall how long
they had been trying to become pregnant, which was defined as being sexually
active without the use of birth control.
Women with the highest
concentrations of the chemicals experienced a longer delay before pregnancy.
Each 10-fold increase in blood concentration of PBDEs was linked to a 30 per
cent decrease in the likelihood of becoming pregnant each month.
“It’s a pretty strong effect,” said
Kim Harley, the lead author of the study and associate director of the Centre
for Children’s Environmental Health Research at UC Berkeley’s School of Public
Health. “They can all become pregnant, but they all had very different amounts
of time it took them to become pregnant.”
Previous studies suggest that 97
per cent of Americans have detectable levels of the substances in their blood.
PBDEs are also found in some foods, particularly dairy products and higher-fat
meat and fish, but household products are considered a major source of
“PBDEs have the ability to just
leach out of these products into our environment,” Ms Harley said. “We’re thinking
the routes are probably ingestion or hand to mouth. But it seems that the
larger route of exposure is house dust.”
How the chemicals might impair fertility
is unclear, she said.
“One of the strongest associations
of PBDEs is with thyroid hormone,” Ms Harley said. “Thyroid hormone does seem
to play an important role in fertility. Either too low or too high levels can
impair fertility. PBDEs also seem to mimic estrogen. It could be through a
hormonal mechanism. But we need more research on that.”
Fertility may be one of the first
biological processes affected by chemical exposures, said Dr. Taylor, director
of reproductive endocrinology and infertility at Yale.
“Fertility is easy to perturb,” he
said. “Miscarriage is another thing that may be related to environmental
exposures. We also have to ask: What are the effects on the next generation? We
know these endocrine-disrupting chemicals can affect the next generation’s
fertility. Is it due to the mother’s exposure?”
Last month, the Environmental
Protection Agency and the two largest manufacturers of one type of PBDE agreed
to phase out the chemical. However, the substances will be in the environment a
long time, Harley said. 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 will stay in our house for years to