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Women exposed to high levels of flame retardants take substantially longer to get pregnant -
Category: News
Women exposed to high levels of flame retardants take substantially longer to get pregnant

Women exposed to high levels of flame retardants take substantially longer to get pregnant, indicating for the first time that the widespread chemicals may affect human fertility, according to a study published Tuesday.
 
 


Furniture cushions, carpet padding and other household items contain hormone-disrupting flame retardants called polybrominated diphenyl ethers, or PBDEs. Two of the most widely used compounds have been banned in the United States since 2004, but they remain ubiquitous in the environment, inside homes and in the food supply.

Epidemiologists from the University of California at Berkeley studied 223 pregnant women in California?s Salinas Valley, an agricultural community with predominantly low-income, Mexican immigrants.

More than 97% of the women had PBDEs in their blood, and those with high levels were half as likely to conceive in any given month as the women with low levels.

?This study provides the first evidence that PBDEs may impact human fertility,? wrote the authors, led by epidemiologist Kim Harley, in the study published online in Environmental Health Perspectives. "If confirmed, this finding would have strong implications to women trying to conceive given that exposure to PBDEs is nearly universal in the United States and many other countries."

Harley said ?the results are surprisingly strong.?

?These findings need to be replicated, but they have important implications for researchers,? she said.

Each ten-fold increase in a woman?s blood was linked to a 30 percent decrease in her odds of getting pregnant.

Previously, laboratory tests have found altered male hormones and reduced sperm counts in animals exposed to PBDEs. But this study is the first to find reduced human fertility.

?Very little research? related to the flame retardants has been conducted in humans, Harley said.

The researchers do not know how the chemicals may be reducing fertility. They did not study the fathers, who probably also were highly exposed, so it is possible that the men?s fertility was reduced, not the women?s, particularly since it is males who are harmed in the animal tests. Some PBDEs mimic estrogen, while others can block testosterone.

Dr. Arnold Schecter, a University of Texas School of Public Health environmental scientist who was not involved in the study, said even though nearly all the women in the study were Hispanic, "the results might be generalizable to many American women."

"Elevated levels of PBDEs might be a risk factor for reduced fertility," said Schecter, who studies how people are exposed to the flame retardants.

None of the women - chosen for the research because they were pregnant - were infertile, and they conceived, on average, after three months.

But the chemicals may be pushing some women into the ranks of the sub-fertile, which means it is difficult to conceive. About 15 percent of the women in the study took longer than 12 months to conceive.

More than 2.1 million couples in the United States are infertile, according to the Centers for Disease Control and Prevention.

?Because exposure to PBDEs is ubiquitous in industrialized nations, even small decreases in fecundability may have wide-reaching public health impacts,? the scientists said in their study.

The tests measured the chemicals in the women's blood while they were pregnant, so their levels when they were trying to conceive could have been higher or lower. A similar study should be done in women before pregnancy, Schecter said.

The PBDE study was part of a decade-long project by the UC Berkeley scientists to examine whether environmental factors are harming the health of Salinas Valley mothers and children. The women are highly exposed to pesticides, which also have been shown to reduce fertility, but the researchers controlled for pesticide exposure in their study, as well as length of time in the United States, smoking and other potential factors.



 
 

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Reference:
www.scientificamerican.com


Dated
2010-02-01



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