Friday, Feb 6, 2009
For the first time, scientists have evidence that perfluorinated chemicals (PFCs), long thought to be inactive in the human body, can disrupt fertility in women. This is particularly troublesome because PFCs are widely used in industrial nations — they are in everything from pesticides and clothing to carpets, upholstery, food packages, Teflon-coated cookware and personal care products. And they persist in the environment as well as the human body for decades.
The University of California in Los Angeles (UCLA) study, just published in Europe’s leading reproductive medicine journal Human Reproduction, found that it was more difficult for women with the higher blood levels of the chemicals to become pregnant. The researchers studied data from a total of 1,240 women in the Danish National Birth Cohort. They took blood samples when the women were between four and 14 weeks into their pregnancies to check for concentrations of two kinds of PFCs — perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS). The women were also interviewed around the 12th week of pregnancy to find out whether the pregnancy was planned or not and how long it took them to conceive. Infertility problems were defined by a length of 12 months or longer to become pregnant, or if infertility treatments had to be used to faciliate a pregnancy.
The levels of PFOS in the women’s blood plasma measured from a low of 6.4 nanograms per milliliter (ng/ml) to a high of 106.7 ng/ml, and, for PFOA, from less than 1 ng/ml to 41.5 ng/ml. The women with the highest levels of PFOS exposure, indicated by the higher blood levels of the chemical, were found to have experienced 70 to 134% more infertility problems than women with the lowest levels of PFCs. Increased exposure to the specific type of PFCs called PFOA also upped the risk of infertility 50 to 154%.
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So what do these chemicals do to a woman’s reproductive system? The researchers said in a press statement that the biological mechanisms by which exposure to PFOS and PFOA might reduce fertility are not known. However, there is good reason to think PFCs may interfere with hormones that are involved in reproduction.
“Our data showed that higher proportions of women reported irregular menstrual periods in the upper three quartiles of PFOA and PFOS compared with the lowest, and so this could indicate a possible pathway,” UCLA scientist Dr. Chunyuan Fei, the study’s first author, said in a statement to the media. “PFOS and PFOA were considered to be biologically inactive, but recently animal studies have shown that these chemicals may have a variety of toxic effects on the liver, immune system and developmental and reproductive organs. Very few human studies have been done, but one of our earlier studies showed that PFOA, although not PFOS, may impair the growth of babies in the womb, and another two epidemiological studies linked PFOA and PFOS to impaired fetal growth.”
The researchers also suggested that the sperm quality in men could be harmed by PFC levels. “Studies on sperm quality and PFOA/PFOS are certainly warranted,” Professor Jorn Olsen, Chairman of the UCLA Department of Epidemiology and principle investigator of the study, stated in a press release. ” We are waiting for further studies to replicate our findings in order to discover whether PFCs should be added to the list of risk factors for infertility.”