Researchers have found that perfluorinated chemicals (PFCs), which are found in a variety of everyday materials from carpets to shampoo, may reduce fertility in women.

Previous studies have linked high levels of PFCs to infertility in animals, but this is the first one to show such an effect on humans, says senior study author Jorn Olsen, who heads the epidemiology department at the University of California in Los Angeles. The study is published today in the journal Human Reproduction.

Infertility is a widespread problem in developed countries. Olsen says that research indicates that 15 percent of couples in the U.S. and Europe would be considered infertile by the World Health Organization (WHO), which considers a pair to be infertile if it takes the woman a year or more to conceive. Smoking, obesity and sexually transmitted infections (such as chlamydia and gonorrhea) are known to up the risk of infertility, but, otherwise, little is know about its causes in otherwise healthy women of childbearing age. 

Curious whether PFCs, which are found in pesticides, clothing, upholstery and personal products, might be a factor, Olsen and his colleagues studied levels of the chemicals in the blood of 1,240 Danish women who became pregnant between 1996 and 2002. They found that 1,052 (85 percent) of the women were fertile, meaning they took less than a year to conceive and 188 (15 percent) were infertile.

The researchers tested their blood for two types of PFCs between their fourth and 14th weeks: perfluorooctane sulfonate (PFOS), which is found in some cloth and paper products, and perfluorooctanoate (PFOA), found in carpets and personal care products.

The scientists discovered that women with high levels of both types were significantly more likely to have had trouble conceiving. Those with PFOS blood levels exceeding 26 nanograms/milliliter were at least 70 percent more likely to be infertile, and those with more than 3.9 ng/ml of PLOA in their blood were at least 60 percent more likely to take longer to get pregnant. There were two key weaknesses with the study, Olsen notes: it only included women who eventually became pregnant (and not those who tried to no avail), and blood tests were only taken once the women were pregnant. Olsen suspects, however, that the measurements would have been similar if blood samples had been taken earlier, because PFCs are known to linger in the body for years.

Olsen now plans to do a study to determine whether PFCs, which are known to pass from mother to child, may lead to birth defects.