A chemical found in common household products and cosmetics has been linked to a decrease in fertility in women, according to a new study. Researchers examined more than 1,000 pregnant women and found that those exposed to higher levels of perfluorinated chemicals (PFCs) had experienced more difficulty getting pregnant.
PFCs are used to make textiles and leather resistant to water, dirt or oil. They are also found in personal care products such as nail polish, dental floss or facial moisturizer. The chemicals resist breakdown and tend to persist in the environment and in the body for decades [Bloomberg].
"If this finding can be replicated, one would have to look for other chemicals to replace these," [Washington Post]
said lead researcher Jorn Olsen. Although experts caution that the correlation doesn't prove causation, many manufacturers have already taken steps to cut back on PFCs. Data for the study was taken from
1,240 women in the Danish Birth Cohort when they were six to 12 weeks pregnant. If they reported that it took them longer than 12 months to get pregnant or if they used drugs designed to increase their chances of conceiving, they were considered to have infertility. This is a generally accepted definition of infertility by experts in the field [ABC News]. The women were divided into four groups based on levels of two types of PFCs,
perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), found in their blood. Compared to women in the group with the lowest levels of PFOS, women with higher levels took from 70 percent to 134 percent longer to conceive. For PFOA, women with higher levels took from 60 percent to 154 percent longer to conceive. The researchers accounted for factors such as age and economic and social factors, although they admit that they lacked information on other factors that could influence fertility such as timing and frequency of intercourse and sperm quality. It is not yet clear how PFCs would delay pregnancy, but Olsen suggests that the chemicals may affect reproductive hormones.
Recent animal studies have found these chemicals may have a variety of toxic effects on the liver, immune system and developmental and reproductive organs, he noted [Washington Post].
Dr. Philip Landrigan, an environmental health researcher, comments that the results are convincing because they show a "dose-response relationship,"
referring to the idea that as the level of exposure goes up, so does the apparent effect on the individual exposed. "When you see that kind of parallel trend, especially for the two PFC compounds they looked at, this is very powerful evidence" [ABC News].
Nevertheless, the study only shows association and does not prove that PFCs cause infertility, and experts are cautious about raising public alarm, saying that more studies are needed. Infertility expert Jamie Grifo says,
"There are probably things in the environment that are affecting us in ways we don't know about, but you have to get to the basic biology of what's the mechanism of action -- that's the missing link. The problem with the study is, it creates more anxiety and fear, but it doesn't answer the question" [Washington Post].
At the urging of the EPA, eight major companies, including Dupont, have already cut back or eliminated PFOA from their manufacturing processes and consumer products. According to this voluntary agreement, the companies will phase out PFOA use completely by 2015. 3M, which eliminated PFOA from its fabric protector Scotchgard in 2001, funded the new study, published in Human Reproduction [pdf].
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Image: flickr / ECohen