Common Chemicals Linked to Infertility
New Study Reveals Possible Link; Experts Say Findings Still Too Preliminary
By CYNTHIA HERRICK, M.D.
ABC News Medical Unit
Jan. 29, 2009
Could your cookware and cleaning supplies make it harder for you to have a baby?
In the current issue of Human Reproduction, researchers suggest that chemicals called perfluorinated compounds, or PFCs for short, might be linked to delays in getting pregnant. But study authors and experts in the field caution that the findings are preliminary and mainly highlight an area that needs more research.
"The finding is interesting," says one of the study's authors, Joseph K. McLaughlin, professor of medicine at Vanderbilt University School of Medicine in Nashville, Tenn. "We need to know more about these chemicals because they are long lasting and have had effects in animals."
And until more is known, the researchers say, changes in health policy are unlikely.
"This is the first study in the world that has looked at this particular association," says lead study author Dr. Jorn Olsen, chair of the Department of Epidemiology at the UCLA School of Public Health. "Normally we don't base our conclusions on public health information on one study. We need to wait for other studies to make policy recommendations."
PFCs Abound in Everyday Environment
PFCs are everywhere. They're found in Teflon cookware, the original Scotchgard, some shampoos, floor wax, food wrapping, carpet treatments and other cleaning products. PFCs are also present in air and water in the form of industrial waste from chemical plants.
"The whole issue of things in our environment affecting reproduction is important, and any studies that bring attention to it are of value," says Dr. Howard Zacur, professor and director of the Division of Reproductive Endocrinology and Infertility at the Johns Hopkins Medical Institutions in Baltimore.
There have already been animal studies demonstrating the toxic effects of PFCs. "In the laboratory, we've seen negative effects in animals," says Dr. Philip Landrigan, professor and chairman of Community and Preventive Medicine at the Mt. Sinai School of Medicine in New York City. "We're now starting to see studies looking at the impact they [PFCs] have in humans."
The study released Wednesday looked at 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.
An Apparent Increase in Risk
Researchers found that for higher levels of PFCs in the blood, the odds of infertility increased from 70 to 134 percent for one kind of PFC called PFOS, while another PFC called PFOA was linked to a 60 to 154 percent increase in the chance of infertility. This apparent increase in risk existed even after researchers took other factors into account, such as age of the parents and economic and social factors.
"The most potent aspect of the study ... is that [the researchers] see a 'dose-response relationship,'" Landrigan says, 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."
Not So Fast, Researchers Say
But McLaughlin is cautious not to over-interpret the findings. "The major strength of the study is that it is a world-class nationwide longitudinal study of pregnant women. Do I believe that PFCs really affect time to pregnancy? It remains to be seen."
Dr. Richard Paulson, chief of the Division of Reproductive Endocrinology and Infertility at the University of Southern California, agrees.
"The study can only show an association and not causation," he says. "The time to pregnancy is dependent on so many different factors that it would be impossible to control for all of them."
In the paper, the authors admit that they did not have information on some other important factors that affect fertility, including the frequency and timing of intercourse and sperm quality.
"Nevertheless, it is provocative to have an association between these chemicals and time to pregnancy," Paulson says. "We should be anxiously awaiting further confirmation of these preliminary results in future, larger, hopefully prospective, studies."
Limiting Your Exposure
The jury is still out on what impact, if any, PFCs have on fertility. Even so, several years ago the U.S. Environmental and Protection Agency negotiated with 3M, the sole manufacturer of PFOS, to stop producing the chemical. Since that time, however, PFOA continues to be used and the EPA does not have enough information to recommend that consumers stop using products that contain it. But they have created a voluntary program for companies to reduce and ultimately eliminate PFOA emissions and product content by 2015.
'Stop Using Teflon'
Landrigan, however, says a more aggressive approach is needed.
"PFCs aren't banned but there are a couple of common sense things people can do to reduce their exposure," he says. "There's a lot we don't know about toxicity but we can use common sense.
"So stop using Teflon frying pans, don't use scotch guard that contains these compounds and, whenever possible, families should think twice about using plastic to store food and should go back to glass."
Michelle Schlief contributed to this report.