BETHESDA, Md., July 14 (UPI) -- The presence of a chemical in men's urine may impair fertility for couples, the National Institutes of Health cautiously reported today.
Paracetamol, from either acetaminophen use or as a byproduct of the body breaking down other chemicals, in men's urine was seen as making it less likely for couple to conceive, based on a study of previous medical data conducted by the agency.
Acetaminophen is a common, non-prescription drug used for pain and reducing fever, though paracetamol is also produced by the body after breaking down aniline, a chemical in rubber, pesticides and coloring agents in food, cosmetics and clothes.
The study's authors cautiously added the findings need to be confirmed by larger studies, which should also determine the source of paracetamol in the men's urine, how and when they were exposed to it and how much they were exposed to.
For the study, published in the journal Human Reproduction, researchers examined urine samples from men and women in the Longitudinal Investigation of Fertility and the Environment collected from 501 couples in Michigan and Texas between 2005 and 2009.
Though women had higher average levels of paracetamol in their urine, there was no association between paracetamol levels and infertility among women.
However, men with high levels of the chemical, above 73.5 nanograms per milliliter of urine, were 35 percent less likely to conceive than were men with low levels of the chemical, less than 5.4 nanograms per milliliter.
While the association was seen in data, the researchers said the single sample in such a small study group -- and the lack of information on acetaminophen use or potential environmental exposure to chemicals causing their bodies to produce it -- requires more robust studies to confirm the recent study's results.
"At this point, our findings need to be corroborated by future research, and there is no cause for alarm," Dr. Melissa Smarr, a postdoctoral fellow in the Division of Intramural Population Health Research at NIH, said in a press release.