High Levels of Urinary Paracetamol May Impair Male Fertility, Study Suggests

Couples in which the male partner had high levels of paracetamol in his urine took longer to achieve pregnancy than couples in which the male had lower levels of the compound, according to a preliminary study by researchers at NIH.

Paracetamol, also known as acetaminophen, is a non-prescription drug widely used as a pain reliever and fever reducer. It also is one of the compounds produced when the body breaks down aniline, a chemical used to make rubber, pesticides and coloring agents used in food, cosmetics and clothing. The study was published online in Human Reproduction.

“At this point, our findings need to be corroborated by future research, and there is no cause for alarm,” said Dr. Melissa Smarr, the study’s first author, a postdoctoral fellow in the Division of Intramural Population Health Research at NICHD.

Smarr explained that the high levels of paracetamol in the urine of certain men in the study were unlikely to result only from taking medications and were more consistent with those seen from environmental exposure, either to aniline or paracetamol or a combination of the two. The findings could have implications for the amount of paracetamol exposure that is considered acceptable.

The authors stressed that their findings need to be confirmed by larger studies that can better identify the sources of paracetamol, the duration of time the participants are exposed and the amount of the compound to which they are exposed.