A preliminary study conducted by researchers at the US National Institutes of Health (NIH) has revealed that high levels of paracetamol in urine may impair male fertility.

The study results demonstrated that couples whereby the male partner had high levels of urinary paracetamol took more time to achieve pregnancy than couples whereby the male partner had lower levels of the compound.

Also known as acetaminophen, paracetamol is a non-prescription drug that is largely used to relieve a person suffering from pain, as well as reduce fever.

The drug is one of the compounds that is produced when the body breaks down aniline, a chemical used to make pesticides, rubber and colouring agents used in cosmetics, clothing and food.

NIH Eunice Kennedy Shriver National Institute of Child Health and Human Development Intramural Population health research division postdoctoral fellow, and the study first author Dr Melissa Smarr said: “At this point, our findings need to be corroborated by future research, and there is no cause for alarm.”

Dr Smarr revealed that the high levels of paracetamol in the urine of certain men involved in the research were unlikely to result only from taking medications.

The presence of paracetamol was more consistent with those seen from environmental exposure, either to aniline or paracetamol or a combination of both.

"At this point, our findings need to be corroborated by future research, and there is no cause for alarm."

The research findings can also have implications for the amount of paracetamol exposure that is considered acceptable.

The current study is a result of the latest analysis of data from the Longitudinal Investigation of Fertility and the Environment (LIFE) study, which was established in a bid to assess the effect of lifestyle and exposure to environmental chemicals on fertility.

Around 501 couples were enrolled in four counties within Michigan and 12 counties in Texas from 2005 to 2009.

According to the study authors, the research results 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 paracetamol to which they are exposed.

Image: Paracetamol, also known as acetaminophen, is a non-prescription drug. Photo: courtesy of winnond / FreeDigitalPhotos.net.