Urinary concentrations of chemical Bisphenol A, or BPA, may cause decreased sperm quality and sperm concentration, researchers have found.
According to critics, BPA mimics the body's own hormones and may lead to negative health effects.
It is found in plastics and epoxy resins used in food and beverage cans.
John Meeker, assistant professor of Environmental Health Sciences at the University of Michigan School of Public Health, Russ Hauser, the Frederick Lee Hisaw Professor of Reproductive Physiology at Harvard School of Public Health and colleagues at Massachusetts General Hospital and the U.S. Centres for Disease Control and Prevention conducted the study.
Researchers measured sperm concentration, sperm motility, sperm shape and DNA damage in the sperm cell.
"We found that if we compare somebody in the top quartile of exposure with the lowest quartile of exposure, sperm concentration was on average about 23 percent lower in men with the highest BPA," Meeker said.
Results also suggested a 10 percent increase in sperm DNA damage.
However, they warn that the results are not conclusive, and further studies are required to confirm their theory.