Contrary to earlier reports, everyday exposure to phthalates - chemical plasticizers used extensively in household products and in certain medical products - may not have harmful effects on fertility in young men, a new study shows.

Previous studies suggested that low levels of phthalate exposure could adversely affect human semen, the authors explain in a report in Epidemiology, a medical journal, but high doses of phthalates are required to provoke male reproductive toxicity in rats.

For their study, Dr. Bosse A.G. Jonsson from Lund University Hospital, Sweden, and colleagues looked for associations between phthalate metabolite levels in urine and semen quality and reproductive hormone parameters in 234 young Swedish men entering the military.

There was “no clear pattern of associations” between any of the phthalate metabolites and any of the biomarkers of reproductive function measured.

In fact, exposure to phthalic acid seemed to be associated with improved reproductive function, as measured by several markers.

“I do not think it is clear whether phthalate constitutes a risk for the male fertility,” said Jonsson. “More studies must be performed.”

“We plan to study biological samples stored in biobanks from pregnant mothers and study the fertility in their grown-up male children,” Jonsson added.

SOURCE: Epidemiology, July 2005.