Lead link to male infertility

American researchers have found that high levels of lead in the environment may be the cause of some cases of unexplained infertility in men. In a study, published in the journal Human Reproduction, they warn that environmental lead exposure limits should be re-evaluated in the light of their findings.

The study involved analysing the semen from 140 men who were undergoing a first IVF cycle with their partners. The effect that the presence of metals, including lead, cadmium and zinc, had on sperm function was recorded. The men were also asked to fill out lifestyle questionnaires in order to rule out other factors that may have potential effects on their sperm function. Lead levels in semen were found to vary greatly among the men, and higher levels of lead were found to correspond with lower fertilisation rates.

The researchers found that higher lead levels affected fertilisation in one of two ways. Either receptors on the head of the sperm failed to recognise and bond to the egg, or the ability of the sperm to penetrate the egg was reduced. Team leader Susan Benoff said that she was very excited by the results, adding that they were not exclusive to IVF patients but were 'true in the general public'. None of the men in the study were exposed to high levels of lead in their employment, suggesting that lead in the environment contributed to poorer sperm function.