Consumption of fruits and vegetables that contain relatively large amounts of pesticide residue may affect men's sperm counts and the number of normal-looking sperm they produce, a potential factor in fertility problems, Harvard University researchers reported last week.

Because of the study's design, the researchers could not determine whether the pesticide residue caused the problems they found in the sperm of 155 men who provided samples at a fertility clinic. But the results were clear enough to "suggest that exposure to pesticides used in agricultural production through diet may be sufficient to affect spermatogenesis in humans," the researchers wrote in their paper, published online in the journal Human Reproduction.

Pesticides have long been suspected of having a possible impact on sperm production of men heavily exposed to them. Yet there has been little evidence that pesticides affect human health, according to Jorge Chavarro, an author of the study.

The researchers used Agriculture Department data to classify pesticide residue in 35 fruits and vegetables between 2006 and 2012. They asked 155 men how much of each they ate (they averaged 0.9 daily servings of high-pesticide produce and 2.3 servings of low- to moderate), then checked their semen samples.

Men who consumed the largest amounts of high-residue fruits and vegetables had 49 percent lower sperm counts, 32 percent fewer normal-appearing sperm, and a 29 percent lower ejaculate volume than men who ate the smallest amounts.

Chavarro said much more research was needed. - Washington Post