CURWOOD: Just ahead: The Nature Conservancy gives itself a scrubbing. First, this Environmental Health Note from Diane Toomey.

TOOMEY: For the first time, researchers have found a possible link between exposure to crop pesticides and low sperm counts in the general population .

Researchers at the University of Missouri looked at two groups of men--one from Minneapolis and another from agricultural areas of Missouri. The men didn’t have any known risk factors for reduced sperm count such as advanced age or smoking. Researchers then analyzed the men's sperm as well as the pesticide levels in their urine.

In general, the men in Minneapolis showed very little exposure to pesticides. So low sperm counts in some of those people couldn’t be attributed to pesticides. But in Missouri, researchers found higher levels of pesticide exposure. And they found that men with elevated levels of three pesticides, in particular, were significantly more likely to have a low sperm count and poor sperm quality. For instance, Missouri men with the highest levels of the common weed killer Alachlor were thirty times more likely to have lower sperm counts and less vigorous sperm. Since these men didn't work in the pesticide industry or on farms, researchers say they were most likely exposed through drinking water.

Researchers caution: although this is a preliminary indication that pesticides might be affecting sperm, this was a small study, with just 86 men enrolled. And more confirmation work will be needed. For instance, researchers will need to examine the effects of pesticide exposure at various stages of sperm development by testing for it weeks prior to sperm collection.

That’s this week’s Health Note. I’m Diane Toomey.

CURWOOD: And you’re listening to Living on Earth.