A new study has found the sperm of men in three urban areas, including Minneapolis, outperforms that of men living in a semi-rural area, raising questions about the environmental factors that affect reproductive health.

The study compared the sperm of men living in Minneapolis, Los Angeles, New York and Columbia, Mo., and found the men from Columbia, in Boone County – a rural, agricultural area – had sperm samples of significantly lower concentration and motility, or movement.

The University participated in the study led by the University of Missouri-Columbia, which researchers say is the first U.S. study to show sperm quality differs substantially in country’s various geographic regions.

In Los Angeles, New York and Minneapolis, researchers found sperm concentrations 38 percent, 75 percent and 67 percent higher, respectively, than Columbia. The sperm motility was higher in all three urban centers, especially in New York and Minneapolis, at 74 percent and 77 percent higher, respectively.

Researchers analyzed samples from 512 men between September 1999 and November 2001. They chose men who had just impregnated a woman as a measure of fertility.

The researchers controlled for such sperm-affecting factors as race, age, smoking and recent fever.

Bruce Redmon, a University professor in the department of medicine and a researcher in the study, said the researchers think the rural, agricultural nature of Columbia might be a factor in the difference.

“We don’t know the cause, but we’re looking at a hypothesis that there may be environmental factors specific to Columbia, Mo., which might affect sperm counts,” Redmon said.

“One thing that would be obvious to look at would be potential chemicals from the agricultural industry,” he said.

To support their hypothesis that environmental factors might play a role in the relatively weak sperm of Columbia’s men, researchers cite a U.S. Geological Survey study that found the widespread presence of herbicides in agricultural area streams and shallow ground water.

Another semi-rural population study also found lower sperm counts in men in Iowa City, Iowa – but Redmon cautions against drawing a comparison between the two because of different testing methods.

Vincent Garry, a University lab medicine and pathology professor, is another researcher who has studied the possible association between pesticides and reproductive health.

He studied northwestern Minnesota’s Red River Valley – an area with the state’s highest levels of both usage of certain pesticides and of aerial application of pesticides – and found a higher rate of birth defects than in other parts of Minnesota including other rural areas.

Redmon said a European study published last year found geological regions were a factor in sperm potency. Researchers found Denmark’s men had lower sperm counts than men in Finland, Scotland and France.

Redmon said the University of Missouri-Columbia study – published Monday in the journal Environmental Health Perspectives – not only collected semen, but also biographical data and blood and urine samples. The biographical data of the men will be analyzed, and the blood and urine samples will be tested for chemicals, pesticides and hormone levels to see what factors might have contributed to the differences.