Semen Quality Lower in Men from Rural Areas

Shanna H. Swan, PH.D.
University of Missouri-Columbia School of Medicine
R01ES09916

Background: Many studies conducted over the last decade have reported large differences in semen quality parameters in men from different areas of the U.S. and in international studies as well. Comparisons of these studies are difficult because semen analyses are highly sensitive to the methods of semen collection and analysis. There are also indications that sperm concentrations declined dramatically during the 20^th century; however, analytical differences again may be at least partially responsible for the decline.

In 1998, NIEHS funded the Study for Future Families, a multi-center study similar in design to multi-center studies being conducted collaboratively in Europe and Japan. The study's goal is to estimate the geographic variability of semen parameters in men in the U.S. and to compare the results to those from other centers worldwide. A NIEHS-supported researcher at the University of Missouri, Columbia, the coordinating center for the U.S. study, recently reported the results of analyses from men in four distinct geographic areas.

Advance: The team studied 512 men in four areas: Columbia, Missouri; Los Angeles, California; New York, New York; and Minneapolis, Minnesota. Sperm concentration and the total number of motile sperm were significantly lower for men from Columbia, Missouri than the other three centers. Total motile sperm was 58% lower in the Missouri men than the men from Minnesota. Although some of the men had low semen quality, it was not low enough to cause infertility, since the men were partners of pregnant women.

Implication: A possible reason for these differences could be higher exposure to pesticides in the more rural Missouri population than the other areas. Fifty-seven percent of the land in the Columbia area is used for farming which far exceeds that of the other areas. Many animal studies have shown that pesticides affect fertility; however, more research is needed to determine if this is the cause for the differences seen in this study. Additional research is being planned in Iowa City, Iowa, an area with even higher exposure to pesticides than Columbia.

Citation: Swan SH, Brazil C, Drobnis EZ, Liu F, Kruse RL, Hatch M, Redmon JB, Wang C, Overstreet JW, The Study For Future Families Research Group. Geographic differences in semen quality of fertile U.S. Males. Environ Health Perspect. 2003 Apr;111(4):414-20.