FRIDAY, April 29, 2005 (HealthDay News) -- Environmental factors may be affecting men's fertility, a new Scandinavian study contends.
Using fishermen as their study subjects, Swedish researchers found that pollutants appeared to affect the ratio of sperm carrying the X or Y (sex-determining) chromosomes.
Dr. Aleksander Giwercman and his colleagues from Lund University, Sweden, evaluated the effects of two types of persistent organochlorinepollutants (POPs) on the semen of 149 fishermen. Some fished off the east coast in the Baltic Sea, which is contaminated with the POPs DDE and CB-153, and others fished off purer waters on the west coast.
The researchers found that larger amounts of both types of pollutants in the men's blood was associated with an increase in the proportion of Y chromosome-bearing sperm, which determines sex. The association held even when the investigators controlled for age, smoking, and hormone levels.
When Giwercman's group compared the 20 percent of the fishermen with the highest exposure to pollutants with those with the lowest exposure, the pollutant DDE was associated with an increase of 1.6 percent in sperm with Y chromosomes, and the pollutant CB-153 with an increase of 0.8 percent.
"This is a novel finding," Giwercman said of the first-of-its-kind research, which was published in the April 28 online issue of Human Reproduction.
The researchers did not study, however, whether the increase in Y chromosomes actually resulted in the birth of more boys than girls.
Experts said consumers can do little on their own to decrease the effect of pollutants, especially if they live in very polluted locations.
The study of fisherman "adds to the ambiguous findings" of what effect pollutants actually have on chromosomes, said Susan Benoff, a fertility expert at North Shore-Long Island Jewish Institute for Medical Research in Manhasset, N.Y.
Another expert, Shanna Swan, a researcher at the University of Rochester Medical Center in Rochester, N.Y., however, found shortcomings in the study. The results only explain a small fraction of the variability in the proportion of Y chromosomes, she said.
To learn more about infertility, visit the American Society for Reproductive Medicine.