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Pesticides, Solvents Linked to Male Infertility

Study says chemicals may affect other parts of body

THURSDAY, July 26, 2001 (HealthDayNews) -- Adding another link to a 20-year chain of evidence, researchers say exposure to pesticides and solvents may contribute to male infertility and even worsen genetic or medical risks for the condition.

Testing a group of infertile men in the south coast of Argentina -- one of the world's most productive farming regions -- researchers say they found a link between pesticides, lower sperm counts and changes in male hormone levels. Developing countries should pay attention to these chemicals, because their environmental regulations fall far short of industrial country levels, the researchers say.

"Our study is a confirmation of previous data of what we've suspected and studied for many years -- that some environmental factors, mainly chemicals, may affect the male reproduction system," says the autho,r Dr. Luc Multigner, a senior investigator for the French Institute of Health and Medical Research in Rennes, France. "There has been no research concerning this question in South America that we know of, while we have plenty of research from Europe and the United States linking environmental issues with infertility in men."

Multigner and colleagues from the Hospital Italiano Garibaldi in Rosario, Argentina, studied 225 men from the Litoral Sur who sought help for infertility between 1995 and 1998. "They were mainly farmers in one part of Argentina, and what we found was that the occupational exposure to pesticides or chemicals containing solvents is a risk factor for male infertility," Multigner explains. "We showed that the men who presented with low sperm parameters were most frequently exposed in the last couple of years to pesticides and solvents."

Multigner also says that the men exposed to pesticides had higher concentrations of estradiol than unexposed men, and that men exposed to solvents had lower concentrations of luteinizing hormones.

"Estradiol is a female hormone," says Dr. Mark Sigman, a spokesman for the American Society for Reproductive Medicine. "There is some evidence in some patients [that] if the ratio between testosterone, the male hormone, and estradiol is decreased -- either because your estrogen level is higher or your testosterone level is lower -- then you are more likely to have fertility problems as a male. But that has not been completely proven. And luteinizing hormones, called LH, are made in the brain. The hormone stimulates the testicles to produce testosterone."

"Our results suggest that toxicants act on the testes and post-testicular sites, including the accessory sex glands," Multigner adds. "The testicles are one of the most vulnerable organs to environmental, physical and chemical agents. Exposure to pesticides and solvents is significantly associated with threshold sperm values much lower than the considered limits for male fertility."

"The interesting finding in this paper is that everyone believes that these chemicals directly effect the testicles," Sigman says. "This shows that there may be other parts of the body involved as well."

Multigner agrees.

"There are two hypotheses about the mechanism of these chemicals in men," he explains. "One of them is that the chemicals have a direct toxic effect on the testicle cells that produce sperm. And the second is that these chemicals may induce endocrine disrupters, which then cause a problem in the male hormonal system, which then leads to troubles in the reproductive system."

The results appear in the July 27 issue of Human Reproduction.

The problem is that Argentina and other developing countries do not have the regulatory controls on pesticides and solvents that Western industrialized countries have, Multigner says. Argentina has become a major user of pesticides, according to the authors, with pesticide exports increasing 270 percent between 1990 and 1998.

"In [the United States] as well as in Europe, we have regulations concerning the use of solvents and pesticides," Multigner says. "The problem is that in less-developed countries there is less regulation and people are less aware of the problem."

But whether there needs to be tighter regulation of pesticides and solvents to prevent infertility is still up for grabs, Sigman says.

"I think there needs to be more data. I believe the U.S. government is studying many environmental chemicals to see if there is this kind of problem. So work still needs to be done."

What To Do: For more on chemicals and male infertility, check out the National Institute for Occupational Safety & Health or Stanford University.

SOURCES: Interviews with Luc Multigner, M.D., Ph.D., epidemiologist and senior investigator, French Institute of Health and Medical Research, Rennes, France; Mark Sigman, M.D., associate professor of surgery and urology, Brown University, Providence, R.I., and spokesman, American Society for Reproductive Medicine; July 27, 2001, Human Reproduction
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