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Pesticides Causing Infertility in the Heartland

Country living may be hazardous to men's fertility
April 2, 2004

By Orna Izakson, E/The Environmental Magazine

When epidemiologist Shanna Swan began comparing fertility in urban versus rural men, she thought she knew what she would find. Just as corn, sorghum, and soybeans grow better in central Missouri's hills and hollers than in a polluted parking lot in urban New York, Los Angeles, or Minneapolis, so too would fertility be higher among men living in the clean, bucolic countryside.

She turned out to be completely wrong. In 2002, when the study appeared in the peer-reviewed journal Environmental Health Perspectives, Swan reported that men in rural Boone County, Missouri, had a 42 percent lower sperm count than their counterparts in urban Minneapolis. The rural men also had lower quality sperm as measured by movement, shape, and other factors.

Swan didn't look for infertility, and men were chosen from among those who came into participating centers with their pregnant partners. A man is considered effectively infertile if his sperm counts fall below 20 million per milliliter, and his fertility is considered impaired below 40 million per milliliter.

The Missouri men had a mean of 59 million per milliliter, compared with 99 million and 103 million in Minneapolis and New York, respectively.

But Swan said some of the Missouri men had counts well below 40 million or even 20 million and still successfully reproduced. It only takes one sperm and one egg to make a baby, but with fewer sperm to start with the couple may have to work harder to conceive. (Home tests check samples relative to the 20 million/milliliter measure only and don't consider other factors that can affect fertility.)

Faulting Farms

Swan, who is a professor of family and community medicine at the University of Missouri in Columbia, and her colleagues reviewed their data to figure out what might account for the difference. The first obvious candidate was farming and the associated pesticides since 57 percent of Boone County land is devoted to agriculture, while 19 percent or less is farmed in the other areas studied.

To test that hypothesis, the researchers looked at urine collected from the men in the first study and checked for the breakdown products of 15 different common farm chemicals.

Those results, published last July in Environmental Health Perspectives, found that men with high levels of the herbicide alachlor were 30 times more likely to have diminished sperm quality. Men with high levels of the insecticide diazanon or the herbicide atrazine were 16.7 or 11.3 times more likely to have poor sperm quality, respectively.

The insecticide diazanon was once commonly used in urban areas but soon won't be allowed for such uses because of its toxicity to children, said Pollyanna Lind of the Northwest Coalition for Alternatives to Pesticides. Now it's used only in agriculture, primarily for fruit and nut crops.

Alachlor is used only in agriculture, primarily on corn, peanuts, beans, sorghum, and soybeans. Atrazine is used broadly, from range lands to some conifer forests as well as on cornfields and even on some residential lawns.

Scientists have been tantalized for decades with discrepancies in sperm quality in different locations, findings that hinted at an environmental connection. Studies in Denmark, Scotland, and the United States have found declining sperm counts over time.

And there are well-documented links between some chemicals that have since been banned and the complete loss of sperm in workers exposed to them, such as dibromochloropropane (DBCP), a pesticide historically used on pineapples.

Persistent organic pollutants such as phthalates, found in plastics, and polychlorinated biphenyls (PCBs) as well as other chemicals that disrupt hormonal processes also have been linked to lowered male fertility.

But despite their reputations, tight jeans, tobacco, and alcohol have little effect on sperm counts, Swan said.

Both of Swan's studies, which were funded by the National Institutes of Health, were groundbreaking, the first to link lowered sperm quality with rural life and the first to look at the reproductive effects of pesticides as they actually occur in the environment.

Critics charge that the studies weren't done properly. Angelina Duggan of CropLife America which represents some of the largest agricultural-chemical companies said Swan's sample was too small, should have considered infertile men, took samples in the heat of summer when sperm counts typically drop, and considered too small a window in the men's lives instead of an overall history that could affect sperm quality.

"We're interested in any of her findings, and we don't make light of them," said Duggan. "But we consider the study preliminary and flawed."

But if the findings are replicated and confirmed, Swan said the news would be "enormously significant because the pesticides we've linked to poor semen quality are among the most commonly used."

That's not only in terms of pounds applied each year but also in terms of what's regularly found in drinking-water supplies. Recent reports by the U.S. Geological Survey found high levels of atrazine and alachlor in the nation's surface waters.

Practicing Precaution

So what should people do if they're looking for clean living? Swan's work suggests that moving to the country may bring its own set of problems. Some ideas that may help:


* Know what's in the drinking water. People can check with the U.S. Geological Survey to see what they've found in various areas, and local utilities must issue annual reports about contaminant levels. If water comes from a well, home testing is available from a variety of labs. Consult state environmental agency or the local agricultural extension office for lists.

* Consider water filters. NSF International tests filters for their ability to remove alachlor and atrazine but not diazanon. Its Web-based database lists which filters are certified to remove those pesticides. If the concentrations of the pesticides are higher than 100 parts per billion, be prepared to change filters more often or to "piggyback" them: put two in a row to take the task in stages.

* The most versatile filters sit on or under the sink. Multipure ($200 and up, with 400-gallon replacement filters costing $38) makes some of the most famous, but Culligan, Everpure, and even Sears make certified models.

* Pur offers the only pour-through pitchers that remove atrazine, but they don't touch alachlor ($17 to $30, replacement filters range from $9 to $13 and are good for 100 gallons). Among faucet-mount filters, only Brita models can remove both ($35, and $20 for 100-gallon replacement filters).

* Support alternatives to pesticides, including organic agriculture. Filters are a Band-Aid, says NCAP's Lind. To address the larger problem, vote with grocery dollars to influence how crops are grown. The best way to keep pesticides out of the water is to keep them from getting into it in the first place.

* Support further research. What else is in the water that's affecting human health? It's hard to say without more testing than is routinely done for pesticide registrations.

"In terms of what we're currently exposed to we have almost no information," Swan said. The tests industry performs for Environmental Protection Agency certification use levels that are very different from normal human exposures, she said.

Swan's study should be a wakeup call to the world, because, for once, it's not hyperbole to say that the future of humankind is at stake.


Orna Izakson is a freelance writer based in Portland, Oregon.