Pesticide, cancer linked
Federal study finds increased risk for exposed farmers
By Bruce Henderson

A widely used farm chemical may increase the risk of prostate cancer in the people exposed to it, says a study of 31,000 N.C. farmers and their wives.

The federal study tracked more than 55,000 men in North Carolina and Iowa, most of them farmers, who apply pesticides. It found that, over a four-year period, 14 percent more of them developed prostate cancer than would be expected in the general population.

Of 45 pesticides evaluated, the study found possible connections to prostate cancer in seven.

Methyl bromide was most widely linked to cancer. Applied as a gas, the fumigant sterilizes soil before planting by killing insects, nematodes, weeds and pathogens.

Six other pesticides -- chlorpyrifos, coumaphos, fonofos, phorate, permethrin and butylate -- appeared to increase risks only among those with a family history of the disease.

Prostate cancer was the most common N.C. cancer in the late 1990s, with about 144 cases in 100,000 people, according to state health statistics.

"Obviously, we're concerned about these results," said Anne Coan, natural resources director of the N.C. Farm Bureau Federation.

Fewer N.C. farmers now use methyl bromide to prepare soil for tobacco transplants, said Coan, who serves on a state advisory panel for the health study. And farmers know more about pesticide hazards than earlier generations.

But no single alternative to methyl bromide exists, she said.

Millions of pounds are still used each year, but methyl bromide is being phased out of use worldwide because it depletes the protective ozone layer of the atmosphere.

Its use in developed nations, including the United States, is to end in 2005.

The United States -- prodded in part by N.C. strawberry, tobacco and pepper growers -- has asked the United Nations for exemptions that would allow continued use of the chemical on a smaller scale. The request says there is no practical alternative.

"Methyl bromide is a heavy hitter and it's been on a lot of target lists for phase-out," said Fawn Pattison of the Agricultural Resources Center in Raleigh, which touts alternatives to toxic pesticides. "We've been concerned about it both for health effects and ozone depletion."

The new report is part of a study of nearly 90,000 N.C. and Iowa pesticide applicators and their spouses that began in 1993.

Known as the Agricultural Health Study, it involves the National Cancer Institute, the National Institute of Environmental Health Sciences and the Environmental Protection Agency.

North Carolina was chosen because of its diversity of agriculture.

Between 1993 and 1999, 566 new prostate cancers developed among the 55,000 farmers, compared to the 495 predicted by its incidence rate in the two states.

The risk of cancer increased the more often farmers used methyl bromide, and the longer they were exposed to it over a lifetime. Methyl bromide is listed by the federal government as a probable occupational carcinogen.

"We cannot rule out the possibility that our observation occurred by chance alone," said Aaron Blair, a National Cancer Institute researcher who helped write the report.

The findings would be confirmed, officials said, if more cancers than normal continue to appear among the study subjects.