WATERLOO - Iowa farmers could face a greater risk of prostate cancer, according to a national study examining the health effects of pesticide application.

The Agricultural Health Study has tracked nearly 9,000 pesticide applicators in Iowa and North Carolina since 1993. Researchers continue to follow the group but have already exposed a trend in increased risk for prostate cancer among farmers using certain pesticides.

"We have a strong statistical association," said Dr. Michael Alavanja, senior project investigator for the National Cancer Institute, "but we allow for the possibility that this could be a random finding."

His team will continue to evaluate members of the study on a yearly basis and attempt to replicate current findings.

All participants were initially cancer free, so the study's design left little chance for typical biases, according to Alavanja. In an attempt to link pesticide use to various forms of cancer, Alavanja said the study offers leading data.

"If anybody is going to do this, we are," he added. "We have the strongest human data thus far."

Rich Pope, a program specialist with Iowa State Extension, said it is extremely difficult to find quality research that studies long-term exposure to pesticides.

"The Agricultural Health Study has been a remarkably good thing for us to have access to," he said, adding that the solid data allows the department to continue to safely use pesticides as treatment tactics.

The study found exposure to the chemical methyl bromide showed a particularly strong correlation with new prostate cancer cases. The pesticide, typically used for grain fumigation and ground sterilization, will soon be removed from the market, according to Pope.

To minimize health risks, all private and commercial pesticide applicators in Iowa must pass a written exam and re-certify their license with further training.

Linda Truax, director of Butler County Public Health, said common sense reminders are still important.

"You need to be wearing protective clothing," she said, listing cover-alls, hats, gloves and masks as appropriate precautionary gear. She warned that liquid pesticides are absorbed by the scalp, so wet hats should be removed immediately. Truax said hand washing is crucial and work clothes should not be washed with family laundry

The initial results of the Agricultural Health Study showed slightly higher instances of prostate cancer in Butler County, as well as Franklin and Grundy. The study confirmed what many already knew.

"Pesticides have benefits and they have risks," said George Cummins, an ISU Extension crop specialist. "Everybody that's ever planted corn knows that corn is treated with some chemicals."

Cummins advised farmers to read product labels closely and plan their strategy accordingly. "If you have symptoms, take your labels with you to hospital," he said. "Tell someone what you are using so that they have some idea of what may be causing problems."

More information is available online: www.uwex.edu/farmasyst/fmain.html; or www.extension.iastate.edu.