According to Iowa Cancer Registry, an estimated 2,900 Iowans will be diagnosed with prostate cancer in 2025. Iowa currently leads the nation in prostate cancer rates. Unlike most states where rates have stabilized or declined, Iowa has seen a troubling increase.
Researchers point to several possible causes, but one risk factor stands out for Iowans; exposure to farming-related chemicals. Across the state, pesticides and fertilizers are widely used to support crop production. While small amounts may be harmless, higher levels can pose serious health risks.
Pesticides are used by farmers to kill or control insects, weeds, fungi or any unwanted organisms that could live in or on their farmland. While in small amounts these pesticides are harmless, they can be harmful when in larger quantities. The most harmful are nitrates.
Nitrates are necessary for plant growth. In farming, it is used as a fertilizer that is highly soluble, meaning it is absorbed almost immediately into the plant. Nitrates in small amounts are not harmful. When nitrates appear in larger amounts, the soil excretes the extra, which is put into rivers, lakes and groundwater when heavy rainfall happens.
In an Interview with KCCI, Des Moines Water Works CEO Ted Corrigan said, “Nitrate that was applied as fertilizer on farm fields, found its way through the soil profile into the field tiles, and then drains out the tiles into the rivers upstream of us.”
At the same time, farmers emphasize the economic necessity of nitrates. Iowa Farmer Kevin Larson said, “As a grain farmer, we need nitrogen fertilizer for corn production. If our usage of that is curtailed, it would make corn production non-profitable.”
Another source of nitrates is animal manure. Manure is a major source of organic nitrogen.
Joanna Schroeder, a previous Agriculture consultant and current associate professor at Iowa State University, said,
“[T]hat’s naturally produced and a natural chemical process, it is often seen as being less harmful.”
Nitrates become a problem with excessive application. Applying more than is needed or when heavy rainfall happens can lead to it running off and polluting the rivers and lakes and then humans and animals are exposed to it by swimming or drinking the contaminated water.
Even non-farmers are exposed to farming-related chemicals through environmental exposure like drift. When the pesticides drift from field to field, it contaminates the air and surfaces around farms. This is one of the major ways that humans are exposed to these nitrates.
The Environmental Protection Agency (EPA) has a set 10 mg/L nitrate limit. Yet in the summer of 2025, central Iowa exceeded that limit for approximately 13 weeks, leading to a lawn watering ban. This was caused by the spring rain, causing agricultural runoffs.
Some farmers are adopting safer practices to reduce chemical overuse. Hybrid farming, for example, implants protective chemicals directly into seeds rather than spraying entire fields. Crop rotation is another strategy, where farmers alternate crops such as corn and soybeans to minimize nitrate loss and till between seasons to reduce runoff.
“Consumers need to be more educated… The agriculture industry needs to become more transparent with the technologies as they develop them, and consumers need to be more open-minded about learning more about agriculture,” Schroeder said.
Consumers at home who are concerned about exposure to nitrates and other pesticides should read and follow directions on the pesticides they might be using at home, such as roundup.
Rodney Williamson, the Vice President of Research and Sustainability at Iowa Corn, said, “Follow the label… The label takes into account the safety. We recommend that farmers or consumers follow the label because many of these pesticides are used by non-farmers, whether in their house or in their yard.”
Labels are designed not just as guidelines but as legal and scientific safeguards to protect both people and the environment. When individuals ignore or misuse pesticide directions, they increase the risk of exposure that can lead to serious health problems or environmental harm.
“There are other potential causes for cancer that need to be investigated… Like exposure to sun, exposure to radon, excessive use of alcohol, tanning beds, genetics, smoking and obesity. There are a whole host of potential causes of cancer,” Williams said.
Cancer is not always caused by a single factor. It often results from a combination of environmental exposures, personal behaviors and inherited risks. This makes it especially important for researchers and public health officials to examine all possible contributors to develop effective prevention strategies.
Iowa’s reliance on agriculture, nitrate fertilizers and livestock manure has created an environment where chemical exposure is nearly unavoidable.
While these practices boost crop yields and support the state’s economy, their overuse has unintended health consequences that may contribute to Iowa’s high prostate cancer rates.
By adopting safer farming techniques, monitoring nitrate use more closely and encouraging greater transparency between the agricultural industry and the public, Iowa has the opportunity to protect both its farmland and the health of its communities. We need to unite as one; the challenge now is finding a balance between agricultural productivity and public well-being.