Iowa is facing an unusual cancer crisis: the state has the second-highest cancer incidence rate in the country and is one of only a few US states where cancer rates are actually increasing. A comprehensive new report from the Iowa Environmental Council and The Harkin Institute identifies four major environmental risk factors linked to this troubling trend: pesticides, nitrate pollution, PFAS (per- and polyfluoroalkyl substances, also called "forever chemicals"), and radon. The research pairs personal stories from Iowans affected by cancer with analysis of peer-reviewed scientific studies, revealing how agricultural practices and industrial operations are creating what experts call a "toxic mix" in the state's air, water, soil, and even homes .

Why Is Iowa's Cancer Rate So Much Higher Than the National Average?

Iowa's cancer rate was more than 10% higher than the national average for the most recent five-year period measured, 2017-2021 . What makes Iowa unique is the sheer concentration of agricultural activity: 85% of the state's land is devoted to animal agriculture or crops. Iowa also has two and a half times as many concentrated animal feeding operations, commonly called factory farms, as the next highest state . This agricultural intensity means residents are disproportionately exposed to the chemicals used in farming operations.

The report examined the three most heavily applied herbicides in Iowa: glyphosate (the active ingredient in Roundup), acetochlor, and atrazine . Research shows that higher risk for each of the most common cancers in Iowa, including breast, prostate, lung and bronchus, colorectal, and skin melanoma, is associated with exposure to these pesticides as well as nitrate, PFAS, and radon . Among Iowans under age 50, six of the ten cancer types linked to these environmental factors have been increasing, suggesting the problem is worsening for younger generations .

How Does Agricultural Pollution Create a "Toxic Mix" in Iowa Communities?

The cancer risk in Iowa isn't caused by a single exposure. Instead, residents face overlapping environmental hazards that compound their risk. Factory farms produce massive amounts of manure, which is often sprayed on fields as fertilizer or, in some cases, illegally discharged into waterways. When this happens, the nitrogen in the manure converts to nitrate pollution in the water supply. According to the report authors, Iowa is "an outlier for the sheer concentration of the amount of nitrogen that is going onto our land that is ending up in our water" .

One Iowa resident, Chris Henning, has watched this problem unfold across her own family and community. Her father was treated for lung cancer, and since her own cancer diagnosis in 2019, two of her sisters have died of cancer and two more have received diagnoses. Testing indicated the sisters' breast cancers are not due to family genetics. Henning grew up on a farm in Greene County, Iowa, and remembers carrying jugs of herbicide to spray milkweeds as a child and watching planes spray fungicides overhead . She now lives just half a mile from the family farm where she grew up, continuing to be exposed to agricultural chemicals.

What Are the Four Major Environmental Risk Factors Linked to Iowa's Cancer Crisis?

• Pesticides: The three most commonly applied herbicides in Iowa are glyphosate, acetochlor, and atrazine, all linked to increased cancer risk in scientific literature.
• Nitrate Pollution: Nitrogen from factory farm manure ends up in drinking water supplies, creating a contamination problem unique to Iowa's agricultural intensity.
• PFAS (Forever Chemicals): These synthetic substances persist in the environment and human body indefinitely, accumulating over time and linked to multiple cancer types.
• Radon: This naturally occurring radioactive gas seeps into homes and is a known lung cancer risk factor present across Iowa.

The report's authors, who included 29 experts ranging from epidemiologists to environmental health professionals, emphasize that existing research on pesticide exposure and cancer risk has mostly focused on pesticide applicators and their families. However, the new analysis suggests that broader community exposure to agricultural chemicals is also a concern .

"Iowans deserve to know what risks we are facing," the authors of the report wrote, and they called for stronger environmental oversight of risk factors such as manure pollution and pesticides .

Iowa Environmental Council and The Harkin Institute Report Authors

Steps to Reduce Your Exposure to Agricultural Chemical Contamination

• Test Your Water: Have your drinking water tested for nitrate and PFAS contamination, especially if you live in an agricultural area. Contact your local health department for testing resources and consider installing a water filter certified to remove these contaminants.
• Understand Your Local Agricultural Practices: Learn about factory farms and pesticide application schedules in your area. During peak spraying seasons, keep windows closed and limit outdoor activities when aerial spraying is occurring nearby.
• Support Policy Change: Advocate for stronger enforcement of existing environmental laws in your state. The report emphasizes that personal behavior changes alone are insufficient; systemic change through better regulation of manure application and agricultural runoff monitoring is essential.
• Test Your Home for Radon: Radon is odorless and invisible, so testing is the only way to know if your home has elevated levels. The EPA recommends testing all homes, and mitigation systems can reduce radon concentrations significantly.

The report authors stress that individual behavioral changes, while important, cannot adequately address Iowa's cancer crisis. As Kerri Johannsen, Senior Director of Policy and Programs with the Iowa Environmental Council, explained, the state has built "a skyscraper of risk factors" for cancer . Each person has individual behavioral and genetic risk factors, but Iowans also face shared environmental exposures that individuals cannot control on their own.

Kerri Johannsen, Senior Director of Policy and Programs with the Iowa Environmental Council

"Even if we are able to eliminate all of those behavioral risk factors, which is not realistic, several floors of this skyscraper are made up of these environmental risk factors that individuals cannot control," Johannsen stated .

Kerri Johannsen, Senior Director of Policy and Programs at Iowa Environmental Council

The report authors recommend that Iowa strengthen enforcement of existing environmental laws, particularly regarding polluters such as factory farms. They call for stricter oversight of manure application, improved monitoring of agricultural runoff, and better water quality testing across the state . Because cancer develops over decades, the authors emphasize that action must be taken now to prevent future cases, even though the health benefits may not be visible for years.

For residents like Chris Henning, the urgency is personal. She has watched her family's cancer diagnoses accumulate over 25 years while living in an agricultural region. She believes that "many political leaders in Iowa seem to be intent on absolving agriculture from its effects," and as a result, "the public is paying the price for many of the things that we do in farming" . The new report suggests she is not alone in her concerns, and that systemic change is necessary to protect Iowa's health.

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