5 Shocking Iowa Environmental Cancer Risks Exposed

Iowa sits at the intersection of industrial agriculture, petrochemical infrastructure, and some of the most intensive pesticide use in the world. For residents of the state, the cumulative environmental burden is not just an abstraction — it translates into measurable, documented health risks. Here are five of the most significant environmental cancer risk factors that Iowa communities face.

1. Nitrate Contamination in Drinking Water

Iowa leads the nation in synthetic nitrogen fertilizer application, and the runoff into rivers and groundwater has created a persistent nitrate contamination problem. The Iowa Environmental Council has documented that nitrate levels in the Des Moines River regularly exceed EPA safe drinking water standards. Research published in the journal Environmental Health Perspectives has linked prolonged exposure to nitrate-contaminated water with elevated risks of colorectal, thyroid, and bladder cancers.

2. Atrazine and Herbicide Runoff

Atrazine — the second most widely used herbicide in the US and the most commonly detected pesticide in US water supplies — is applied across millions of Iowa corn acres each spring. The International Agency for Research on Cancer (IARC) classifies atrazine as possibly carcinogenic to humans. Iowa water utilities spend millions each year filtering it out, but rural residents on private wells often have no protection.

3. CAFO Hydrogen Sulfide and Air Quality

Iowa is home to more than 10,000 Confined Animal Feeding Operations (CAFOs). The concentrated manure lagoons at these facilities emit hydrogen sulfide, ammonia, and particulate matter. Communities within 1–2 miles of large hog CAFOs report elevated rates of respiratory illness, and emerging research suggests chronic low-level hydrogen sulfide exposure may contribute to lung cancer risk.

4. PFAS Contamination Near Military Bases and Airports

Per- and polyfluoroalkyl substances (PFAS) — known as “forever chemicals” — have been detected in groundwater near multiple Iowa National Guard installations and airports where fire-fighting foam (AFFF) was historically used. The Iowa DNR has identified contamination sites in Sioux City, Des Moines, and Burlington. PFAS are linked to kidney and testicular cancers and are not biodegradable.

5. Agricultural Pesticide Drift in Rural Communities

Pesticide drift — when sprayed chemicals travel beyond target fields — is a documented hazard in Iowa’s densely farmed landscape. Studies of rural Iowa children show measurable pesticide metabolites in urine during and after planting season. Long-term exposure to organophosphate pesticides has been associated with non-Hodgkin’s lymphoma and leukemia in multiple epidemiological studies.

What Is Being Done?

The Iowa Nutrient Reduction Strategy aims to cut nitrogen and phosphorus loading by 45%, but progress has been voluntary and slow. Advocacy groups including the Iowa Environmental Council and Environmental Defense Fund are pushing for stronger CAFO buffer requirements and mandatory setbacks from drinking water sources. Federal infrastructure funding is being used to upgrade some rural water systems, but coverage remains uneven.

Understanding the full scope of environmental health risks is essential for policy action. Explore our environmental tools and resources to learn more about pollution, carbon tracking, and sustainability strategy.

Related Story: Discover how PFAS ‘Forever Chemicals’ contaminate US drinking water — and which communities are at greatest risk.

The Agricultural Chemical Burden: Nitrates, Pesticides, and Iowa’s Water

Iowa leads the nation in corn and soybean production, and with that distinction comes one of the heaviest agricultural chemical loads in the country. The Iowa Nutrient Reduction Strategy estimates that Iowa’s rivers export over 500,000 metric tons of nitrate-nitrogen annually — a number that reflects decades of intensive fertilizer application across millions of cropland acres. For Iowa residents, that agricultural footprint translates directly into drinking water risk.

Nitrate contamination in drinking water is the most widespread water quality problem in rural Iowa. The Iowa Environmental Council has documented that more than 400 community water systems and thousands of private wells exceed or approach the EPA’s 10 mg/L maximum contaminant level for nitrate. The federal standard was set in 1962 primarily to prevent methemoglobinemia (“blue baby syndrome”) in infants — but emerging research suggests that long-term nitrate exposure at levels below that standard may significantly elevate cancer risk in adults. A 2018 study in the International Journal of Epidemiology found that drinking water nitrate concentrations above 3.87 mg/L were associated with elevated colorectal cancer rates in Iowa, even when exposure was below regulatory limits. That finding suggests that federal water safety standards, unadjusted since the 1960s, may not be protective for cancer risk.

Pesticide contamination compounds the problem. Iowa waterways regularly test positive for atrazine, metolachlor, and acetochlor — herbicides applied to corn and soybean fields at rates that make their presence in surface water and some groundwater effectively continuous through the agricultural season. The U.S. Geological Survey’s National Water Quality Assessment has repeatedly documented that Iowa streams are among the most pesticide-contaminated in the United States. The Environmental Protection Agency classifies atrazine as a possible human carcinogen, and independent researchers have associated it with elevated thyroid cancer and lymphoma risk. The full carcinogenic impact of Iowa’s agricultural pesticide cocktail — including synergistic effects between multiple chemicals — remains inadequately studied.

Industrial Agriculture and CAFO Pollution: The Air and Water Nexus

Iowa’s approximately 10,000 permitted concentrated animal feeding operations (CAFOs) are a second major environmental health driver. These operations — which house millions of hogs, cattle, and poultry — generate vast quantities of liquid manure that are applied to cropland or stored in open lagoons. The environmental health impacts operate through multiple pathways.

Hydrogen sulfide, ammonia, particulate matter, and volatile organic compounds released from CAFO operations create what researchers call “industrial hog odor” — but the health implications go beyond smell. Studies of communities near large hog CAFOs in Iowa and North Carolina have documented elevated rates of respiratory symptoms, asthma, neurological effects, and a stress-related inflammatory response associated with chronic odor exposure. Hydrogen sulfide, at high concentrations, is acutely toxic and has caused worker deaths in manure pit accidents; at lower chronic exposure levels, it has been associated with neurological and respiratory damage.

Manure spills and lagoon failures have repeatedly contaminated Iowa waterways. The 2019 flood year was particularly severe, with breached manure storage structures sending millions of gallons of agricultural waste into Iowa rivers. Fish kills, algal blooms, and downstream drinking water contamination followed. For residents whose well water sits downstream or downwind of a CAFO, the risk is not hypothetical — it is a feature of the landscape. Environmental health advocates have documented significant disparities in CAFO siting, with operations disproportionately located in lower-income and minority communities.

Radium in the Drinking Water: Iowa’s Hidden Radioactive Risk

A less-publicized but serious risk is radium contamination in Iowa groundwater. Radium is a naturally occurring radioactive element that leaches into groundwater from geological formations — particularly in central and northwest Iowa, where glacial deposits overlie radium-bearing bedrock. The EPA’s maximum contaminant level for combined radium (Ra-226 and Ra-228) is 5 picocuries per liter (pCi/L), set because radium is a known human carcinogen that deposits in bone tissue and delivers continuous ionizing radiation.

The Iowa Department of Natural Resources has found that dozens of community water systems in Iowa have historically exceeded or approached radium MCLs. While many systems have installed treatment — ion exchange or lime softening can effectively remove radium — private well users often have no monitoring or treatment. The Iowa Geological Survey estimates that a significant portion of private wells in radium-bearing geology may have elevated concentrations, many never tested. Unlike bacterial contamination, radium in water has no taste, odor, or color — making it undetectable without laboratory testing.

The Cancer Geography of Iowa: What the Data Show

Iowa’s cancer burden is measurable in population health data. The Iowa Cancer Registry, one of the oldest and most comprehensive state cancer registries in the nation, has documented persistently elevated rates of several cancers that researchers link to environmental exposures. Non-Hodgkin lymphoma rates in Iowa have historically been among the highest in the Midwest, a pattern that epidemiologists have associated with pesticide exposure in agricultural populations. Bladder cancer — strongly linked to nitrate and trihalomethane exposure in drinking water — shows elevated incidence in rural Iowa counties with intensive agriculture.

The challenge for researchers is isolating the effect of any single environmental exposure in a population that faces multiple overlapping chemical burdens, complex dietary patterns, occupational exposures (farming is itself a high-cancer-risk occupation), and access barriers to early cancer detection. Iowa’s environmental justice landscape means that the residents most exposed to agricultural chemicals, CAFO pollution, and contaminated water are often least able to afford the healthcare and water treatment that might mitigate their risk.

What Iowa Residents Can Do: Testing, Filtration, and Advocacy

For Iowa residents concerned about environmental cancer risks, the most actionable first step is water testing. The Iowa State University Extension and Outreach offers low-cost water testing services for private well owners. Testing for nitrates, bacteria, radium, arsenic, and volatile organic compounds provides the baseline information needed to assess risk and evaluate treatment options.

For homes with documented nitrate or radium contamination, certified point-of-use treatment systems can significantly reduce exposure. Reverse osmosis systems effectively remove nitrate, radium, and many pesticides from drinking water. Ion exchange systems are effective for radium. The Iowa Department of Natural Resources maintains a list of certified water treatment professionals and can connect residents with resources.

Beyond individual action, systemic change requires policy engagement. The Iowa Environmental Council, Iowa Citizens for Community Improvement, and national organizations like the Environmental Working Group — which maintains a publicly searchable database of contaminants in municipal water systems — provide resources for residents who want to understand their exposure and engage with state and federal regulatory processes. Iowa’s water quality future depends on both individual awareness and collective pressure for stronger agricultural pollution controls, updated federal contaminant standards, and equitable enforcement of existing environmental law.