A new analysis by Food and Water Watch has identified geographic clusters where heavy glyphosate herbicide use correlates with elevated rates of non-Hodgkin lymphoma (NHL), a blood cancer, particularly across Iowa and the Upper Midwest. The research overlaid county-level data on glyphosate application from the U.S. Department of Agriculture (USDA) with cancer incidence rates from the National Cancer Institute (NCI), revealing a troubling pattern that reinforces years of scientific concern about the widely used weed killer .

What Does the New Analysis Actually Show?

Food and Water Watch examined counties in the top 20 percent for glyphosate use per square mile and compared them to NHL incidence data. The findings are striking: among U.S. counties spraying the most glyphosate that have reported NHL rates, 60 percent have NHL rates above the national average . Even more concerning, 71 percent of these high-glyphosate counties have late-stage NHL rates above the national average .

Iowa emerged as a particular hotspot. In the state that grows more corn than any other in the nation, 82 percent of counties with high glyphosate use have NHL rates above the national average, and half of those are in the top 20 percent for NHL rates nationwide . This matters because both corn and soybeans, Iowa's major crops, have been genetically engineered to tolerate glyphosate spraying, making the herbicide a standard agricultural practice across the state.

The timing of this analysis is significant. Iowa already has the second-highest overall cancer rate in the nation and is one of only three states where cancer rates are rising, according to the National Institutes of Health .

Why Is Glyphosate So Widely Used?

Glyphosate, commonly known by the brand name Roundup, was introduced by Monsanto in the 1970s and became ubiquitous in agriculture after the company developed genetically modified crops designed to survive glyphosate spraying . This innovation made weed control simpler for farmers, but it also dramatically increased the chemical's use across millions of acres. Today, glyphosate-based herbicides are the most widely used pesticides in the United States .

The scientific community has grown increasingly concerned about the chemical's health effects. In 2015, the International Agency for Research on Cancer (IARC), part of the World Health Organization (WHO), classified glyphosate as probably carcinogenic to humans, specifically noting links to NHL . A 2019 study found that people with high glyphosate exposure had a 41 percent increased risk of developing NHL, describing the evidence as "a compelling link" between the chemical and the cancer .

"Since our study was published, evidence has accumulated that glyphosate-based herbicides cause DNA damage and affect DNA repair mechanisms, both of which can result in cancer, and that blood cancers such as NHL may be the most impacted," said Lianne Sheppard, a University of Washington professor who organized a recent scientific symposium on glyphosate research.
Lianne Sheppard, Professor, University of Washington

What Are Farmers and Communities Actually Exposed To?

The exposure picture in agricultural regions is complex and layered. Sarah Green, executive director of the Iowa Environmental Council, emphasized that farmers and rural residents face multiple chemical exposures simultaneously, not just glyphosate alone . The chemicals of concern in Iowa include:

Glyphosate: The herbicide applied to genetically modified corn and soybeans, now linked to elevated NHL rates in high-use counties.
Atrazine: Another widely used herbicide applied to corn crops that has raised separate health concerns among researchers.
Acetochlor: A pre-emergent herbicide used on corn that adds to the chemical burden in agricultural communities.
Nitrates from fertilizers and manure: Nitrogen-based chemicals that contaminate groundwater and have been linked to various health effects.

"We know cancer rates in Iowa have reached crisis levels, and growing research shows that Iowans face outsized risks from exposure to agricultural chemicals, including glyphosate, atrazine, acetochlor, and nitrates from fertilizers and manure application. What's especially notable is that Iowans aren't exposed to just one risk factor, we're often exposed to several at the same time," stated Sarah Green.
Sarah Green, Executive Director, Iowa Environmental Council

How to Reduce Your Glyphosate Exposure

While the Food and Water Watch analysis focuses on agricultural exposure, consumers can take steps to minimize their contact with glyphosate-based products:

Choose organic produce when possible: Organic certification prohibits synthetic pesticides including glyphosate, reducing your dietary exposure to the herbicide residues that may be present on conventionally grown crops.
Avoid using Roundup and similar glyphosate products at home: If you use herbicides for yard maintenance, switch to mechanical removal, mulching, or alternative weed control methods that don't rely on chemical sprays.
Support local farmers who use reduced-chemical practices: Farmers markets and community-supported agriculture (CSA) programs often feature growers who minimize or eliminate glyphosate use, giving you direct access to lower-residue food.
Advocate for policy changes in your community: Support legislation that limits pesticide use in public spaces and schools, and push for stronger regulation of glyphosate in your state.

What Do Regulators Say About the Risk?

There's a significant disconnect between international and U.S. regulatory positions. While the World Health Organization's cancer research agency classified glyphosate as probably carcinogenic, the U.S. Environmental Protection Agency (EPA) maintains that glyphosate is "not likely to be carcinogenic to humans" . This disagreement has fueled ongoing debate and litigation.

Tens of thousands of people across the United States have sued Monsanto and Bayer, the German company that acquired Monsanto in 2018, alleging that glyphosate exposure caused them to develop NHL . Monsanto and Bayer continue to maintain that their glyphosate products do not cause cancer. The legal battles remain ongoing, with the outcomes potentially influencing future pesticide regulation.

The Food and Water Watch analysis arrives at a moment of heightened political attention to glyphosate policy. The organization noted that the research comes as Bayer pushes what it calls "Cancer Gag Acts" across the country, legislation that would give pesticide manufacturers immunity from health-related lawsuits . In Iowa, where opposition to such legislation is particularly strong, 89 percent of voters oppose pesticide immunity laws, according to Food and Water Watch .

What's the Bottom Line?

The Food and Water Watch analysis provides a geographic snapshot of a troubling correlation: counties with the highest glyphosate use tend to have elevated NHL rates, especially in the Midwest. While correlation does not prove causation, the pattern aligns with decades of scientific research linking glyphosate exposure to increased cancer risk. For people living in agricultural regions, particularly Iowa and surrounding states, the accumulation of evidence suggests that reducing exposure to glyphosate and other agricultural chemicals should be a public health priority. For consumers nationwide, choosing organic produce and supporting farmers who minimize pesticide use remains one of the most direct ways to reduce dietary glyphosate exposure.

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