There's a strong correlation between pesticide use and cancer risk, especially in the Midwestern United States where farming is the main source of exposure to carcinogens. Counties with the highest pesticide use tend to have above-average cancer rates.
The link is even more clear when specific pesticides are matched with the cancers they’re known to cause. Take glyphosate and non-Hodgkin lymphoma. In Iowa, 95 percent of the counties with the most glyphosate use have more than their fair share of late-stage non-Hodgkin lymphoma diagnoses and 61 percent are non-Hodgkin lymphoma hotspots.
TAKE ACTION: Tell Your State Legislators to Ban the Pesticides Behind America’s Rural Cancer Crisis!
Glyphosate is the most-used weedkiller in the country. It’s the main ingredient in Monsanto (now Bayer)’s flagship herbicide Roundup. Use has skyrocketed since the 1990s when Monsanto started selling genetically modified seeds engineered to produce plants that are impervious to its pesticide.
Monsanto had long been aware of glyphosate’s carcinogenicity, and the EPA was, too. In 1985, the consensus position of eight Environmental Protection Agency scientists was that glyphosate was a Class C carcinogen, but Monsanto convinced the EPA to overrule its experts. Relying on studies funded – and manipulated – by Monsanto, the EPA decided that glyphosate was not likely to be carcinogenic to humans.
Eventually, the truth came out. In 2015, the World Health Organization's International Agency for Research on Cancer (IARC) found considerable evidence that glyphosate caused non-Hodgkin lymphoma.
In 2025, the second-most-used weedkiller, atrazine, the main ingredient in Syngenta (ChemChina)'s AAtrex, was also found to be a “probable human carcinogen.”
That the top two most-used herbicides are carcinogens explains the mysterious rise of cancer among young adults in the Corn Belt.
Cancer rates for young adults in their 20s, 30s and 40s are trending up even as overall cancer rates decline—with the highest rates in the states that use the most glyphosate and atrazine.
In the six leading states for corn production—Iowa, Nebraska, Illinois, Minnesota, Indiana, and Kansas—rates are 5 percent higher than in the overall population.
A 2024 analysis of population-level data in the journal Frontiers in Cancer Control and Society found that “the impact of pesticide use on cancer incidence may rival that of smoking."
“Iowa has a super high rate (of cancer) and when you look at all of our modifiable risk factors … tobacco, obesity, too many calories, highly processed foods, lack of physical activity, alcohol consumption, getting vaccinated for HPV, sun exposure, and so on, Iowa doesn’t really stand out dramatically at any of those,” Dr. Richard Deming, medical director at MercyOne Cancer Center in Des Moines, told Investigate Midwest. “But one thing that distinguishes Iowa from other states is our environmental exposure to agricultural chemicals.”
TAKE ACTION: Tell Your State Legislators to Ban the Pesticides Behind America’s Rural Cancer Crisis!