Environmental exposures to carcinogens under investigation as potential factors
Published October 30, 2025 3:47pm EDT
While the rest of the country’s cancer rates are falling, those in Iowa, Nebraska, Illinois, Minnesota, Indiana and Kansas — known as the Corn Belt — are rising at an alarming rate, data shows.
The spike in America’s corn-producing states caught the attention of the University of Iowa’s Holden Comprehensive Cancer Center, which gathered a panel to investigate the trend.
One of the experts, Dr. Marian Neuhouser, a professor at the Fred Hutchinson Cancer Center in Seattle, served on the panel as an expert in nutrition and obesity.
“The panel came about after they noticed that the trends for cancer incidence were increasing at a faster rate in Iowa than in other states,” Neuhouser told Fox News Digital.
A data analysis by The Washington Post based on federal health datasets found that the number of people diagnosed with cancer in the six Corn Belt states has outpaced the national average since the mid-2010s.
In 1999, cancer rates in the Midwest were on par with the national average. Now, among residents aged 15 to 49, those rates are about 5% higher, a pattern that began diverging in the 2000s and has steadily widened.
The Post based its findings on data from the National Cancer Institute and the Centers for Disease Control and Prevention, which track cancer incidence nationwide.
The analysis compared rates from 1999 through 2022 using multi-year averages for Iowa and excluding 2020 due to pandemic disruptions.
Experts probe causes
Neuhouser noted that some of the increases involve cancers that are preventable or detectable through screening.
Researchers are examining both environmental and lifestyle factors that could be driving the increase.
Outdoor UV exposure and high rates of binge drinking could be contributors, according to the Iowa Cancer Registry, part of the National Institutes of Health’s surveillance network.
Iowa’s Environmental Health Sciences Research Center has described the state as a “hot spot for environmental exposures to carcinogenic agents.”
The soil and groundwater in the region reportedly contain some of the nation’s highest levels of natural radon and nitrate, largely because of fertilizer use in farming. Both substances have been linked to high risks of lung and gastrointestinal cancers.
Meanwhile, the widespread application of pesticides and herbicides, including glyphosate, continues to generate debate among scientists and regulators.
Risk of chemical exposure
Dr. Anne McTiernan, professor of epidemiology at the Fred Hutchinson Cancer Center in Seattle, has analyzed decades of research on glyphosate and cancer risk.
“Glyphosate, a broad-spectrum herbicide, has been used in the U.S. for decades and is reported to be the most widely used pesticide globally,” she told Fox News Digital.
The World Health Organization’s International Agency for Research on Cancer classified glyphosate as “a 2A carcinogen (“probably carcinogenic to humans”), which is the second-highest grade of carcinogen, according to McTiernan.
Her review of studies through 2025 found that people with long-term, high exposure to glyphosate, such as those working on farms, had a roughly 40% higher risk of developing non-Hodgkin lymphoma compared to those who were never exposed.
This level of increased risk, combined with lab evidence that glyphosate can damage DNA and cause cellular stress, is considered strong enough to support a causal link, according to the expert.
Role of obesity and alcohol
Lifestyle factors are also compounding risk. Per CDC data, about 21% of Iowa adults report heavy drinking or binge drinking, compared to roughly 17% nationally.
The Iowa Department of Health and Human Services reports that about 35% of adults in the state are classified as obese, placing it among 19 states with obesity prevalence at or above that level. Nationwide, the CDC reports an adult obesity rate of roughly 40%.
Neuhouser noted that 13 separate cancers are linked to obesity.
“Everyone would like to be able to narrow down cancer risk … to one exposure, but cancer is so complex that it’s usually several factors working together,” she said.