Watch the full episode on Iowa Starting Line’s YouTube.
YouTube | Instagram | TikTok | Twitter | Bluesky | Threads | LinkedIn
When Don Carpenter hears the planes coming. From his home near the Maquoketa River in Cascade, he watches aircraft make their methodical passes over the cornfields, leaving invisible trails of herbicide in their wake. Each pass, he said, brings the same thought:
What are we doing to ourselves?
Carpenter remembers when his family and others farmed differently. Pesticides used to be limited to a month, not the season-long effort seen now. Of course, many things have changed: farmland has consolidated into fewer hands. Fewer kinds of crops are grown at a much larger scale. And yields by every measure have gone through the roof. Pesticides are part of that story.
Iowa spreads more pesticides today than any other state in the country.
Today, Iowa spreads more pesticides than any other state in the country, according to a Food & Water Watch analysis of USDA data. Fifty-three million pounds every year. That's 17 pounds for every man, woman, and child who calls this place home. And we do this because it works—Iowa produces more corn than anywhere else, feeds the world,1 and keeps our economy humming.
But there's another number worth knowing: Iowa has some of the highest cancer rates in the nation. And while researchers are careful to say there's no single smoking gun, a growing body of science is starting to connect some uncomfortable dots between what we're putting on our fields and what's happening to our neighbors.
This week on The Hot Spot, we're diving deep into that science—what it says, what it doesn't, and why the gap between research and regulation matters for all of us. Because at the heart of this story is a question every Iowan deserves an honest answer to: What does it actually cost to be the world's corn capital?
But first…
House Rs tap Kaufmann - House Republicans named State Rep. Bobby Kaufmann of Wilton the new Majority Leader. When the chamber returns to Des Moines next January, he’ll be in charge of wrangling the caucus with Speaker of the House Pat Grassley of New Hartford.
"I am honored by the trust placed in me by my colleagues to serve as Majority Leader," Kaufmann said. "This is a role I will not take lightly. I am committed to uniting our caucus to advance policies that strengthen our economy, support our families, and ensure our children will have bright futures. I look forward to working with Speaker Grassley to address the challenges and opportunities facing Iowa with bold, practical solutions."
State Rep. Matt Windschidtl of Missouri Valley vacated the seat to run in Iowa’s 4th Congressional District… a seat that is ALSO now open as US Rep. Randy Feenstra runs for Iowa Governor.Norris enters race - Des Moines School Board chair and former Michelle Obama Chief of Staff Jackie Norris threw her hat into the crowded race to take on US Sen. Joni Ernst. She brings a ton of experience campaigning statewide for caucuses (President Barack Obama) and gubernatorial candidates (Gov. Tom Vilsack). Has the state changed since then? Definitely. But those relationships will matter as she tries to position herself within a crowded field: State Sen. Zach Wahls, state Rep. JD Scholten, Nathan Sage, and a certain Paralympian who is doing a bad job of keeping the lid on his ambitions to run.
Read our intern Victor Robbins’ full write-up.Smart money leaves - An interesting report from Common Sense Institute Iowa shows 34% more college graduates leave Iowa than stay, representing $17.6 billion in lost income from just the 2023 graduating class alone. With 77,000 working-age men leaving the workforce since 2020, Iowa now has just 67 workers for every 100 available jobs.
Amendment gets tested - Despite Iowa's new "strict scrutiny" constitutional amendment for gun rights, the all-Republican-appointed state Supreme Court is finding some limits, according to some reporting by the Des Moines Register. The court upheld restrictions for people with mental health commitments and domestic violence records. The rulings suggest even conservative justices see boundaries on gun access… To be clear, don’t read this and think that we’re going to see some sweeping regulations in Iowa. These are really narrowly focused. But still worth thinking about.
How pesticides help fuel Iowa’s cancer crisis
Don Carpenter remembers when farming looked different. Growing up on his family’s 160-acre dairy farm in Cascade, Iowa, he watched his father apply pesticides for about a month each spring: a seasonal ritual that seemed manageable, contained.
“It’s what you did,” the 54-year-old Carpenter said. “You didn’t know any better.”
The north fork of the Maquoketa River winds through Cascade on its way through Dubuque County. Along its length, acres of farmland stretch on, row by row, on either side of the river.
"Every time that plane goes over and comes near the river, I just shake my head," he said. "I understand you have to take care of the corn, but it just drives me nuts that they're spraying (pesticides) so close to a body of water."
From family farms to chemical dependence
Thirty million acres—nearly three-fourths—of Iowa’s area is used for crops and rotational pastures. While the number of farms in the state has decreased, these operations and their size have grown dramatically over the years. In 1950, the average farm size in Iowa was 169 acres. By 2012, the average farm size was 345 acres; it had doubled.
Carpenter said he’s watched these “super farms” buy out family operations like his.
In 2024, Iowa produced 2.5 million bushels of corn for grain production—the most of any state in the country. Farmers apply herbicides to 96-97% of corn acres annually. More than 53 million pounds of pesticides are applied across the state each year.
Pesticides encompass a range of chemicals that control any number of unwanted organisms: herbicides, which eliminate or inhibit the growth of unwanted plants; fungicides, which do the same to fungus; and insecticides, which get rid of bugs.
Pesticides are applied multiple times during the growing season to limit weeds and harmful insects. The very corn in the field is genetically engineered to be resistant to particular formulations of pesticides.
“Iowa farmers spread more pesticide, fertilizer and manure than any other state,” said Jennifer Breon, an Iowa organizer with Food & Water Watch.
Pesticides are part of why Iowa’s fields are so productive. Research into pesticide exposure also connects them to our cancer crisis.
Science linking certain pesticides to cancer
Iowa Starting Line spoke to researchers ranging from oncologists to toxicologists, most of whom pointed to The Agricultural Health Study (AHS) as the highest quality study of agricultural exposure and its impact on health. Since 1993, the study has tracked 89,000 farmers and their spouses across Iowa and North Carolina. In general, participants in the AHS had lower overall cancer incidence, attributed to low rates of smoking and increased physical activity.
However, a 2019 review of two decades of AHS data found agricultural exposures led to a disproportionate rate of prostate cancer among these farming couples.
According to the 2025 Iowa Cancer Registry, prostate cancer accounted for 14% of Iowa’s new cancers, almost as common as breast cancer. The AHS also found these couples suffered from elevated rates of lip cancer, certain B-cell lymphomas like multiple myeloma, acute myeloid leukemia (AML), thyroid cancer, testicular cancer, and peritoneal cancer.
The most widely used of our herbicides is glyphosate. It’s found in products like Roundup, which was manufactured by Monsanto until Bayer bought the company in 2018. It’s estimated that 16 million pounds of glyphosate-based herbicides are applied in Iowa each year.
In 2015, the International Agency for Research on Cancer (IARC) changed glyphosate’s classification to “probably carcinogenic,” following a review of data surrounding exposure’s link to non-Hodgkin lymphoma (NHL). One analysis that used data from the AHS showed glyphosate-based herbicides were associated with a 41% increase in NHL risk.
Despite the growing evidence of its connection to cancer, the chemical remains in wide use. The US Environmental Protection Agency said it is “unlikely to be a human carcinogen.” The federal agency is currently updating its evaluation of glyphosate’s carcinogenic potential.
And that’s part of how the process works: the slow grind of regulators taking in and sometimes adjusting to what research says.
Minding the regulatory gap
Experts point out that regulation doesn’t automatically adjust to the most recent science. It’s not even standard across nations. A 2019 paper found that of the 1.2 billion pounds of pesticides used in the US in 2016, 322 million pounds were pesticides banned by the European Union; 40 million were pesticides banned in China; 26 million were banned in Brazil.
This evolution in understanding creates what Dr. David Cwiertny, the director of the Center for Health Effects of Environmental Contamination at the University of Iowa, calls a "gray area" where policy still considers something safe while emerging science suggests it may not be. That lag between scientific discovery and policy is time in which vulnerable populations continue to be exposed to something that could be harming them.
Cwiertny’s team measures pesticide concentrations in waterways, air, and dust throughout agricultural regions. He said they rarely find a water sample that doesn't contain at least one or two major chemicals, even in remote areas—what Cwiertny calls "ubiquity" that reflects decades of sustained use.
Charles Benbrook, an agricultural economist who has advocated against the increased application of chemicals like glyphosate, has called for the EPA to not approve chemicals based on limited exposure scenarios, but based on the widespread, repeated use that is seen across states like Iowa.
"The pesticide risk assessment and regulatory decision process as carried out by EPA and its sister regulators in the state... is basically broken,” Benbrook said.
He was most recently in Iowa advocating against a bill that would restrict the ability of individuals to sue pesticide manufacturers like Bayer for health issues, such as cancer, that could be linked to the companies’ products.
An analysis by Food & Water Watch found that since the bill was first introduced in 2023, Bayer has spent $209,750 lobbying for it, including registering seven Iowa lobbyists. That is 5x what they spent in the two cycles prior, and nearly double what Bayer spent lobbying in Iowa in the decade prior from 2013-2023. The bill failed but will likely be back on the table in next year’s session.
The challenge for public health researchers is that this exposure creates a complex web of risk factors that defy simple cause-and-effect relationships. Unlike clear-cut cases of occupational exposure or accidental releases, the kind of chronic, low-level exposure most Iowans face makes definitive connections nearly impossible to establish.
"Here in Iowa, the challenge is there's a variety of risk factors and it's not any one thing,” Cwiertny said.
For Don Carpenter, this is an unsatisfying reality. He lives near the Maquoketa River, and each summer, he watches as planes spray cornfields that border its waters.
“ I just want one person. I don't care which political party, but I just want one person to be like a dog with a bone and just keep harping on this, that we need to do something about it,” he said. “And I don't have faith in any of 'em that they can do that.”
Question for you
Does Don’s frustration speak to you like it does to me? This feeling that the powers that be seem uninterested, maybe afraid to tackle the long-term costs of how we farm.
But here’s something I keep thinking about: How do we have this conversation so that it doesn’t pit farmers against public health? If you take seriously the reporting here, you know that farmers are following the incentives that allow them to keep producing. The farmers I spoke to for this series care about their communities and their land. They’re trying to make a living. Not trying to hurt themselves or anyone else.
So here’s the big question:
How do we bridge the gap? How do we have an honest conversation about pesticides and health that acknowledges the system that created these problems?
What would it look like if we approached this as a shared problem instead of a fight? Write me back with your thoughts—I'd love to hear from farmers, health experts, and everyone in between. Send your answers to zach@iowastartingline.com.
Before you go
Support this work by doing these four things:
Subscribe to Cornhole Champions on YouTube and like our videos to improve their reach.
Join the game by signing up for my Substack newsletter and get these episodes straight to your email on Wednesday mornings.
Sign up for Iowa Starting Line's flagship newsletter.
Cornhole Champions is a weekly podcast powered by Iowa Starting Line. It’s produced by me and edited by Rebecca Steinberg. Our music is by Avery Mossman and show art by Desirée Tapia. We are a proud member of the Iowa Writers Collaborative.
Your friendly neighborhood reporter,
Zachary Oren Smith
Political correspondent
Iowa Starting Line
