What’s Driving Iowa’s Outlier Cancer Rate? It’s Complicated
In Iowa, a state with a population of around 3.2 million, around 6,000 people will die from cancer in a given year.
Cancer is an unfortunate topic that has been front of mind for many Iowans this year as the incidence rate remains high compared to the rest of the country. For Sentient, I dove into a causation question that is impossible to answer, and learned a lot about how the Iowa Cancer Registry is reacting to accusations that they do not focus enough on agriculture — and their plans to do more.
Each year, the Iowa Cancer Registry is tasked with reporting on the status of the disease within the state. In 2024, their report made national headlines because of Iowa’s outlier status as the state with the fastest growing cancer incidence and the second highest incidence rate behind Kentucky. The state registry chose to focus its report on the carcinogenic effects of alcohol and high rates of binge drinking in the state, with no mention of the millions of gallons of factory farm manure pumped into Iowa waterways each year.
In its 2024 “strategies to significantly reduce the burden of cancer in Iowa” section, the Iowa Cancer Registry did not mention agricultural pollution once.
In Iowa, animals in factory farms (around 55 million chickens, 53.4 million hogs, 11.5 million turkeys, and 3.7 million cattle and cows) produce around 109 billion pounds of manure. Some of that manure is sprayed on crops as fertilizer. Some of it is illegally discharged from manure lagoons into public waterways. Pesticides and other chemicals are also sprayed on crops and can leach into groundwater. These non-behavioral exposures to carcinogens are causing some experts — including those criticized for not doing enough — to call for further research into the intense industry that uses the vast majority of land in the state.
The issue with cancer, like many other diseases, is that causation is difficult to tie to one source, says Peter Thorne, professor of Occupational and Environmental Health at the University of Iowa College of Public Health. If someone was diagnosed with bladder cancer who lived in an area with high levels of arsenic (a known human carcinogen) in their drinking water, but that person was also exposed to chemicals in their water, and pesticides, and might also eat grilled meat, exactly what caused the bladder cancer is difficult to prove. Another carcinogenic exposure pathway in Iowa is radon, a colorless, odorless radioactive gas that is present in Iowa due to prior glacial activity.
“In a case like that, you can’t say this person’s bladder cancer derived from that one exposure,” Thorne tells Sentient. “You don’t have sufficient data on that person’s lifetime exposure to say that, and even if you did, you can’t be sure that in their case, [one thing] caused it.”
You know, Nina, it doesn't help with our legislators just lie to us. Rep. Bobby Kaufmann stood at one of his listening posts and said, "Everyone knows glyphosate causes cancer," and then his pal Sen. Gruenhagen must've recovered from a stroke and reminded him that was the wrong line. So a week later he wrote an extensive Op Ed in the Register saying it doesn't! No wonder no one trusts politicians...
Nina, I can only hope that some very specific legitimate studies concerning manure, pesticides and/or nitrates will be funded so we're able to get a better handle on any contributions they might have to our cancer crisis. Unfortunately I won't be holding my breath living in this state or these current times! How very sad another elephant in the room is ignored.
-Great reporting, keep it up