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People living near concentrated animal feeding facilities (CAFOs) in California, Texas and Iowa have higher rates of cancer, a new study suggests, suggesting that air and water pollution from large farms may be contributing.
Research published in journals environmental researchcoming in just a few weeks Reports from several years in Iowa They found that pesticides and CAFO pollution in the state are partly to blame for the increased cancer rates.
In a new study, researchers at Yale University looked at the incidence of all cancers and the density of CAFOs within counties in Texas, California, and Iowa over the past 20 years. High exposure counties were defined as those in the top 25% of CAFO densities in the state. The researchers found that the incidence of all types of cancer was 4% higher in California counties with high exposure and 8% higher in Iowa and Texas counties with high exposure when compared with counties with low CAFO density.
They found that certain cancers were more strongly associated with each state’s CAFO density. For example, stronger associations were found for bladder cancer in California, colorectal cancer in Iowa, and lung and bronchial cancers in Texas.
Iowa has the highest number of CAFOs in the country. According to federal data California ranks fifth and Texas ranks sixth.
Lead author Jiyoung Sung, an associate research fellow at Yale School of the Environment, said there are “multiple pathways” by which CAFOs cause increased cancer rates. They emit air pollutants such as ammonia, hydrogen sulfide, particulate matter and volatile organic compounds, which can form secondary pollutants in the air, she said.
“Exposure to these substances is associated with inflammation, oxidative stress, and immunosuppression, all of which can contribute to the development of cancer,” she said.
“Exposure to these substances is associated with inflammation, oxidative stress, and immunosuppression, all of which can contribute to cancer development.” – Ji-young Song, Yale University
Additionally, CAFOs are a major source of water pollution due to the large amounts of fertilizer that is stored as fertilizer or applied to fields. This can lead to nitrate contamination in the water, which can lead to the formation of carcinogens. Nitrate pollution in water has been linked to a variety of cancers, including colon, bladder, and thyroid cancers.
“Up until now, policymakers have been able to say we don’t know how nitrates will affect our health, especially when it comes to cancer,” said Sarah Green, executive director of the Iowa Environmental Council. “As more and more research results emerge, those in power can no longer say they don’t know.”
Song and his colleagues warn in their study that nitrate contamination could disproportionately impact rural homes with private wells.
“Private wells are largely unregulated, and many households may be unaware of the risk of contamination or lack the resources to treat their water,” they wrote.
The study did not test people’s actual exposure and does not conclusively prove that CAFOs cause cancer, the authors wrote. Some cancers, such as breast cancer in Texas and Iowa, were not associated with CAFO density.
Wendy Brannen, vice president of communications and marketing for the National Pork Producers Council, said Son and her colleagues acknowledged that the study had certain limitations, including that poverty, limited access to health care, and lower rates of cancer screening may be behind the association.
CAFOs and cancer rates in Iowa
research will follow report Agricultural pollutants, including pollutants from pesticides and CAFOs, are contributing to Iowa’s high cancer rates, according to research from the Iowa Environmental Council and the Harkin Institute. Iowa has the second highest cancer rate in the nation. Only 1 of 3 states with cancer on the riseaccording to the National Institutes of Health.
Credit: “Environmental Risk Factors and Iowa’s Cancer Crisis” report.
Iowa’s CAFOs, along with fertilizers applied to crops, contribute to Iowa’s Des Moines and Raccoon Rivers being in the top 1% of nitrate pollution in rivers nationwide. It is estimated that 80% of pollution comes from agriculture. Just this week, the Iowa Department of Natural Resources announced a study Fertilizer spills into waterways.
“In Iowa…these findings are particularly clear,” Amanda Starbuck, director of research at the Food and Water Service, said of the new Yale University study. “Iowa’s factory farms produce 109 billion pounds of fertilizer each year, more than 25 times the state’s population, contributing to an increase in nitrate water pollution linked to cancer.”
Adam Shriver, co-author of last month’s report from Iowa and director of health and nutrition policy at the Harkin Institute, said Iowa needs to do better tracking of fertilizer applications so residents and regulators can better understand where contamination may occur.
“It seems logical that we would need a system with a geospatial map of where all the fertilizer is being applied to get a better picture of what is happening in our waterways,” he said.
Brannen said a separate report on cancer in Iowa released last month by the Iowa Cancer Registry found that Iowa farmers as a whole had 13 percent less cancer incidence than the state’s general population.
“The most rigorous, long-term study available, which followed real farmers for 30 years, found that Iowa farmers were significantly less likely, if not more likely, to develop cancer than the general population,” she said. “That discovery should make headlines here.”
Son said the next step in understanding the role of CAFOs in cancer is to obtain more detailed data.
“Right now we are looking at the entire county, which helps us identify patterns, but we want to understand direct exposure to individuals to get more accurate exposure estimates,” she said.
Featured image: Diri Sueda/Unsplash+
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Brian Bienkowski is the editor-in-chief of The New Lede. He is a veteran journalist with over 15 years of experience covering the environment and human health. Prior to joining TNL, he was a senior editor at Environmental Health News for nearly a decade, overseeing the newsroom and two local bureaus. He was also the founder, producer, and host of the EJ podcast Agents of Change from 2020 to 2024.
Bienkowski has received multiple awards for her editing and reporting, including honors from the Healthcare Journalists Association, Columbia School of Journalism, Hunter College, and the Environmental Journalists Association. He has a master’s degree in environmental journalism from Michigan State University and lives in northern Michigan.
