• Applicators who used weedkiller dicamba had elevated risk of liver cancer and intrahepatic bile duct cancer, a 2020 review of Agricultural Health Study data showed. Among farmers in the Agricultural Health Study, a greater use of herbicide atrazine increased risk of lung and prostate cancer, a 2022 study showed. Iowa’s ag risks may be higher than other states• Nitrate is found at potentially harmful levels in 1-in-20 Iowa public drinking water systems and in more than 12,000 private wells in Iowa. “Farmers generally have elevated rates of prostate cancer related to the general population,” said Laura Beane Freeman, National Cancer Institute principal investigator of the Agricultural Health Study. About 43 million Americans — or about 13 percent of the population — relies on private wells for drinking water.