Iowa ranks second among states for cancer incidence and is one of three where rates are still rising as the national rate falls. Nearly half its counties have cancer rates above Louisiana’s Cancer Alley; the state expects 21,700 diagnoses and about 6,400 deaths this year.
A 2026 report by the Iowa Environmental Council and Harkin Institute identified agriculture as a contributor to Iowa’s high and rising cancer rates, citing nitrate pollution, pesticides and “forever chemicals.” The article notes there is no single explanation for cancer risk, which can involve genetics, behavior and environmental exposures; some cancers may take decades to emerge.
Research cited in the article says long-term nitrate exposure as low as 3 milligrams per liter can increase cancer risk. Public water systems serving about 1.2 million Iowans recorded at least one test at or above that level from 2021 to 2023. The federal limit is 10 mg/L and was set to prevent “blue baby syndrome,” not cancer. A Palo Alto County private-well sample measured 6.9 mg/L; about 282,000 Iowans rely on private wells, whose water quality is not federally regulated.
