Analysis by Paul Mathewson, Sydney Evans, Tyler Byrnes, Anna Joos, & Olga V Naidenko
Overview
Nitrate contamination of drinking water, common in agricultural areas, increases the risk of certain cancers and impacts fetal development during pregnancy. Building on previously published methodology, this study evaluates nitrate-attributable disease cases and adverse birth outcomes as well as their economic costs for Wisconsin. Nitrates are the most common contaminant in groundwater in Wisconsin.
Key Points
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Widespread Contamination: Nitrate is the most common groundwater contaminant in Wisconsin, affecting both private and public water supplies. Two-thirds of Wisconsin residents rely on groundwater for drinking water.
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Serious Health Impacts: Nitrate exposure from drinking water is linked to 111–298 annual cancer cases (including colorectal, ovarian, thyroid, bladder, and kidney cancers) and hundreds of birth complications such as very low birth weight and preterm births.
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High Economic Burden: The direct medical costs from nitrate-related diseases and birth outcomes are estimated tens of millions of dollars per year, underscoring the economic stakes of agricultural pollution.
Summary
Nitrate contamination — primarily from fertilizer and manure runoff — poses one of Wisconsin’s most urgent environmental health threats. Two-thirds of the state’s residents use groundwater as the primary source of drinking water. Here, we analyze nitrate exposure from drinking water in Wisconsin based on nitrate test results for community water systems for the period of 2010-2017 and a novel methodology for estimating nitrate exposure for the 28% of state’s residents who use private wells.
Important Takeaways
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Nitrate Contamination Is Statewide: Found in both public systems and private wells, nitrate pollution affects millions of Wisconsinites.
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Health Risks Are Severe: Chronic nitrate exposure is linked to multiple cancers and fetal development complications.
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Hundreds of Cases Each Year: The analysis attributes up to 300 cases of cancer and 200 birth complications annually to nitrates in drinking water.
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Rising Contamination Trend: Groundwater nitrate levels are increasing over time.
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Tens of Millions in Annual Costs: The public health and medical expenses of nitrate contamination total $23–$80 million yearly, creating both human and financial urgency for stronger pollution controls.
