Health damages of nitrate exposure in drinking water: Inclusion of non-fatal conditions increases the social costs of nitrogen.

Nitrogen pollution of surface and groundwater remains largely unregulated resulting in negative impacts to human health and the environment. Policy interventions designed to internalize the negative externality of nutrient pollution have relied on low and highly uncertain damage estimates. Here we address an important gap in monetizing the health costs attributable to drinking water nitrate contamination in public water supplies. We consider fifteen adverse health conditions linked to elevated levels of drinking water nitrate including cancers, birth anomalies, and other non-fatal conditions. We apply our approach to public water suppliers in the U.S. state of Minnesota, estimating the avoidable nitrate-attributable direct medical and quality of life costs at $745 million (±82) annually statewide, a burden disproportionately shouldered by poor and rural communities. We simulated marginal increases in nitrate concentrations in over 600 public water suppliers, finding increasing nitrate contamination in an average public water supplier by 1 mg nitrate-N/L is associated with annual health damages of $4 million, while increasing nitrate concentration by 5 mg nitrate-N/L is associated with an additional $80 million in annual damages. We find communities face significant monetized costs even with nitrate exposure levels below the federal drinking water standard. Long-lived but non-fatal health conditions account for the greatest share of damages, suggesting that valuation methods that look only at avoided fatalities are likely to miss a substantial portion of the disease burden of water pollution.