Study: Nitrate in Wisconsin’s Drinking Water Linked to Cancer, Preterm Births and Up To $74 Million in Yearly Healthcare Costs

Nitrate contamination of drinking water in Wisconsin may cause nearly 300 cases a year of colorectal and other cancers and increase the risk of very premature births, very low birth weight and birth defects, according to a peer-reviewed study by scientists from Clean Wisconsin and the Environmental Working Group.

The study, published in the journal Environmental Monitoring and Assessment, estimates annual medical costs in Wisconsin of up to $34 million for treating colorectal cancers attributable to nitrate pollution. Annual medical costs in the state for nitrate-attributable very preterm births, very low birth weights and neural tube defects may reach $40 million.*

The report found a 40 percent reduction in nitrates statewide would reduce associated medical costs by more than one-fifth. Scott Laeser, water program director for Clean Wisconsin, told Wisconsin Public Radio: “We have to recognize that there's a cost of inaction, and what this study attempts to do is quantify that cost of inaction."

Nitrate is the most common groundwater contaminant in Wisconsin, and nitrate concentrations are increasing in wells across the state. Fertilizer and manure runoff are the main causes of nitrate water contamination in Wisconsin and other agricultural areas.

As a sign of growing concern about nitrate and fecal matter in the state’s water supply, in 2018 the state imposed restrictions on manure-spreading in 15 counties where drinking water was contaminated with nitrates and other bacteria.

The federal drinking water standard for nitrate of 10 parts per million, or ppm, was set more than 50 years ago to protect against blue baby syndrome, a potentially fatal condition that starves infants of oxygen if they ingest too much nitrate. But newer studies have linked an increased risk of cancer and changes in fetal development to drinking water contaminated with nitrate at just one-tenth of the federal standard.

Based on risk estimates from different epidemiological studies, EWG and Clean Wisconsin researchers reported that each year, up to 137 to 149 cases of very low birth weight and 72 to 79 cases of very preterm birth could be due to nitrate exposure from drinking water in the state, as well as 66 to 233 annual cases of colorectal cancer, the most common cancer associated with nitrate.^{1, 2, 3} Nitrate in drinking water is also associated with kidney, thyroid, bladder and ovarian cancers.^{4, 5}

Researchers estimated that annual medical costs for treatment of drinking water nitrate-attributable colorectal cancers in Wisconsin range between $10 and $34 million. Direct costs can include those associated with inpatient and outpatient care, specialty and ancillary medical services, tests and medications, as well as copayments and deductibles. Additional costs can come from an inability to work or reduced work hours following diagnosis and treatment, caretaker expenses and loss of quality of life.^{6, 7, 8}

Extrapolating from calculations by the American Cancer Society,⁹ the study estimated that every year up to $14 million in lost earnings could be due to nitrate-attributable colorectal cancer in Wisconsin. Drawing on a 2009 study by the National Cancer Institute,¹⁰ researchers estimated that nitrate-attributable costs of caretaker time can reach up to $8 million a year.

The new study reports that annual medical costs for nitrate-attributable very preterm births, very low birth weights and neural tube defects may reach $40 million. In addition to immediate medical costs and the costs for families and caretakers, overall costs include life-long consequences and health complications for the child.^{11, 12,  13}

In Wisconsin, about 90 percent of very low birth weight babies are born very preterm, according to 2019 data from the Centers for Disease Control and Prevention. Compared to children born full term, infants born preterm are more likely to suffer from sensory, neural, behavioral, respiratory and motor difficulties,¹⁴ may require special education to assist with academic studies and general development,¹⁵ and may earn less as adults.¹⁶

The prevention of ongoing nitrate pollution of drinking water sources and installing treatment to remove nitrate from drinking water holds the promise of eliminating or mitigating these future costs, both economic and personal.

* All costs reported have been converted, where necessary, to 2019 dollars using the medical services component of the Consumer Product Index.