Report calls for stricter fertilizer rules as US nitrate pollution crisis grows

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Lax regulations and mismanaged applications in the US are to blame for the tons of nitrogen fertilizer that runs off into waterways each year and contributes to water and air pollution, cancer and environmental damage, according to a report released Monday. 

US farmers annually apply over 11 million metric tons of nitrogen fertilizer, according to the US Department of Agriculture (USDA), making it the most used fertilizer in the country. The new report, published by the Natural Resources Defense Council (NRDC), finds that an estimated half of these nutrients aren’t taken up by crops, but leach into the environment instead in ways that cost the US billions of dollars annually in water treatment costs, beach closures and habitat loss. Most of the costs hit small and rural farming communities, the report states.

 “Excessive fertilizer use is poisoning water, air and wildlife … it is outrageous and unacceptable,” said J.P. Rose, a director of soil health, nature at NRDC and co-author of the new report. “We need commonsense guardrails on nitrogen overapplication and runoff.”  

Regulations, technical assistance and financial support aimed at preventing fertilizer overuse and mismanagement could help stop this nitrate pollution crisis without reducing farm productivity, the authors write. 

“Communities should not be forced to choose between having clean water and growing food,” the report states. 

“Communities should not be forced to choose between having clean water and growing food.” – NRDC Report 

Farm associations have long defended fertilizer applications as critical tools for farmers and have resisted efforts to tighten regulations. However, the findings come on the heels of several other reports and studies over the past few months that have found large-scale crop and animal farms are contributing to nitrate pollution throughout the US and may be, in part, behind increasing cancer rates in agricultural communities. 

Contaminating water systems and people 

The NRDC report adds to prior work warning of over-use of fertilizers. 

The group analyzed scientific studies, federal data and other past reports, concluding that the overuse of nitrogen fertilizers is harming human health, ecosystems and the climate. 

Excess nitrogen can be converted into nitrate when it enters water. Agricultural fertilizers and manure from large-scale livestock operations are key sources for nitrates, though they also can occur at low levels in the environment naturally. 

Nitrate exposure can cause dangerously low oxygen levels in babies’ blood, causing what’s known as “blue baby syndrome.” Scientific research shows nitrate exposure is linked to several types of cancer, including kidney, bladder, colorectal and ovarian cancers. The NRDC cited a study, for example, that estimated that nitrate-polluted drinking water may be behind up to 12,594 cases of cancer each year in the US. 

In Iowa — one of the nation’s top farm states — researchers in March released a report finding that more than a dozen types of cancer that are linked to pesticide, per- and polyfluoroalkyl substances (PFAS), nitrate and radon exposure are afflicting Iowans at much higher rates than the US population, according to the most recent data. 

Iowa has the second-highest rate of cancer in the nation and is only one of three states where cancer is rising, according to the National Institutes of Health. For many types of cancer, the state’s numbers dwarf national averages. 

Water treatment facilities in agricultural areas are frequently battling excessive nitrates. Last week, for example, Des Moines’ water utility asked residents to cut back on water use because nitrate levels are so high in the drinking water supplies that the utility is having a hard time treating the nitrates in the water. Iowa’s Des Moines and Raccoon rivers are in the top 1% of rivers nationwide for nitrate concentration, with 80% of the contamination coming from agriculture.

“Clean water is a right, not a luxury,” Rose said. 

In addition to human health concerns, excessive nitrate can spur algal blooms that kill wildlife and degrade key habitats.  Nitrogen fertilizers are also a driver of nitrous oxide emissions, which are estimated to be 273 times more potent at trapping heat in the atmosphere than carbon dioxide and also damage the ozone layer. 

Silvia Secchi, a researcher and professor at the University of Iowa who studies the environmental impacts of agriculture, said the NRDC report was a “little narrow in scope” and ignored two major factors driving nitrate pollution — concentrated animal feeding operations (CAFOs) and the ethanol mandate, which is responsible for around a third of the corn grown in the US. 

“Yes, we’re overusing fertilizer, but we wouldn’t need to use as much if we didn’t need to meet the ethanol mandate,” she said. “And CAFOs are a major source of nitrate pollution. It’s important to have that systemic perspective.”  

More than 80 health and environmental groups last month sent a letter to Health and Human Services Secretary (HHS) Robert F. Kennedy Jr. and Environmental Protection Agency administrator Lee Zeldin urging the officials to protect Americans from a “public health emergency” driven by nitrate pollution.

“It is imperative that EPA and HHS act now to address this public health emergency in Iowa and across the country,” the letter states. “Your agencies should immediately identify and eliminate sources of nitrate pollution in drinking water and provide funds to communities to reduce nitrate to safe levels.”

The National Corn Growers Association and the American Soybean Association did not return requests for comment on the NRDC report or escalating concerns over nitrate pollution. The Fertilizer Institute responded but did not have an expert available. 

Regulations need to catch up 

The federal Clean Water Act and Safe Drinking Water Act are not adequate for dealing with nitrate runoff, the report states. The Clean Water Act largely targets “point source” pollution, such as discharges from heavy industry, and farm runoff often evades scrutiny. The Trump administration has signaled it wants to further restrict the Clean Water Act by removing remote and seasonal streams, wetlands and other bodies of water from the EPA’s scope, which critics say would only further worsen the nitrate pollution crisis. 

Under the Safe Water Drinking Act, the EPA has set a threshold of 10 milligrams per liter (mg/L) for nitrates in drinking water. However, multiple studies over decades have shown that some cancers are linked to nitrate consumption in drinking water at levels far below 10 mg/L. And in April, an Environmental Working Group (EWG) study found that more than 60 million Americans get their water from water systems that have had nitrate levels at or above 3 mg/L in at least one test from 2021 to 2023. Agricultural states were the most impacted.  

“Yes, we’re overusing fertilizer, but we wouldn’t need to use as much if we didn’t need to meet the ethanol mandate.” -Silvia Secchi, University of Iowa

An EPA spokesperson said the agency completed its most recent review of nitrate drinking water regulations in 2024 and “determined that the nitrate rule was not a candidate for revision at that time, which means that the current rules are sufficient to keep water clean and safe for human consumption.”

The new report outlines several steps to tackle the nitrate problem, including mandatory nitrogen application limits, bolstered monitoring and technical assistance for farmers, and rewards for farmers who reduce nitrogen pollution through cover crops, riparian buffers and other conservation practices. 

“Enforceable standards can help establish a level and equitable playing field for the agriculture industry,” the report states. “Currently, farmers who invest in voluntary best management practices to reduce nitrogen pollution often must compete with farmers who decline to do so.” 

Rose said his research team acknowledges that nitrogen is essential to modern agriculture. “We are not at all seeking to ban nitrogen fertilizer, this is just an issue of when too much of a good thing becomes a bad thing,” he said. 

Secchi said increased regulations would work, but “the best way in the US to reduce nutrient pollution is not to grow so many of the crops that cause the problem in the first place.”

“An off-ramp from corn ethanol is critical, that would free up land for pasture-based livestock production, to produce food that people actually eat, and for extended rotations that reduce the need for fertilizer,” she said. “And in the meantime, we could do a better job at regulating CAFOs.”

Featured image: Unsplash +/James Baltz