EPA Restarts Assessment of Health Risks from Nitrate in Water

The agency will evaluate the hazards from agriculture’s primary water pollutant.

Farming regions in northeastern Nebraska and elsewhere have some of the highest concentrations of nitrate in streams and groundwater due to decades of fertilizer use. Photo © J. Carl Ganter/Circle of Blue.

The U.S. Environmental Protection Agency, reversing a Trump-era decision, is restarting a human health assessment of nitrate and nitrite, a move that has potentially far-reaching regulatory implications for one of the country’s most pervasive drinking water contaminants.

The EPA suspended its nitrate assessment in December 2018. It was one of nine chemicals that the Trump administration deemed no longer a priority for evaluation by the agency’s health assessment division known as the Integrated Risk Information System, or IRIS.

That changed in June when the EPA quietly reinserted the nitrate assessment into the IRIS agenda “to address an agency priority.”

 In addition to generating heat-trapping greenhouse gases, over-application of nitrogen-rich fertilizer and manure contributed to steadily rising levels of nitrate in streams and groundwater…

The decision to take a closer look at the chemical comes at a time of increased scrutiny and public concern over nitrate exposure and human health. Nitrate forms when nitrogen is exposed to oxygen in the air. An exponential increase in the use of synthetic, nitrogen-based fertilizers since 1950 supercharged the production of corn and soybeans. The number of large livestock feeding operations — and the amount of manure they produce — also increased rapidly.

Nutrients are essential to crop production. But the convergence of high rates of chemical fertilizer use and immense manure production led to well-documented risks to human health and the environment. In addition to generating heat-trapping greenhouse gases, over-application of nitrogen-rich fertilizer and manure contributed to steadily rising levels of nitrate in streams and groundwater, particularly in the 11 Corn Belt states across the Great Lakes and Midwest, California’s Central Valley, North Carolina, and Washington’s Yakima Valley.

The federal environmental agency’s attention to the hazards of exposure to nitrate has been historically feeble. Evidence of widespread nitrate contamination in surface waters, and in groundwater used as a source for drinking, has been documented for decades by the U.S. Geological Survey, and many state health and environmental departments. The federal environmental agency has left it up to the states to oversee nitrate contamination, which is growing steadily worse.

One of the primary sources of nitrate pollution is large livestock feeding operations, which produce some 1.4 billion tons of liquid and solid manure annually, according to the most recent accounting by the U.S. Department of Agriculture. Nitrogen-rich feces and urine, untreated, is spread […]

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