More than 62 million Americans (roughly 1 in 5) may be exposed to potentially dangerous levels of nitrates in their tap water, a new report finds.
Nitrates, compounds of nitrogen and oxygen naturally found in air, water, soil, and plants, become a health risk when rainfall leaches nitrogen-rich fertilizers used in agriculture into groundwater, streams, and rivers, and reaches public water systems several miles downstream.
Low levels of invisible, tasteless, and odorless nitrates in drinking water have been linked to thyroid disease, stomach, kidney, bladder, and colon cancers, premature birth and birth defects, and other health problems, according to a report released Thursday by the Environmental Working Group (EWG), a nonprofit health advocacy group.
Thirteen-year-old Ben is so concerned about nitrates in the tap water in his hometown of Des Moines, Iowa, that he recently sent a letter and poem to his local legislators.
“I remember when you could drink water from the tap, but now it’s a health concern,” Ben wrote to Iowa Congressman Dr. Austin Bathe. “Don’t ignore this issue!”
Des Moines is a hotspot for nitrate contamination in its source water, with concentrations so high in local rivers that the city was forced to build one of the world’s largest nitrate removal plants. Operating costs are over 100,000 yen per day.
“I’ve read Ben’s letters and poems many times, and they still take my breath away,” said Beiss, an internist. Beis has been calling attention to Iowa’s nitrate levels in scathing and sometimes satirical videos on social media. “Isn’t it sad that our children have to worry about water that could be harmful to their health?”
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Iowa kids are writing about water pollution and asking adults to do something. #water #iowa
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Federal guidelines established in 1962, which have never been updated, set a safe level for nitrates at 10 milligrams per liter. However, a growing number of peer-reviewed studies are showing an association with health effects at concentrations as low as 5, 3, and even 2 milligrams per liter.
To determine how many Americans are exposed to these low levels of nitrates, researchers used the EWG Tap Water Database, which aggregates data from approximately 50,000 public water systems in the United States.
“We measured nitrate concentrations in public drinking water in cities and towns in all 50 states from 2021 to 2023 and mapped exposures down to 3 milligrams per liter,” said report author Ann Schechinger, EWG’s senior director of agriculture and climate research.
“This is the first map of its kind. No one has done this before,” Schechinger said. “You can search by postcode, so people can check their own nitrate and other pollutant levels.”
The report does not cover private well water, which is not regulated by the U.S. Environmental Protection Agency.
More than 6,000 community water systems serving more than 62.1 million people tested for nitrate levels of 3 milligrams per liter or higher, the report said. Studies have linked these levels to childhood cancer and other health problems.
More than 3,200 of the 6,000 systems tested above 5 milligrams per liter, levels associated with colorectal and ovarian cancer.
The Los Angeles Department of Water and Power, which serves about 4 million people, tested for concentrations of 3 milligrams per liter or higher on 255 different occasions, according to the report. Phoenix was the only other major city with a population of more than 1 million people with test results of 3 milligrams per liter or higher. Philadelphia; Las Vegas; San Jose, California. and Columbus, Ohio.
A spokesperson for the Fertilizer Association, which represents the industry, told CNN in an email that U.S. farmers have doubled corn production over the past 30 years with only small increases in fertilizer use.
““Nitrates are natural compounds that occur in the environment,” said Christopher Glenn, vice president of public affairs at TFI. “Fertilizers are one source, but other sources include atmospheric nitrogen deposition from organic mineralization, septic systems, urban stormwater, industrial and motor vehicle emissions.” As the EWG report suggests, blaming rising nitrate levels in drinking water primarily on fertilizer use is an oversimplification of a complex issue. ”
More than 3 million people in 606 water systems in the United States were exposed to nitrates above the legal limit of 10 milligrams per liter.
Seventy of these systems had nitrate levels of 20 milligrams per liter or more, twice the federal standard. Another 21 systems detected concentrations of 30 milligrams per liter or more. A water system serving 31 people near Dinuba, California, tested at a concentration of 50 milligrams per liter. This is the highest price in the United States.
Most of the highest-level communities were very small, serving fewer than 1,000 people, but not all of them. More than 500,000 people in Fresno, California, were drinking tap water that contained up to 14 milligrams of nitrate per liter.
More than 35,000 people in Garden City, Kansas, were exposed to up to 37 milligrams per liter of nitrate, and about 32,000 people in La Verne, California, were using tap water with 26 milligrams per liter.
“Almost all of the water systems with extremely high levels are groundwater systems that are pumping water from local wells,” said Christopher Jones, a biologist and chemist and former research engineer at the University of Iowa who monitored the state’s water quality. Jones is currently running to become Iowa’s next Secretary of Agriculture.
“Forty milligrams per liter of a substance in groundwater is not unheard of, it’s not at all,” said Jones, who was not involved in the EWG report.
Experts say the main source of nitrates in groundwater comes from livestock manure and other nitrogen-rich fertilizers that farmers and ranchers spread on crops.
Without proper protection measures, rainfall and irrigation water can easily flow into groundwater and wells, as well as into rivers and streams that feed into public water systems. And you don’t have to be close to agriculture to be affected, Schechinger said.
“Nitrate pollution can affect people far downstream from the farm,” she says. “Your water may come from a reservoir on the outskirts of a major city, but the streams and rivers that feed that reservoir come from miles upstream where your farm may be.
“Although this is an agricultural issue, it affects people in really small rural towns and big cities across the country,” Schechinger said.
Public water systems that regularly test for levels above the legal limit of 10 milligrams per liter must notify residents and take steps to purify the water.
This requires expensive mitigation systems, costs that water utilities often pass on to consumers. Des Moines spent more than $4 million building an ion exchange treatment plant in 1990.
The best choice for consumers is a reverse osmosis system, which forces water through a semipermeable membrane that traps up to 99 percent of contaminants, Jones said.
“You’ll want to install a reverse osmosis system on your cold water faucet in your kitchen and use it for drinking, coffee and cooking,” he said. “You don’t have to put it all over your house. There are no risks associated with things like bathing or washing dishes in high nitrate water.”
If you use water from a refrigerator filter, he said, it should also be connected to a reverse osmosis system.
“Don’t look to bottled water as a solution; it’s generally less regulated than tap water,” Schechinger says. “Look up your postcode in our tap water database to see if you need filtration. We also provide information on home water filters.”
Experts say until stricter regulations are passed, it’s up to consumers to decide their course of action.
“It’s a matter of peace of mind,” Jones said. “If you know the water coming out of your faucet has nitrate levels above 3 milligrams per liter and you want peace of mind, we recommend installing a reverse osmosis system on your kitchen cold water faucet.”
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