Over the summer, Bluestem Prairie looked at the problem of nitrates in Minnesota's drinking water in the posts Nitrates in Southwestern Minnesota water: 'Do not give the water to infants' in Ellsworth and Strib scrutinizes MN Department of Ag action on nitrate-related Groundwater Protection Rule.
Over at MinnPost, there's a reprint of a Circle of Blue article that dives into the possible consequences of nitrate pollution. According to MinnPost, Circle of Blue is "an independent, non-partisan, nonprofit journalism organization that works to inform the world’s most important decisions about water, food, and energy in a changing climate."
On ‘Cancer Road,’ a group of southeastern MN families ask if nitrate exposure is to blame
By Keith Schneider, Circle of Blue/ via MinnPostThe amount of nitrogen applied to U.S. corn crops has increased 120 million pounds annually since 2000, according to the U.S. Department of Agriculture (USDA).
This story comes from Circle of Blue, an independent, non-partisan, nonprofit journalism organization that works to inform the world’s most important decisions about water, food, and energy in a changing climate.
BERNE, Minn. — It was a hot afternoon in mid-July and 60-year-old Brian Bennerotte was making a pilgrimage of sorts, navigating a shotgun-straight gravel road south of Minneapolis on a journey through landscape stitched with crop and livestock farms as far as the eye can see.
Bennerotte is one of only three surviving members of the third generation of Bennerottes who once farmed along a mile-long stretch of County Road B west of where it intersects with State Highway 57. As a long-haul truck driver, Bennerotte rarely gets back here. But with a visitor at his side, he finds his way.
From the passenger seat of a rented vehicle he scans both sides of the road, then points to a dust-scoured barn leaning into the wind. The building is all that remains of his family’s farmstead, which once encompassed 200 acres and a home large enough for Bennerotte’s parents to raise five boys and a girl.
Down the road a bit further, he recognizes neighboring properties: There is the Glarner farm, and the Spreiter farm and the Serie farm. All are connected by circumstances of geography, topography, agriculture, and social commerce.
All also are joined by cancer and disease.
Among the four families who lived for decades along County Road B, 12 people developed cancer and seven died. Bennerotte was one of three people who developed lymphoma. The disease nearly killed him in 1983 when he was 20 years old. His father and three brothers would not survive their own bouts with cancer.
For some, County Road B has a different name: Cancer Road.
“Every family along here was affected. Every one,” said Bennerotte.
Nitrate contamination
Though the causes of the cancers are not proven, a key suspected culprit is believed to be the elevated levels of nitrates that have contaminated the drinking water for County Road B families. Just as they do throughout U.S. farm country, nitrates commonly flow into well water and other water sources as runoff from fields treated with commercial fertilizer and livestock manure. Over the last decade, a growing number of peer-reviewed medical studies have linked exposure to nitrates in drinking water to elevated incidences of cancer.
Many of the County Road B cancers — breast, blood, colon, lymphoma — have been specifically associated in medical studies in the U.S. and overseas with exposure to nitrates in drinking water.
The groundwater in the area has the highest levels of nitrates in Dodge County, according to the county’s water monitoring data. And wells used by each of the families contained nitrate levels well above what authorities consider safe, the data shows.
“It’s eyebrow raising that you have this cluster in this area where you have high levels of nitrates and kidney cancers and bladder and breast cancers,” said Paul Mathewson, science program director at the environmental advocacy group Clean Wisconsin. He acknowledged that it is often difficult to pinpoint specific causes for specific cancers but said the County Road B cases show a strong link. “Those are some of the cancers that have been associated to increased risk with respect to nitrate contamination,” he said.
Mathewson is the lead author of a 2020 peer-reviewed study that identified nitrate contamination in drinking water as the probable cause of nearly 300 cases a year of colorectal and other cancers in Wisconsin.
The concerns have broad implications for all of U.S. farm country. The U.S. Geological Survey has found that 22% of private wells in rural areas exceed the 10 parts per million (ppm) safety limit for nitrates.
In Minnesota alone, authorities in 2017 found elevated levels of nitrates in 80 public water systems. In Iowa, 55,000 drinking water wells were contaminated with elevated nitrate concentrations, according to 2017 data. Private water wells serve about one-third of Wisconsin families; state authorities in 2022 found 10 percent of them exceed the 10 ppm nitrate safety limit.
And in Nebraska, the U.S. Environmental Protection Agency (EPA) reported in 2018 that groundwater beneath almost a fifth of Nebraska, over 13,000 square miles, is contaminated with nitrates at more than 5 parts per million, the concentration now considered by scientists to be a health concern.
Water quality data analyzed by the Environmental Working Group, a Washington-based research and advocacy group, found in 2020 that one in four residents of Illinois, Iowa, Kansas, Nebraska, and Wisconsin — 6.9 million people — were drinking nitrate-contaminated water from community water systems.
The cancer connection
Nitrogen is considered a necessity by most U.S. corn growers, who see the fertilizer as a key tool for boosting yields and harvesting bumper crops. But commercial nitrogen fertilizer and nitrogen-rich livestock and poultry manure are the leading sources of the nitrate contaminants — formed when nitrogen combines with oxygen — that drain into surface and groundwater, according to state environment and agriculture agencies.
The amount of nitrogen applied to corn has increased 120 million pounds annually since 2000, according to the U.S. Department of Agriculture (USDA). And the amount of nitrogen-rich and untreated liquid and solid manure from livestock being spread on farmland — most of it in the Midwest — grew to 1.4 billion tons by 2018, 300 million more tons than in 2007, USDA data shows. As much as 70% of the nitrogen applied to farmland, according to many studies, leaked off fields and drained as toxic nitrates into the region’s waters.
Exposures to nitrates in drinking water have long been known to pose a serious threat to infants because the presence of nitrates inhibits the ability of blood to carry oxygen. In 1962, U.S. health authorities set 10 parts per million as the safe limit for nitrates in drinking water for preventing “blue baby syndrome.”
The science tying nitrates to cancer has been building over the last 20 years and continues to build. The Centers for Disease Control and Prevention says that when nitrates are ingested, they react with proteins and enzymes to form a group of chemicals called N-nitroso compounds, “which are known to cause cancer in animals and may cause cancer in humans.”
In 2001, researchers at the University of Iowa evaluated data from a long-term study of more than 20,000 women in Iowa and found increased risks of bladder and ovarian cancers associated with elevated nitrate levels in public drinking water supplies used by the women.
More recently, medical researchers have been conducting epidemiology studies, looking at large groups of people and what they’re exposed to and their rates of cancers. The results, some scientists say, indicate that exposure to nitrates in drinking water poses a health threat at much lower concentrations than the 10 ppm federal drinking water standard.
A 2018 peer-reviewed paper by National Cancer Institute researchers and other scientists evaluated 30 epidemiology studies of low-level exposure to nitrates in public drinking water systems, finding that many studies “observed increased risk with ingestion of water nitrate levels that were below regulatory limits.”
While noting that the number of studies “are still too few to allow firm conclusions about risk,” the researchers reported that the “strongest evidence for a relationship between drinking water nitrate ingestion and adverse health outcomes … is for colorectal cancer, thyroid disease, and neural tube defects.”
In 2019 the Environmental Working Group published a peer-reviewed study that found that exposure to nitrate in drinking water was causing over 12,000 cancer cases annually in the U.S.
“In the past decade or so there’s been a lot of new research making a strong, compelling case that even at nitrate levels that are much lower than 10 parts per million you’re seeing these increased risks,” said Mathewson. “There needs to be greater awareness. The science is out there.”
That view is not entirely universal. The Fertilizer Institute, the trade organization for the $27 billion U.S. commercial fertilizer industry, issued this statement in 2017: “The U.S. Agency for Toxic Substances and Disease Registry does not characterize nitrate as a carcinogen,” and added that the EPA expressly notes “conflicting results across studies, and design limitations in a number of epidemiological studies that have investigated associations between nitrate or nitrite exposure and cancer.”
Comments