Tainted Tap, a report from October 2020, details the nitrate pollution related to America’s widespread groundwater pollution. Concentrated animal feeding operations (CAFOs), large-scale animal feedlots, generate massive amounts of waste that often go without sewage treatment. Instead, the waste may be applied to farming fields. The implications are serious.
“The National Groundwater Association estimates that 38 percent of the U.S. population relies on groundwater for its drinking water supply, and an estimated 42 million people in the country rely primarily on drinking water from private wells.”
from the report Tainted Tap
The Environmental Working Group estimated 12,600 cases of cancer per year may be linked to nitrate pollution in the US drinking water. Most of the cases were colorectal, with some ovarian, thyroid, kidney, and bladder cancer. Although the Safe Drinking Water Act has an enforceable limit of no more than 10mg/L of nitrates in the water, that level has not been reassessed in almost 60 years.
Evidence has stacked up in that time, and it warrants reassessing our approach to Nitrates.
- One study of postmenopausal women in Iowa found that ovarian cancer risk was 2.03 times greater for women consuming drinking water with nitrate levels greater than 2.98 mg/L, compared to those consuming concentrations below 0.47 mg/L.
- A 2010 study of 357 pregnant women in rural Minnesota observed that methemoglobin levels at 36 weeks gestation were higher among women with 3 to 10 mg/L tap water nitrate levels compared to women with less than 3 mg/L of nitrate in their tap water. Methemoglobin forms from the nitrate in an infant’s gastrointestinal tract, which disrupts blood’s ability to carry oxygen.
Based on an analysis of eight studies related to nitrates in drinking water and colorectal cancer, EWG scientists found the “acceptable risk” level to be 0.14 mg/L — a level much lower than EPA’s threshold of 10mg/L, and nitrate water treatment is expensive.
- Over a six-year period, the Des Moines, IA utility spent more than $500,000 on average per year on operations and maintenance.
- That figure jumped to $1.4 million in 2015 when the annual average nitrate concentrations and the high number of days when water at intake locations exceeded the EPA’s safe water threshold for nitrates.
Contamination coming from runoff still presents problems if removed from drinking water. Nitrogen-rich water leads to algae blooms that steal oxygen from the fish and other aquatic life. The blooms harm humans and animals, too. The disruption to aquatic ecosystems should send up that red flag warning about potential ecosystem collapse.
The best way to address the downstream effects whether the toxic algae blooms or the increased risk of cancer in humans relying on the groundwater is the same. We must demand, support, and take action that protects groundwater in the first place. Everything depends upon it.