NEWTON, Mass. — Millions of Americans face exposure to elevated nitrate levels in their drinking water, a study finds, which puts them at greater risk of developing health problems.
The research, conducted by researchers at the Silent Spring Institute, revealed that Latino populations in particular are disproportionately affected by high nitrate levels in water, which has been associated with health problems such as cancer and birth defects.
“Since the lead crisis in Flint, Michigan, there’s been a real push to document other types of disparities in drinking water quality in the U.S. and understand the factors that drive them,” says lead author Dr. Laurel Schaider, an environmental chemist at the institute, in a media release. “Because at the end of the day, everyone should have access to clean and safe drinking water regardless of your race or where you live.”
Nitrate contaminates water from common sources such as fertilizers, sewage treatment systems, and animal manure. The Environmental Protection Agency’s mandated “safe level” of nitrate in drinking water is 10 parts per million (ppm), but recent studies have shown that nitrate levels as low 5 ppm can cause certain cancers and birth defects, the authors say. Above 10 ppm, infants are at risk of suffering from “blue baby syndrome,” which hampers the ability for blood to carry oxygen through the body.
“Nitrate is also a good marker for the presence of other contaminants in drinking water,” says Schaider.
Dr. Schaider and her team compiled data from 39,466 public water systems providing drinking water to 70% of the U.S. population. For each water system analyzed, the researchers recorded the number of people relying on the system and the source of the drinking water: either groundwater or surface water.
The team found that 1,647 public water systems, which provide drinking water for over 5.6 million Americans, had an average nitrate concentration of 5 ppm or higher. The highest proportion of water systems with high nitrate levels were found in the West and Midwest.
Dr. Schaider’s team connected the data to minority populations by corresponding the water system contamination data with U.S. census reports on race, ethnicity, poverty, home ownership and proportions of households in urban areas. They say that as the proportion of Hispanic residents increases, so does the odds that their drinking water will contain potentially dangerous level of nitrate.
The study was published in the journal Environmental Health.