Uranium and arsenic in drinking water puts certain communities at greatest risk

A new analysis of uranium and arsenic contamination in drinking water shows ugly evidence of how environmental racism persists in the US. Counties with more Latino residents and American Indian residents have been burdened with “significantly higher” concentrations of arsenic and uranium in their drinking water, the new research shows. In some of the most contaminated areas in the US, larger proportions of Black residents have also been linked to more of the toxic metals in public water systems.

“The racial and ethnic makeup of your community should really not be connected to the quality of the water that you drink. And this is something that needs to be taken very seriously,” says Irene Martinez-Morata, lead author of the research published in December in the journal Nature Communications and a PhD candidate in environmental health sciences at the Columbia Mailman School of Public Health.

Low levels of uranium and arsenic, generally within the Environmental Protection Agency’s regulatory limits, have been found in many community water systems across the US. But many counties with a larger proportion of Hispanic / Latino, Indigenous, and Black residents have been burdened with heavier pollution. Martinez-Morata and her colleagues used computer models to analyze how pollution concentrations differed between counties with different demographic makeups.

A 10 percent larger proportion of Hispanic or Latino residents was linked to a 17 percent higher concentration of uranium and a 6 percent higher concentration of arsenic in drinking water, they found. Similarly, a 10 percent bigger proportion of American Indian and Alaska Native residents was associated with a 2 percent higher concentration of uranium and a 7 percent higher concentration of arsenic in drinking water. In some counties in the West and Midwest with the most arsenic and uranium pollution, a 10 percent increase in non-Hispanic Black residents was associated with between about 1 and 6 percent higher arsenic and uranium levels.

The new research doesn’t delve into how these disparities developed in each county. But in the US, people of color have often borne the brunt of policies that have piled up environmental hazards in their communities. Other research has found that Americans of color are also more likely to live in counties with worse air quality and that Black and Latino populations in the US are exposed to disproportionately more air pollution than is caused by their consumption.

The new research on uranium and arsenic is based on EPA records from 2000 to 2011, the most recent publicly available data. The researchers combined that data with demographic information for each county. They were ultimately able to scrutinize uranium levels in 1,174 counties and arsenic concentrations in 2,585 counties. (There are around 3,000 counties in the US.)

Low levels of uranium has been detected in two-thirds of the EPA’s monitoring records for community water systems in the US, according to a related study published by Columbia researchers last April. You can explore their findings on an interactive map, which also includes arsenic and other metals that might contaminate water.

Keep in mind that nearly all the community water systems reported uranium levels below the EPA’s regulated limit of 30 micrograms per liter. But while researchers are still trying to understand what low levels of uranium exposure do to the body, doctors say there’s no real safe amount for humans. On top of their regulatory limits for contaminants, the EPA has aspirational but unenforceable goals for “the level of a contaminant in drinking water below which there is no known or expected risk to health.” That goal is zero for both uranium and arsenic. Chronic exposure to high levels of uranium have been linked to a heightened risk of hypertension, cardiovascular disease, kidney damage, and lung cancer. Arsenic, meanwhile, is a known carcinogen.

There are different ways these toxic metals can get into drinking water. Uranium and arsenic are both naturally present in Earth’s crust, so weathering rocks can potentially contaminate groundwater. But human activity can also be to blame. For decades, arsenic was widely used as a pesticide — leaving the carcinogen behind in soil and water. And there are more than 500 abandoned uranium mines on Navajo Nation land, some of which have poisoned water sources. That legacy of pollution has been linked to kidney disease, cancer, and a neuropathic syndrome in children. The Havasupai Tribe has also fought to stop a newer uranium mine near the Grand Canyon, concerned about its potential to contaminate the tribe’s main water source.

In September, the EPA announced the launch of a new national office focused on achieving environmental justice and protecting civil rights. Martinez-Morata hopes her team’s new research will help inform those efforts by pinpointing which communities would benefit most from better enforcement of drinking water standards and funding for cleanup. “I hope that our work serves practical applications, and at least as a call for action,” she tells The Verge.