Worrying levels of uranium and various other problematic metals can be found in drinking water across the US, according to a new study published in the Lancet Planetary Health.

The analysis by Columbia University researchers found that the average levels of uranium (a naturally radioactive element ) and arsenic (a potentially harmful heavy metal) found in US water systems exceeded the maximum contaminant levels set by the US Environmental Protection Agency (EPA).

Some regions of the US are harder hit than others, as you can see in the maps below.

The researchers found that contamination was particularly high in semi-urban areas with a high Hispanic population. In these regions, concentrations of arsenic, barium, chromium, selenium, and uranium were found at concerning levels.

The impact of this on human health is not known – but the study notes that Hispanic populations are impacted by numerous health disparities, including diabetes, plus liver, kidney, and cardiovascular disease, which may possibly be linked to exposure to these chemicals.

“Previous studies have found associations between chronic uranium exposure and increased risk of hypertension, cardiovascular disease, kidney damage, and lung cancer at high levels of exposure,” Anne Nigra, PhD, assistant professor of Environmental Health Sciences at Columbia Mailman School of Public Health, said in a statement. 

“Our objectives were to estimate CWS metal concentrations across the U.S, and identify sociodemographic subgroups served by these systems that either reported high metal concentration estimates or were more likely to report averages exceeding the U.S. EPA’s maximum contaminant level."

Long-term ingestion of inorganic arsenic is directly linked to developmental effects, diabetes, pulmonary disease, and cardiovascular disease, according to the World Health Organization (WHO). Arsenic exposure can also lead to skin problems, resulting in pigmentation changes and skin lesions. Some evidence suggests exposure may be a precursor to skin cancer.

Although uranium is radioactive, the main risk of ingesting the metal is chemical toxicity, not radiation. Exposure to elevated levels of uranium over a long period of time can damage your kidneys.

As scary as these metals may sound, uranium and arsenic can be found in Earth's crust and naturally occur in the environment at relatively low levels. However, people can also be exposed to higher levels of these metals through contaminated groundwater and industrial processes.

In light of this fact, the study authors argue that the consistent association between elevated metal concentrations and certain communities suggests that their findings are most likely a reflection of failed regulatory policy, not just natural geology. 

“Additional regulatory policies, compliance enforcement, and improved infrastructure are therefore necessary to reduce disparities in CWS metal concentrations and protect communities served by public water systems with elevated metal concentrations,” said Nigra. “Such interventions and policies should specifically protect the most highly exposed communities to advance environmental justice and protect public health."