NEW YORK — Although the United States has come a long way in terms of cleaning up pollution, a new report finds problem areas still remain. A review of the nation’s public water supplies reveals many communities and regions across America are still dealing with high levels of arsenic in their water. Researchers from Columbia University’s Mailman School of Public Health warn drinking water contaminated with this substance can lead to cancer.

“Systematic studies of inequalities in public drinking water exposures have been lacking until now. These findings identify communities in immediate need of additional protective public health measures,” says Anne Nigra, a postdoctoral research fellow in environmental health sciences, in a university release.

Among the most at-risk populations, the study finds community water systems relying on groundwater, supplies serving small populations in the Southwest, and Hispanic communities all have the highest likelihood of exceeding the national maximum contaminant levels (MCL).

“Our objective was to identify subgroups whose public water arsenic concentrations remained above 10 μg/L after the new maximum arsenic contaminant levels were implemented and, therefore, at disproportionate risk of arsenic-related adverse health outcomes such as cardiovascular disease, related cancers, and adverse birth outcomes,” adds senior author and Professor of Environmental Health Sciences Ana Navas-Acien, PhD.

The dangers of arsenic

Arsenic is a naturally occurring element in many minerals, usually combining with other substances like sulfur. It is also highly toxic and a natural human carcinogen. Arsenic is also a common contaminant in aquifers around the United States. Previous studies by the Columbia researchers find that reducing MCL from 50 to 10 μg/L can prevent between 200 and 900 cancer cases each year.

The study compared arsenic levels in community water systems during 2006-2008 versus 2009-2011, when officials began monitoring for compliance of the Environmental Protection Agency’s 10 μg/L arsenic limit. Researchers estimated the three-year average of arsenic concentrations for 36,406 local water systems and 2,740 counties. They also compared the differences in arsenic levels between various U.S. regions and sociodemographic groups for those same three years.

Their data comes from two of the largest EPA reports on public water. Researchers studied around 13 million records on 139,000 public water systems which serve 290 million people every year. Those water sources are spread across 46 states, Washington D.C., the Navajo Nation, and American Indian tribes across the country.

Who is most at risk?

On a positive note, the results reveal the average water system arsenic concentration decreased by 10 percent nationwide when comparing 2006-2008 readings to 2009-2011. That decrease was 11.4 percent in the American Southwest and a stunning 37 percent in New England.

Despite the overall progress, the readings are still too high among certain populations. Researchers find predominantly Hispanic communities, some areas of the Southwestern U.S., the Pacific Northwest, and the Central Midwest all have regions with excessive arsenic contamination. In addition, communities relying on groundwater and those serving under 1,100 people had higher arsenic levels.

Community water systems not complying with the arsenic MCL are more likely to be supplying Hispanic populations (38%), in the Southwest (61%), or relying on groundwater (95%).

“Our findings will help address environmental justice concerns and inform public health interventions and regulatory action needed to eliminate exposure inequalities,” the Columbia researchers say.

“We urge continued state and federal funding for infrastructure and technical assistance support for small public water systems in order to reduce inequalities and further protect numerous communities in the U.S. affected by elevated drinking water arsenic exposure,” Nigra adds.

The study appears in the journal Environmental Health Perspectives.

About Chris Melore

Chris Melore has been a writer, researcher, editor, and producer in the New York-area since 2006. He won a local Emmy award for his work in sports television in 2011.

Our Editorial Process

StudyFinds publishes digestible, agenda-free, transparent research summaries that are intended to inform the reader as well as stir civil, educated debate. We do not agree nor disagree with any of the studies we post, rather, we encourage our readers to debate the veracity of the findings themselves. All articles published on StudyFinds are vetted by our editors prior to publication and include links back to the source or corresponding journal article, if possible.

Our Editorial Team

Steve Fink


Chris Melore


Sophia Naughton

Associate Editor

1 Comment

  1. john says:

    The headline…several communities, but then there is no mention of any community…