High arsenic concentrations found in drinking water serving numerous US regions

By Sarah MooreReviewed by Emily Henderson, B.Sc.Dec 9 2020

Those living in the Southwestern states of the US are more likely to be exposed to high concentrations of arsenic in their drinking water, a new study finds.

Water Quality Control. Image Credit: Happy_Nati/Shutterstock.com

Links between arsenic contamination and cancer

A team of researchers at Columbia University Mailman School of Public Health published the results of their new study in the journal Environmental Health Perspectives this month. The team conducted a national study to determine those at a high risk of consuming high levels of highly toxic human carcinogen, arsenic, via their drinking water.

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”.

Ana Navas-Acien, Professor of Environmental Health Sciences

Previous research has highlighted the significant impact reducing arsenic levels in the human water supply has on reducing cases of cancer. Therefore, in identifying those exposed to greater levels of the carcinogen, scientists can target those most at-risk to reduce new cases of cancer that are completely avoidable.

Assessing levels of arsenic in community water systems

To protect US citizens from the detrimental health implications of arsenic exposure, the US Environmental Protection Agency (EPA) enforced its maximum contaminant level (MCL) for arsenic content in public water systems (10 µg/L) in 2006. The team at Columbia University assessed data collected between 2006-2008 and 2009-2011 on the arsenic concentrations of 36,406 community water systems across different 46 US states. A total of around 13 million records were analyzed.

Researchers found that average arsenic concentrations in community water systems decreased by 10% nationwide from 2006-2008 to 2009-2011. The Southwest saw an average reduction of 11.4%, and New England saw a considerable reduction of 37%. There was a reduction in the percentage of community water systems whose water exceeded the limit of 0 μg/L MCL between 2006-2008 and 2009-2011, 3.2% and 2.3%, respectively.

However, while average arsenic concentrations across the country reduced, the data revealed that concentrations in specific regions remained high, including regions serving particular sociodemographic subgroups, such as Hispanic communities, areas in the Southwestern U.S, the Pacific Northwest, and the Central Midwest. Community water systems supplying water with levels of arsenic that exceeded the recommended limit were most likely to be found in the Southwest (61%), and serving Hispanic communities (38%).

The paper’s first author, Anne Nigra, and senior author Ana Navas-Acien explain the significance of their results, “Our findings will help address environmental justice concerns and inform public health interventions and regulatory action needed to eliminate exposure inequalities.”

The study is the first of its kind to investigate the differences in arsenic contamination across geographic subgroups. The results highlight the inequality in water quality across regions and populations in the US and identify smaller populations located in the Southwest, and Hispanic communities as those at particular risk of arsenic exposure.

As lead author Nigra states, “This research has important implications for public health efforts aimed at reducing arsenic exposure levels, and for advancing environmental justice”. The evidence produced by the team at Columbia University will be invaluable in guiding the development of new public health measures to protect those most at risk.

Nigra stresses the importance of encouraging funding to improve the infrastructure for small public water systems to address the issue of high arsenic concentrations in particular water supplies. The implementation of public health measures and continued infrastructure development will hopefully reduce the prevalence of arsenic-related health implications, such as cancer.