Dec. 9 (UPI) -- Arsenic drinking water regulations have been standardized across the United States for more than a decade, but a new survey suggests some communities remain exposed to higher levels than others.
In a new study, scientists at Columbia University's Mailman School of Public Health surveyed arsenic concentrations in public drinking water across the country.
The results, published Wednesday in the journal Environmental Health Perspectives, showed populations in the Southwest and Hispanic communities are exposed to arsenic levels exceeding the national maximum containment level.
The research marks the first time scientists have examined differences in arsenic exposure across sociodemographic subgroups.
"This research has important implications for public health efforts aimed at reducing arsenic exposure levels, and for advancing environmental justice," first author Anne Nigra, said in a news release.
"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," said Nigra, a postdoctoral research fellow in environmental health sciences.
Arsenic is a naturally occurring and highly toxic contaminant that has been linked with heart disease, various cancers and birth defects. It's most common in groundwater sources.
More than a decade ago, regulators lowered the maximum arsenic containment level from 50 to 10 micrograms per liter. Scientists estimated the change would prevent several hundred cancer cases per year.
For the study, researchers compared arsenic concentration levels measured in water systems between 2006 and 2008 to measurements collected between 2009 and 2011, after initial monitoring period for compliance with EPA's stricter standard.
On average, arsenic concentrations in drinking water decreased across the United States -- 10 percent nationwide, 11.4 percent in the Southwest and 37 percent in New England.
Despite stricter containment standards, researchers found a minority of communities were exposed to higher levels of arsenic in drinking water, including Hispanic communities in the Southwestern U.S, Pacific Northwest and Central Midwest.
Smaller communities reliant on groundwater sources were more likely to be exposed to arsenic levels above the maximum containment level.
The findings highlight the many ways health disparities among different sociodemographic groups are perpetuated by environmental injustices. A number of studies have shown minority communities are routinely exposed to more heavily polluted air.
"Our findings will help address environmental justice concerns and inform public health interventions and regulatory action needed to eliminate exposure inequalities," said Nigra.
"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," she said.