The likelihood of exceeding maximum pollutant concentrations was significantly higher for water systems in the southwest and for Hispanic communities.
A new national study of public water systems found that arsenic levels in the US were not consistent even after implementing the latest national regulatory standard. In the first study to assess the differences in arsenic exposure in public drinking water by geographic subgroup, researchers examined by Columbia University The Mailman School of Public Health confirmed that there are inequalities in arsenic exposure in drinking water across certain sociodemographic subgroups and over time. Community groundwater systems that rely on groundwater to serve smaller populations in the Southwest and Hispanic communities are more likely to continue to exceed national containment limits, raising concerns about environmental justice. The results are published online in Environmental health prospects.
“This research has important implications for public health efforts that aim to reduce arsenic exposure and promote environmental justice,” said Anne Nigra, PhD, postdoctoral researcher in environmental health and lead author. “So far, there has been a lack of systematic studies on inequalities in public drinking water exposure. These results identify communities in need of additional public health protections immediately. ”
‘Our aim was to identify subgroups whose arsenic concentrations in public water remained above 10 μg / l after the introduction of the new maximum arsenic contaminant levels and therefore have a disproportionate risk of arsenic-related health effects such as cardiovascular diseases, related cancers and negative birth results “, said Ana Navas-Acien, PhD, professor of environmental health science and senior author.
Arsenic is a highly toxic human carcinogen and water pollution that is present in many aquifers in the United States. Previous research by the Columbia research team showed that reducing MCL from 50 to 10 μg / L prevented an estimated 200-900 cancer cases per year.
The researchers compared arsenic concentrations in the municipal water system during (2006-2008) with those after (2009-2011) the initial monitoring period for compliance with the EPA maximum level of arsenic (10 μg / L arsenic). They estimated the three-year mean arsenic concentrations for 36,406 local water systems and 2,740 counties and compared the differences in means and quantiles of water arsenic between the three-year periods for US regions and socio-demographic subgroups.
The analyzes were based on data from two of the largest EPA public water databases available. Using arsenic monitoring data from the third semester (2006-2011), the researchers examined approximately 13 million analytical records from 139,000 public water systems that serve 290 million people annually. Included were data from 46 states, Washington DC, the Navajo Nation, and Native American tribes representing 95 percent of all public water systems and 92 percent of the total population nationally served by public water systems.
Regional differences
From 2006-2008 through 2009-2011, average arsenic concentrations in the municipal water system decreased by 10 percent nationwide, by 11.4 percent in the Southwest and by 37 percent in New England. Despite the decline in arsenic concentrations, arsenic concentrations in public drinking water remained higher for several socio-demographic subgroups – particularly Hispanic communities, the American Southwest, the Pacific Northwest, and the central Midwest. Likewise, communities with smaller populations that rely on groundwater were more likely to have high levels of arsenic.
The percentage of municipal water systems with average arsenic concentrations above 10 μg / L MCL was 2.3% in 2009-2011 compared to 3.2% in 2006-2008. Community water systems incompatible with the arsenic MCL were more likely in the Southwest (61 percent), served by groundwater (95 percent), served smaller populations (an average of 1,102 people), and served Hispanic communities (38 percent).
Nigra and Navas-Acien say estimating arsenic exposure from public drinking water for socio-demographic and geographic subgroups is critical to assessing whether US inequalities in arsenic exposure persist and maximum pollutant concentrations are met in order to support future arsenic regulations at national and international level State level efforts to inform and investigate whether inequalities in exposure by subgroup contribute to differences in arsenic-related diseases. “Our results will help address environmental justice concerns and inform public health and regulatory measures to address inequalities in exposure.”
“We strongly urge state and federal funding to support infrastructure and technical assistance for small public water systems to reduce inequalities and further protect numerous communities in the United States that are affected by increased arsenic pollution from drinking water,” said Nigra.
Reference: December 9, 2020, Environmental health prospects.
DOI: 10.1289 / EHP7313
