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Analysis of drinking water data highlights importance for U.S. environmental justice priorities

  • Analysis of drinking water data highlights importance for U.S. environmental justice priorities

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A new framework developed by EWG scientists will help U.S. state and federal efforts to improve drinking water quality and advance the priorities of environmental equity.

EWG scientists created the framework to show how demographic data like race and ethnicity can be used to evaluate where cumulative cancer risk from tap water contamination plagues communities already threatened by other environmental injustices.

The research shows how policymakers can make safe drinking water a part of the equation when analyzing the effects of new and existing public health and environmental policies. The study was published in the peer-reviewed International Journal of Environmental Research and Public Health.

National and local studies offer evidence of racial and ethnic disparities in exposure to air pollution. Further evidence shows similar disparities in drinking water quality. But drinking water research has been hampered by a lack of relevant data on water service areas, and water use and quality.

The new framework was designed as a tool for the Environmental Protection Agency, the EPA’s National Environmental Justice Advisory Council and other decisionmakers to analyze tap water contamination when identifying communities with significant, urgent environmental quality issues.

EWG’s new framework fills an important gap in a key EPA instrument called the Environmental Justice Screening and Mapping Tool, or EJSCREEN, which is used to identify communities facing multiple environmental injustices.

EJSCREEN aggregates and evaluates 11 environmental indicators – such as the presence of lead paint, proximity to Superfund sites and existence of nearby wastewater discharges. But it does not analyze drinking water quality.

Assessing cumulative cancer risks

EWG researchers developed the framework by evaluating the cancer risk posed by toxic cocktails of tap water contaminants in California and Texas, extremely populous states that are home to more than one in five U.S. residents.

They found that community water system service areas that served populations that skewed more Hispanic or Black in the two states, according to the U.S Census Bureau’s American Community Survey 5 Year Estimates for 2015-2019, had a statistically significant increase in cancer risk due to exposure to tap water contamination, compared to areas with lower ratios of these populations.

To reach this conclusion, the researchers calculated the cumulative effects, over a lifetime of exposure, of 30 carcinogenic tap water contaminants found across more than 7,000 tap water systems in the two states.

The contaminants included 21 that are federally regulated, including arsenic, nitrate, radium and disinfection byproducts, and nine that are not, including hexavalent chromium and 1,4-dioxane.

To develop the framework, the scientists conducted case studies of California and Texas,  drawing on combined data from three sources: the U.S. Census Bureau’s American Community Survey, the boundaries of the service areas for over 7,000 community tap water systems and the results of federally mandated tests conducted by those systems.

The new study builds on earlier EWG peer-reviewed research, published in 2019 in the journal Heliyon, finding that cumulative exposure to chemical mixtures found in U.S. tap water could result in more than 100,000 cancer cases nationwide.

The EPA has not updated its list of regulated drinking water contaminants since 2000. It rarely revisits the maximum levels it sets for regulated contaminants, even when the latest science shows a clear risk to public health from cancer or other serious illnesses at amounts far lower than legal limits.

Federal regulators assess the public health risks of tap water pollutants one at a time, even though drinking water rarely, if ever, contains just one contaminant.

Long overdue infrastructure investments

Drinking water infrastructure across the U.S. is long overdue for large investments to significantly reduce contamination and better protect public health.

Some water quality issues can be addressed with in-home water filters, but no filter can remove all contaminants. Many of the most effective filters are unaffordable for many people facing the worst contamination.

Our study didn’t evaluate the levels of, or risks from, carcinogenic contaminants in private wells, which are not tracked by any government entity.

Since 2005, EWG has conducted and compiled state drinking water test data – the results of drinking water tests that community water systems conduct to show compliance with federal drinking water quality regulations. The results are available in EWG’s Tap Water database. The 2021 Tap Water database update will be released later this year.

Everyone should have access to safe, affordable drinking water, wherever they live. EWG will continue to push policymakers to evaluate the threat posed by the combinations of carcinogens that so many people have no choice but to drink.

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