Nearly One-Third of U.S. Residents Exposed to Dangerous, Unregulated Contaminants in Drinking Water, Analysis Finds

More than 97 million United States residents have been exposed to contaminants in their drinking water that are unregulated and could affect their health, a new analysis by Silent Spring Institute has found.

Hispanic and Black communities have a higher likelihood of their water being contaminated by unsafe levels of toxic chemicals, a press release from Silent Spring said. They are also more likely to live close to sources of pollution.

The findings add to increasing concern about U.S. water quality and contamination’s disproportionate impact on communities of color.

Nearly 100 contaminants are regulated under the country’s Safe Drinking Water Act, which means public water utilities are required to test for them, as well as take measures to make sure levels don’t exceed set limits.

“Yet, we know there are thousands of other harmful chemicals that are not regulated that make their way into groundwater and surface waters, and some of these chemicals can ultimately end up in drinking water supplies,” said co-author of the findings Laurel Schaider, a Silent Spring Institute senior scientist, in the press release.

Schaider and the research team reviewed U.S. Environmental Protection Agency (EPA) data compiled from 2013 to 2015 under the Unregulated Contaminant Monitoring Rule program. They analyzed figures from 4,815 public water systems only to discover that 27 percent had detectable levels of one or more of the following: 1,4-dioxane, a solvent listed by EPA as a likely human carcinogen that is used in consumer products; per- and polyfluoroalkyl substances (PFAS) “forever chemicals,” widely used in products such as non-stick cookware and waterproof rain gear and associated with thyroid disease, high cholesterol, cancer and other health issues; chlorodifluoromethane (Freon 22), a gas that contributes to depletion of the ozone layer and was previously used in fluoropolymers like Teflon and as a refrigerant; and 1,1-dichloroethane, a solvent found in plastics, pesticides and paints that is associated with cancer.

Communities with more Hispanic and Black residents were found to be generally more likely to have exposure to the unregulated contaminants through their drinking water and more often lived near pollution discharge sites such as wastewater treatment plants, military training areas, industrial sites and airports.

“Our findings show that the percentage of Hispanic and Black residents in a community is a consistent predictor of poorer water quality,” said lead author of the study Aaron Maruzzo, a Silent Spring Institute scientist, in the press release.

Maruzzo said the racial disparities were not explainable by income or other ways of measuring socioeconomic status, which suggested that issues like racism and historical redlining could be a factor in the disproportionate placement of industrial facilities.

The new study builds on earlier research by the institute, which found that Hispanic communities are more likely to have exposure to higher nitrate levels in their drinking water. A legal limit was set by the EPA on nitrate decades ago for the protection of infants from fatal “blue baby syndrome.”

More recent evidence has suggested that nitrate exposure at levels lower than the federal standard can also increase the risk of bladder and colorectal cancer.

A study from 2023 co-authored by Shaider investigated community water systems from 20 states and discovered that those with more Hispanic and Black residents reported higher PFAS levels in their drinking water.

The new analysis by Silent Spring is the first to scrutinize disparities in PFAS exposure, as well as other unregulated contaminants, within all U.S. states, territories and Tribal lands.

Schaider said that, since recent testing has shown PFAS to be much more prevalent in drinking water than was previously believed, the number of individuals impacted by contaminants when the data was collected is an underestimate.

In April of last year, EPA announced new standards for six PFAS chemicals in drinking water. The new findings highlight the necessity of federal regulatory action for more contaminants, as well as the need for the federal government to provide additional resources to communities of color concerning the impacts of pollution.

“Ultimately, we need to do a better job at protecting source waters and reducing discharges of pollutants into water bodies that feed into our drinking water supplies,” Schaider said.