(CNN) – Toxic chemicals are found in the drinking water supplies of several major metropolitan areas in the US, including Miami, New Orleans, and Washington, DC, according to a new report from the Environmental Working Group (EWG).
The findings, released by the environmental advocacy group this week, show levels of perfluoroalkyl substances (PFAS), which are toxic and can affect human health.
The group tested drinking water at 44 sites in 31 states and Washington for perfluoroalkyl substances (PFAS).
Of the areas tested, only Meridian, Mississippi, had no detectable levels of the toxic chemicals. The community draws its drinking water from wells deeper than 700 feet, the group said.
Water supplies in Brunswick County, North Carolina, and Quad City, Iowa, contained the highest levels of the chemicals, more than 100 times the EWG’s recommended limit. The advocacy group’s recommended PFAS limit is 1 part per trillion in drinking water, about 70 times stronger than the federal recommendation.
PFAS stands for perfluoroalkyl and polyfluoroalkyl substances and includes chemicals known as PFOS, PFOA, and GenX.
PFAS chemicals appear in a wide range of everyday items, such as food packaging, clothing, and carpeting.
Estimates have identified more than 4,700 different PFAS variants, but federal regulations so far only target two of them: PFOS and PFOA. Some of these chemicals are known to cause serious health problems, including cancer, immune system, and thyroid problems.
Martin Shafer is a principal investigator with the National Atmospheric Deposition Program (NADP) at the University of Wisconsin-Madison. This spring and summer, Shafer and his colleagues looked at 37 rainwater samples collected over a week from 30 different locations, mostly near the East Coast, but also as far away as Alabama and Washington. They found that each sample contained at least one of the 36 different compounds being studied.
While total PFAS concentrations are typically below 1 nanogram per liter (ng/l), the highest total concentration was nearly 5.5 ng/l in a sample in Massachusetts. Some samples contained total PFAS levels around 4 ng/l.
The U.S. Environmental Protection Agency (EPA) has issued a health advisory of 70 ng/l for PFOS and PFOA individually and combined in drinking water. However, many states have proposed or have established drinking water standards that are significantly lower. Wisconsin, for example, has proposed a precautionary action limit of 2 ng/l for PFOS and PFOA combined.
Shafer said he suspects PFAS chemicals are entering stormwater through a variety of routes, including direct industrial emissions and evaporation from PFAS fire-fighting foam.
This is the first new study of stormwater in the United States. Last year, the North Carolina Air Quality Board began testing at the chemical company Chemours, which produces PFAS GenX, and in February 2019 found GenX concentrations in stormwater above 500 ng/l. The state subsequently allowed the company’s plant to install equipment to significantly reduce emissions.
The University of North Carolina is the unit that conducted the study of PFAS in air and stormwater. “It’s not just a local problem, PFAS compounds are transported significantly over long distances. In fact, they’ve turned up in the Arctic and in Alaska Natives,” said Brooks Avery, a chemistry professor at the University of North Carolina.