As the world grapples with climate change, population growth and depletion of freshwater resourcesmore people are willing to rely on treated wastewater to sustain their daily lives.
The wastewater, even after treatment, contains high levels of harmful “permanent chemicals” that contaminate the drinking water of millions of Americans, according to researchers. study published Monday which analyzes wastewater samples across the country.
A study by researchers at Harvard and New York University found high levels of six types of chemicals known as PFAS, or per- and polyfluoroalkyl substances, in the samples. Chemicals, has been associated with cancer and other diseasesThey are known as permanent chemicals because they do not break down in the environment. Last year, the Environmental Protection Agency began regulating PFAS in drinking water.
The researchers found that the samples contained higher amounts of organofluorines, a wider range of chemicals that include PFAS and are used in pharmaceuticals, refrigerants and non-stick coatings. Most of these chemicals are not regulated, and the health consequences of exposure to many of them are still unknown.
“What are all these other compounds? Are they other PFASs that we're not measuring that industry is targeting? said Bridger Ruyle, associate professor of environmental engineering at New York University, who led the study. “What does that mean for exposure?”
A study published in the journal “Proceedings of the National Academy of Sciences” found that wastewater treatment plants do not effectively remove these compounds from wastewater. In most places, in fact, PFAS in wastewater became more concentrated after treatment, according to the researchers.
The pollution is especially worrisome, researchers said, given that water shortages in many parts of the United States mean wastewater is reused or discharged into rivers and lakes. And if that wastewater isn't sufficiently diluted before it's reintroduced into the drinking water supply, a growing concern as runoff declines due to overuse and climate change, “you have a pollution problem,” Professor Ruyle said.
About 50 percent of the country's drinking water supply is downstream of one or more wastewater sites, he added. The study used modeling to show that PFAS from wastewater are already contaminating the drinking water of up to 23 million people in the United States.
The results “underscore the importance of further limiting ongoing sources of PFAS,” the researchers said.
A new study highlights how widespread pollution is complicating efforts to reuse wastewater, which includes household sewage as well as contaminated water from businesses and factories. Sludge remaining after sewage treatment is also used to fertilize agricultural fields across the country and Contamination of that sludge with PFAS also raises concerns about its practice.