A wastewater treatment plant in California
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Wastewater treatment facilities are a major source of PFAS contamination in US drinking water: they release enough of the “permanent chemical” to raise concentrations above safe levels for an estimated 15 million or more people. Long-acting prescription drugs can also leach into the water supply.
Although these plants clean the wastewater, they do not destroy all the pollutants added upstream, and the chemicals left behind flow back into the same waterways that supply drinking water. “It’s a funnel for the environment,” he says Bridger Ruyle at New York University. “You catch a bunch of stuff from a lot of different places, and it’s all released in one place.”
Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are of particular concern because they contain carbon-fluorine bonds, which make them very persistent in the environment. It has been linked to regular exposure to several types of PFAS increasing the risk of many health problemsfrom liver damage to different types of cancer. The US Environmental Protection Agency (EPA) recently set strict drinking water limits for six of the most well-studied PFASs.
Wastewater treatment facilities are a known source of PFAS contamination sewage sludge they produce it as a by-product, which is sometimes used for fertilizer. To find out if similar contamination remains in treated water, Ruyle and his colleagues measured the concentration of PFAS and other molecules with carbon-fluoro bonds in wastewater from eight large treatment facilities in the US.
Their findings suggest that US wastewater treatment plants release tens of thousands of pounds of fluorine-containing compounds into the environment each year, including large amounts of PFAS. Once treated wastewater flows from a facility, it mixes with natural water in rivers and lakes. “That’s going to create a downstream drinking water problem,” Ruyle says.
Applying these figures to a model of the US drinking water system, the researchers estimated that the wastewater could raise the concentration of PFAS above EPA limits in the drinking water of about 15 million people. During droughts, when there is less natural water to dilute wastewater, the model suggests concentrations would rise above the limit for 23 million people. And Ruyle says that these may be conservative estimates; their model assumes that natural waters do not already contain PFAS.
“It proves that wastewater treatment plants are a really important source of these compounds,” he says Carsten Prasse at Johns Hopkins University in Maryland, who was not involved in the study. There are ways remove or destroy PFAS in water, and more drinking water facilities are installing such systems, but currently, “our wastewater treatment plants are not set up to deal with it,” he says.
Perpetual chemicals alone would be a problem, but the researchers also found that PFASs made up only a small fraction of the total volume of fluorinated chemicals released from the facility. Most were not PFAS at all, but other compounds used in common pharmaceuticals, such as statins and SSRIs. These pharmacies are also concerned for ecosystems and people.
“Another person could be drinking a cocktail of prescription fluoridated medications,” says Ruyl. However, the effects of long-term exposure to low doses of these compounds are not well understood, he says.
“We need to start discussing whether we should be using a lot of fluoride in medicine,” says Ruyl. Fluoridation is widely used in drugs to improve their effect on the body, but “preventing widespread chemical contamination should also be important,” he says.
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