The US Environmental Protection Agency (EPA) has proposed the first limitations on a set of pervasive and dangerous ‘forever chemicals’ in US drinking water. The chemicals, known for their strong carbon–fluorine bonds, are difficult to destroy and have become widely dispersed in the environment. Scientists and engineers are busy developing ways to extract the chemicals more efficiently from water and soil and break them down, but water utility companies warn that meeting the EPA’s new standards will be expensive in the short term — possibly prohibitively so for small water-treatment facilities.
“This is a huge deal, in terms of protecting public health, but also in terms of what it’s going to take to accomplish,” says Michelle Crimi, an environmental engineer at Clarkson University in Potsdam, New York.
Tainted water: the scientists tracing thousands of fluorinated chemicals in our environment
Proposed on 14 March, the regulation targets perfluorinated and polyfluorinated alkyl substances (PFAS), a class of thousands of nearly indestructible compounds used in everything from non-stick cookware and waterproof clothes to industrial materials and cosmetics. Once called miracle chemicals for their hallmark durability, PFAS accumulate in the environment and in people; even minute amounts increase the risk of cancer, as well as the risk of developmental and other health problems1, research shows.
The EPA suggested a voluntary limit for PFAS in drinking water in 2016, but this is the first time it has advanced a mandatory requirement. The core of the proposal would restrict two of the most dangerous PFAS compounds, PFOA and PFOS, to four parts per trillion. That is the lowest level that is detectable using current laboratory tests, although the agency has determined that there are risks associated with much lower concentrations. Another four chemicals would be regulated as a mixture.
Similar movements to rein in PFAS are afoot internationally. At the extreme end of the spectrum, the European Union is considering legislation that would ban the production of PFAS altogether.
Achieving the EPA’s proposed regulation won’t be cheap. PFAS contamination has been found in around 2,800 communities in the United States, according to the Environmental Working Group, an advocacy organization based in Washington DC, and research by the group suggests that it probably affects the water supplies of at least 200 million people2. And although the use of PFOA and PFOS has mostly been phased out in the United States, the group has identified around 30,000 industrial facilities that could be using countless other compounds in the PFAS family.
How to destroy ‘forever chemicals’: cheap method breaks down PFAS
Numerous states have already set limits on PFAS in drinking water, and water providers have demonstrated that existing technologies such as carbon filtration can reduce PFAS amounts to undetectable levels. But installing such technologies nationally could be costly, with the financial burden falling disproportionately on smaller water-treatment systems. For facilities large and small, adding PFAS filtration will have to be weighed against other priorities, such as replacing lead pipes, says Chris Moody, a regulatory analyst with the American Water Works Association (AWWA), which is based in Denver, Colorado, and represents more than 4,300 utility companies that provide some 80% of the US drinking-water supply.
By one measure, the EPA estimates that implementing its proposal nationally would cost around US$772 million annually, but a study commissioned by the AWWA using similar assumptions suggests that the price tag could be around $2.9 billion a year. The EPA says that more than $9 billion is already available through a US infrastructure law enacted in late 2021, but Moody stresses that this is just a start: the AWWA-estimated cost over 20 years is $58 billion.
If history is any indicator, however, costs will probably come down over time, says Melanie Benesh, vice-president of government affairs at the Environmental Working Group. “With regulation often comes market innovation,” she adds.
Scientists and engineers started investigating technologies years ago, when the risks posed by PFAS became clear. Research has focused on methods to more efficiently remove PFAS from drinking water, clean up groundwater contamination or destroy the chemical compounds.
The upshot is that a variety of promising technologies are now available, from carbon filtration and ion-exchange systems that can separate PFAS from drinking water to electrochemical and gasification methods to break down PFAS, says Patrick McNamara, an engineer at Marquette University in Milwaukee, Wisconsin. But scaling them up to be practical could be challenging, he adds.
For her part, Crimi is working with the US Department of Defense to test a technology that could be used to clean up plumes of PFAS contamination in groundwater before they leach into drinking-water supplies. Starting as early as this year at Peterson Space Force Base in Colorado Springs, groundwater will be collected inside a horizontal well and funnelled through a reactor developed by Crimi’s team that uses ultrasound waves to break the carbon–fluorine bonds in PFAS3.
“We know it’s effective in the lab,” she says, but there are always things to learn when scaling up to field operations.
The EPA is accepting comments on the proposal until mid-April.
Source: Resources - nature.com