In the 1950s, Dupont developed per- and polyfluoroalkyl substances or PFAS, which were integrated into a huge array of products over the next decades, including cooking pans, popcorn bags, pizza boxes, candy wrappers, fabrics, carpeting, and firefighting foam that was widely used on Air Force bases. The chemicals are very stable and highly resistant to heat, water, and degradation; they are known as forever chemicals because the bonds they contain are so resilient, and can last 'forever' in water, soil, and other places in the environment. These persistent chemicals have been linked to many health problems, and they contaminate many drinking water systems.
New research has some good news, however. There are microbes called Acetobacterium that can break down the tough carbon-fluorine bonds in a type of PFAS called unsaturated perfluorinated compounds. These microbes are often found in places that contain wastewater and they may pave the way to a low-cost method for treating PFAS contamination. They could be injected into areas where groundwater seeps into wells to help reduce PFAS levels. The findings have been reported in Science Advances.
"This is the first discovery of a bacterium that can do reductive defluorination of PFAS structures," said corresponding study author Yujie Men, an associate professor at the University of California (UC) Riverside.
In this study, the researchers have also identified the microbial enzymes that are responsible for breaking the carbon-fluorine bonds. Now, scientists will be able to modify and improve these enzymes so they can work even more efficiently and can break carbon-fluorine bonds in even more types of PFAS.
The enzyme's mechanism can be used to search for other enzymes that work in similar, and potentially better ways. This understanding also paves the way for engineering improvements in these enzymes, added Men.
The US Environmental Protection Agency (EPA) has recently imposed limits on PFAS contamination in drinking systems because the chemicals are associated with an increase in the risk of cancer and other diseases and health problems. That limit is now four parts PFAS per million parts tap water. Many water providers are now looking for ways to reduce excess PFAS levels.
Sources: UC Riverside, Science Advances