Researchers are struggling to assess the dangers of nondegradable compounds used in clothes, foams and food wrappings.
Water and soil near military bases worldwide are rich in PFASs because of fire-fighting foams sprayed there during training exercises. The foams tend to be complex formulations and can contain hundreds of PFASs. They were introduced in the 1960s to extinguish fuel fires, and performed so well that the US military set them as the standard for fire protection at bases and major airports. They represent a small fraction of fluorochemical production, but are a major part of the contamination problem because they get discharged directly into the environment, says Jennifer Field, an environmental chemist at Oregon State University in Corvallis, who collaborates with Higgins.
Field and Higgins’s research teams analyse the water using mass spectrometers: machines that separate out and weigh the molecules present in a sample, and then break these compounds into ionized fragments before weighing each smaller piece again. It’s easy to spot known PFASs, such as PFOS and PFOA, because their characteristic fingerprints are already known. But for fragments with unfamiliar masses, researchers must deduce the structures, and then surmise what the original compounds might be. “You start using a chemist’s brain and a pencil and a piece of paper to sketch things out,” says Mark Strynar, an analytical chemist at the US Environmental Protection Agency’s National Exposure Research Laboratory in Research Triangle Park, North Carolina.