6:2 Fluorotelomer Sulfonic Acid (6:2 FTS)

6:2 FTS is a polyfluoroalkyl substance within the broader PFAS family. It contains a six-carbon fluorinated segment connected to a two-carbon non-fluorinated segment and a sulfonic acid functional group. It has been widely associated with fluorotelomer-based products, including certain aqueous film-forming firefighting foams, surface treatments and industrial applications. Unlike fully fluorinated PFAS such as PFOS, 6:2 FTS is considered a precursor PFAS because environmental and biological processes can transform it into more persistent perfluoroalkyl carboxylic acids. Its mobility, persistence and potential transformation products have increased regulatory and scientific attention.