“…The resulting worldwide environmental PFAS-contamination led to regulatory measures and a phase out of some of the most critical PFAS. This phaseout, however, facilitated the introduction of fluorinated replacement chemicals and thus, the structural diversity of PFAS increased and a shift towards shorter chain homologues was observed [1]. These ultrashort chain PFAS (herein defined as < C 4 ) are more mobile in aquatic environments and fulfil the proposed criteria for persistent mobile and toxic (PMT) or very persistent and very mobile (vPvM) substances that are foreseen to be included into REACH by the European Commission [2].…”