The study investigated fluorinated chemicals in humans and their changes over 2–3 weeks (T1 vs T2). Samples were collected in Norway, from September 2016 to November 2017. Exposure sources to known per- and polyfluoroalkyl substances (PFASs) and unrecognized fluorinated chemicals were studied. Methods measured 64 PFASs and extractable organofluorine (EOF). Up to 81% of detected fluorinated chemicals were unrecognized, with a median of 38%. About 36% of participants showed EOF concentration changes >25%. Trifluoroacetic acid (TFA) comprised ~33% of EOF and was the most abundant PFAS. No link was found between unrecognized EOF and diet or personal care at T1, but T2 proportions correlated with vegetable/potato consumption. In a separate cohort, fluorinated medication users had higher TFA and EOF. Further research is needed to identify TFA sources and other fluorinated chemicals.