Finfish intake is associated with persistent chemical burden and a PFAS-mediated pathway to γ-glutamyltransferase in Korean adults

Seafood carries nutrients and persistent chemicals in the same meal, yet population studies have treated it as one food group. Cycle 5 (2021–2023) of the Korean National Environmental Health Survey gave us 4279 adults, of whom 1564 formed a probability subsample with serum measurements of five per- and polyfluoroalkyl substances (PFAS) and 25 persistent organic pollutants. All six seafood categories entered the same models. Finfish dominated them. Each doubling of finfish intake corresponded to 4.4–14.1% higher serum PFAS, 4.8–13.0% higher levels of six of seven retained polychlorinated biphenyls, and 13.2% higher blood mercury. Shellfish added three PFAS: PFOA (+ 9.4%), PFOS and PFNA (both + 5.9%). Crustaceans and seaweed added no positive contribution. One quartile up across the PFAS mixture corresponded to 2.8% higher γ-glutamyltransferase (GGT; ψ = 0.028, 95% CI 0.011 to 0.042). We then split the null finfish–GGT association in two: a positive indirect effect through PFAS (+ 0.032; 0.015 to 0.051), and a negative non-mediated component whose interval included zero (− 0.054; − 0.133 to 0.026).