Associations between serum isomers of perfluoroalkyl acids and metabolic syndrome in adults: Isomers of C8 Health Project in China

•We provided evidence on isomeric-specific associations between serum PFAAs and metabolic syndrome in adults.•Branched PFOS isomers were associated with metabolic syndrome with an apparent “threshold” effect.•Both serum PFOS and PFOA were associated with elevated fasting blood glucose.