The occurrence of chlorinated derivatives of bisphenol S (Cl x -BPS) and BPS was investigated in nine types of paper products (n = 125), including thermal paper, corrugated boxes, mail envelopes, newspapers, flyers, magazines, food contact paper, household paper, and business cards. BPS was found in all paper product samples, while Cl x -BPS were mainly found in thermal paper (from below the limit of detection (