Structure-guided suspect screening reveals novel BPS derivatives in thermal price labels and implications for their contamination of packaged fresh foods

Bisphenol S (BPS), considered a “regrettable substitute” for the well-known endocrine disruptor bisphenol A (BPA), has also been demonstrated to pose health risks. An underinvestigated exposure route is the placement of thermal price labels on fresh food packaging. Here, a structure-guided suspect screening strategy was employed to characterize BPS derivatives in 137 supermarket price labels. A total of 26 candidate features were identified by high resolution mass spectrometry, among which 9 BPS derivatives were confirmed by authentic standards, and 4 candidates were identified with a confidence of level 2. DBSP, BPS, BPS-MAE and D-90 were the major derivatives, with maximum concentrations ranging from 7.5 to 40 mg/g. A novel derivative, HDPS was first identified as a component coexisting with DBSP in thermal price labels. The concentrations of DBSP were higher than those of BPS and had a significant negative correlation (r = −0.53, P < 0.001), suggesting an ongoing substitute for BPS. Analysis of matched food samples revealed consistent contamination trends: BPS was detected in 89.0% of samples, followed by DBSP (86.1%), BPS-MAE (60.6%), and BPA (59.8%). High levels of BPS (129.4 ng/g), BPA (124.8 ng/g), DBSP (78.1 ng/g) and BPS-MAE (63.8 ng/g) could be observed in individual cling film-wrapped food items with attached price labels. Dietary intake assessments revealed a median ∑BPs exposure level of 5.6 ng/kg bw/day, but a level of 92 ng/kg bw/day in high-exposure scenarios. The estimated DBSP, BPS, and BPA exposure levels exceeded the stringent EFSA TDI for BPA. This study provides insight into the potential contamination of fresh food caused by thermal labels, informing policies for preventing “regrettable substitutions”.