The occurrence and risk assessment of bisphenol A and its analogues - bisphenol B, F, S, Z and AF in the urine of lactating sows

Bisphenols (BP) are pollutants that are globally and widely distributed and adversely affect the health of humans. However, knowledge of their presence in animals, especially farm animals such as pigs, remains limited. In this study, the incidence of bisphenol A (BPA) and its five analogues - bisphenol B (BPB), bisphenol F (BPF), bisphenol S (BPS), bisphenol Z (BPZ) and bisphenol AF (BPAF) - was monitored in lactating sows on an actual pig farm. The urine samples of 27 sows were collected twice on the 3rd day after parturition, and stored at -20 degrees C until analysis using MDGC/MS. None of the lactating sows produced bisphenol-free urine. In contrast, the urine of all sows contained at least two bisphenols (eight females), most often five (10 females) or all six bisphenols (five females). The average concentrations of bisphenols in urine were in the order of BPB > BPA and BPS > BPZ > BPAF > BPF. The most frequently detected bisphenol was BPB (96.0% of samples) followed by BPA (89.0%), BPAF (78.0%), BPS (63.0%), BPF (52.0%) and BPZ (37.0%). Additionally, the proportion of BPB in the total bisphenol concentration in urine samples was the highest (28.74 to 93.85%) while that of BPF was the lowest (2.33 to 16.70%). Estimated daily intakes of bisphenols as well as hazard quotients were much lower than risk thresholds established for the human population, indicating safe doses for the health status of lactating sows. However, these findings are limited as the mechanism of BPA analogue' activity is still unclear, and the long-term effects of small doses of bisphenols and the potential harmful impact of BP mixtures are unknown. Knowledge of the occurrence of bisphenols in pig farming may contribute to the elimination of BPA and its analogues from this sector, which is crucial for the safety of animal products as well as the welfare of pigs.