Toxicokinetic modelling of the transfer of non-dioxin like polychlorinated biphenyls from feed into edible tissues of pigs

Non-dioxin-like polychlorinated biphenyls (ndl-PCBs) are persistent environmental pollutants that accumulate in the tissues of exposed animals and humans. Contaminated feed can lead to ndl-PCB contaminated foods of animal origin; such foods are the main route of human exposure. Therefore, predicting ndl-PCB transfer from feed into animal products is important for human health risk assessment. Here, we developed a physiologically based toxicokinetic model describing the transfer of PCBs-28, 52, 101, 138, 153 and 180 from contaminated feed into the liver and fat of fattening pigs. The model is based on a feeding study with fattening pigs (PIC hybrids) that were temporarily fed contaminated feed containing known concentrations of ndl-PCBs. The animals were slaughtered at different ages, and ndl-PCB concentrations in muscle fat and liver were determined. The model accounts for animal growth and excretion via the liver. According to their elimination speed and half-lives, they can be categorized into fast (PCB-28), intermediate (PCBs 52 and 101) and slow (PCBs 138, 153 and 180). Using a simulation with realistic growth and feeding patterns, the following transfer rates were found: 10 % (for fast), 35-39 % (intermediate) and 71-77 % (slow eliminated congeners). Using the models, the highest level of 3.8 μg/kg dry matter (DM) was calculated for any sum of ndl-PCBs in pig feed to ensure that the current maximum levels in pig meat and liver (40 ng/g fat) will not be exceeded. The model is included as part of the Supplementary Material.