BeefPOP: a physiologically based toxicokinetic model describing the fate of polychlorinated biphenyls in growing beef cattle

Polychlorinated biphenyls (PCBs) are persistent organic pollutants that bioaccumulate in livestock and threaten food safety. Understanding PCB kinetics in farm animals is essential for effective risk management. This study introduces BeefPOP, a mechanistic model that couples fugacity and physiologically based toxicokinetic concepts with animal feeding and physiology to simulate PCB kinetics in growing cattle. The model was optimized and evaluated using data from a toxicokinetic experiment involving Simmental cattle under controlled PCB exposure. BeefPOP demonstrated satisfactory predictive performance for adipose tissue PCB concentrations, with good accuracy (deviations below 1.4-fold of the biological observations and mean absolute percentage errors below 20%), and adequacy (R² > 0.79). Predictions for muscle and liver were slightly less satisfactory. Eighteen prospective scenarios were simulated, considering two cattle categories (Angus crossed Hereford steers and Charolais bulls), three growth itineraries (slow, fast, and compensatory growth), and three sources of PCB exposure (wall paint, contaminated feedstuff, and soil). Prospective simulations showed that PCB concentrations in adipose tissue were mostly influenced by growth rate, followed by cattle category and source of exposure. The highest bioconcentration factor was found in slow-growing Charolais bulls under wall paint exposure. Fast-growing early maturing cattle (i.e., Angus crossed Hereford steers) diluted PCBs more effectively due to shorter raising periods and higher lipid accretion. Such use of the model underscores the complex interplay between contaminant properties, growth physiology, and farming practices on PCB toxicokinetics. BeefPOP can support food safety risk management by predicting the fate of lipophilic contaminants in growing cattle under diverse farming scenarios.