Physiologically based kinetic models for farm animals: Critical review of published models and future perspectives for their use in chemical risk assessment

Physiologically based kinetic (PBK) models in the 10 most common species of farm animals were identified through an extensive literature search. This resulted in 39 PBK models, mostly for pharmaceuticals. The models were critically assessed using the WHO criteria for model evaluation, i.e. 1) purpose, 2) structure and mathematical representation, 3) computer implementation, 4) parameterisation, 5) performance, and 6) documentation. Overall, most models were calibrated and validated with published data (92% and 67% respectively) but only a fraction of model codes were published along with the manuscript (28%) and local sensitivity analysis was performed without considering global sensitivity analysis. Hence, the reliability of these PBK models is hard to assess and their potential for use in chemical risk assessment is limited. In a risk assessment context, future PBK models for farm animals should include a more generic and flexible model structure, use input parameters independent on calibration and include assessment tools to assess model performance. Development and application of PBK models for farm animal species would furthermore benefit from the setup of structured databases providing data on physiological and chemical-specific parameters as well as enzyme expression and activities to support the development of species-specific QIVIVE models. •We performed an extensive literature search to identify PBK models for 10 farm animal species.•39 models were identified and were found to be suboptimal for applications in chemical risk assessment.•Chemical risk assessment will benefit from the development of generic open source PBK models and databases on model input parameters.•PBK model development will benefit from the collection of enzyme expression, activity data and QIVIVE models.