An integrated in vitro and in silico testing strategy applied to PFAS inhibition of antibody production to define a tolerable daily intake

Per- and polyfluoroalkyl substances (PFAS) are widely used chemicals known for their persistence, bioaccumulation, and adverse health effects, particularly on the immune system. Epidemiological studies link PFAS exposure to immunosuppression, with increased infection susceptibility and reduced vaccine efficacy. In this paper, we describe the workflow we used to establish an integrated testing strategy (ITS) combining in vitro and in silico methods to model PFAS inhibition of antibody production and to define a tolerable daily intake. This strategy was based on data generated within an EFSA-sponsored project. Using human peripheral blood mononuclear cells, the effects of PFAS on antibody production were assessed. Mathematical models were then applied to determine PFAS free concentrations in vitro , while Physiologically Based Kinetics (PBK) modeling enabled quantitative in vitro to in vivo extrapolation (QIVIVE) to translate in vitro effects into external doses. In addition, the Universal Immune System Simulator was used to predict immune-related outcomes and threshold doses for sensitive populations. Following this strategy, we were able to demonstrate that the oral equivalent effect doses derived through QIVIVE were similar to, or lower than, the tolerable weekly intake established by EFSA for PFAS, indicating that our approach is conservative. We demonstrate the possibility of using alternative methods for studying PFAS toxicity, offering insights into their dynamics and kinetics without animal testing. The strategy provides a promising framework for assessing other chemicals, advancing toxicology toward more human-relevant and ethical practices.