In silico screening of Styrene–Butadiene rubber tire-additive mixtures reveals species-specific molecular toxicity potential and environmental implications

Tire-wear particles release diverse additive mixtures into aquatic environments, but the formulation-level drivers of species-specific molecular toxicity remain poorly resolved. Here, we combined full factorial design, molecular docking, and molecular dynamics simulations to evaluate the predicted molecular toxicity potential of 96 styrene-butadiene rubber tire-additive schemes across three coexisting Daphnia species ( D. pulex , D. magna , and D. galeata ), using arginine kinase as an energy-metabolism target protein. Binding-energy-based responses varied substantially among additive schemes and species. The largest differences between the highest- and lowest-predicted toxicity schemes reached 69.3% for D. pulex , 75.8% for D. magna , and 76.3% for D. galeata . Across the tested schemes, D. magna showed the strongest predicted sensitivity, whereas D. galeata generally showed the weakest. Scheme A3B2C2D1E2F2 produced the greatest interspecific divergence, with stronger predicted molecular interaction potential in D. magna than in D. pulex or D. galeata . Full factorial analysis indicated that additive effects were not strictly additive, with higher-order interactions contributing to species-specific response patterns. Antioxidant-related factors, particularly aniline antioxidant-associated components, were more frequently linked to elevated predicted toxicity potential. Molecular interaction analysis showed that van der Waals forces dominated additive–arginine kinase binding, while changes in polar and nonpolar residue contributions suggested a secondary role for hydrophilic interactions. Overall, this study provides a formulation-level computational screening framework for prioritizing tire-additive combinations with lower predicted molecular toxicity potential and for guiding future experimental validation of safer tire formulations.