Updated project metadata. Cytochrome P450 enzymes play an important role in bioactivating or detoxifying polycyclic aromatic hydrocarbons (PAHs). We exposed mice to doses of benzo[a]pyrene (BaP) or a mixture of PAHs to characterize dose- and time-response relationships of specific cytochrome P450s. Mice exposed to the highest PAH exposures exhibited 1.7-5-fold higher intrinsic clearance rates for BaP, compared to controls, and higher Vmax values, indicating higher amounts of enzymes capable of metabolizing BaP. This study demonstrates that PAHs induce enzymes in dose- and time-dependent patterns in animal models at exposure levels researchers use to characterize hazards and at relevant human exposure levels to PAH mixtures found at Superfund sites. Accounting for these potential changes in enzyme profiles, relative rates of PAH bioactivation and detoxification, and resulting risk will help reduce uncertainty and improve risk assessments for PAHs at contaminated sites.