Ranking of the PCBs and their metabolites chemical classes using (A) in vitro testing data, (B) physicochemical descriptors, or (C) combination of the two. Groupings based on the number of chlorine atoms (left panels) or metabolite class (right panel) are shown. ToxPi scores from the analysis shown in Figure 4 were used to generate box-and-whisker plots for each group. Individual box-and-whisker plots indicate the median (line), mean (cross), interquartile range (box), and min–max span (whiskers). Chemical names and abbreviations of PCBs and metabolites are listed in Table S1. Note: PCB, polychlorinated biphenyls; ToxPi, Toxicological Prioritization Index.