V79 CBPI and frequency of micronuclei (percentage of binucleated cells containing micronuclei (%Mn/BN)) determined by the in vitro CBMN assay following 1 cell cycle exposure to Au_5nm, Au_30nm, SiO₂, BaSO₄, and CeO₂ ENPs (A, B, C, D, and E, respectively). Positive controls used were ethyl methanesulfonate (EMS) at 600 µg/ml and tungsten carbide-cobalt (WC/Co) at 30 and 100 µg/ml. These data were generated in laboratory 2, where the results were considered statistically significant (*) when P ≤ .05 (n = 2).