“Dose-dependent cytotoxicity was noted following exposure of cells to ≥250 μM of CoCl2 for … h and ≥100 μM concentrations of CoCl2 for 48–96 h. Pretreatment of cells with ZnCl2 for 4 or 24 h provided significant protection against cobalt chloride-induced cytotoxicity when measured with MTT assay.”