Toxic effect of different ZnO particles on mouse alveolar macrophages

► ZnO particles had similar toxicity in MH-S cells and Ana-1 cells. ► Zinc ions induced metallothionein synthesis to reduce oxidative damage at low dose. ► At high dose, excessive zinc destroyed mitochondrial function, caused cell necrosis. ► Zinc ions first cause toxicity in MH-S cells, and their toxicity exist a threshold. ► Toxic difference of ZnO particles depended on the role of nondissolved ZnO particles.