Cellular and biochemical parameters of lung injury and inflammation in bronchoalveolar lavage (BAL). Tracheally instilled ZnO and SiO2-coated ZnO induced a dose-dependent lung injury and inflammation at 24 hours. (A) Significant increases in BAL neutrophils were observed at 1 mg/kg of both NPs (n = 6/group). At the lower dose of 0.2 mg/kg (n = 4-6/group), only the SiO2-coated ZnO (n = 4) induced significant neutrophil influx in the lungs. (B) Similarly, significant increases in LDH, myeloperoxidase and albumin were observed at 1 mg/kg of both NPs, and at 0.2 mg of SiO2-coated ZnO. (*P < 0.05, vs. control, #P < 0.05, SiO2-coated ZnO versus ZnO).