BALF cellular and biochemical parameters following repeated high dose exposure to TiO
NPs. The numbers of cells (A), macrophages (B), and neutrophils (C), and LDH (D) and β-glucuronidase activities (E) were assessed 24 hr post inhalation (blue squares) or instillation (green circles) exposure. Values are group means ± SE (n = 5). *, significantly different from corresponding controls; Φ, significantly different between exposure methods (p < 0.05).