Lung histology sections from mice 70 days after exposure to biopesticide. Arrows indicate interstitial inflammation with PAS positive foreign materials. Exposures were 50 μL of sterile pyrogen-free water (Controls), Vectobac® or Dipel® through a single intratracheal instillation (A-F) or repeated (2 × 5 × 1 h) aerosol exposures (G-H). Control slides (A-B) show the pulmonalis and bronchiole wall and with no inflammatory changes. Interstitial inflammation is apparent after Vectobac® instillation (C-E) as indicated by arrows. Instillation of Dipel® resulted in small focal areas with accumulation of inflammatory cells interstitially and inflammation was observed also peripherally even to the level of the pleura (F). Patches of interstitial inflammation were also observed in 3 out of 17 mice after repeated aerosol exposures to Vectobac® (G-H). Sections are stained with periodic acid-Schiff (PAS). Magnifications were ×32 (F), ×80 (A, C, D, E), ×200 (B, G) or ×320 (H).