Environmental silica in badger lungs: a possible association with susceptibility to Mycobacterium bovis infection

Badger lungs contain dark granular foci (0.2 to 2.0 mm) comprising aggregates of enlarged macrophages containing birefringent crystalline particles. Particles were examined from the lungs of three badgers; many were silicates and a significant number were pure silica (SiO2). The particles and the accompanying pathology resembled mixed dust fibrosis and silicosis in humans, diseases associated with increased susceptibility to tuberculosis.