Experimental pulmonary fluorosis.

An experimental study was undertaken to observe effects of fluoride ingestion on lung tissue. The study was conducted on 15 albino rabbits of either sex and experimental fluorosis was induced by daily oral administration of sodium fluoride (NaF) solution. Rabbits were divided into three groups according to the quantity of fluoride ingestion: Group A: rabbits fed with 10 mg/kg/day NaF, Group B: 20 mg/kg/day NaF; and Group C: controls. After six months, the rabbits were sacrificed and their lung tissue was submitted for histopathological examination and fluoride content estimation. On gross examination, pale areas on the surface and dark brown congested areas on cut-section of lungs were seen in rabbits of groups A and B. Histopathological changes of alveolar haemorrhage, congestion, edema fluid, necrosis of alveolar epithelium, distortion of alveolar architecture and desquamation of epithelium of respiratory tract with damage to tracheal cartilage were observed in these groups. These changes were more marked in group B rabbits. Fluoride content of lung tissue homogenate was significantly higher in groups A and B (mean 1.206 ppm and 1.978 ppm respectively) as compared to control (0.1585 ppm). It was concluded that prolonged fluoride ingestion damages pulmonary tissues of rabbits. To the best of our knowledge, effect of chronic fluoride ingestion on lungs has not been reported in the literature, therefore, we had undertaken this study to analyse the effect of chronic fluoride ingestion on lungs.