Lung damage after long-term exposure of adult rats to sodium fluoride

INTRODUCTION Fluorides, when taken in amounts exceeding the standard therapeutic dosage, are regarded as toxic substances. Chronic fluorosis causes marked destruction of lung tissues. The study aimed to determine whether the effect of a chronic toxic dose of sodium fluoride on the lung of an adult male albino rat is reversible or irreversible. This was done through light and electron microscopic studies. Morphometric study was also done. MATERIAL AND METHODS Forty adult male rats were used. The animals were divided into 3 groups: control group; group I (chronic fluorosis group) in which sodium fluoride was given daily for 3 months; and group II (recovery group) in which sodium fluoride was given daily for 3 months and after that the rats survived for another month. RESULTS The lung of group I was characterized by presence of blood and lymph congestion. Thickening of alveolar septa was also observed with rupture of septa and widening of the air spaces. The area % of collagen (1.13 ±0.5), septal wall thickness (13.47 ±6.1), and number of macrophages (5 ±2.5) increased in comparison to the control group (p ≤ 0.05). With discontinuation of sodium fluoride (group II), no much improvement was observed. CONCLUSIONS Chronic fluorosis has many pathological effects on the lung which are irreversible.