Long term effects of alumina on components of bronchoalveolar lavage fluid from rats

Significant differences in several components of bronchoalveolar lavage fluid (BAL fluid) have previously been reported in aluminium potroom workers compared with controls. The present paper describes the long term effects in rats of one time exposure to potroom aluminium oxide without fluorides (primary alumina (PA)) or with adsorbed fluorides (secondary alumina (SA)) on components of BAL fluid. Alumina dust (40 mg) suspended in saline was instilled intratracheally; controls received saline. Bronchoalveolar lavage (BAL) was performed one, four, and 12 months after exposure. The number of cells in BAL fluid was increased significantly (p < 0.05) by SA but not PA. The increase was mainly macrophages, but the concentrations of neutrophils also increased about 10-fold one and 12 months after exposure. Although albumin and hyaluronan concentrations did not differ from those of controls, fibronectin concentrations were significantly (p < 0.001) increased one year after exposure both in PA exposed and SA exposed rats. The results indicate that SA, possibly because of adhered fluorides, induces early changes in alveolar cell populations including persistent neutrophilia. These cellular changes may have a destructive effect. The late pronounced increase of fibronectin in both PA and SA exposed rats indicates a delayed effect of alumina on the extracellular matrix.