Long-term exposure of dogs to a sulphite aerosol: II. Effects on biochemical and cellular lung parameters

During exposure of 8 Beagle dogs for 290 days to particulate sulphur(IV) no clinical symptoms were seen which could be correlated with the pollutant. However, significant changes were observed in some of the biochemical and cellular parameters in the bronchoalveolar lavage (BAL) fluid. In the second half of the exposure period the protein and albumin content of the BAL fluid increased indicating changes in the transudation kinetics of serum proteins into the alveolar lumen. The lysosomal enzyme beta-N-acetyl-glucosaminidase also increased in the BAL fluid indicating a higher release of this enzyme from phagocytes. At the same time alveolar macrophages showed a reduced phagocytosis rate in vitro for polystyrene particles and a reduced production of oxygen-derived free radicals. These results indicate a reduced unspecific defence capacity of the alveolar macrophages as well as a change in their lysosomal activity. In conclusion, chronic exposure to particulate S(IV) at a low concentration can initiate pathobiochemical pathways in the lungs indicating the possibility of a health risk.