Particle-induced Pulmonary Alveolar Proteinosis and Subsequent Inflammation and Fibrosis

This review analyzes the published data on cases of pulmonary alveolar proteinosis (PAP) in workers inhaling crystalline aluminum, indium, silicon, and titanium particles and possible sequelae, that is, inflammation and fibrosis, and compares these findings with those from animal experiments. In inhalation studies in rodents using crystalline indium and gallium compounds, pronounced PAP followed by inflammation and fibrosis down to very low concentration ranges have been reported. Crystalline aluminum, silicon, and titanium compounds also induced comparable pulmonary changes in animals, though at higher exposure levels. Laboratory animal species appear to react to the induction of PAP with varying degrees of sensitivity. The sensitivity of humans to environmental causes of PAP seems to be relatively low. Up to now, no cases of PAP, or other pulmonary diseases in humans, have been described for gallium compounds. However, a hazard potential can be assumed based on the results of animal studies. Specific pa...