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Dust overloading of lungs - investigations of various materials, species differences, and irreversibility of effects


Journal of Aerosol Medicine 3 (1990), Nr.1, S.111-128
ISSN: 0894-2684
ISAM <1991, Davos>
Fraunhofer ITA ( ITEM) ()
dust; exposure; Inhalation; inhalation experiment; lung; lung overloading; particles; pulmonary system; rat; respiratory system; toner

In separate inhalation investigations, rodents were exposed to various dusts. The animals inhaled various concentrations of these particle for up to 2 years. Alveolar clearance retardation was detectable above a retained pulmonary burden of 0.5 mg per rat lung, and a substantial decrease in the clearance rate (about a factor of 6) was observed following heavy dust loading, exceeding 10 mg dust per rat lung. Above a threshold lung burden, signs of lung overloading persisted 15 months after cessation of exposure in F-344 rats. Retardation of alveolar clearance was also observed in hamsters, commencing at higher lung burdens than in rats. At high dust explosure levels, persistent pulmonary inflammation was present in both species. In rats the concentration of lavagable cells remained constant, with decreased macrophages and increased polymorphonuclear neutrophils (PMN) noted, while in hamsters, the cell count increased substantially in both macrophages and PMN's. A retarded particle clear ance was also observed in mice at a lung burden above 1 mg/lung. These results, accompanied by published accounts, indicate that the lung overloading phenomenon is noted among a variety of species and materials. It is generally observed upon exceeding a threshold lung burden with particle of low solubility and low acute toxicity for considerable periods of time.