PULMONARY ALVEOLAR PHOSPHOLIPO-PROTEINOSIS INDUCED BY ORASOL NAVY BLUE DUST

1 Orasol Navy Blue (ONB) is a water-insoluble nitroaromatic dye to which workers may be exposed to the dust. 2 Rats and guinea pigs exposed for 30 min to 173 mg m(-3) did not show toxic signs or respiratory tract histopathology. 3 Rats, mice and guinea pigs were exposed 6 h a day for 20 or 100 days to 2.05 mg m(3) ONB dust (particle size, 33.6% < 5 mu m) Except for decreased body weight of guinea pigs during the exposure period, no adverse signs were seen over a 1-year period from the first exposure. Respiratory tract histopathology was not seen in mice or guinea pigs. Rats showed scattered alveolar lesions characterized by aggregations of macrophages, PAS-positive debris, cholesterol, sudanophilia and birefringence, with preservation of the interstitium and no fibrogenic response, The number and size of these lesions was related to the duration of exposure. 4 The similarity of the lesions seen in the rat following exposure to ONB dust and those seen in humans from other exogenous causes of pulmonary alveolar phospholipoproteinosis suggests that overexposure of humans to a respirable dust of ONB may produce this lesion. 5 The rat is a convenient model to investigate pulmonary alveolar phospholipoproteinosis by exposure to respirable dusts.