EFFECT OF CHRONIC INHALATION OF SULFURIC-ACID MIST UPON MUCOCILIARY CLEARANCE FROM THE LUNGS OF DONKEYS

  • 1 January 1979
    • journal article
    • research article
    • Vol. 2  (6) , 1351-1367
Abstract
The effect of chronic inhalation exposures to sulfuric acid mist upon mucociliary clearance from the lungs was studied, using the donkey as an analog for man. Four animals were exposed 1 h/day, 5 days/wk, for 6 mo. The mean mass concentration of acid mist was 102 .mu.g/m3 for 2 animals, and 106 .mu.g/m3 for the other 2. The mass median aerodynamic diameter was .apprx. 0.5 .mu.m. Clearance was monitored by serial, external in vivo measurements of the retention of an insoluble, radioactively tagged ferric oxide aerosol which was inhaled following exposure to the acid mist. Bronchial clearance became erratic within the 1st wk of exposure; rates were significantly different, unusally slower, than control on many test days, although the degree of response varied among the 4 animals. Two animals exhibited a sustained impairment of clearance towards the end of the 6 mo. exposure period and continued to have erratic clearance during a 3 mo. follow-up period. No changes in the regional deposition of the ferric oxide occurred during the course of the study in any of the animals. Alterations in bronchial mucociliary clearance may be an early physiologic effect resulting from the inhalation of sulfuric acid mist, and this may be a factor in the pathogenesis of chronic bronchitis in populations exposed to the sulfur oxide-particulate-complex in the ambient air, which often includes sulfuric acid.