Elution of benzo[alpha]pyrene from carbon particles in the respiratory tract of mice.

The effect of carrier particle size on the rate of dissociation of benzo[alpha]pyrene (BaP) from carrier particles deposited in the respiratory tract of mice was studied. BaP-coated carbon particles (in two size ranges, 0.5-1.0 and 15-30 mum) plus 103Ru-tagged carbon tracer particles were intratracheally instilled in mice. The clearance of carbon particles and the simultaneous rate of elimination of BaP from the respiratory tract was measured. BaP adsorbed to 15- to 30-muM carbon particles was eliminated from the lung at essentially the same rate as the carbon particles were cleared. In contrast, BaP adsorbed to 0.5- to 1.0-muM carbon particles was eliminated from the lung approximately 4 times faster than the carbon particles were cleared. The persistence of carcinogens and their rates of elution from carrier particles are discussed in relation to the pathogenesis of lung cancer in animals treated with carcinogen-carrier particle preparations.