Lung retention of inhaled 14C-BaP and 14C-NP when adsorbed on carbon particles

Studies were conducted to evaluate the influence of particle association of polycyclic aromatic hydrocarbons on their retention in the respiratory tract. Vaporization and condensation of premixed powders dispersed from a Wright dust feeder were used to produce submicron aerosols of 2% (by mass) 14C-benzo(a)pyrene (BaP) or 2% 14C-nitropyrene adsorbed on carbon black (CB). There was close correspondence of the particle size distributions of the 14C radiolabel, specific for the organic compounds, and the total mass, representative primarily of the carbon black particles. Following 2 h nose only exposure of rats to these aerosols, lung retention of 14C was biphasic. Percentages in the long-term retention component (1.2% for 14C-BaP-CB and 3.7% for 14CC-NP-CB) were much greater than those previously measured for aerosols of the organic compounds alone (0.014% for 14C-BaP and 0.065% for 14C-NP). The amount of 14C covalently bound to lung macromolecules (as a percentage of inhaled activity) were also much greater for the BaP-CB and NP-CB than for the pure compounds. These data suggest that adsorption of BaP and NP on carbon black enhances interactions with target molecules. 4 references, 4 figures, 1 table