Influence of Adsorption to Carbon Black Particles on the Retention and Metabolic Activation of Benzo[a]Pyrene in Rat Lungs Following Inhalation Exposure or Intratracheal Instillation

Abstract

AbstractThere is a need to define the influence of adsorption of organic compounds onto particles on the biological fate of these compounds when inhaled. In this study, rats were exposed by nose-only inhalation (2 h) to 2 mg/m3 or 20 mg/m3 of pure [14C]BaP or [14C]BaP adsorbed onto carbon black particles at 0.2 mg/m3, 2.0 mg/m3, or 20 mg/m3 (total mass concentration ≃ 100 mg/m3). In separate studies, rats were intratracheally instilled with amounts of pure [14C]BaP and [14C]BaP on carbon black that were similar to those deposited in lungs by inhalation. In all cases, clearance of 14C from lungs had a rapid short-term component and a slower long-term component of clearance. As a percentage of the calculated initial lung deposition after inhalation or instillation, the long-term retention of 14C was similar for all amounts of pure [14C]BaP used and also similar for both methods of administration. The long-term lung retention of 14C as a percentage of the initial lung deposition was increased 16–60 times as ...