Deposition, retention, and biological fate of inhaled benzo(a)pyrene adsorbed onto ultrafine particles and as a pure aerosol

doi:10.1016/0041-008X(82)90005-9

Toxicology and Applied Pharmacology

Volume 65, Issue 2, 15 September 1982, Pages 231-244

https://doi.org/10.1016/0041-008X(82)90005-9 Get rights and content

Abstract

The effect of ultrafine, airborne, carrier particles on the deposition, retention, and biological fate of inhaled polycyclic aromatic hydrocarbons (PAHs) was studied. Using a radiolabeled model PAH, [³H]benzo(a)pyrene ([³H]BaP), Fischer-344 rats were exposed by nose-only inhalation (30 min) to this compound, as a coating (15% by mass) on insoluble ⁶⁷Ga₂O₃ particles or as a pure aerosol. These aerosols were produced by vapor condensation methods in a dynamic aerosol generation system. The concentrations of [³H]BaP in the coated and homogeneous aerosols were 0.6 and 1.0 μg/liter of air, respectively, while the mass median diameter of both these aerosols was approximately 0.1 μm. Pulmonary retention of ³H radioactivity was longer in animals exposed to the [³H]BaP coated on the ⁶⁷Ga₂O₃ particles. The time required to clear 90% of the initial lung burden of ⁶⁷Ga₂O₃-associated ³H radioactivity detected 30 min postexposure was approximately 1 day as compared to 4 hr for animals exposed to the pure [³H]BaP aerosol. Tracheal clearance of 90% of the ⁶⁷Ga₂O₃-associated ³H radioactivity (as a fraction of the amount detected 30 min postexposure) required 1 day, while only 1.5 hr were required to clear the same percentage of ³H radioactivity from the tracheas of rats exposed to the pure [³H]BaP aerosol. The rates of clearance of this ³H material to other tissues suggested that a substantial amount of the [³H]BaP coated on ⁶⁷Ga₂O₃ was cleared from lungs by mucociliary clearance and subsequent ingestion, whereas the majority of the pure [³H]BaP aerosol was cleared by direct absorption into blood. In both cases, the ultimate fate of the majority of the [³H]BaP and its metabolites was excretion in feces. However, clearance of the ⁶⁷Ga₂O₃-associated [³H]BaP by ingestion may have been the cause for the higher levels and longer retention times of ³H radioactivity in stomach, liver, and kidneys when compared to the levels found in these same tissues from animals exposed to the pure [³H]BaP aerosol. Thus, particle association of BaP not only increased the respiratory tract retention of this PAH, but also increased the dose of this compound and its metabolites to stomach, liver, and kidneys.

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Deposition, retention, and biological fate of inhaled benzo(a)pyrene adsorbed onto ultrafine particles and as a pure aerosol

Abstract

Fund. Appl. Toxicol.

J. Colloid Interface Sci.

Atmos. Environ.

Toxicol. Lett.

Toxicol. Appl. Pharmacol.

J. Aerosol Sci.

Atmos. Environ.

Size distribution pattern of polycyclic hydrocarbons in air-borne particulates

Environ. Lett.

Mode of formation of carcinogens in human environment

Nat. Cancer Inst. Monogr.

The EPA program to assess the public health significance of diesel emissions

J. Air Pollut. Control Assoc.