Lung retention and metabolic fate of inhaled benzo(a)pyrene associated with diesel exhaust particles
The effect of ultrafine, insoluble, carrier particles on the lung retention and metabolic fate of inhaled PAHs was investigated with a radiolabeled model PAH, (/sup 3/H)benzo(a)pyrene (/sup 3/H-BaP). Fischer-344 rats were exposed (30 min) by nose-only inhalation to /sup 3/H-BaP adsorbed (approximately 0.1% by mass) onto diesel engine exhaust particles. The total mass concentration of these aerosols was 4-6 micrograms/liter of air with a mass median diameter of 0.14 micron. Lung clearance of the inhaled particle-associated /sup 3/H radioactivity occurred in two phases. The initially rapid clearance of this inhaled radiolabel had a half-time of less than 1 hr. The second, long-term component of lung clearance had a half-time of 18 +/- 2 days and represented 50 +/- 2% of the /sup 3/H radioactivity that had initially deposited in lungs. In contrast, previous inhalation studies with a pure /sup 3/H-BaP aerosol showed that greater than 99% of the /sup 3/H radioactivity deposited in lungs was cleared within 2 hr after exposure. By HPLC analysis, the majority of diesel soot-associated /sup 3/H radioactivity retained in lungs was BaP (65-76%) with smaller amounts of BaP-phenol (13-17%) and BaP-quinone (5-18%) metabolites also being detected. No other metabolites of BaP were detected in lungs of exposed rats. Tissue distribution and excretion patterns of /sup 3/H radioactivity were qualitatively similar to previous inhalation studies with /sup 3/H-BaP coated Ga2O3 aerosols. These findings suggest that inhaled PAHs may be retained in lungs for a greater period of time when these compounds are associated with diesel engine exhaust particles. These results may have significant implications for the health risks that may be involved with human exposure to particle-associated organic pollutants.
- Research Organization:
- Inhalation Toxicology Research Institute, Lovelace Biomedical and Environmental Research Institute, Albuquerque, New Mexico
- OSTI ID:
- 7188782
- Journal Information:
- Toxicol. Appl. Pharmacol.; (United States), Vol. 73:1
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
BENZOPYRENE
BIOLOGICAL HALF-LIFE
INHALATION
METABOLISM
TISSUE DISTRIBUTION
EXHAUST GASES
CLEARANCE
DIESEL ENGINES
LIQUID COLUMN CHROMATOGRAPHY
PARTICULATES
RATS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMALS
AROMATICS
CHROMATOGRAPHY
CONDENSED AROMATICS
DISTRIBUTION
ENGINES
FLUIDS
GASEOUS WASTES
GASES
HEAT ENGINES
HYDROCARBONS
INTAKE
INTERNAL COMBUSTION ENGINES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
ORGANIC COMPOUNDS
PARTICLES
RODENTS
SEPARATION PROCESSES
VERTEBRATES
WASTES
560305* - Chemicals Metabolism & Toxicology- Vertebrates- (-1987)
550501 - Metabolism- Tracer Techniques