Inhaled particle retention in rats receiving low exposures of diesel exhaust

Journal Article · Mon Jan 01 04:00:00 EST 1990 · Journal of Toxicology and Environmental Health; (USA)

DOI:https://doi.org/10.1080/15287399009531399· OSTI ID:6905356

Strom, K A; Garg, B D; Johnson, J T; D'Arcy, J B; Smiler, K L ^[1]

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1. General Motors Research Laboratories, Warren, MI (USA)

To study the effects of a low concentration exposure on the retention and clearance of submicron particles from the lungs, we exposed male Fisher 344 rats to diesel exhaust diluted to 50 micrograms diesel exhaust particles (DP)/m3, 20 h/d, 7 d/wk for 52 wk. Lung burdens (amount of DP in lungs) and the alveolar macrophage burdens were measured up to 52 wk postexposure. By 1 yr postexposure at least 80% of the DP was eliminated from the lungs and similarly cleared from the lavaged pool of macrophages. The DP remaining in the lungs was observed in alveolar, parabronchial and paravascular maculae. In contrast to previous high concentration exposure studies, only trace amounts of particles were observed in the mediastinal lymph nodes. To study the concentration dependence of particle retention, rats were exposed to equivalent exposures of 18 d x mg DP/m3 delivered at 5700 micrograms/m3 for 3 d, 1600 micrograms/m3 for 12 d, 250 micrograms/m3 for 72 d, or 50 micrograms/m3 for 365 d. Higher lung and macrophage burdens were initially achieved with the brief, high concentration exposures. During the postexposure period, animals exposed to the higher concentrations cleared more of the lung burden. Exposure to lower concentrations resulted in higher long-term lung burdens. These results are consistent with a model of lung clearance in which the macrophage burden and the duration of exposure are both important to the formation of the maculae. In a brief high concentration exposure, the macrophage burden rises rapidly, but then declines rapidly. However, in longer low concentration exposures, the macrophage burden will not reach the same peak, but stays at intermediate levels during the exposure and stimulates a steady development of the lung maculae from particle-laden macrophages leaving the active pool of pulmonary phagocytes.

• OSTI ID: 6905356
• Journal Information: Journal of Toxicology and Environmental Health; (USA), Journal Name: Journal of Toxicology and Environmental Health; (USA) Vol. 29:4; ISSN JTEHD; ISSN 0098-4108
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL CELLS
ANIMALS
BIOLOGICAL MODELS
BODY
BODY BURDEN
CLEARANCE
CONNECTIVE TISSUE CELLS
DIESEL ENGINES
ENGINES
EXCRETION
EXHAUST GASES
EXPOSURE CHAMBERS
FLUIDS
GASEOUS WASTES
GASES
HEAT ENGINES
INTERNAL COMBUSTION ENGINES
LAVAGE
LUNG CLEARANCE
LUNGS
LYMPH NODES
LYMPHATIC SYSTEM
MACROPHAGES
MAMMALS
METABOLISM
ORGANS
PARTICLE SIZE
PHAGOCYTES
RATS
RESPIRATORY SYSTEM
RETENTION
RODENTS
SIZE
SOMATIC CELLS
VERTEBRATES
WASTES