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In situ microscopic analysis of asbestos and synthetic vitreous fibers retained in hamster lungs following inhalation.

Authors
Rogers-RA; Antonini-JM; Brismar-H; Lai-J; Hesterberg-TW; Oldmixon-EH; Thevenaz-P; Brain-JD
Source
Environ Health Perspect 1999 May; 107(5):367-375
NIOSHTIC No.
20027691
Abstract
Hamsters breathed, nose-only, for 13 weeks, 5 days/week, 6 hr/day, either man-made vitreous fiber (MMVF)10a, MMVF33, or long amosite asbestos at approximately 300 World Health Organization (WHO) fibers/cc or long amosite at 25 WHO fibers/cc. [World Health Organization fibers are longer than 5 Ám and thicker than 3 Ám, with aspect ratio >3.] After sacrifice, fiber burden was estimated (left lungs) by ashing and scanning electron microscopy (ashing/SEM) or (right middle lobes) by confocal laser scanning microscopy (CLSM) in situ. In situ CLSM also provided three-dimensional views of fibers retained, undisturbed, in lung tissue. Fibers of each type were lodged in alveoli and small airways, especially at airway bifurcations, and were seen fully or partly engulfed by alveolar macrophages. Amosite fibers penetrated into and through alveolar septa. Length densities of fibers in parenchyma (total length of fiber per unit volume of lung) were estimated stereologically from fiber transsections counted on two-dimensional optical sections and were 30.5, 25.3, 20.0, and 81.6 mm/mm3 for MMVF10a, MMVF33, and low- and high-dose amosite, respectively. Lengths of individual fibers were measured in three dimensions by tracking individual fibers through series of optical sections. Length distributions of amosite fibers aerosolized, but before inhalation versus after retention in the lung were similar, whether determined by ashing/SEM or in situ CLSM. In contrast, the fraction of short MMVF10a and MMVF33 fibers increased and the geometric mean fiber lengths of both MMVFs decreased by approximately 60% during retention. Most likely due to fiber deposition pattern and differences in sampling, fiber burdens [MMVF10a, MMVF33, and amosite (high dose; 269 WHO fibers/cc)] determined by ashing/SEM were 1.4, 1.5, and 3.5 times greater, respectively, than those calculated from in situ CLSM data. In situ CLSM is able to provide detailed information about the anatomic sites of fiber retention and also fiber lengths and burdens in good agreement with ashing/SEM results.
Keywords
Asbestos-fibers; Asbestos-dust; Respirable-dust; Respiratory-system-disorders; Pulmonary-system-disorders; Inhalation-studies; Analytical-methods; Analytical-processes; Statistical-analysis; Synthetic-fibers; Man-made-mineral-fibers; Laboratory-animals; Animal-studies; Aerosol-particles; Aerosols
Contact
R.A. Rogers, Department of Environmental Health, Building I, Room 1315, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115 USA
CODEN
EVHPAZ
Publication Date
19990501
Document Type
Journal Article
Funding Amount
96500
Funding Type
Cooperative Agreement
Fiscal Year
1999
NTIS Accession No.
NTIS Price
Identifying No.
Cooperative-Agreement-Number-U60-CCU-109979
Issue of Publication
5
ISSN
0091-6765
Source Name
Environmental Health Perspectives
State
MA; CO
Performing Organization
Harvard School of Public Health
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