Page:NIOSH Manual of Analytical Methods - Chapter L.pdf/1

 L.

MEASUREMENT OF FIBERS by Paul A. Baron, Ph.D., NIOSH/DART Adapted from Baron [1] CONTENTS:

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Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fiber Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phase Contrasting Light Microscope Counting (PCM). . . . . . . . . . . . . . . . . . . . . a. Microscope-related parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . b. Sample preparation techniques. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . c. Quality assurance schemes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . d. Qualitative fiber analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . e. Sampling volume for asbestos abatement applications. . . . . . . . . . . . . . . . . f. Other techniques. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. Polarizing Light Microscopy (PLM) of Bulk Materials. . . . . . . . . . . . . . . . . . . . . . a. Sampling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . b. Sample preparation and analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . c. Accuracy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. Electron Microscopy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. Scanning Electron Microscopy (SEM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. Transmission Electron Microscopy (TEM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8. Optical Detection (Light Scattering). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9. Fiber Classification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10. Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11. Figures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12. References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

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143 144 145 146 146 148 149 149 150 151 151 152 153 154 154 154 156 157 158 159 161

INTRODUCTION Fiber-related disease has provided much of the impetus for fiber research in recent years. Asbestos has been the fiber type most commonly associated with disease. The name “asbestos” is a commercial term applied to the fibrous forms of several minerals that have been used for similar purposes and includes chrysotile, amosite, crocidolite, and the fibrous forms of tremolite, anthophyllite, and actinolite. The three primary diseases associated with asbestos exposure are asbestosis, the result of inflammation and collagen formation in lung tissue; lung cancer; and mesothelioma, an otherwise rare form of cancer associated with the lining surrounding the lungs. A current theory describing the toxicity of fibers indicates that fiber dose, fiber dimension, and fiber durability in lung fluid are the three primary factors determining fiber toxicity [2]. The dose, or number of fibers deposited in the lungs, is clearly an important factor in determining the likelihood of disease. Both fiber diameter and length are important in the deposition of fibers in the lungs and how long they are likely to remain in the lungs. Figure 1 indicates some of the factors that determine fiber deposition and removal in the lungs. Fiber length is thought to be important because the macrophages that normally remove particles from the lungs cannot engulf fibers having lengths greater than the macrophage diameter.

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NIOSH Manual of Analytical Methods