Inorganic Fibrous Materials

The physiochemical environment of the earth has placed certain elements in common association and produced a variety of minerals. Minerals, classified according to a well-known and well-documented system based on the chemistry of the compounds, have been presented in several compendiums (e.g., Strunz, 1941 Palache, Berman and Frondel, 1944). Several glossaries aid in identifying minerals and cross-reference the more than 6000 names that have been used for the approximately 3000 known minerals (Embrey and Fuller, 1980 Fleischer, 1987). Each year about 100 new minerals are proposed to the International Mineralogical Association Commission on New Minerals and Mineral Names, of which about half are accepted as new species (Skinner and Skinner, 1980). 

Most minerals occur in a variety of morphologies. Although it is not exhaustive, the list we recorded as occurring in fibrous form (Appendix 1) contains more than 350 entries, each with a reference. The format follows that proposed in Dana s System of Mineralogy, (Palache, et al., 1944), one of the standard references in the field. The names of fibrous minerals are alphabetically arranged within each chemical group that is, elements, oxides, hydroxides, carbonates, sulfates, phosphates, and so on. A similar, parallel system has been adopted for the list of synthetic fibers (Appendix 2). The list of synthetics includes glassy fibers produced from natural materials, as well as whiskers. 

Over the past 40 years a great deal of research has been done on the nucleation and growth of fibers for industrial uses. The predominant industrial fiber is a silica-based glass. Whiskers, with a high degree of internal structural perfection, have been produced under a variety of special conditions from an extraordinarily wide range of compounds. 

The published information on industrial materials is found in patent literature and compendiums such as those of Wilke (1973) and Bracke (1984). For many synthetic fibers, information on the precise chemical composition is unavailable or buried in a patent that describes a series of commercial fibers distinguished from each other by exceedingly small variations in composition. 

The data in the references provided for each entry in the Appendices are extremely variable. Except for those of the asbestos minerals, the general descriptions of most minerals give little more than cursory mention of their occurrence as fibers. A journal citation indicates some information on composition, crystal structure, size, morphological characteristics, and other 

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Whatever distinguishes asbestos fibers—their composition, structure, or other peculiar properties that may contribute to the health hazard—they need to be examined in context, as representative of a class of inorganic fibrous materials. Perhaps then the factors that initiate adverse biologic reactions, and might be responsible for the induction of disease, could be identified. 

Hrapka, I. (1977, 1978). Structural Examination of Inorganic Fibrous Materials (Hungarian with English Abstract). Wojnarovitsne, Part 1. Epitoanyag, Budapest 29 498—503 Part 2. Epitoanyag, Budapest 30 13—18. 

This brief summary of the composition and structural characteristics of glass fibers, whiskers, and carbon and graphite fibers illustrates the ranges of synthetic inorganic fibrous materials. The purposes of the construction of these materials is to capitalize on the physical and chemical advantages of the fibrous morphology, size, and state. 

Use Floor polishes, paints, adhesives, paper coatings, catalyst supports, latex products, textile cleaning treatments, photosensitized paper, binder for inorganic fibrous materials, reactant for synthetic silicates. 

Ceramic fiber reinforcements n. Non-metallic inorganic fibrous materials, available in a wide spectrum of forms, both continuous and discontinuous. 

A natural inorganic fibrous material, mainly composed of chrysolite, that was used as an effective reinforcing material in the past. Asbestos is a proven lung cancer producing agent and... 

The entire spectrum of inorganic fibers can be divided into two classes, based on differences in the crystallinity of the solids (Ray, 1978). Synthetic fibers have been known as man-made mineral fibers (MMMF) and manmade vitreous fibers (MMVF). But fibrous materials can be approached or divided in other ways. For example, in the Concise Encyclopedia of Chemical Technology (1985) the entry for chemical fibers includes both manmade and natural polymers, with the discussion centering on carbon-based compounds such as acetates, acrylics, and cellulose. Fibers of other inorganic compounds were not mentioned in the encyclopedia under this entry, but silica glass fibers were described under the heading Optical Fibers. ... 

Manufacture of inorganic materials as fibers is now common. Industry has developed fibers to respond to a range of technological demands. In the process the new fibrous materials have often provided impetus for innovation and development of new uses. The study of synthetic fibers is a rapidly expanding area of research. A variety of sources such as the Journal of... 

The confusion and frustration of nonepidemiologists, especially those who must act on hehalf of the public, contribute further to the disarray. For ethical reasons, they propose regulations that seek the lowest possible level of asbestos exposure. But economics, not to mention common sense, continues to bring the results of these decisions to our attention. Inorganic fibers are ubiquitous. Are asbestos and other fibrous materials major health hazards for the world s population ... 

Health hazards associated with exposure to fibrous materials have been studied since the turn of the century. Fibers less than 5 microns in diameter are likely to become airborne and, as part of the enviromnent, may be inhaled or ingested. The relationship of fiber size to cell size and function, especially clearance once the fiber is inside the human body, sets off a cascade of events that can, and often does, lead to disease. The dimensions, dose, and durability of inorganic fibers are the salient determinants of disease (Lei-neweber, 1981). 

After a thousand years of use, asbestos is being replaeed by other, often fibrous, materials. It remains to be seen whether the substitutes will be as successful, commercially and financially, or more or less hazardous. We are certainly not going to do without fibrous inorganic materials nor expunge them from our environment. 

Whisker, whisker-crystal A modern technical term originating in the field of solid-state physics for highly elongate crystals resembling mineral fibers that are synthesized from a variety of inorganic substances, usually at elevated temperatures or pressures. Whiskers are synthetic fibrous materials (see chapter 2). 

The purpose of this book is to introduce fibrous inorganic materials, their unique features, and their chemical and structural variety. This survey of fibrous materials, together with a summary of their health and biological effects, provides an opportunity to examine the current theories of disease induction and the hazards associated with exposure, not only to asbestos but to other inorganic fibers as well. 

Class D. Inorganic materials of high surface area or unusual surface properties which increase the water-retaining capacity of the mix. These include very fine clays (bentonites), pyrogenic silicas, condensed silica fume, milled asbestos and other fibrous materials. 

Skiimer HC, Ross M, Frondel C. 1988. Health effects of inorganic fibers. In Asbestos and other fibrous materials Mineralogy, crystal chemistry, and health effects. New York, NY Oxford University Press, 103-162. 

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