What Is an Inorganic Fiber?

Abstract

Fibers are everywhere around us. They are essential parts of the human body, our hair, for example; the threads in our clothing, natural or synthetic; the insulation in our houses. Natural fibers have been useful to humans for more than ten thousand years. They were mixed with clay before firing to strengthen and reinforce pottery vessels, making them more durable. Textiles that combined the fibers of flax and asbestos were known in ancient times for their seemingly magical resistance to fire and decay. It was industrialization, however, that caused a dramatic increase in the use of natural inorganic or mineral fibers. By the late nineteenth century asbestos had become an important commodity with a variety of commercial applications. It served as insulation to control heat generated by engines and, because of its incombustibility, as a fire retardant in its more recent general use as building insulation. Asbestos fibers are found worldwide in many products: as reinforcement in cement water pipes and the inert and durable mesh material used in filtration processes of chemicals and petroleum, for example. However, asbestos is not the only inorganic fiber in use today. Synthetic inorganic fibers abound. Glass fibers have replaced copper wire in some intercontinental telephone cables. Fiberglas (a trade name) has become the insulation material of choice in construction. Carbon and graphite fiber composites are favored materials for tennis racket frames and golf clubs. Fibrous inorganic materials have become commonplace in our everyday lives. As the use of inorganic fibers increased, there were some indications that fibers might be hazardous to our health. Since the first century A.D. it was suspected that asbestos might be the cause of illness among those who mined and processed the material. Asbestosis, a debilitating and sometimes fatal lung disorder, was documented and described in the nineteenth century. Within the last 25 years, lung cancer and mesothelioma have also been linked to asbestos exposure among construction and textile workers, as well as others exposed to dusts containing asbestos fibers. Although the etiology and specific mechanisms that give rise to these two cancers are not yet understood, concern for the health of exposed workers led the governments of the United States and other countries to specify the maximum allowable concentrations of asbestos in the ambient air of the workplace.