Uses and Health hazard of Asbestos

Asbestos is the common name of several naturally occurring, hydrated silicate minerals that possess a crystalline structure and low thermal conductivity. They are incombustible in air and separable into filaments. These minerals occur as extremely thin flexible fibers having great tensile strength and thermal stability, and they can be spun into yarn and made into textiles.

Uses

Asbestos has become very widely used because it is a low-cost material with very desirable chemical and physical properties. This unique combination makes the economical replacement of asbestos very difficult in many applications. Heat and fire resistance, the most widely known property, is not as great as is popularly believed. Asbestos cannot be classified as a refractory, but its properties are sufficient to withstand superheated steam and other high-temperature industrial environments. Whereas major loss of strength can occur at temperatures in the range of 300–500℃, useful performance can be obtained at higher temperatures, in some cases up to 1700℃.

Health hazard

Asbestos-Related Diseases

The mining and use of asbestos have always been associated with disease among the workers involved. However, because priorto1900 the number of people involved was not large, there was little to draw attention to these hazards. It is now well-established that as best fibers can produce several medical effects, the most common of which are pleural thickening, asbestosis, mesothelioma, and cancer. These asbestos-related diseases can appear from several years to tens of years after the first exposure to airborne asbestos dust; the former increasing incidence of cases in many countries could be regarded as a result of past dust exposure, which was too high.

Cancer

Cancer of the larynx, stomach, colon, and rectum may be associated with asbestos. There is also an increase in the incidence of bronchial tube cancer or lung cancer in people who have had asbestosis. It is not yet certain whether asbestos can contribute to cancer when asbestosis is not already present. Over half the British death certificates recording asbestosis also record lung cancer.