The term "Asbestos" describes a variety of naturally occurring fibrous minerals or rocks. There are two classifications of asbestos minerals the serpentine group, and the amphibole group. Chrysotile is classified in the serpentine group, while the amphibole group includes amosite, crocidolite, actinolite, tremolite, anthophylite and a number of other minor forms of asbestos. Actinolite, Tremolite, and Anthophylite have been used very sparingly in industry and are not often found in North American products. The three common forms of asbestos are Chrysotile (sometimes referred to as white asbestos), Amosite (sometimes referred to as brown asbestos), and Crocidolite (sometimes referred to as blue asbestos). Of the three common asbestos forms Chrysotile is by far the most prominent accounting for approximately 90% of world wide production and use. Amosite and Crocidolite are relatively rare and account for the remaining 10%. Asbestos mineral deposits are common in virtually all areas of the world. Asbestos is currently, or was previously mined, in many areas of the world, most notably in Canada, the United States, Australia, Russia, South Africa, Zimbabwe, and Bolivia.
Asbestos has been known to man and used for centuries in thousands of applications and products. The ancient
Greeks used asbestos to create incombustible textiles, and the Romans used it in their building materials. Specific
fibre characteristics vary among the different forms of asbestos but generally asbestos fibres are incombustible, have high tensile strength, and have outstanding thermal, acoustical, and electrical insulating properties. As a result of these unique chemical and physical properties asbestos became a useful ingredient in a numerous commercial and industrial products. The major commercial exploitation of asbestos did not occur until the discovery of the huge Chrysotile asbestos deposits in the province of Quebec in the late 1800's. By the year 1900, there were thousands of power looms producing asbestos textiles in England and the United States. The asbestos textile was used for insulation blankets, gaskets, and packing material. The textile industry was the primary user of asbestos until around 1930. Beginning in the mid 1940's, and over the next thirty-five years the asbestos industry diversified to include mechanical pipe insulations, cement products, plasters, gypsum board filling compounds, grouts, compressed papers, mill boards, floor tiles, sheet floorings, acoustic tiles, roofing felts, mastics, duct tapes and sealants, protective coatings, fireproofing, and numerous other products By 1969, thousands of asbestos containing materials were being manufactured and their presence on a building construction site was as common then as gypsum board or plywood are today. Asbestos fibrated construction materials became the industry standard, and were used in a multitude of building construction and industrial applications particularly where durability and/or fire resistance was required. Asbestos became known as the miracle fibre of the twentieth century. It has been estimated that asbestos has been used in over three thousand applications and products.
Asbestos fibres can divide both horizontally and longitudinally many times and ultimately end up as microscopic fibrils that are invisible to the naked eye. These microscopic fibers are extremely aerodynamic and can remain airborne for extended periods of time, hours or even days. Serious respiratory diseases such as asbestosis, lung cancer, and mesothelioma have been associated with inhalation of asbestos fibres. A latency period of between 10 and 25 years is common between initial exposure and recognizable symptoms of asbestos related disease. There are three main diseases associated with the inhalation of asbestos fibres Asbestosis, Lung Cancer and Mesothelioma.
Asbestosis is a chronic lung disease not unlike "silicosis" affecting hard rock miners, and "black lung" affecting coal miners that are exposed to prolonged high levels of dust. Asbestosis is generally dependant on prolonged exposure to high levels of airborne asbestos fibres. The asbestos fibres gradually cause the lungs to become scarred, and lose their natural elasticity. The breathing capacity of the lungs and the ability to exchange oxygen and carbon dioxide with the bloodstream is reduced. As the breathing capacity of the lungs decreases, the general health of individual also deteriorates. Asbestosis is not necessarily a fatal disease, however, the weakened body is susceptible to other diseases, and an inordinate amount of stress, which usually results in a shortened life span.
Lung Cancer such as pulmonary and bronchial carcinoma results in uncontrolled multiplication of cells in the lower lobes of the lungs. Of great interest, and of considerable importance from the aspect of preventative medicine is the discovery that the combined carcinogenic properties of asbestos and cigarette smoking produces a multiplicative effect on lung cancer incidence. Despite the recent advances in medical science, lung cancer is still considered a fatal disease.
Mesothelioma is a form of cancer resulting in the malignant growth of the mesothelium tissue. The mesothelium tissue is found in various parts of the abdominal cavity such as the lining of the lungs (pleura), the intestinal lining (peritoneum), and surrounding the heart (pericardium). Although relatively rare, mesothelioma is almost always fatal.
Certain types of asbestos containing materials are considered more hazardous than others. The term "friable" describes a material that can be easily crumbled or pulverized by hand pressure. The asbestos fibres in "non-friable" materials are bound within a matrix, or are mixed with binder agents, and do not become airborne as easily as fibres in friable materials. In general the more friable an asbestos containing material is, the greater the potential for airborne fibre release. Regulatory agencies began implementing legislation that regulated asbestos exposure in the work place in the early 1970's. Over the years, additional information on the adverse health effects of asbestos exposure has resulted in numerous revisions of the safe handling of asbestos legislation to better protect workers, and building occupants. Asbestos control legislation ultimately caused a significant decline in the use of asbestos and aggressive research into the development of asbestos free substitutes.
The mere presence of asbestos in a building does not necessarily mean that the health of the occupants is endangered. As long as asbestos containing materials remain in good condition, and are not disturbed, exposure to airborne asbestos fibres is unlikely. Asbestos building products can become hazardous if they have the potential to becoming airborne due to natural deterioration, damage, or physical disturbance. Routine maintenance, housekeeping activities, renovations, and demolitions all have the potential of causing asbestos fibres to become airborne, unless strict asbestos abatement procedures are utilized. The safe handling of asbestos materials is a complicated procedure that must follow stringent regulatory board requirements. Asbestos abatement projects should only be performed by trained professionals who have the specialized equipment and experience to ensure worker, and building occupant safety by complying with the strict regulations, guidelines, and procedures established by the regulatory agencies. A list of some (but by no means all) asbestos containing building products, and common industrial products:
Flooring Systems paper backed sheet vinyl flooring, sheet flooring, vinyl tile, construction paper, and asphaltic
Wall & Ceilings gypsum board filling compound, stippled and smooth plaster, spray applied texture coat (popcorn
ceilings), cementitious wall-board, mill board, acoustic ceiling tiles, and acoustic spray applications.
Fireproofing spray applied fireproofing, trowel applied fireproofing, and pre-manufactured fireproofing products.
Mechanical/Electric preformed pipe and tank insulation, insulating cement, jacketing material, duct tape and
sealant, gasket and packing material, through penetration fire-stop grout, paper insulation within incandescent light
fixtures, electrical wire insulation, arc shields.
Roofing Systems paper, felt, and asphaltic mastic.
Miscellaneous rain water leader (drain pipe), underground piping, adhesives, caulking, sealants, window putty,
mortars, grouts, laboratory fume hoods and countertops, exterior siding, welding gloves, ironing board pads,
automotive break pads and clutch facings.