Asbestosis

Asbestos is a fibrous, incombustible form of magnesium and calcium silicate used in making insulating materials. By the late 1970s, over 6 million tons of asbestos were being produced worldwide. About two-thirds of the asbestos used in the United States is used in building materials, brake linings, textiles, and insulation, while the remaining one-third is consumed in such diverse products as paints, plastics , caulking compounds, floor tiles, cement, roofing paper, radiator covers, theater curtains, fake fireplace ash, and many other materials.

It has been estimated that of the eight to eleven million current and retired workers exposed to large amounts of asbestos on the job, 30 to 40 percent can expect to die of cancer . Several different types of asbestos-related diseases are known, the most significant being asbestosis. Asbestosis is a chronic disease characterized by scarring of the lung tissue. Most commonly seen among workers who have been exposed to very high levels of asbestos dust, asbestosis is an irreversible, progressively worsening disease. Immediate symptoms include shortness of breath after exertion, which results from decreased lung capacity. In most cases, extended exposure of 20 years or more must occur before symptoms become serious enough to be investigated. By this time the disease is too advanced for treatment. That is why asbestos could be referred to as a silent killer.

Exposure to asbestos not only affects factory workers working with asbestos, but individuals who live in areas surrounding asbestos emissions. In addition to asbestosis, exposure may result in a rare form of cancer called mesothelioma, which affects the lining of the lungs or stomach. Approximately 5–10% of all workers employed in asbestos manufacturing or mining operations die of mesothelioma.

Asbestosis is characterized by dyspnea (labored breathing) on exertion, a nonproductive cough, hypoxemia (insufficient oxygenation of the blood), and decreased lung volume. Progression of the disease may lead to respiratory failure and cardiac complications. Asbestos workers who smoke have a marked increase in the risk for developing bronchogenic cancer.

Increased risk is not confined to the individual alone, but there is an extended risk to workers' families, since asbestos dust is carried on clothes and in hair. Consequently, in the fall of 1986, President Reagan signed into law the Asbestos Hazard Emergency Response Act (AHERA), requiring that all primary and secondary schools be inspected for the presence of asbestos; if such materials are found, the school district must file, and carry out an asbestos abatement plan. The Environmental Protection Agency (EPA) was charged with the oversight of the project.

[Brian R. Barthel ]

RESOURCES

BOOKS

Agency for Toxic Substances and Disease Registry. Annual Report. Atlanta, GA: U. S. Department of Health and Human Services, 1989 and 1990.

Nadakavukaren, A. Man & Environment: A Health Perspective. Prospect Heights, IL: Waveland, 1990.

PERIODICALS

Mossman, B. T., and J. B. L. Gee. "Asbestos-Related Diseases." New England Journal of Medicine 320 (29 June 1989): 1721–30.