Document 5bXbq6MbGO788Y0jgnmdpME0e

and gastrointestinal cancers. How does asbestos cause dis ease? The answer is not known. Asistos fibers too fine to be seen by the human eye become air borne during various industrial processes and are inhaled and sub sequently may be swallowed. Scientists believe that the most harmful fibers are so fine that an electron microscope is needed Jo see them. Because of their size and shape, asbestos fibers can penetrate body tissues. Because of their du rability, they remain in the body for many years after entry. * How much asbestos exposure is hazardous? The answer is not known. In the case of asbestosis and lung cancer, the risk increases with in creasing amount of exposure. As bestos-induced disease is not likely to appear.until 15 to 55 or more years after first exposure. The time between first exposure and the appearance of disease appears re lated both to the amount and dura:->n of exposure; more intense osure sometimes results in as bestos-related disease within 15 years. However, one study of workers in an asbestos plant showed that some workers who were exposed only a month or two have developed asbestos-related diseases many years later. Typical ly, the firs't 10 to 15 years after initial exposure are free of signs or symptoms. Early X-ray changes may appear in lung tissue after 10 to 15 years, but may not be accom panied by other significant symp toms. Some investigators have re ported evidence of impaired lung function in workers with less than 10 years of exposure to asbestos. What specific diseases may increase in risk through exposure to asbestos on the job? Asbestosis--This is a chronic lung ailment that can produce shortness of breath and lung damage. The disease results from inhalation of asbestos dust; ( g cancer--There is a close as sociation between asbestos expo sure and increased occurrence of lung cancer; Figure 1 shows the special micro scope developed to examine asbes tos libers, which have been ex posed lo a magnetic Held In order to align the samples. Mesothelioma--A cancer that in volves the thin membrane lining the chest and abdomen. Most mesotheliomas can be traced to prior asbestos exposure; Other cancers--Several studies have indicated a link between as bestos exposure and increased occurrence of cancers of the esoph agus (food tube leading to the stomach), colon, stomach, and rec tum. What are the signs and symp toms of asbestosis? Asbestosis is a chronic lung dis ease whose signs and symptoms result from permanent changes in lung tissue due to asbestos expo sure. The earliest and most prom inent sign is shortness of breath on exertion. It rarely becomes ap parent until at least a decade after first exposure. The disease process usually has to be rather advanced to produce shortness of breath. A dry, crackling sound (rales), coming from the lungs during inhalation, is the most characteristic physical sign of asbestosis. Clubbing of the fingers is sometimes found, usually later in the disease. A bluish dis coloration of the skin and the lin ing of the mouth and of the tongue also may occur in the later stages of the disease. A physical exam with X-rays will show diffuse scar- Figure 2 shows the computerized image analysis system that auto matically detects and counts Indi vidual asbestos fibers within each sample. ring of the lungs as asbestosis de velops, and lung function tests will show impairment of the maximum volume of air a worker can inhale. Does asbestosis lead to lung cancer? Scientists do not believe asbes tosis necessarily leads to lung can cer, but the presence of this dis ease does indicate that a worker received considerable asbestos exposure and has a greater risk of developing asbestos-associated cancers than an unexposed person. Both types of disease can be caused by the same environmental agent, and the development of each may be independent of the other. What are the symptoms of lung cancer? A cough, or a change in cough habit, is found in most lung cancer patients. Chest pain is the second most common symptom. It usually is felt as a persistent ache unre lated to cough and is commonly experienced on the side on which the tumor is located. Bloodstreaked sputum, coughed up from the lungs, is the initial sympton of a small per cent of lung cancers. How is lung cancer diag nosed? July 1979, NATIONAL SAFETY NEWS 8006 0688 HFM- 003983