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Understanding Asbestos

What is an Asbestos Screening?

An asbestos screening is a medical evaluation and educational session for sheet metal workers who may have been exposed to asbestos.

Is Asbestos Screening the Same as a Complete Physical?

No. During a normal screening, individuals get a brief physical examination. In the case of asbestos, the exam focuses only on the heart and lungs. A screening does not take the place of regular examinations with your private physician.

What Else is Included in an Asbestos Screening?

Each screening involves a brief physical exam including a review of the individual’s medical history and work history concerning exposure to asbestos. Also included is a chest X-ray, and a spirometry test which measures lung capacity and function. The last part of the screening is an educational session about the potential health effects of asbestos and how to avoid future exposure to it. It is also an opportunity to ask questions about any other work hazard.

Are the Test Results Confidential?

Yes. Each participant gets a personal letter with his or her individual results. This letter is not sent to anyone else without the individual’s written permission.

How Long Does it Take to Get Results Back?

Individual results will be sent out about four to eight weeks after the screening, depending on the screening physician or clinic.

What if The Screening Tests Show a Problem?

If screening results show evidence of asbestos-related disease, we suggest that you schedule a follow-up meeting with the union; information will be shared regarding continuing care and legal rights at this meeting, with physicians and attorneys on hand to answer questions.

Diseases From Asbestos

There are several medical diseases that occur as a result of asbestos exposure. The ones of greatest concern and importance are pleural plaques, asbestosis, lung cancer, colon cancer, and mesothelioma.

Pleural Plaques

Pleural plaques are also called pleural fibrosis, pleural thickening, and pleural asbestosis. A majority of people with heavy exposure to asbestos develop pleural abnormalities. The pleura is a thin lining that surrounds the lung. Inhaled asbestos fibers travel to the outside of the lung and cause a scar to form in this lining. When they reach a certain size they are visible on chest X-rays as a plaque. Most of these plaques alone do not cause significant disability, but they do show that significant exposure has occurred, and that other asbestos-related diseases may be present. Some types of plaques can cause loss of lung function as well. Based on information from studies in New York and Boston, as well as results from the national sheet metal screening program, about half of all sheet metal workers with 30 years of exposure will have pleural plaques.

Parenchymal Asbestosis (Pulmonary Asbestosis)

Parenchymal asbestosis is a scar formation in lung material itself. These scars can interfere with lung function, because they block the transport of oxygen from the air in the lungs into the blood vessels that travel through the lungs. Oxygen can only cross the membranes of the lung if the membranes are thin; asbestosis causes them to thicken. The extent of scar formation determines the amount of shortness of breath that results. Some persons can have mild scarring and have little loss of exercise capacity; others with more extensive disease get out of breath with mild exertion. As a general rule, the greater the exposure the more the disease, but some people seem to form scars more or less readily and so we see a variety of disease from the same exposure. These scars are visible on X-rays in most cases, although in early stages of disease the scars can be too small to detect. There is a system of grading the degree of disease on the X-ray called the ILO classification. Physicians who have received special training in this system are called “A” or “B” readers. Each X-ray is scored on the type of scar formation and the density of the scars. The scars are also detected on pulmonary function testing. Asbestosis makes the lung stiffer and smaller, so the volume of air in the lungs is decreased. Oxygen transport as measured by “diffusion capacity” is also decreased. Once again, the changes can be subtle, and test results should be interpreted by someone with experience in asbestos-related diseases. Once this scar formation takes place it is irreversible. If exposure to asbestos ceases, the scarring does not usually progress, although in a small number of individuals it does get worse. Because of the damage to the lungs, a person with asbestosis is at increased risk of lung infections and should get regular medical care along with influenza vaccines.

Lung Cancer and Respiratory Cancers

Lung cancer is a serious problem for asbestos workers. In general, insulators (a heavy exposure group) working in the trade for 20 years and have never smoked have a risk that is five times that of a non-asbestos worker. However, an insulator who smokes has a 50–90-fold increase in risk; cigarettes and asbestos act together to cause cancer. Evidence shows that if an insulator quits smoking his/her risk of cancer falls over several years back to the range of the nonsmoker. Because the effect of the asbestos is irreversible, one of the most important changes any worker exposed to asbestos can make is to quit smoking. The risk of cancer of the larynx is also increased by asbestos exposure.

Colon Cancer and Gastrointestinal Cancer

There is also a higher incidence of cancers of the gastrointestinal tract among asbestos workers. In people exposed to asbestos for more than 20 years, the rate of colon cancer is increased by a factor of two. It is important for all sheet metal workers to have regular checkups to detect early signs of colon cancer.


Mesothelioma is a rare cancer of the pleura (lung lining) and the peritoneum (abdomen lining) that occurs in people exposed to asbestos. It is almost impossible to treat and is usually fatal. Although asbestos workers get mesothelioma at a rate far greater than non-exposed people, it is still a much more rare disease than lung cancer. Pleural plaques are not cancer, nor do they turn into mesothelioma. They both occur in the lining of the lung, but they are separate diseases.

What is Your Risk?

All these diseases occur more frequently in heavily exposed populations; much of the information comes from studies of insulators. We can then try to estimate the risk of disease in other groups by estimating the relative degree of exposure.

There is no safe level for exposure to a carcinogen. Risk of disease will only lessen—not disappear—as exposure lessens. Although asbestos is currently used less frequently than years ago it is present in buildings constructed through the early 1970s and still used for brake and clutch linings among other uses. Those who work in buildings with asbestos insulation (on duct work, pipes, structural steel, in roofing materials, etc.) must be aware of the special precautions needed for the handling of asbestos.


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