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Health Effects of Asbestos


Asbestos health risk increases with increasing exposure. Most of the cases of severe health problems resulting from asbestos exposure have been experienced by workers in industries such as shipbuilding, mining, milling, and fabricating. They were exposed over many years, sometimes to extremely high levels of asbestos in the air, without the benefit of worker protections now afforded by law. These employees worked directly with asbestos materials on a regular basis and, generally, for long periods of time as part of their jobs.

If you are exposed to a substance such as asbestos, many factors will determine whether harmful health effects will occur and what the type and severity of those health effects will be. These factors include the dose (how much), the duration (how long), how often, the route or pathway from which you are exposed (breathing, eating, drinking, or skin contact), your individual characteristics such as age, gender, nutritional status, family traits, life-style, and state of health, and other chemicals to which you are exposed, such as cigarette smoke. Cigarette smoking works synergistically with asbestos exposure to greatly increase your chance of getting lung cancer. The greater the total exposure to asbestos, the greater the chance you will become ill. Some experts believe that there is no definite safe exposure level for asbestos. The best way to protect yourself is to limit your exposure as much as possible.

Data also indicate that fiber size and shape is the most important factor for the cancer-causing potential of asbestos. Most studies indicate that longer fibers (greater than 1/5000th, of an inch, 5 microns) are more likely to cause injury than shorter fibers (less than 1/10,000th of an inch, 2.5 microns).

There are no known acute (short-term) effects from asbestos. That means that even inhaling high amounts of asbestos would not cause immediate symptoms the way exposure to a toxic gas leak or chemical spill might. Therefore, symptoms such as a scratchy or sore throat, congestion, coughing, or lung irritation would not be due to a recent asbestos exposure, but might be the result of inhalation of other irritating or allergenic dusts, or possibly due to illnesses, such as a cold or flu.

The chronic (long-term) health effects after exposure to asbestos take years to develop. Information on the health effects of asbestos in humans comes mostly from studies of people who were exposed in the past to high levels of asbestos in the workplace over a long period of time. Disease caused by asbestos include: asbestosis, pleural plaques, lung cancer, and mesothelioma.

Asbestosis is a chronic lung disease whose signs and symptoms result from permanent changes in lung tissue due to asbestos exposure. The earliest and most prominent sign is shortness of breath. Symptoms rarely become apparent until at least ten years after the first exposure. Asbestos fibers become lodged in the lungs, irritating the lung tissues and inflaming the small air tubes and sacs in the lungs. As the inflammation continues, permanent tissue damage, called fibrosis, develops. This damaged tissue does not expand and contract like normal lung tissue, and so breathing becomes difficult. Shortness of breath will increase over time, even after the exposure stops. Asbestosis is a serious disease, and can eventually lead to disability or death in people exposed to high amounts of asbestos. Asbestosis does not usually occur in people exposed to low levels of asbestos.

Asbestos workers were also found to have increased chances of getting two types of cancer: cancer of the lung tissue itself, and mesothelioma, a cancer of the thin membrane that surrounds the lung and other internal organs. Both lung cancer and mesothelioma are usually fatal. These diseases do not appear immediately, but develop only after a number of years. There is a substantial latency period (10-40 years in humans) between the exposure to asbestos and the occurrence of lung cancer or mesothelioma.

Early symptoms of lung cancer are coughing, chest pains, and coughing up blood. Smoking greatly increases the risk of developing lung cancer from exposure to asbestos. A smoker who is heavily exposed to asbestos is 30 to 90 times more likely to develop lung cancer than a non-smoker exposed to asbestos.

Mesothelioma is a rare and deadly form of cancer that is almost always caused by exposure to asbestos. It is truly an “asbestos cancer” and it may result from relatively light exposure to asbestos. This cancer occurs in the lining of the chest and abdomen. Early symptoms are shortness of breath or pain in the chest or abdomen. This risk of this cancer is not increased by smoking.

Members of the public who are exposed to low levels of asbestos may have increased chances of getting cancer, but the risk is small. Present measures of risk are derived from the incidence of disease observed in heavily exposed workers. Although there is little or no historical exposure data for these workers, we know that they were exposed for years to levels that may have been hundreds or thousands of times higher than levels to which the public might ever be exposed today.

The health effects from swallowing asbestos are unclear. Some groups of people who have been exposed to asbestos fibers in their drinking water have higher-than-average death rates from cancer of the esophagus, stomach, and intestines. However, it is very difficult to tell whether this is caused by asbestos or by something else and medical science has been inconclusive on this subject.

If you get asbestos fibers on your skin, very few of these fibers, if any, pass through the skin into your body. Asbestos workers often developed “asbestos warts” on their hands, but this is a benign condition. There are no known serious health effects from skin exposure.

Asbestos has not been shown to affect reproduction or cause birth defects.

Are there medical tests to determine exposure?

Anyone frequently exposed to asbestos on the job should have regular medical exams. The worker should discuss their work history with a physician, and the examination should include a complete medical history, physical examination, and possible a chest x-ray and lung function test.

The most common test used to determine if you have been exposed to asbestos is a chest x-ray. The x-ray cannot detect the asbestos fibers themselves, but can detect early signs of lung disease caused by asbestos. However, since lung disease caused by asbestos may take many years to develop, x-rays cannot detect recent asbestos exposure. While other substances besides asbestos can sometimes produce similar changes in the lungs, this test is usually reliable for detecting asbestos-related effects. The examination should also assess for other diseases that may mimic the symptoms of asbestosis, especially other lung and heart conditions. There are no simple blood or urine tests for asbestos.