It is the long-term (chronic) effects of asbestos that are debilitating and deadly. Every kind of asbestos causes cancer, and every kind of asbestos can cause asbestosis.
Asbestosis is a progressive disease that may develop fully in seven to nine years and may cause death as early as 13 years after the first exposure. In many cases, though, the latency period is 20 years or more. When asbestos fibers (sometimes so small they are invisible) are inhaled, they lodge in and irritate the lung. This irritation sets up a reaction—an inflammation in the small air tubes and sacs of the lung. As the inflammation heals, it leaves scar tissue, called fibrosis. In the lung, this fibrosis causes the lining of the air sacs to thicken so that it is hard for oxygen to pass from the air into your bloodstream. Slowly, as the scarring progresses, the worker begins to suffocate.
This lack of oxygen and hard breathing puts a strain on the heart, so a worker suffering from asbestos may either die of suffocation or of a weak heart leading to heart failure. This entire process is called asbestosis. (Asbestosis is not the same thing as cancer, although both asbestosis and cancer are caused by asbestos exposure.)
Once the process of fibrosis or scarring starts in asbestosis, it is irreversible and progressive. A worker suffering from asbestosis will begin to notice shortness of breath, a dry cough, and sometimes pain in the upper chest or back. As the ability to breathe is limited, fingers and toes become “clubbed” — rounded with flattened nails. This is a sign of decreased oxygen reaching the blood. Because these are vague symptoms, it is easy for doctors to blame them on other causes instead of asbestos exposure. These may be the only symptoms as the disease progresses, so early diagnosis is important.
Cancer is the most serious hazard of exposure to asbestos and it takes less exposure to asbestos to cause cancer than it does to cause asbestosis. Early diagnosis is difficult, the cancer spreads rapidly, and it can rarely be cured. Two kinds of cancer are very strongly related to asbestos: lung cancer and mesothelioma. In addition, asbestos also causes cancer of the throat, stomach, esophagus, and bowel. Lung cancer caused by exposure to asbestos is the same type of cancer that is caused by smoking. When a person exposed to asbestos is also a smoker his chances of getting lung cancer are much greater.
Mesothelioma is a type of cancer that is almost always caused by exposure to asbestos. There are two main types of mesothelioma: pleural mesothelioma, occurring in the lining of the lung, and peritoneal mesothelioma, occurring in the abdominal lining. Unlike other asbestos-related diseases, mesothelioma can result even at low levels of exposure to asbestos fibers. It is the most serious asbestos-related condition. Diagnosis is difficult and usually occurs many years after exposure. It is not very responsive to therapy.
Gastrointestinal cancers such as esophageal, laryngeal, stomach, colon and rectum have been connected to asbestos exposure. These cancers are thought to be caused by swallowing asbestos fibers.