Prolonged exposure to airborne asbestos fibers increases a person's risk of developing respiratory problems, because the fibers are inhaled, and become embedded in lung tissue. People with prolonged asbestos exposure are likely to have more asbestos fibers remain in their lungs, increasing their risk for three major diseases: mesothelioma, lung cancer, and asbestosis.
A cancer of the mesothelium, the thin membrane that lines the chest and abdominal cavity, and covers the organs within each of these cavities. Mesothelioma is a relatively rare cancer, accounting for only 1% of all cancer diagnoses, and almost all cases of mesothelioma are linked to asbestos exposure. Inhaled asbestos fibers work their way into the chest cavity or the abdominal cavity, and lodge in the mesothelium. The disease progresses slowly; symptoms may not appear for 15 years, sometimes for as long as 40 years after the initial exposure.
The membrane thickens into a hard, inflexible rind, forming bumps and nodules. The enlarging cancerous tissue produces large amounts of fluid that crowds the pleural or abdominal cavity, and the cancer itself compresses nearby organs. Pleural mesothelioma may invade the heart, the lungs, and the diaphragm. Peritoneal mesothelioma leaks fluid into the abdominal cavity, and the cancer may invade the esophagus, the liver or the stomach and small intestines. It may also encroach on large blood vessels, making surgical removal of the cancer difficult, sometimes impossible.
Mesothelial cells provide lubricating secretions which allow the organs in the chest and the abdomen to move freely. As the cancer progresses the mesothelial cells go into overdrive, and produce far more fluid than is needed, and more than the cavity can comfortably accommodate. In mesothelioma of the chest cavity, this excess fluid is called pleural effusion. Fluid pressure on the lungs and heart create a severe, crushing pain. Ascites is the term for excess fluid in the abdomen, and there it also creates pressure and causes severe pain.
As the tumor mass enlarges, patients with pleural mesothelioma may suffer frequent respiratory infections, a persistent cough, shortness of breath, constant, overwhelming fatigue, and severe chest pain. Peritoneal mesothelioma may cause weight loss, digestive and bowel problems, and abdominal pain. Mesothelioma victims cannot sleep comfortably, and frequently lose appetite as well. By the time the symptoms are severe enough for the victim to seek medical help, the disease may be far advanced, even metastasized to other organs. Once the mesothelioma has metastasized, it is far advanced, and incurable.
Pleural mesotheliomas, involving the lungs, occur about four times as frequently as peritoneal mesothelioma. In pleural mesothelioma usually only one lung is involved. Among mesothelioma victims there are five times as many men as women, a fact which reflects the distribution of men and women in jobs with high exposure to asbestos. Men and women are equally represented among victims of as peritoneal mesothelioma.
The largest number of asbestos related deaths occurs from lung cancer. People who have worked in asbestos mines or in factories where asbestos products were manufactured, or who have worked installing asbestos products have a significantly higher risk for lung cancer. People with occupational exposure to asbestos who also smoke tobacco sharply increase their risk for developing lung cancer. Common symptoms include a persistent cough, chest pain, shortness of breath, hoarseness, and anemia.
Asbestosis is a progressive disease of the lungs caused by inhaling asbestos fibers. The fibers penetrate lung tissue, irritating it and causing it to scar. The changes in lung tissue by scarring, although non-cancerous, are serious and potentially disabling. The scar tissue makes it harder for oxygen to penetrate into the alveoli, the tiny sacs in the lung where oxygen exchange takes place. Asbestosis victims make a characteristic crackling sound when they inhale. Asbestosis also causes a chronic shortness of breath and fatigue, so that many asbestosis victims require constant oxygen. There is no treatment that can reverse asbestosis.