Mesothelioma and Asbestos

Asbestos is Leading Risk Factor for Mesothelioma

The main risk factor for developing mesothelioma is exposure to asbestos. Asbestos refers to a family of fibrous minerals made of silicate. Asbestos was once used in many products such as insulation, floor tiles, door gaskets, soundproofing, roofing, patching compounds, fireproof gloves and ironing board covers, and even brake pads. As the link between asbestos and mesothelioma has become well known, the use of this material has almost stopped. Most use stopped after 1989, but it is still used in some products.

Experts have linked this drop in asbestos use to the fact that the rate of development of mesothelioma is no longer increasing [in the U.S.]. Still, up to 8 million Americans may already have been exposed to asbestos.

Exposure to asbestos particles suspended in air and building materials is much less hazardous except when they are being removed. Since asbestos is a naturally occurring mineral, it can also be found in dust and rocks in certain parts of the United States as well as the world. According to the U.S. Environmental Protection Agency, as many as 733,000 schools and public buildings in the country today contain asbestos insulation. As many as 10% to 15% of schools in the United States may contain asbestos insulation.

People who may be at risk for occupational asbestos exposure include some miners, factory workers, insulation manufacturers, railroad workers, ship builders, gas mask manufacturers, and construction workers, particularly those involved with installing insulation. Several studies have shown that family members of people exposed to asbestos at work have an increased risk of developing mesothelioma, because asbestos fibers are carried home on the clothes of the workers.

The incidence rate for mesothelioma in men is dropping, probably because they are no longer being exposed directly to asbestos in their work. But the incidence rate for mesothelioma in women is steady, which suggests that they are being exposed in a way that is not directly tied to work, but more to their environment either at home or work. One example would be asbestos in buildings where they work or live. A study from California also links mesothelioma to naturally occurring asbestos deposits in mountains.

Another important point about asbestos and mesothelioma is that the risk of mesothelioma does not drop with time after exposure to asbestos. The risk appears to be lifelong and undiminished. There are 2 main forms of asbestos — serpentine and amphiboles.

Serpentine fibers are curly and pliable. Chrysotile is the only type of serpentine fiber and it is the most widely used form of asbestos.

Amphiboles are thin, rod-like fibers. There are 5 main types — crocidolite, amosite, anthrophylite, tremolite, and actinolyte. Amphiboles (particularly crocidolite) are considered to be the most carcinogenic (cancer-causing). However, even the more commonly used chrysotile fibers are associated with malignant (cancerous) mesotheliomas and should be considered dangerous as well.

When asbestos fibers are inhaled, most are cleared in the nose, throat, trachea (windpipe), or bronchi (large breathing tubes of the lungs). Fibers are cleared by sticking to mucus inside the air passages and being coughed up or swallowed. The long, thin, fibers are less readily cleared, and they may reach the ends of the small airways and penetrate into the pleural lining of the lung and chest wall. These fibers may then directly injure mesothelial cells of the pleura, and eventually cause mesothelioma.

Asbestos fibers can also damage cells of the lung and result in (formation of scar tissue in the lung), and/or lung cancer. The risk of lung cancer among people exposed to asbestos is increased by 7 times, compared with the general population. Indeed, , mesothelioma, and lung cancer are the 3 most frequent causes of death and disease among people with heavy asbestos exposure.

Peritoneal mesothelioma, which forms in the abdomen, may result from coughing up and swallowing inhaled asbestos fibers. Cancers of the larynx, pancreas, esophagus, colon, and kidney may also come from asbestos exposure, but the increased risk is small. The risk of developing a mesothelioma is related to how much asbestos a person was exposed to and how long this exposure lasted. People exposed at an early age, for a long period of time, and at higher levels are most likely to develop this cancer.

Mesotheliomas take a long time to develop. The time between first exposure to asbestos and diagnosis of mesothelioma is usually between 20 and 50 years.


asbestosis – Asbestosis is a breathing disorder caused by inhaling asbestos fibers. Prolonged accumulation of these fibers in your lungs can cause scarring of lung tissue and shortness of breath. Asbestosis symptoms can range from mild to severe, and usually don’t appear until years after exposure.

According to information provided by the Mayo Clinic, symptoms of asbestosis include shortness of breath, initially only with exertion but eventually even while resting; decreased tolerance for physical activity; coughing, chest pain, and even finger deformity (clubbing) in some cases.

Asbestosis may cause such a reduced flow of oxygen as to be disabling or even fatal. It can also lead to complications like high blood pressure in the lungs, heart problems, lung cancer, other lung damage including those affecting the lining of the lungs and chest cavity, the pleura. These include pleural thickening and hardening (pleural plaques), and abnormal accumulation of fluid between the layers (pleural effusion).

Asbestosis itself does not increase your risk of developing mesothelioma, but it indicates that you were exposed to asbestos and therefore are also at risk for developing malignant mesothelioma.

adenocarcinoma (A-den-oh-KAR-sih-NOH-muh) – Cancer that begins in cells that line certain internal organs and that have gland-like (secretory) properties.

Although commonly associated with lung cancer, adenocarcinoma is a type of cancer that develops in cells lining glandular types of internal organs, such as the lungs, breasts, colon, prostate, stomach, pancreas, and cervix. Another type of adenocarcinoma, mucinous adenocarcinoma, accounts for only 10-15% of all adenocarcinomas and is particular to aggressive carcinomas that are comprised of at least sixty percent mucus.

Non-small cell lung cancers make up over three quarters of all new lung cancer cases in the United States. While there is only one type of small cell lung cancer, there are three types of non-small cell lung cancer. The three types of non-small cell lung cancer are squamous carcinoma, large cell carcinoma, and adenocarcinoma. When adenocarcinoma develops in the lung’s air sacs, it is called bronchioalveolar adenocarcinoma. About forty percent of all lung cancer cases diagnosed today is adenocarcinoma.

Like other cancers, adenocarcinoma is the growth of abnormal cells. These cancerous cells multiply out of control and form a tumor. In the lung, as the tumor grows, it destroys parts of the lung. Eventually, the tumor’s abnormal cells can spread (metastasize) to other parts of the body, including the local lymph nodes in the chest and the central portion of the chest, called the mediastinum; the liver; the bones; the adrenal glands; and other organs, including the brain.

Adenocarcinoma is more likely than other types of lung cancer to be contained in one area of the body. If it is truly localized, it may also respond better than other lung cancers to treatment, especially surgical removal of the tumor and draining lymph nodes.

Adenocarcinoma is the most common form of lung cancer. Most of this type of cancer is found in smokers. However, it also is the most frequent type of lung cancer seen in nonsmokers. It is the most common form of lung cancer seen in women and people younger than 45.

As with other forms of lung cancer, you are more likely to get adenocarcinoma if you:

  • Are exposed to asbestos. Asbestos is a fibrous mineral that is used in home insulation, fireproofing, tiles for floors and ceilings, automobile brake linings, and other products. It is believed that asbestos fibers can cause lung cancer. People at risk of lung cancer include workers who are exposed to asbestos on the job (miners, construction workers, shipyard workers and auto mechanics who work with brakes), and people who live or work in buildings in which building products that contain asbestos are deteriorating. In addition to the adenocarcinoma type of lung cancer, individuals who have been exposed to asbestos, and particular types of asbestos, are also at a significant greater risk of developing a specialized type of lung cancer called mesothelioma.
  • Are exposed to other carcinogens in the workplace. These include uranium, arsenic, vinyl chloride, nickel chromates, coal products, mustard gas, chloromethyl ethers, gasoline, diesel exhaust and high levels of talc dust.
  • Smoke cigarettes. Smokers have 13 times more risk of developing lung cancer than nonsmokers. Cigarette smoke is associated with most cases of adenocarcinoma. Smoking is by far the leading risk factor for lung cancer, substantially more significant than all the other risk factors combined.
  • Breathe cigarette smoke. Nonsmokers who inhale the cigarette fumes of smokers have an increased risk of lung cancer.
  • Are exposed to radon gas. Radon is a colorless, odorless radioactive gas that is formed in the ground. It seeps into the lower floors of homes and public buildings and can contaminate drinking water. Radon exposure is the second leading cause of lung cancer. It’s not clear whether elevated radon levels contribute to lung cancer in nonsmokers. However, research has shown that radon exposure contributes to increased rates of lung cancer in smokers and in people exposed to higher levels of radon, such as miners. You can test the levels of radon in your home and surrounding area by using commercially available radon testing kits.

Your doctor will ask you whether you smoke or whether you live with a smoker. If you smoke, your doctor will ask you how much you smoke and how long you have smoked. Your doctor also will ask whether you have worked in an industry where you may have been exposed to asbestos or other carcinogens.

Call your doctor promptly if you have any of the symptoms of lung cancer, especially if you are a smoker or you have worked in an industry with high exposure to asbestos.

The outlook depends on the stage of the cancer and the overall health of the patient. In general, the prognosis is poor, especially if the lung cancer has spread to areas outside of the chest wall or has involved the lymph nodes of the mediastinum. This cancer can only be cured when surgery or radiation therapy can completely remove the tumor. However, many lung cancers are diagnosed at a stage when this is not possible. About 17 percent of people with adenocarcinoma survive more than 5 years after diagnosis.

Asbestos exposure increases the risk of lung cancer by nine times. A combination of asbestos exposure and cigarette smoking raises the risk to as much as 50 times.

A person who has had lung cancer is more likely to develop a second lung cancer than the average person is to develop a first lung cancer.

Repeated respiratory infections, such as bronchitis or pneumonia, can be a sign of lung cancer.

Asbestos Information

Asbestos and asbestos containing materials are responsible for causing asbestos cancer and asbestos disease cases around the world. Two of the most dangerous forms of asbestos disease are mesothelioma and asbestosis. Asbestos has been used in thousands of products for more than a century because it is highly versatile, abundant, and relatively cheap. Since asbestos is a naturally occurring mineral, it requires no manufacturing. Instead, asbestos only has to be mined, crushed, and added into products during the manufacturing process. Since asbestos is basically a rock, it is highly impervious to heat. It also happens to be chemically inert. Since its basic mineral structure is shaped in long, thin fibers, it can be broken down into these fibers to add strength and flexibility to nearly any product. A characteristic of asbestos is what is known as tensile strength. It allows products to be flexible yet strong while not adding excessive weight. Asbestos is one of few minerals that can actually be woven. Asbestos was commonly woven into materials that made excellent insulators, but were too brittle to be used by alone because they would crumble. Asbestos made insulation products flexible and durable since it was not affected by heat. Asbestos is not a very effective insulator by itself. All these qualities add up to a very useful and inexpensive product but some of them also make asbestos toxic to those that inhale asbestos fibers. There are six forms of asbestos characterized by differences in structure and color. Asbestos is also divided into two categories: serpentine and amphibole asbestos. Serpentine asbestos is made of curly fibers and amphibole asbestos is made of long, straight fibers. Both types of asbestos are considered dangerous, though it is thought amphibole asbestos forms, including crocidolite and amosite, may be more dangerous to humans.

Asbestos Exposure

Unfortunately, there are many opportunities for asbestos exposure since asbestos was used so abundantly in both industrial and consumer products. Most people that develop asbestos cancer and other asbestos diseases, including mesothelioma and asbestosis, usually have a history of chronic exposure to asbestos. Mesothelioma is somewhat unique in this respect, as mesothelioma cases have developed in people with limited asbestos exposure. As a result, there is no established “safe” level of asbestos exposure. Workers are exposed to asbestos when the substance or products containing asbestos are cut, crushed, sanded, drilled or otherwise disturbed. When left undisturbed, asbestos-containing materials can be relatively safe. In cases where asbestos materials are mined, installed, removed, demolished, or serviced, exposure can be a risk unless strict asbestos abatement techniques are employed. When inhaled, microscopic asbestos fibers can make it past the body’s natural defenses and deep into the lungs causing asbestos disease. Once within the lungs, the fibers can irritate lung tissue leading to asbestos cancer. If asbestos fibers make their way to the alveoli or air sacs in the lungs where oxygen and carbon dioxide exchange takes place, they can cause irritation and scarring called asbestosis. Asbestos fibers that pass through the alveoli and into the pleural mesothelium, can eventually lead to asbestos cancer in the form of tumors and malignant mesothelioma.

Asbestos Products

The following is a list of products that commonly contain asbestos:Roofing shinglesFelt and tar joint compoundCement pipesWall boardCeiling tilesSiding gasketsLaboratory hoodsMastics and sealantsBrake liningsFire doorsInsulation on some wiringCooling towersPaintTaping compound (thermal)Flexible duct connectorsGreenhouse materialsAppliance insulationSheet vinyl floor coveringPlaster sprayed-on fireproofingRefractory cement chalk boardsInsulation on steam pipesHeat resistant gloves and suitsAsbestos blankets Cork Board

Asbestos History

Asbestos was first discovered to be dangerous at the beginning of last century. It has been known as a carcinogen since the 1960s and was subsequently banned in more than 30 countries under grounds that there is no safe level of asbestos exposure. Mining and manufacture of most asbestos products has been ceased in the U.S., yet we continue to import more than 30 million pounds of asbestos in foreign products each year. A new recommendation by an EPA-sponsored panel of asbestos industry members and other experts on the topic called for a ban of all importation, manufacture, and mining of asbestos and asbestos containing products in the U.S. Although this may be a good sign, it also means that new risks of asbestos exposure are still developing. Since asbestos cancer and asbestos diseases take years and even decades to develop, many more cases of asbestos disease will be diagnosed.

Asbestos Legislation

On March 1, 2007, Senator Patty Murray (D-WA) introduced S. 742: Ban Asbestos in America Act of 2007 to the 110th Congress. This is an act to amend the Toxic Substances Control Act to reduce the health risks posed by asbestos-containing materials and products having asbestos-containing material, and for other purposes. The bill is an effort to ban all production and use of asbestos in America , launch public education campaigns to raise awareness about its dangers and expand research and treatment of diseases cause by asbestos. Murray’s legislation, which was first introduced in the 107th Congress, will also authorize additional studies to determine which commercial products today still contain asbestos, increase funding for asbestos-related diseases, and call for a national mesothelioma registry to help public health professionals track this deadly asbestos-related disease. Studies estimate that during the next decade, 100,000 victims in the United States will die of an asbestos related disease – equaling 30 deaths per day. The bill passed in the Senate on Oct. 4, 2007 by Unanimous Consent.

Currently, the companion to this bill, H.R. 3339, the Bruce Vento Ban Asbestos and Prevent Mesothelioma Act of 2007, is in committee in the House of Representatives. The House bill toughened the legislation, under the direction of the Environment and Hazardous Material Subcommittee of the House’s Energy and Commerce Committee, eliminating an exception for present at 1 percent or less by weight, making the ban a matter of federal statute rather than EPA regulation, and adding enforcement provisions. The bill must pass committee to make it before the full House for a vote.

Critically needed medical research funding provisions from Sen. Murray’s and Congresswoman McCollum’s legislation have not yet been added to the Committee Print. Supporters are urged to contact their Representative in Washington, DC, to urge inclusion of the research funding and swift passage of the complete bill once the funding is in place.