Mesothelioma and Asbestos

Mesothelioma is one of the most insidious dangers associated with asbestos. Appearing up to 50 years after asbestos exposure, malignant mesothelioma is an incurable form of asbestos cancer, and few people who contract the disease live for more than five years after diagnosis. In most cases, mesothelioma affects people who were exposed to asbestos in the past.

Mesothelioma is considered a relatively rare form of cancer. However, because few doctors were familiar with the disease, and because many of its symptoms can be mistaken for signs of other diseases, it is believed that mesothelioma has been significantly underreported as a cause of death.

Mesothelioma

The MesotheliumThe mesothelium is the tissue that lines parts of the body cavity. Mesothelial cells also cover the outer surface of most internal organs and protect them by producing a lubricant that allows organs to move around. The mesothelium of the chest is the pleura, that of the abdomen is the peritoneum, and that of the area around the heart is the pericardium.

Mesothelioma is a cancer in which cells of the mesothelium become abnormal and divide without control or order. The cancer cells can invade and damage nearby tissues and organs; they can also metastasize to other parts of the body. Most cases of mesothelioma begin in the pleura or peritoneum, causing pleural mesothelioma or peritoneal mesothelioma respectively. Rarely, they begin in the pericardium. Regardless of the location, mesotheliomas are divided into three main cell types: epithelioid, which comprises 50% to 70% of all cases, has the best prognosis; sarcomatoid comprise 7% to 20% of all mesotheliomas; the mixed/biphasic type makes up the remaining 20% to 35%.

Over 40 years ago, researchers identified a link between occupational crocidolite asbestos exposure in South African miners and the development of mesothelioma 30 to 40 years later. Between 70% and 90% of patients who develop mesothelioma have been exposed to asbestos, often through work, and cases tend to be clustered near shipyards, in veterans - particularly Navy Veterans, and plants that produce asbestos products.

High Risk OccupationsIn the past several decades, mesothelioma mortality has risen by 5% to 10% per year in most industrialized countries. This trend has been attributed to the increased use of asbestos in shipbuilding, manufacturing and construction from World War II onwards. Because of the long latency period before mesothelioma manifests, the benefits of removing asbestos from people's home and work environments and establishing health and safety regulations governing the use of asbestos may not be seen for at least another decade; deaths due to mesothelioma are expected to rise in Western Europe and the U.S. at least until 2020. Unregulated use of asbestos in other parts of the world may cause the epidemic to continue even longer in those regions.

In the U.S., between 2,000 and 3,000 new cases of mesothelioma are diagnosed each year. More men are diagnosed with mesothelioma than women, although the gap between men and women is closing. The rate of female patients with mesothelioma has remained relatively steady while men's rates have dropped. It is thought that this discrepancy is due to fewer men being exposed to asbestos at work since health and safety regulations have been enacted in what have often been male-dominated occupations such as construction, railroad work, and shipbuilding.

Before regulations regarding asbestos were put into place, workers often brought home asbestos on their clothing, exposing their family members to the fibers as well. Also, people who live or work near asbestos-related operations can be exposed to asbestos that is released into the environment. Naturally occurring asbestos can also be found in dust and rocks in certain areas; a 2005 study found that living close to such an area significantly increases the risk of developing mesothelioma.

As with other cancers, the risk of developing mesothelioma increases with age, with the average age of mesothelioma patients around 60 years, but it can strike at any age. The risk of developing mesothelioma increases as the duration and intensity of asbestos exposure increases. People exposed at younger ages are at higher lifetime risk of contracting the disease because they have more years in which the disease can develop. Studies have shown that approximately six percent of asbestos workers over the age of 35 die of mesothelioma. Researchers have also found that insulation workers, who are often exposed to asbestos, are 344 times more likely to die from mesothelioma than the general population.

Asbestos

Although people often refer to "asbestos" as though it were a specific mineral, it is actually a commercial name given to a group of naturally occurring silicate mineral fibers. What sets these fibers apart from others are the following characteristics: they are occur in bundles that can be easily separated from each other or split into thinner fibers; they have high tensile strength; they are flexible enough to be spun into threads and woven into cloth; they are resistant to fire, heat, and chemicals; and they do not conduct electricity.

Asbestos Fibers at 650X MagnificationSince asbestos fibers are very fine, if they are inhaled they can make their way into the smallest passageways of the lung where they cannot be coughed out. When asbestos fibers contaminate food or water and are swallowed, some of the fibers can stick in the digestive system. Once the fibers are inhaled or ingested, the body's defenses try to break them down and remove them, but if that is unsuccessful, the fibers can cause inflammation, scarring and cancer. In addition, the lymphatic system can carry the fibers to other parts of the body where they can do more damage.

Asbestos occurs two main forms: serpentine, which has curly fibers, and amphiboles, which have straight, needle-like fibers. There is one kind of serpentine fiber, chrysotile, and five kinds of amphibole fibers: anthophyllite asbestos, grunerite asbestos (amosite), riebeckite asbestos (crocidolite), tremolite asbestos, and actinolite asbestos. The vast majority of asbestos produced worldwide today is chrysotile. Amphiboles (particularly crocidolite) are often considered to be the most carcinogenic. However, chrysotile fibers are also associated with mesothelioma. In fact, some studies indicate that chrysotile asbestos is as dangerous as amphibole asbestos.

Between 1900 and 2003, the U.S. produced about 3.29 million metric tons of asbestos and used approximately 31.5 million metric tons. The first asbestos mines in the U.S. began operating in the 1890s; the last asbestos mine in the U.S. was closed in 2002.

Products Containing AsbestosBecause of its many useful properties and because it was relatively inexpensive to mine and use, asbestos was commonly used in building materials such as insulation, cement, vinyl floor tile, popcorn ceilings, caulking, roofing shingles, and joint compound. Asbestos was also used in brake linings, high-temperature gaskets, and textiles.

By the 1970's, however, the links between asbestos and diseases such as mesothelioma were too numerous to ignore. Eventually, new uses of asbestos were banned in the U.S. and safety and health regulations regarding the handling of asbestos were enacted.

Unfortunately, for many people those regulations came too late. It is estimated that, from 1940 to 1980, approximately 27.5 million workers in the U.S. were exposed to asbestos at work. And according to the Environmental Protection Agency, over 700,000 schools and public buildings in the U.S. may still contain asbestos insulation.

 

 

source: http://www.asbestos.net/mesothelioma/info/mesothelioma-and-asbestos