ASBESTOS

How Asbestos Exposure Affects the Body and Causes Mesothelioma

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The naturally occurring mineral asbestos was used in a variety of construction materials throughout much of the twentieth century. This unique mineral is fire-resistant and acts as an excellent insulator. Because to these qualities, manufacturers of construction materials mixed asbestos into paints, glues, cements, fiberboard, insulation, roofing, siding, flooring, and paper in order to enrich such building materials with asbestos’ advantageous characteristics.

However, when asbestos-containing materials are damaged or disturbed, the toxic fibers that make up asbestos can be released into the air. If inhaled, these fibers can cause significant damage to the lungs and result in lung cancer, asbestosis, or mesothelioma.

Unfortunately with mesothelioma, other areas of the body can be affected as well, including the abdomen (peritoneal mesothelioma) and heart (pericardial mesothelioma).

When most unwanted particles become inhaled or ingested, microscopic hairs called cilia will typically catch and expel them from the body. If these particles fail to be expelled, they will eventually reach the small air sacs in the lungs called the alveoli. Once this occurs, it is up to the immune system to break them down.

Asbestos fibers, however, are not easily expelled or removed from the body. In many cases, the fibers will attach themselves to the lining of the lungs and remain there for several decades. While attached, the alveoli often become inflamed and scarred.

In time, a person exposed to asbestos will become short of oxygen as carbon dioxide builds up in the blood. The increased stiffness of the lungs will also make it more difficult to breathe in and out.

Evidence has proven that inhaling asbestos on just one occasion can cause the development of mesothelioma and other asbestos-related diseases. Someone who smokes and is exposed to asbestos is at an even greater risk of contracting lung cancer or another respiratory disease.

Those who have been exposed to asbestos should seek the advice of their medical doctor and schedule routine examinations and tests. Such tests would include X-rays and CT scans, which are two of the common ways to detect mesothelioma. If an asbestos-related disease is diagnosed during the early stages of development, treatment is much more likely to have a positive effect.

Why is Asbestos so Dangerous?

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The fact that asbestos is composed of readily separated fibers is what contributes to the easy inhalation and ingestion of asbestos. The shape of these fibers reacts negatively with human tissue and biological processes. When inhaled or swallowed, these fibers can become lodged in the tissues of the linings of organs, most commonly the lungs and digestive system. Over time, the lodged fibers cause inflammation and cellular damage, which can eventually lead to a variety of terminal diseases. Even though the dangers of asbestos have been recognized since antiquity, the caustic mineral was used to make a number of products, many of which were commonly found in the home. Today, the use of asbestos in the United States is more regulated, but most U.S. residents are under the impression that asbestos was banned in the late-1980s. The Environmental Protection Agency tried to enforce a ban in 1989, but the ban was thrown out by the Fifth Circuit Court of Appeals in 1991. Asbestos is known to cause asbestosis, lung cancer, mesothelioma, and asbestos exposure increases the risk of gastrointestinal, colorectal, throat, kidney, esophagus, and gallbladder cancer. Those who suspect they may have been exposed to asbestos should speak with a doctor to be medically assessed for asbestos exposure.

Why is Asbestos Used?

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The mineral's innate resistance to heat and fire is what has made asbestos so valuable in both industrial and domestic products. Another valuable feature is its reluctance to conduct electricity. The fibers are fine, flexible and can be spun into thread and woven into cloth that is flameproof, difficult to tear, and carries excellent insulation properties. It is virtually indestructible by heat, salt water, corrosive chemicals (especially alkalies), and any chemical or biological process. The fibers mix well into other materials, such as asphalt or cement, and make such products stronger, more flexible, and fire-retardant. They do not dissolve or evaporate with water, which makes the light fibers easy to mix.

Where can Naturally Occurring Asbestos be Found?

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Though asbestos can be found throughout the United States, a map compiled from a U.S. Geological Survey database of records, along with literature on the history of asbestos mining, shows a strong band of asbestos deposits running down the eastern shoulder of the Appalachian Mountains from northern New Jersey through northern Georgia and into Alabama. In Fairfax County, Virginia, a total of eleven square miles is underlain with naturally occurring asbestos. The county has set up specific procedures in monitoring and reporting requirements for construction in the area. Another strip of asbestos deposits can be found running up the middle of Vermont and stretching into Maine. Clusters can be found in (but are not limited to) Michigan's Upper Peninsula, throughout the Rocky Mountains, across Northern and Central Washington, in Northeast and Southwest Oregon, and a high concentration is found north of Tucson, Arizona. Many deposits are located in California along fault lines, the Sierra foothills, the Klamath Mountains, and the Coast Ranges of California. California is also home to one of the largest asbestos deposits in the world, which is located within the Clear Creek Management Area.

Russia (presently the world's leading supplier), China, Kazakhstan, Brazil, Zimbabwe, and more than 15 other countries have a history of asbestos production. Only China's mining operations are growing, and they mostly serve that country's needs. Chrysotile asbestos is still mined heavily in Canada, which supplied 89 percent of the asbestos used in the United States between 2002 and 2005. Canadian labor authorities estimate the minerals are present in almost two-thirds of the earth's crust.

The intentional mining of asbestos in the United States reportedly ended in 2002, but the United States is still exporting more than one thousand metric tons a year , including asbestos-containing materials (ACMs) and reexports of materials that have come into the United States from overseas. The U.S. Geological Survey reports the United States imports nearly two thousand metric tons a year.

Types of Asbestos

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The six recognized asbestos minerals, which are considered silicates (molecules that include silicon and oxygen), include:

* Chrysotile - (Also known as white or green asbestos, from the Greek word meaning "fine, silky hair") Appears as curly, whitish fibers and constitutes 95 percent of the asbestos in use. Chrysotile is mined throughout the world, but most of the United State's chrysotile supply comes from Canada, Africa, and former USSR. Scientists believe this to be the least toxic of all asbestos forms.
* Crocidolite - (Also known as riebeckite or blue asbestos) Composed of straight fibers, most crocidolite comes from southern Africa and Australia. It is believed to be the most toxic form of all asbestos minerals.
* Amosite - (Also known as cummingtonite-grunerite or brown asbestos) The trade name "amosite" is an acronym for Asbestos Mines of South Africa, after the Amosa mines. Amosite is also straight in shape, but brittle in structure and excellent for use in heat insulation.
* Anthophyllite - This form of asbestos is brittle, white, and contains various forms of iron. It has been found to have excellent resistance to chemicals and heat.
* Tremolite - In rough form, tremolite appears white and chalky. Tremolite can also be naturally found in other mineral forms aside from asbestiform. It has been the major ingredient in industrial and commercial talc.
* Actinolite - Typically prismatic, flat in structure, and elongated. Actinolite also comes in forms other than asbestiform and has poor resistance to chemicals.

The last five amphibole (which translates to "ambiguous" in Greek) types have a slightly more complex crystal structure than chrysotile and are not used as extensively in commercial products as chrysotile. Due to their structure, amphiboles tend to stay in the lungs longer than chrysotile and are more likely to cause illness because of this factor. Some hypothesize very small contaminations of amphibole fibers within chrysotile are most to blame for cancer deaths caused by asbestos exposure.

Asbestiform minerals are found in serpentine and ultramafic rock. These rocks are located throughout the United States, especially near mountainous regions. California is exceptionally bountiful in asbestos, where the mineral can be found in at least 44 of the state's 58 counties (some geologists report asbestos is found in 50 of the 58 counties). Asbestos fibers especially form near fault zones, where temperature, pressure, and time have transformed the molecules into the asbestiform crystals.

Environmental Asbestos

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Asbestos can be found naturally in the air outdoors and in some drinkable water, including water from natural sources.[20] Studies have shown that members of general (non-occupationally exposed) population have tens of thousands to hundreds of thousands of asbestos fibers in each gram of dry lung tissue, which translates into millions of fibers and tens of thousands of asbestos bodies in every person's lungs.[21]

Asbestos from natural geologic deposits is known as "Naturally Occurring Asbestos" (NOA). Health risks associated with exposure to NOA are not yet fully understood, and current US federal regulations do not address exposure from NOA. Many populated areas are in proximity to shallow, natural deposits which occur in 50 of 58 California counties and in 19 other U.S. states. In one study, data was collected from 3,000 mesothelioma patients in California and 890 men with prostate cancer, a malignancy not known to be related to asbestos. The study found a correlation between the incidence of mesotheliomas and the distance a patient lived from known deposits of rock likely to include asbestos, the correlation was not present when the incidence of prostate cancer was compared with the same distances. According to the study, risk of mesothelioma declined by 6 percent for every 10 kilometers that an individual had lived away from a likely asbestos source.[22]

Portions of El Dorado County, California are known to contain natural asbestos formations near the surface.[23][22] The USGS studied amphiboles in rock and soil in the area in response to an EPA sampling study and subsequent criticism of the EPA study. The study found that many amphibole particles in the area meet the counting rule criteria used by the EPA for chemical and morphological limits, but do not meet morphological requirements for commercial-grade-asbestos. The executive summary pointed out that even particles that do not meet requirements for commercial-grade-asbestos may be a health threat and suggested a collaborative research effort to assess health risks associated with "Naturally Occurring Asbestos".[24]

Large portions of Fairfax County, Virginia were also found to be underlain with tremolite. The county monitored air quality at construction sites, controlled soil taken from affected areas, and required freshly developed sites to lay 6 inches (150 mm) of clean, stable material over the ground.

Health Issues About Asbestos

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Chrysotile asbestos, like all other forms of industrial asbestos, has produced tumors in animals. Mesotheliomas have been observed in people who were occupationally exposed to chrysotile, family members of the occupationally exposed, and residents who lived close to asbestos factories and mines.[1] Brown asbestos, like all asbestos, is hazardous. Amosite is the most hazardous of the asbestos minerals due to its hollow straight fiber structure that can stay airborne for up to 72 hours. It also does not get trapped by water as easily as the serpentine fibers do of crysotile. Tremolite often contaminates chrysotile asbestos, thus creating an additional hazard.

Asbestos exposure becomes a health concern when high concentrations of asbestos fibers are inhaled over a long time period.[18] People who become ill from asbestos are almost always those who are exposed on a day-to-day basis in a job where they work directly with the material. As a person's exposure to fibers increases, either by breathing more fibers or by breathing fibers for a longer time, that person's risk of disease also increases. Disease is very unlikely to result from a single, high-level exposure, or from a short period of exposure to lower levels.[18]

[edit] Other asbestos-related diseases

* Asbestos warts – caused when the sharp fibers lodge in the skin and are overgrown causing benign callus-like growths.

* Pleural plaques – discrete fibrous or partially calcified thickened area which can be seen on X-rays of individuals exposed to asbestos. They do not become malignant or cause other lung impairment.

* Diffuse pleural thickening – similar to above and can sometimes be associated with asbestosis. Usually no symptoms shown but if extensive can cause lung impairment.

[edit] Asbestos as a contaminant
Asbestos fibres (SEM micrograph)

Most respirable asbestos fibers are invisible to the unaided human eye because their size is about 3.0-20.0 µm in length and can be as thin as 0.01 µm. Human hair ranges in size from 17 to 181 µm in width.[19] Fibers ultimately form because when these minerals originally cooled and crystallized, they formed by the polymeric molecules lining up parallel with each other and forming oriented crystal lattices. These crystals thus have three cleavage planes, just as other minerals and gemstones have. But in their case, there are two cleavage planes that are much weaker than the third direction. When sufficient force is applied, they tend to break along their weakest directions, resulting in a linear fragmentation pattern and hence a fibrous form. This fracture process can keep occurring and one larger asbestos fiber can ultimately become the source of hundreds of much thinner and smaller fibers.

As asbestos fibers get smaller and lighter, they more easily become airborne and human respiratory exposures can result. Fibers will eventually settle but may be re-suspended by air currents or other movement.

Friability of a product containing asbestos means that it is so soft and weak in structure that it can be broken with simple finger crushing pressure. Friable materials are of the most initial concern due to their ease of damage. The forces or conditions of usage that come into intimate contact with most non-friable materials containing asbestos are substantially higher than finger pressure.

Lung Cancer and Asbestos

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Asbestos has also been linked to cancers of the lung, as opposed to the pleural lining of the lungs. These are likely the result of malfunction caused due the exposure and inhalation of asbestos fibers, which can also cause chronic respiratory conditions such as asbestosis.

Pericardial Mesothelioma and Asbestos

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Pericardial mesothelioma occurs in the lining of the heart and is extremely rare. Like peritoneal mesothelioma, very little is known about the relationship between the malignancy and asbestos exposure but nearly all patients have asbestos exposure history. Physicians surmise that because the cancer occurs in the heart’s lining, the asbestos fibers may impact the heart through the bloodstream.

Peritoneal Mesothelioma and Asbestos

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Peritoneal mesothelioma is less common and doctors have not exacted relationship between the asbestos exposure and the malignancy. However, nearly all peritoneal mesothelioma patients have a history of asbestos exposure. Peritoneal mesothelioma occurs in the lining of the abdominal cavity, near the digestive tract. Doctors surmise that ingested asbestos fibers lodge in the outer tissue of the organs and cause a similar inflammation as in the pleura.

Pleural Mesothelioma and Asbestos

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Pleural mesothelioma, the most common variety, is caused by inhaled asbestos fibers which lodge themselves in the pleural lining of the lungs. Asbestos fibers, which are microscopic but durable, then irritate the inner tissue, causing the growth of harmful scar tissue and eventually mesothelioma.

Asbestos Cancer

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Mesothelioma is sometimes referred to asbestos cancer. It is referred to this because the only known cause of mesothelioma is exposure to asbestos. Asbestos exposure causes mesothelioma in different ways depending on the variety of the malignancy.

Is Asbestos Banned?

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Contrary to what many people believe, asbestos is not and has never been banned in the United States. In 1976, Congress passed a law to regulate toxic substances (known as the Toxic Substances Control Act) but a total ban was not suggested. In 1989, the Environmental Protection Agency finalized regulations to ban asbestos under the aforementioned act, but two years later, a New Orleans circuit court of appeal overturned the regulation. The result was that new uses of the dangerous mineral were banned but old ones remained.

Many other industrialized nations have banned asbestos including the European Union and a handful of other countries, such as Chile, Croatia, Australia, Argentina, and Saudi Arabia. Several countries, especially those who continue to make money from the mining of asbestos, consistently fight against asbestos bans.

A few current U.S. senators, with the assistance of asbestos watchdog groups, hope to encourage the government to reconsider a ban on all asbestos products. A new bill, called the "Ban Asbestos in America Act of 2007" (S.742), was introduced by Senator Patty Murray on March 1, 2007.

Why are Airborne Fibers Dangerous?

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Inhaled asbestos fibers remain in the body and cannot be expelled. Because of this, the fibers can easily penetrate body tissues and may deposit themselves in airways and in the lung tissue. The more you're exposed, the more likely you might develop an asbestos-related disease. Most people exposed to asbestos on a very casual basis probably will not develop such a disease.

Once the fibers are lodged in the body, they will cause inflammation which may eventually result in the formation of cancerous tumors, particularly on the mesothelium - the lining of the lungs. Other affected areas may include the peritoneum - the lining of the abdomen - and the pericardium - the lining around the heart. There are various type of mesothelioma treatment options for each type.

With some recent exceptions found in workers at the World Trade Center disaster, asbestos-related diseases, such as pleural mesothelioma, usually take decades to surface. That's why current cases of mesothelioma and other asbestos-related diseases involve many individuals who were employed in shipyards during World War II, performing jobs that exposed them to friable asbestos on a daily basis. Shipyard workers are among those most affected by aggressive asbestos cancer.

Why is Asbestos a Health Concern?

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Studies estimate that approximately 3,000 different types of commercial products include asbestos. In and of itself, the mineral is not harmful, as long as it's intact. However, when the asbestos in these products is damaged and the fibers become airborne, concerns begin to arise.

"Friable" asbestos - that which is dry and can be easily crumbled with the hand - is the culprit. Such asbestos is more likely to release fibers into the air. Spray-applied asbestos fireproofing, which was used in millions of buildings throughout the world, is of the friable variety. However, some non-friable asbestos can also release airborne fibers, particularly when sanded, chopped, hammered, cut, or otherwise manipulated. That's why, when demolishing a building that contains asbestos, proper removal and disposal in a designated asbestos landfill is essential before the building is torn down.

What is Asbestos?

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For most individuals, especially those born in the last 40 years, the mention of asbestos conjures up thoughts of a dangerous substance that's sickened many people and caused myriad deaths around the world. That's an accurate description.

A common misconception on the part of many individuals, however, is that asbestos is a hazardous man-made substance, conjured up in factories around the world for commercial use. The truth is, however, that asbestos is a naturally-occurring mineral that can be found in hundreds of countries on just about every continent. As a matter of fact, asbestos is still mined in several of these countries, including Canada and Russia. Other countries have outlawed the mining of asbestos.

Asbestos is a highly-fibrous mineral with long, thin, separable fibers. The thin fibers can be spun and woven together, and possess valuable heat-resistant properties that make asbestos suitable for insulation and other such products. Indeed, for decades, asbestos was the material of choice for many industries that were manufacturing products for which heat resistance, low electrical conductivity, flexibility, and high tensile strength were essential factors. Today, there are other alternatives.

There are two kinds of asbestos. The serpentine variety is curly. Chrysotile asbestos, most commonly used for industrial purposes, is from the serpentine family. Other asbestos fibers, from the amphibole family, are very straight and needle-like. Amosite, crocidolite, tremolite, actinolite, and anthophyllite are amphibole asbestos varieties.

Currently, chrysotile asbestos is the only type mined on a wide-scale though a handful of countries continue to mine other forms. However, worldwide outrage about the use of dangerous asbestos has forced many countries to reconsider their position on mining.