Asbestos is a fire-resistant fibrous mineral that was commonly used to insulate buildings until it was discovered to be a health hazard. Asbestos fibers are able to be woven much like plant fibers (such as cotton). Asbestos fibers are hundreds of times thinner than human hair, and a microscope is needed to see them. These minerals are useful because of their resistance to most chemicals and heat. Asbestos is classified as a silicate and includes six minerals: chrysotile, crocidolite, amosite, tremolite, anthophyllite, and actinolite.
Asbestos, along with crystalline silica, is classified as a group-1 carcinogen, according to the International Agency for Research on Cancer (IARC). A Group-1 carcinogen is an agent, group of agents, mixture, or exposure circumstance that has been found, with sufficient evidence, to cause or contribute to the development of cancer in humans.
Worldwide, asbestos has been banned in 40 countries. Countries that continue to mine and export asbestos include Russia, Canada, Kazakhstan, China, and Brazil. Public concern has encouraged some of these governments to make worker exposure limits more stringent (on a level similar to that in the United States). The slower rates of change in these countries have been attributed to factors such as lack of governmental support for trade unions and social movements. One example of this is the formation of the workers social protection organization, ABREA, in Brazil in 1995. This organization has lobbied the government on behalf of workers for greater health protection as well as to ban asbestos in associated products, such as automobile brakes. Despite such changes, asbestos continues to be mined and exported. For example, Canada continued to supply the United States with more than 80% of its asbestos needs between 2002 and 2005. The United States also continues to export asbestos (including re-exports coming in from other countries) despite ending intentional mining in 2002.
Despite being banned for health and safety concerns in developed countries such as the European Union, Australia, and Japan, asbestos continues to be used extensively in developing countries such as India and China. The United States is an exception to the trend in developed countries, where asbestos is still being used in construction, typically with the use of cement asbestos piping.
Asbestos is a known contaminant of materials such as vermiculite and talc. Vermiculite is a silicate mineral that resembles mica and has a variety of industrial uses. One vermiculite mine operated by Grace and Company in Libby, Montana was found to be contaminated with asbestos. In 1999, the U.S. Environmental Protection Agency (EPA) declared the mine site a Superfund clean-up area. The federal government uses funds from the Hazardous Substance Trust Fund, also called the Superfund, to remove hazardous substances.
Asbestos fibers were used in a wide range of manufactured goods that included many construction materials (tiles and shingles), as well as coatings, textiles, and paints. These materials are not dangerous unless the asbestos in the materials becomes airborne. This may happen if the asbestos material is torn, cut, or damaged. Additionally, when the asbestos material begins to deteriorate with age, it may crumble or become dust, which may then become airborne. At this point, the fibers in the material may be either inhaled or ingested. In construction materials made in the United States, most asbestos use was banned in 1977 by the American Consumer Product Safety Commission.
The main routes for exposure are inhalation and ingestion. When inhaled, these fibers cause damage in the lungs by causing scarring (asbestosis), which may lead to lung cancer. In other cases, the asbestos may become lodged in the mesothelial lining of the lungs (also known as the pleura) to cause a type of cancer called pleural mesothelioma. Exposure to the fibers through inhalation was first linked to the development of lung disease in 1890. The first deaths attributed to asbestos exposure were reported in 1907. Most of the resulting lung diseases were due to occupational exposure. Some occupations in which asbestos exposure was particularly high include plumbers, electricians, people in the armed forces, and firefighters.
If ingested, exposure to these fibers may lead to cancers of the esophagus, stomach, and/or colon. The World Health Organization (WHO) estimates that nearly 100,000 people die worldwide each year from asbestos-related diseases. In the workplace, the WHO estimates that 125 million are exposed each year and of these, one person in every million dies from malignant mesothelioma. It is predicted that deaths due to asbestosis will continue over the next 10-15 years before they decrease.
Peak usage of asbestos-containing material occurred during the 1960s and 1970s. During this period, new technologies made it possible to incorporate asbestos into materials, such as plastics, to make them stronger and more fire-resistant. It normally takes a long time, usually several decades, before any asbestos-related disease manifests after exposure to asbestos-containing material. Due to the long latency period (or period between exposure and disease development), global incidence of lung disease related to asbestos exposure will also take decades to manifest.
Products that were produced before the 1970s that may contain asbestos include automobile brake pads, cement roofing, steam pipes and ducts, floor tiles, and any insulation associated with furnaces and ovens.
In one recent review, it was found that even with the use of power tools in the process of removal, in most of these situations airborne levels of asbestos fibers will not rise above those deemed excessive by current regulations.
Legislation controlling exposure was introduced in the United Kingdom in 1931, but the United States did not enact legislation limiting exposure until 1971. This regulation was done under Section 112 of the Clean Air Act of 1970. Shortly thereafter, asbestos was banned from clothing, sprayed fire-proofing materials used on buildings, patching compounds, gas heaters, and hairdryers. In 1986, the EPA proposed a 10-year plan for the eventual banning of asbestos from commercial use. This proposal was overturned in 1991 by a federal appeals court.
Although asbestos usage has been curtailed in many areas, it still presents a potential danger because of its widespread use earlier in the 20th Century. It may also lead to health problems in various countries where there are naturally occurring asbestos deposits in the land.
Asbestos removal is needed in situations where structures containing asbestos will be demolished or treated in some way where damage to the location may result in debris becoming airborne. In this situation, all possible steps need to be taken by a group of asbestos removal professionals in order to isolate the material and properly dispose of it so that it is not released into the environment.
The EPA and Occupational Safety and Health Administration regulate asbestos removal. Although the federal government has regulated the banning and phasing out of asbestos-containing materials in different industries, the removal of asbestos-containing materials is regulated differently in each state. When buildings containing asbestos are demolished, most states require separate removal and disposal procedures.
Asbestos has been banned from certain commercial products, such as clothing and hair dryers, but it is still being used in construction products, such as ceiling tiles, and vinyl wall coverings and coatings. Efforts have been moving forward to phase it out from general use, but it continues to be used in some sectors of the industry.
Detecting asbestos: If a material is suspected to contain asbestos, it should be monitored regularly for signs of wear or damage. Examples include insulation around plumbing in older homes, which should be monitored for damage and walls that are known to have spray-applied insulating material containing asbestos. If there is slightly damaged material, access should be limited to this area, and the material should not be touched or disturbed, according to the U.S. Environmental Protection Agency (EPA). Any damage or worn materials containing asbestos, such as gloves, stove-top pads, or ironing board covers, should be discarded.
To determine if a product contains asbestos, a sample may be sent to an EPA-certified asbestos lab for testing. Once identified as containing asbestos, the material will then need to be disposed of by a professional who takes all precautions to prevent exposure. For example, wetting the material, sealing material with polyvinyl acetate (PVA) paint, using approved vacuum cleaners, and wrapping waste asbestos in polythene may help reduce the risk of exposure during removal. The waste is disposed of as hazardous waste in landfill sites. These professionals need to operate under the Code of Practice for the Safe Removal of Asbestos with the National Occupational Health and Safety Commission and be licensed by the state in which they operate.
Asbestos repair and removal: For asbestos products that post health threats, the EPA recommends two possible corrections: repair and removal. Since these are two distinct and separate possible solutions, the consumer's decision depends on the circumstances. For example, if the material in question is in a house that will be demolished, then repair is out of the question. In this case, the asbestos will need to be removed.
Repair does not remove the asbestos, but only isolates and confines it so that fibers will not be freed into the environment. This option is usually taken when the material in question will not be disturbed. Repair entails sealing (encapsulation) or covering (enclosure). By sealing off the material from the outside air, the possibility of asbestos from this material becoming airborne is eliminated, at least as long as the integrity of the seal holds. Repair is usually less expensive than removal but may make later removal more difficult and costly. Asbestos repairs should also be done by trained professionals, since there is always a risk of exposure to fibers when asbestos is handled. Minor repairs done by the consumer are not recommended since improper handling of asbestos materials could create a hazard where none previously existed.
Removal of asbestos is generally recommended to be done by professionals who are qualified to handle asbestos. These professionals can usually be found by doing a state-by-state search using online databases.
Removal poses the greatest risk of fiber release and should be avoided unless remodeling or other major structural changes are required in a building. Removal may also be recommended if asbestos material is damaged and cannot be repaired.
In most circumstances, as long as removal is done under strict adherence to state and federal regulations by licensed professionals, risk to the consumer should be minimal. In these cases, the asbestos is removed and disposed, so there is no further exposure to the consumer and no further risk. The main danger involved with asbestos removal is present only if consumers seek to undertake this task themselves. In this case, the consumer is responsible for all safety measures and precautions. In some cases, consumers also forfeit any legal rights if they decide to do the job by themselves.
Exposure to asbestos is mainly through occupations that include construction, auto body construction, and processing of talc, vermiculite and other products. In states such as California, the presence of natural and man-made sources of asbestos plays significant roles in exposure. It has been found that winds can carry dust from asbestos mines over long distances. This dust may then be blown over nearby cities and pose a risk for residents. Recent examples include asbestos mines in Quebec, Montana, and California. In Randsburg, California, it was found that toxic dust from nearby abandoned mines were the source of toxic dust containing asbestos and arsenic at high enough levels to cause concern. In areas such as in Quebec where asbestos mining continues to this day, it has been found that there is a very strong correlation between living near the mines and the appearance of lung disease related to asbestos exposure. Recently, Canadians have called for a complete ban on asbestos mining in Quebec, but the government is waiting to make a decision that may hinge on incoming studies on cancer risks of asbestos.
A large body of evidence correlates asbestos exposure and the development of a type of cancer called malignant mesothelioma. This cancer of the lining of the lungs, or pleura, generally progresses rapidly and has a poor prognosis.
Reliable data on long-term, low-level exposure are difficult to obtain because of the few studies that have been done in this area. Nevertheless, long-term, low-level exposure, like that in public buildings, probably does not represent any additional health hazard beyond that from breathing outdoor air.
Extensive studies examining the potential advantages and disadvantages associated with removal and repair are lacking. Generally, buildings containing asbestos will require removal procedures if these are to be demolished. However, if the building is to remain standing, then repair is the best choice. If removal is chosen in this situation, it will be more costly, and the potential problem is the unnecessary risk for creating airborne asbestos if procedures are not done correctly.
Asbestos removal is a two-part process: isolation of the material and disposal. First, appropriate procedures are done to ensure all materials are wetted to prevent airborne fibers. These procedures vary from state to state as well as with the type of asbestos involved. Removal is done with hand tools with all persons involved wearing proper ventilators and protective clothing and equipment. After the material is removed and isolated, it is sealed in bags. It is then disposed of at a designated landfill.
Removal protocols may vary depending on the type of asbestos and in what area it is located. For example, the process for removing wall siding contaminated with asbestos would be different from removing floor tiles that are contaminated. In each case, the asbestos would need to be kept wet so that any possibility of it becoming airborne is low. The material is sealed in bags and prepared for transport to a designated disposal site.
General: Asbestos fibers may enter the body through skin contact, ingestion, or inhalation. Most of the research on adverse health effects from asbestos pertains to the effects due to inhalation of the fibers. The concentrations of fibers inhaled were in amounts that overcame normal pulmonary defense and clearance mechanisms. Asbestos is one of the most common occupational carcinogens, causing about half of the deaths from cancer due to workplace exposure. Asbestos workers who also smoke have been shown to be at a much higher risk of disease than those who do not smoke.
Lung diseases associated with asbestos exposure include pulmonary fibrosis, lung cancer, asbestosis, pleural plaques, benign pleural effusion, and malignant mesothelioma. Tumors may develop even after relatively short exposures to asbestos, with the risk increasing greatly after five years of occupational exposure.
Complications of asbestos exposure :
Asbestosis: Asbestosis is a disease similar to pulmonary fibrosis. It results in the widespread formation of scar tissue in the lungs after asbestos fibers are inhaled into the air sacs. The body cannot get rid of the fibers. As the body tries to respond to the infiltration, scarring results in the lung tissue. This is a chronic inflammatory condition that is widely seen in patients involved in mining occupations. People with asbestosis usually exhibit severe shortness of breath (dyspnea) and have an increased risk for cancer.
Autoimmune dysfunction: Exposure to silicates, such as asbestos, has also been linked to the development of autoimmune dysfunction. Some malignancies from asbestos exposure may be considered a failure in the body's immune system to fight tumor growth. No safe level of exposure for asbestos has ever been established.
Benign pleural effusion: Accumulation of fluid in the pleural space may occur after asbestos exposure.
Lung cancer: Lung cancer is most likely to develop in people who have both been exposed to asbestos and who smoke at the same time. The risk of developing cancer also increases with the presence of chronic inflammatory conditions such as asbestosis.
Malignant mesothelioma: Asbestos exposure may also cause malignant mesothelioma, a cancer of the lining of the chest and abdominal cavity. Although the latency period is generally thought to be 20-40 years between the first exposure and the diagnosis of mesothelioma, it may actually be longer. It is not clear from the literature exactly how continuous or sporadic asbestos exposure needs to be in order to result in disease. It has been found, however, that even short exposures can result in disease. Other co-factors in the incidence of mesothelioma include genetic susceptibility, diet, virus exposure, immune system impairment, and inflammation. Increased occurrence of mesothelioma within certain families has been observed. Diets high in fruits and vegetables seem to have a protective effect. Serum levels of antioxidants (such as alpha-tocopherol and ascorbic acid) have been documented to be reduced in patients with mesothelioma. Viruses, although still a controversial area, have been linked to increased risk of developing mesothelioma. This has been observed to occur with simian virus 40, although some studies have challenged the reliability of this link. This virus is known to have been a contaminant in early versions of polio vaccines. Certain asbestos fiber types are also linked with greater risk for mesothelioma. It is known that exposure to amphibole fibers is much more likely to produce mesothelioma than chrysotile fibers. This is thought to be due to the higher iron content of amphibole fibers, which speeds up the production of free radicals, which are naturally occurring molecules that can damage many cells in the body. Although occupational exposure has been the focus of much research, populations living even long distances from an asbestos source, such as naturally occurring sites in California, may still be at an increased risk of mesothelioma. It has been found that desert winds in areas of California may carry toxic dust from these areas over long distances to expose populations in nearby cities.
Effective treatment for advanced cases of malignant mesothelioma has not been developed, although it is usually approached in a multimodal fashion with emphasis on surgical resection, chemotherapy, or radiotherapy. There are more experimental treatment options for mesothelioma that have appeared in the last decade. For instance, drugs that fight blood vessel growth (anti-angiogenic drugs) have been suggested as a potential treatment option. Other conditions that involve fibrosis, such as asbestosis, are also difficult to treat, although the prognosis is better than that of malignant mesothelioma. Treatment usually entails procedures to relieve the pain and discomfort resulting from the condition as well as supplying extra oxygen to make up for the lost lung capacity.
Pleural plaques: Asbestos exposure may lead to pleural plaques, or the formation of fibrotic scars, and a thickening of the pleural membranes.
Pulmonary fibrosis: Asbestos exposure may lead to pulmonary fibrosis, or the thickening of lung tissue, which gradually forms scar tissue. Pulmonary fibrosis decreases the area of actual usable lung tissue for breathing and results in decreased lung capacity.
Preventing asbestos exposure :
Removing asbestos: The initial public outcry to rid public buildings of asbestos has resulted in costly removals. Many of these removals have been deemed unnecessary as long as the asbestos material is not disturbed and will not create fibers that may become airborne. If the material is in good condition, it is recommended not to disturb it. Any material containing asbestos will not release fibers as long as the material is not damaged. Of course, asbestos removal may be the only choice in the case of buildings that need to be extensively renovated or demolished. As long as licensed professionals are contracted to do the work, the process should be effective and environmental contamination with asbestos would be minimal.
The main safety issue is with the risk that any material involved could be damaged so that airborne asbestos fibers are produced. This damage may occur during repair or removal of appliances associated with asbestos material. This would also include activities such as sanding, drilling, or sawing of insulating material that may contain asbestos.
FUTURE RESEARCH OR APPLICATIONS
Worldwide, all forms of asbestos have been banned in 40 countries due to their potential health hazards. However, other countries have maintained or increased their production of asbestos. This increase is especially typical for developing countries, such as India and China, where asbestos production is linked to economic growth and a booming construction industry. Chrysotile-type asbestos, for example, is still being used in cement building materials in developing countries such as India and China.
Asbestos continues to be used and mined in countries such as Canada, Russia, and China. Most developed countries in the world, including the European Union, Australia, and Japan, have banned its use. The United States has only banned asbestos in certain commercial applications, but it continues to use it in other areas of industry while trying to regulate exposure so that exposure to asbestos is a minimum in areas such as construction.
Disease latency is the amount of time it usually takes for disease to appear after a person is exposed to a disease-causing agent, such as asbestos. It may take decades before a person exposed to asbestos actually exhibits signs of disease caused by this exposure. Since the disease latency is 20-40 years, asbestos-related disease or death are not expected to decrease for several decades.
It appears that little of the technology used for asbestos removal has changed over the past couple of years.
This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
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