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Asbestos (from Greekἄσβεστος or asbestinon, meaning "unquenchable" or "inextinguishable") is a set of six naturally occurring silicate minerals exploited commercially for their desirable physical properties. They all have in common their asbestiform habit, long, (1:20) thin fibrous crystals. The inhalation of asbestos fibers can cause serious illnesses, including malignant lung cancer, mesothelioma (a formerly rare cancer strongly associated with exposure to amphibole asbestos), and asbestosis (a type of pneumoconiosis). Long exposure to high concentrations of asbestos fibers is more likely to cause health problems, as asbestos exists in the ambient air at low levels, which itself does not cause health problems. The European Union has banned all use of asbestos and extraction, manufacture and processing of asbestos products.[
Asbestos became increasingly popular among manufacturers and builders in the late 19th century because of its sound absorption, average tensile strength, and its resistance to heat, electrical and chemical damage. When asbestos is used for its resistance to fire or heat, the fibers are often mixed with cement or woven into fabric or mats. Asbestos was used in some products for its heat resistance, and in the past was used on electric oven and hotplate wiring for its electrical insulation at elevated temperature, and in buildings for its flame-retardant and insulating properties, tensile strength, flexibility, and resistance to chemicals.
Serpentine White Chrysotile, CAS No. 12001-29-5, is obtained from serpentinite rocks which are common throughout the world. Its idealized chemical formula is Mg3(Si2O5)(OH)4. Chrysotile fibers are curly as opposed to fibers from amosite, crocidolite, tremolite, actinolite, and anthophyllite which are needlelike. Chrysotile, along with other types of asbestos, has been banned in dozens of countries and is only allowed in the United States and Europe in very limited circumstances. Chrysotile has been used more than any other type and accounts for about 95% of the asbestos found in buildings in America. Applications where chrysotile might be used include the use of joint compound. It is more flexible than amphibole types of asbestos; it can be spun and woven into fabric. The most common use is within corrugated asbestos cement roof sheets typically used for outbuildings, warehouses and garages. It is also found as flat sheets used for ceilings and sometimes for walls and floors. Numerous other items have been made containing chrysotile including brake linings, cloth behind fuses (for fire protection), pipe insulation, floor tiles, and rope seals for boilers.
Amphibole Brown Amosite, CAS No. 12172-73-5, is a trade name for the amphiboles belonging to the Cummingtonite-Gruneritesolid solution series, commonly from Africa, named as an acronym from Asbestos Mines of South Africa. One formula given for amosite is Fe7Si8O22(OH)2. It is found most frequently as a fire retardant in thermal insulation products and ceiling tiles.
Historic usage Asbestos use in human culture dates back at least 4,500 years, when evidence shows that inhabitants of the Lake Juojärvi region in East Finland strengthened earthenware pots and cooking utensils with the asbestos mineral anthophyllite. Asbestos was named by the ancient Greeks. One of the first careful descriptions of the material is attributed to Theophrastus in his text On Stones, around 300 BC, although the naming of minerals was not very consistent at that time (the modern Greek word ἀσβεστος stands for lime, not for the material known as asbestos in English). The term asbestos is traceable to Roman naturalist Pliny the Elder's manuscript Natural History, and his use of the term asbestinon, meaning "unquenchable". While Pliny is popularly attributed with recognising the detrimental effects of asbestos on slaves, examination of primary sources shows that this is not so.Charlemagne, the first Holy Roman Emperor, is said to have had a tablecloth made of asbestos.
Wealthy Persians, who bought asbestos imported over the Hindu Kush, amazed guests by cleaning the cloth by simply exposing it to fire. According to Biruni in his book of Gems, any cloths made of asbestos (Persian: آذرشست, āzarshast or Persian: آذرشب, āzarshab) were called (Persian: شستكه) shastakeh. Some of the Persians believed the fiber was fur from an animal (named samandar, Persian: سمندر) that lived in fire and died when exposed to water., hence the old mistaken myth that the salamander tolerated fire
. While traveling to China, Marco Polo described observing miraculous garments that were cleaned by being placed in fires. These garments were likely made from asbestos. Some archeologists believe that ancients made shrouds of asbestos, wherein they burned the bodies of their kings, in order to preserve only their ashes, and prevent their being mixed with those of wood or other combustible materials commonly used in funeral pyres. Others assert that the ancients used asbestos to make perpetual wicks for sepulchral or other lamps. In more recent centuries, asbestos was indeed used for this purpose. Although asbestos causes skin to itch upon contact, ancient literature indicates that it was prescribed for diseases of the skin, and particularly for the itch. It is possible that they used the term asbestos for soapstone, because the two terms have often been confused throughout history.
Health problems Left-sided mesothelioma : CT chest Amosite and crocidolite are the most hazardous of the asbestos minerals because of their long persistence in the lungs of exposed people. Tremolite often contaminates chrysotile asbestos, thus creating an additional hazard. Chrysotile asbestos, like all other forms of 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. The most common diseases associated with chronic exposure to asbestos include: asbestosis and pleural abnormalities (mesothelioma, lung cancer)  Asbestos exposure becomes a health concern when high concentrations of asbestos fibers are inhaled over a long time period. People who become ill from inhaling asbestos are often those who are exposed on a day-to-day basis in a job where they worked directly with the material. As a person's exposure to fibers increases, because of being exposed to higher concentrations of fibers and/or by being exposed for a longer time, then 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.
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. Although pleural plaques are themselves asymptomatic, in some patients this develops into pleural thickening. Diffuse pleural thickening: similar to above and can sometimes be associated with asbestosis. Usually no symptoms shown but if exposure is extensive, it can cause lung impairment.
asbestos is a known carcinogen that has killed untold thousands of people worldwide. While the health risks associated with asbestos are well known, the substance still is not universally banned. Many countries have banned the use of asbestos, but the United States is not among them. Respiratory Health Risks Inhaling asbestos fibers can cause pleural plaques and pleural thickening (two types of scarring of the lining of the lungs), asbestosis (a chronic inflammatory condition that affects the lungs), lung cancer (tumors and cancerous growths in the lobes of the lung) and mesothelioma (a rare cancer that can affect the lungs, as well as other tissues in the chest and abdominal cavity). Other Health Risks Inhaling or ingesting asbestos can also lead to cancers of the gastro-intestinal tract, ovarian cancer, throat cancer, chronic obstructive pulmonary disease and a rare form of mesothelioma that affects the testicles.
U.S. Asbestos Practices The use of asbestos has not been banned in the United States, although many applications of the material are no longer permitted. The Environmental Protection Agency attempted to ban the substance in the late 20th century, but its efforts were thwarted in a court case in the early 1990s. Asbestos Bans The use of asbestos has been banned in Australia, France and Brazil, among many other countries. The Developing World Many poorer countries of the developing world--including those in Southeast Asia and Africa--rarely regulate the handling or disposal of asbestos. Countries in the West, such as Canada, export asbestos to these countries, and this practice is criticized by many humanitarian organizations. Read more: Why Is Asbestos Banned? | eHow.comhttp://www.ehow.com/facts_6115342_asbestos-banned_.html#ixzz0BbqqR9nD
The Case for a Global Ban on Asbestos The Asbestos Cancer Pandemic Top Occupational exposures to asbestos. About 125 million people around the world are exposed to asbestos in their work environments (WHO 2006), and many millions more workers have been exposed to asbestos in years past. As noted by Stayner et al. (1997), the U.S. National Institute for Occupational Safety and Health (NIOSH) has estimated that current occupational exposures to asbestos, even at the U.S. Occupational Safety and Health Administration (OSHA) permissible exposure limit, will cause five deaths from lung cancer and two deaths from asbestosis in every 1,000 workers exposed for a working lifetime.
In 2000, an estimated 43,000 deaths worldwide resulted from malignant mesothelioma, and a much larger number of lung cancer deaths were due to occupational exposures to asbestos (Driscoll et al. 2005). Population-attributable risk for lung cancer among males exposed to asbestos ranges between 10% and 20% (Albin et al. 1999). An estimated 20,000 asbestos-related lung cancers and 10,000 cases of mesothelioma occur annually across the population of Western Europe, Scandinavia, North America, Japan, and Australia (Tossavainen 2000). The national incidence rates for mesothelioma in Australia are the highest in the world (Leigh and Driscoll 2003).
In the United Kingdom, at least 3,500 people die from asbestos-related illnesses each year, and this number is expected to increase to 5,000 in future years. Asbestos accounts for more than half of the work-related cancer deaths in Great Britain (Rushton et al. 2008). The British mesothelioma death rate is now the highest in the world, with 1,749 deaths in men (1 in 40 of all cancer deaths in men < 80 years of age) and 288 in women in 2005 (Rake et al. 2009). The projected lifetime risk of fatal mesothelioma in all British men born in the 1940s is 0.59%, or about 1 in 170 of all deaths. By 2050, there will have been approximately 90,000 deaths from mesothelioma in Great Britain, 65,000 occurring after 2001 (Hodgson et al. 2005). Environmental exposures to asbestos.Nonoccupational, environmental exposure to asbestos from the use of construction materials that contain asbestos is also a serious and often neglected problem throughout the world. In developed countries, large quantities of asbestos remain as a legacy of past construction practices in many thousands of schools, homes, and commercial buildings. In developing countries, where asbestos is used today in large quantities in construction, asbestos-contaminated dust is now accumulating in thousands of communities, with virtually all people burdened with asbestos fibers in their lungs and bodies (Brophy et al. 2007; Kazan-Allen 2005).
Both community-based and industrial exposures to asbestos and asbestiform fibers increase risks for mesothelioma (Pasetto et al. 2005). In a study of women residing in Canadian asbestos-mining communities, Camus et al. (1998) found a 7-fold increase in the mortality rate from pleural cancer. In California, residential proximity to naturally occurring asbestos was significantly associated with increased risk of mesothelioma (Pan et al. 2005); the risk of mesothelioma decreased approximately 6.3% for every 10-km increase in residential distance from the nearest asbestos source. Driece et al. (2009) reported that environmental exposures to asbestos waste on the surfaces of roads and yards in a contaminated community of 130,000 residents in the Netherlands result in several cases of malignant mesothelioma each year. The currently observed increase in female cases of mesothelioma in the United Kingdom, many with no occupational exposure to asbestos, suggests widespread environmental contamination (Rake et al. 2009). In a study in Libby, Montana, (Vinikoor et al. 2010), respiratory symptoms were positively associated with the frequent handling of vermiculite insulation. Residents of this mining community who were children when the mine closed experienced respiratory symptoms associated with asbestos-contaminated vermiculite exposure.
The Need for a Universal Ban on Asbestos The profound tragedy of the asbestos pandemic is that all illnesses and deaths related to asbestos are preventable. Safer substitutes for asbestos exist, and they have been introduced successfully in many nations. Currently, asbestos cement products account for > 85% of world consumption (Virta 2005), and in about 100 countries, asbestos-containing pipes and sheets are manufactured to be used as low-cost building materials (Tossavainen 2004). However, these asbestos cement water-pipe products could be replaced with ductile iron pipe, high-density polyethylene pipe, and metal-wire–reinforced concrete pipe. Many substitutes exist for roofing as well as interior building walls and ceilings, including fiber-cement flat and corrugated sheet products that are made with polyvinyl alcohol fibers and cellulose fibers. Virtually all of the polymeric and cellulose fibers used instead of asbestos in fiber-cement sheets are > 10 µm in diameter and therefore nonrespirable (WHO 2005). For roofing, lightweight concrete tiles can be made and used in the most remote locations using locally available plant fibers, such as jute, hemp, sisal, palm nut, coconut coir, and wood pulp. Galvanized iron roofing and clay tiles are among the other alternative materials (World Bank Group 2009).
If global use of asbestos were to cease today, a decrease in the incidence of asbestos-related diseases would become evident in approximately 20 years (WHO 2006). The asbestos cancer pandemic may take as many as 10 million lives before asbestos is banned worldwide and all exposure is brought to an end (LaDou 2004). But the world’s current production of asbestos continues at an alarming rate; therefore; these figures may not reflect the true burden of this pandemic. An international ban on the mining and use of asbestos is urgently needed. The risks of exposure to asbestos cannot be controlled by technology or by regulation of work practices. Scientists, physicians, and responsible authorities in countries allowing the use of asbestos should have no illusion that “controlled use” of chrysotile asbestos is an effective alternative to a ban on all use of asbestos (Castleman 2003; Egilman and Roberts 2004). Even the best systems of workplace controls cannot prevent occupational and environmental exposures to products in use, or exposures to asbestos discarded as waste. Safer substitute products are in use in countries all over the world where asbestos is banned. To protect the health of all—now and in future environments—the CollegiumRamazzini again calls on all countries of the world to join in the international endeavor to ban the mining, manufacture, and use of all forms of asbestos.
Date: FEB,25,2011Name: CHRISTIAN S. GEÑORGACourse: BS- ENTREPRENEURSHIP Year/Section: II-ASubject:earth scienceDay/Time Schedule: 7:30 – 8:30