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  1. 1. Asbestos<br />
  3. 3. ASBESTOS<br />TO BAN OR NOT TO BAN?<br />
  4. 4. DEFINITION:<br />ASBESTOS - (from Greekἄσβεστος or asbestinon, meaning<br /> "unquenchable" or "inextinguishable")[1][2] is a set of six<br />naturally occurring silicate minerals exploited <br />commercially for their desirable physical properties.<br />
  5. 5. ADVANTAGES:NOT TO BAN<br />* 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.<br />
  6. 6. * Six minerals are defined by the United States Environmental Protection Agency as "asbestos" including that belonging to the serpentine classchrysotile and that belonging to the amphibole class amosite,crocidolite, tremolite, anthophyllite and actinolite. There is an important distinction to be made between serpentine and amphibole asbestos due to differences in their chemical composition and their degree of potency as a health hazard when inhaled. However asbestos and all commercial forms of asbestos (including chrysotile asbestos) are known to be human carcinogens based on sufficient evidence of carcinogenicity in humans.<br />
  7. 7. valve and pipe image by DariaMiroshnikova from<br />Many pipes are insulated with asbestos cement.<br />Unlike other applications of asbestos, asbestos cement is not banned in the United States. In 1999, the EPA was forced to clarify which asbestos products were banned for safety after losing a blanket asbestos ban in court. The EPA failed to demonstrate certain building materials containing asbestos were any more dangerous than other materials, <br />
  8. 8. Durability<br />The mineral fibers of asbestos mixed into cement add longevity to the product. For example, asbestos cement roof shingles last on average 50 to 60 years. Other construction materials, such as wood and plastic, are not expected to last nearly as long. When adding asbestos to cement, the fibers are technically a type of stone. <br />Inexpensive<br />Cement is a fairly inexpensive construction material, as it is just the binder. The real cost comes in the additive material known to increase the strength of the concrete, called the "pozzolan." Asbestos minerals are naturally occurring and less expensive in comparison to other cement additives. This leads to a cheaper construction piece, like a wall sheet or pipe, but with the same durability. <br />Fireproofing<br />Fire is a serious threat to any building, residential or commercial. Asbestos fibers are mineral, resistant to fire and even chemical damage. Asbestos doesn't burn, so using asbestos cement in areas prone to fire exposure, such as around electrical components or in commercial buildings with high heat sources, is ideal. <br />Health Concerns<br />While asbestos cement should not allow asbestos fibers to become airborne, it can occur with careless construction methods and without proper maintenance. Long-term exposure to asbestos fibers is linked to causing lung cancer and mesothelioma. Asbestos fibers are microscopic, so someone may not even be aware the fibers are in the air. Any asbestos cement showing signs of wear needs immediate attention. <br />High Repair Costs<br />While the durability is good, eventually even asbestos cement must be repaired or replaced. While not impossible, great care and special equipment is needed to work on asbestos-containing materials to prevent the fibers from releasing. For example, asbestos materials should remain wet or removed intact. Workers should use masks or other breathing filters while working. Therefore, the savings on asbestos cement at construction could easily become negated down the road from repair and replacement costs. <br />
  9. 9. Asbestos became more widespread during the industrial revolution; in 1866 it was used as insulation in the U.S. and Canada. Development of the first commercial asbestos mine began in 1874 in the Appalachian foothills of Quebec.[20] By the mid 20th century uses included fire retardant coatings, concrete, bricks, pipes and fireplace cement, heat, fire, and acid resistant gaskets, pipe insulation, ceiling insulation, fireproof drywall, flooring, roofing, lawn furniture, and drywall joint compound.<br />
  10. 10. otheRasbestos-relatediseasesAsbestos 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.<br />
  11. 11. conclusion:<br />Asbestos must to be ban.<br />
  12. 12. end<br />
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