Asbestos

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File:Blue asbestos.jpg
Blue asbestos (crocidolite) from Wittenoom, Western Australia. The ruler is 1 cm.
File:Blue asbestos (teased).jpg
Blue asbestos showing the fibrous nature of the mineral

The word Asbestos is derived from a Greek adjective meaning inextinguishable. It is distinguished from other minerals by the fact that its crystals form long, thin fibers. Deposits of asbestos are found throughout the world. The primary sites of commercial production are: the Commonwealth of Independent States, Canada, Brazil, Zimbabwe, Russia and South Africa.

The Greeks termed asbestos the "miracle mineral" because of its soft and pliant properties, as well as its ability to withstand heat. Asbestos was spun and woven into cloth in the same manner as cotton. It was also utilized for wicks in sacred lamps. Romans likewise recognized the properties of asbestos and it is thought that they cleaned asbestos tablecloths by throwing them into fire.[citation needed]

Asbestos became increasingly popular among manufacturers and builders in the late 19th century due to its resistance to heat, electricity and chemical damage, sound absorption and tensile strength. 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 is used in brake shoes and gaskets 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.

The inhalation of asbestos fibers can cause serious illnesses, including mesothelioma. Since the mid 1980s, many uses of asbestos are banned in many countries.

Types of asbestos and associated fibres

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Chrysotile asbestos
File:Asbestos fibres.jpg
Asbestos fibers

Six minerals are defined as "asbestos" including: chrysotile, amosite, crocidolite, tremolite, anthophyllite and actinolite.

White asbestos

Chrysotile, CAS No. 12001-29-5, is obtained from serpentine rocks which is common throughout the world. The rocks are called serpentine because their fibers curl; chrysotile fibers are curly as opposed to fibers from amosite, crocidolite, tremolite, actinolite, and anthophyllite which are needlelike.[1] 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 is used more than any other type and accounts for about 95% of the asbestos found in buildings in America.[2] 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. Chrysotile, 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.[3]

Brown asbestos

Amosite, CAS No. 12172-73-5, is a trade name for the amphiboles belonging to the Cummingtonite - Grunerite solid 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.[2] This type of asbestos, like all asbestos, is hazardous.

Blue asbestos

Crocidolite, CAS No. 12001-28-4 is an amphibole from Africa and Australia. It is the fibrous form of the amphibole riebeckite. Blue asbestos is commonly thought of as the most dangerous type of asbestos (see above and below). One formula given for crocidolite is Na2Fe2+3Fe3+2Si8O22(OH)2. Notes: chrysotile commonly occurs as soft friable fibers. Asbestiform amphibole may also occur as soft friable fibers but some varieties such as amosite are commonly straighter. All forms of asbestos are fibrillar in that they are composed of fibers with widths less than 1 micrometre that occur in bundles and have very long lengths. Asbestos with particularly fine fibers is also referred to as "amianthus". Amphiboles such as tremolite have a crystal structure containing strongly bonded ribbonlike silicate anion polymers that extend the length of the crystal . Serpentine (chrysotile) has a sheetlike silicate anion which is curved, and rolls up like a carpet to form the fiber.[4] Tremolite often contaminates chrysotile asbestos, thus creating an additional hazard.

Other asbestos

Other regulated asbestos minerals, such as tremolite asbestos, CAS No. 77536-68-6, Ca2Mg5Si8O22(OH)2; actinolite asbestos (or smaragdite), CAS No. 77536-66-4, Ca2(Mg, Fe)5(Si8O22)(OH)2; and anthophyllite asbestos, CAS No. 77536-67-5, (Mg, Fe)7Si8O22(OH)2; are less commonly used industrially but can still be found in a variety of construction materials and insulation materials and have been reported in the past to occur in a few consumer products.

Other natural and not currently regulated asbestiform minerals, such as richterite, Na(CaNa)(Mg,Fe++)5(Si8O22)(OH)2, and winchite, (CaNa)Mg4(Al,Fe3+)(Si8O22)(OH)2, may be found as a contaminant in products such as the vermiculite containing zonolite insulation manufactured by W.R. Grace and Company. These minerals are thought to be no less harmful than tremolite, amosite, or crocidolite, but since they are not regulated, they are referred to as "asbestiform" rather than asbestos although may still be related to diseases and hazardous.

In 1989 the United States Environmental Protection Agency (EPA) issued the Asbestos Ban and Phase Out Rule which was subsequently overturned in the case of Corrosion Proof Fittings v. U.S. Environmental Protection Agency, 1991. This ruling leaves many consumer products that can still legally contain trace amounts of asbestos. For a clarification of products which legally contain asbestos read the EPA's clarification statement.[5]

Production trends

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Asbestos output in 2005

In 2005, the world mined 2,200,000 tons of asbestos, Russia was the largest producer with about 40% world share followed by China and Kazakhstan, reports the British Geological Survey.[6]

Uses

Historic usage

Asbestos was named by the ancient Greeks who also recognized certain hazards of the material. The Greek geographer Strabo and the Roman naturalist Pliny the Elder noted that the material damaged lungs of slaves who wove it into cloth.[7][8] Charlemagne, the first Holy Roman Emperor, is said to have had a tablecloth made of asbestos.[9][10][11]
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[12]. 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.[13][14]
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.[15] Others assert that the ancients used asbestos to make perpetual wicks for sepulchral or other lamps.[11][13] 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 alumen plumosum, because the two terms have often been confused throughout history.[15]

Asbestos became more widespread during the industrial revolution, in the 1860s it was used as insulation in the U.S. and Canada. Development of the first commercial asbestos mine began in 1879 in the Appalachian foothills of Quebec.[16] 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.[11]

Approximately 100,000 people have died, or will die, from asbestos exposure related to ship building. In the Hampton Roads area, a shipbuilding center, mesothelioma occurrence is seven times the national rate.[17] Thousands of metric tons of asbestos were used in World War II ships to wrap the pipes, line the boilers, and cover engine and turbine parts. There were approximately 4.3 million shipyard workers during WWII, for every thousand workers about 14 died of mesothelioma and an unknown number died from asbestosis.[16]

Asbestos fibers were once used in automobile brake pads and shoes. Since the mid-1990s, a majority of brake pads, new or replacement, have been manufactured instead with Aramid fiber (Twaron or Kevlar) linings (the same material used in bulletproof vests).

Kent, the first filtered cigarette on the market, used crocidolite asbestos in its "Micronite" filter from 1952 to 1956.[18]

The first documented death related to asbestos was in 1906.[10] In the early 1900s researchers began to notice a large number of early deaths and lung problems in asbestos mining towns. The first diagnosis of asbestosis was made in England in 1924.[8] England protected asbestos workers about ten years sooner than the U.S. By the 1930s, England regulated ventilation and made asbestos an excusable work related disease.[8][19] The term Mesothelioma was not used in medical literature until 1931, and was not associated with asbestos until sometime in the 1940s.[10]

The United States government and asbestos industry have been criticized for not acting quickly enough to inform the public of dangers, and to reduce public exposure. In the late 1970s court documents proved that asbestos industry officials knew of asbestos dangers and tried to conceal them.[16]

In Japan, particularly after World War II, asbestos was used in the manufacture of ammonium sulfate for purposes of rice production, sprayed upon the ceilings, iron skeletons, and walls of railroad cars and buildings (during the 1960s), and used for energy efficiency reasons as well. Production of asbestos in Japan peaked in 1974 and went through ups and downs until about 1990, when production began to drop severely.[20]

Modern usage

Serpentine group

Serpentine minerals have a sheet or layered structure. Chrysolite is the only asbestos mineral in the serpetine group. In the United States, chrysotile has been the most commonly used type of asbestos. According to the U.S. EPA Asbestos Building Inspectors Manual, chrysotile accounts for approximately 95% of asbestos found in buildings in the United States. Chrysotile is often present in a wide variety of materials, including :

  • joint compound
  • mud and texture coats
  • vinyl floor tiles, sheeting, adhesives
  • roofing tars, felts, siding, and shingles
  • "transite" panels, siding, countertops, and pipes
  • fireproofing
  • caulk
  • gaskets
  • brake pads and shoes
  • clutch plates
  • stage curtains
  • fire blankets
  • interior fire doors
  • fireproof clothing for firefighters
  • thermal pipe insulation

In the European Union and Australia it has recently been banned as a potential health hazard[21] and is not used at all. Japan is moving in the same direction, but more slowly. Revelations that hundreds of workers had died in Japan over the previous few decades from diseases related to asbestos sparked a scandal in mid-2005.[22] Tokyo had, in 1971, ordered companies handling asbestos to install ventilators and check health on a regular basis; however, the Japanese government did not ban crocidolite and amosite until 1995, and a full-fledged ban on asbestos was implemented in October 2004.[22]

Amphibole group

Five types of asbestos are found in the amphibole group: amosite, crocidolite, anthophyllite, tremolite, and actinolite. Amosite, the second most likely type to be found in buildings, according to the U.S. EPA Asestos Building Inspectors Guide, is the "brown" asbestos.

Amosite and crocidolite were formally used in many products until the early 1980s. The use of all types of asbestos in the amphibole group was banned (in much of the Western world) by the mid-1980s, and by Japan in 1995. These products were mainly:

  • Low density insulation board and ceiling tiles
  • Asbestos-cement sheets and pipes for construction, casing for water and electrical/telecommunication services
  • Thermal and chemical insulation (i.e., fire rated doors, limpet spray, lagging and gaskets)

Health Issues

By the first century, Greeks and Romans had already observed, at least in passing, that slaves involved in the weaving of asbestos cloth were afflicted with a sickness of the lungs. [23].

Prior to 1900

Early concern about the health effects of asbestos exposure can be found in several sources. Among the earliest were reports in Britain. The annual reports of the Chief Inspector of Factories reported as early as 1898 that asbestos had 'easily demonstrated' health risks[24]

At about the same time, what was probably the first study of mortality among asbestos workers was reported in France [25]. While the study describes the cause of death as chalicosis, a generalized pneumoconiosis, the circumstances of the employment of the fifty workers whose death prompted the study suggest that the root cause was asbestos or mixed asbestos-cotton dust exposure.

1900s - 1910s

Further awareness of asbestos-related diseases can be found in the early 1900s, when London doctor H. Montague Murray conducted a post mortem exam on a young asbestos factory worker who died in 1899. Dr. Murray gave testimony on this death in connection with an industrial disease compensation hearing. The post-mortem confirmed the presence of asbestos in the lung tissue, prompting Dr. Murray to express as an expert opinion his belief that the inhalation of asbestos dust had at least contributed to, if not actually caused, the death of the worker[26].

The record in the United States was similar. Early observations were largely anecdotal in nature and did not definitively link the occupation with the disease, followed by more compelling and larger studies that strengthened the association. One such study, published in 1918, noted:

All of these processes unquestionably involve a considerable dust hazard, but the hygienic aspects of the industry have not been reported upon. It may be said, in conclusion, that in the practice of American and Canadian life insurance companies asbestos workers are generally declined on account of the assumed health-injurious conditions of the industry [27].

1920s and 1930s

Widespread recognition of the occupational risks of asbestos in Britain was reported in 1924 by a Dr. Cooke, a pathologist, who introduced a case description of a 33-year old female asbestos worker with the following: 'Medical men in areas where asbestos is manufactured have long suspected the dust to be the cause of chronic bronchitis and fibrosis...[28]." Dr. Cooke then went on to report on a case in 1927 involving a 33-year old male worker who was the only survivor out of ten workers in an asbestos carding room. In the report he named the disease "asbestosis[29]."

Dr. Cooke's second case report was followed, in the late 20's, by a large public health investigation (now known as the Merewether report after one of its two authors) that examined some 360 asbestos-textile workers (reported to be about 15% of the total comparable employment in Britain at the time) and found that about a quarter of them suffered from pulmonary fibrosis [30]. This investigation resulted in improved regulation of the manufacturing of asbestos-containing products in the early 1930s. Regulations included industrial hygiene standards, medical examinations, and inclusion of the asbestos industry into the British Workers' Compensation Act [31].

The first known US workers' compensation claim for asbestos disease was in 1927[32]. In 1930, the first reported autopsy of an asbestosis sufferer was conducted in the United states and later presented by a doctor at the Mayo Clinic, although in this case the exposure involved mining activities somewhere in South America[33].

In 1930, the major asbestos company Johns-Manville produces a report, for internal company use only, about medical reports of asbestos worker fatalities.[34] In 1932, A letter from U.S. Bureau of Mines to asbestos manufacturer Eagle-Picher states, in relevant part, "It is now known that asbestos dust is one of the most dangerous dusts to which man is exposed".[35] In 1933, Metropolitan Life Insurance Co. doctors find that 29% of workers in a Johns-Manville plant have asbestosis.[34] Likewise, in 1933, Johns-Manville officials settle lawsuits by 11 employees with asbestosis on the condition that the employees' lawyer agree to never again "directly or indirectly participate in the bringing of new actions against the Corporation."[35] In 1934, officials of two large asbestos companies, Johns-Manville and Raybestos-Manhattan, edit an article about the diseases of asbestos workers written by a Metropolitan Life Insurance Company doctor. The changes minimize the danger of asbestos dust.[35] In 1935, officials of Johns-Manville and Raybestos-Manhattan instruct the editor of Asbestos magazine to publish nothing about asbestosis.[35] In 1936, a group of asbestos companies agrees to sponsor research on the health effects of asbestos dust, but require that the companies maintain complete control over the disclosure of the results.[34]

1940s

In 1942, an internal Owens-Corning corporate memo refer to "medical literature on asbestosis . . . . scores of publications in which the lung and skin hazards of asbestos are discussed."[36] Either in 1942 or 1943, the president of Johns-Manville, Lewis H. Brown, says that the managers of another asbestos company were "a bunch of fools for notifying employees who had asbestosis." When one of the managers asks, "do you mean to tell me you would let them work until they dropped dead?" The response is reported to have been, "Yes. We save a lot of money that way."[37] In 1944, a Metropolitan Life Insurance Company report finds 42 cases of asbestosis among 195 asbestos miners.[38]

1950s

In 1951, asbestos companies removed all references to cancer before allowing publication of research they sponsor.[39]. In 1952, Dr. Kenneth Smith, Johns-Manville medical director, recommends (unsuccessfully) that warning labels be attached to products containing asbestos. Later, Smith testifies: "It was a business decision as far as I could understand . . . the corporation is in business to provide jobs for people and make money for stockholders and they had to take into consideration the effects of everything they did and if the application of a caution label identifying a product as hazardous would cut into sales, there would be serious financial implications."[40]. In 1953, National Gypsum's safety director writes to the Indiana Division of Industrial Hygiene, recommending that acoustic plaster mixers wear respirators "because of the asbestos used in the product." Another company official notes that the letter is "full of dynamite," urges that it be retrieved before reaching its destination. A memo in the files notes that the company "succeeded in stopping" the letter, which "will be modified."[41].

Asbestos as a contaminant

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.[42] 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, the more easily they 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.

Naturally occurring asbestos

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 from a likely asbestos source.[43]

Portions of El Dorado county are known to contain natural asbestos formations near the surface.[44][43] 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".[45]

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 of clean, stable material over the ground.[43]

Asbestos in the environment

Asbestos is in the air we breathe and some of the water we drink, including water from natural sources.[46] 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.[47]

The EPA has proposed a concentration limit of 7 million fibers per liter of drinking water for long fibers (lengths greater than or equal to 5 µm). The OSHA, (Occupational Safety and Health Administration) has set limits of 100,000 fibers with lengths greater than or equal to 5 µm per cubic meter of workplace air for 8-hour shifts and 40-hour work weeks.[48]

Asbestos is not part of a ASTM E 1527-05 Phase I Environmental Site Assessment (ESA). A Building Survey for Asbestos is considered an out-of-scope consideration under the industry standard ASTM 1527-05 Phase I ESA (see ASTM E 1527-05). ASTM Standard E 2356-04 should be consulted by the owner or owners' agent to determine which type of asbestos building survey is appropriate, typically either a baseline survey or a design survey of functional areas. Both types of surveys are explained in detail under ASTM Standard E 2356-04. Typically, a baseline survey is performed by an EPA (or State) licensed asbestos inspector. The baseline survey provides the buyer with sufficient information on presumed asbestos at the facility, often which leads to reduction in the assessed value of the building (due primarily to forthcoming abatement costs). Note: EPA NESHAP and OSHA Regulations must be consulted in addition to ASTM Standard E 2356-04 to ensure all statutory requirments are satisfied, ex. notification requirements for renovation/demolition. Asbestos is not a material covered under CERCLA's innocent purchaser defense.

In some instances, the U.S. EPA includes asbestos contaminated facilities on the Superfund National Priorities list (NPL). Buyers should be careful not to purchase facilities, even with a ASTM E 1527-05 Phase I ESA completed, without a full understanding of all the hazards in a building or at a property, without evaluating non-scope ASTM E 1527-05 materials, such as asbestos, lead, PCBs, mercury, radon, et al. A standard ASTM E 1527-05 does not include asbestos surveys as standard practice.

Asbestos construction in developing countries

Countries like India and China have continued widespread use of asbestos. The most common is corrugated asbestos-cement Sheets or A/C Sheets for roofing and for side walls. Millions of homes, factories, schools or sheds and shelters continue to use asbestos. Eternit Everest, Hyderabad Industries and RamCo are some of the major asbestos products manufacturers in India.

Cutting these sheets to size and drilling holes to receive 'J' bolts to help secure the sheets to roof framing is done on site. There has been no significant change in production and use of A/C Sheets in developing countries following the widespread restrictions in developed nations.

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.

Litigation

Template:Global

Main article: Asbestos and the law

Asbestos litigation is the longest, most expensive mass tort in U.S. history, involving more than 8,400 defendants and 730,000 claimants as of 2002 according to the RAND Corporation[49], and at least one defendant reported claim counts in excess of 800,000 in 2006[50].

Current trends indicate that the worldwide rate at which people are diagnosed with the disease will likely increase through the next decade[51]. Analysts have estimated that the total costs of asbestos litigation in the USA alone is over $250 billion.[52]

Litigation exists outside the United States in England, Scotland, Ireland, the Netherlands, France, Australia, and Japan among other nations. See the companion article for further information.

The volume of the asbestos liability has concerned manufacturers and insurers and reinsuers[53]. The amounts and method of allocating compensation have been the source of many court cases, and government attempts at resolution of existing and future cases.

One notable asbestos lawyer, Peter Angelos, used the the vast fortune he gained from asbestos lawsuits to buy the Baltimore Orioles. [54]

Critics of safety regulations

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According to Natural Resources Canada, chrysotile asbestos is not as dangerous as once thought. According to their fact sheet, "...current knowledge and modern technology can successfully control the potential for health and environmental harm posed by chrysotile".[55] In May of 1998, Canada requested consultations with the European Commission concerning France's 1996 prohibition of the importation and sale of asbestos.[56]

Canada claimed that the French measures contravened provisions of the Agreements on Sanitary and Phytosanitary Measures and on Technical Barriers to Trade, and the GATT 1994.[56]

The EC said that substitute materials had been developed in place of asbestos, which are safer to human health. It stressed that the French measures were not discriminatory, and were fully justified for public health reasons. The EC said that in the July consultations, it had tried to convince Canada that the measures were justified, and that just as Canada broke off consultations, it was in the process of submitting substantial scientific data in favour of the asbestos ban.[56]

Critics of Canada's support of the use of chrysotile asbestos argue that Canada is ignoring the risks associated with the material. The CFMEU pointed out that selling asbestos is illegal in Canada, but it is exported and most exports go to developing countries. Canada has pressured countries, including Chile, and the UN to avoid asbestos bans[57]

Asbestos regulation critics include the controversial Junkscience.com author and Fox News columnist Steven Milloy and the asbestos industry.[58] Critics sometimes argue that increased regulation does more harm than good and that replacements to asbestos are inferior. An example is the suggestion by Dixy Lee Ray and others that the shuttle Challenger exploded because the maker of O-ring putty was pressured by the EPA into ceasing production of asbestos-laden putty.[59][60] However, scientists point out that the putty used in Challenger's final flight did contain asbestos, and failures in the putty were not responsible for the failure of the O-ring that led to loss of the shuttle.[61][60]

Asbestos was used in the first 40 floors of the World Trade Towers and ended up contaminating the air around lower Manhattan after the towers collapsed.[62] Steven Milloy suggests that the World Trade Center towers could still be standing or at least would have stood longer had a 1971 ban not stopped the completion of the asbestos coating above the 64th floor.[63] This was not mentioned in the National Institute of Standards and Technology's report on the towers' collapse. Insulation that replaced asbestos is believed to have equivalent fire resistance, and any sort of sprayed-on insulation, including asbestos-based material, would have been removed in large areas by the impact of the planes and subsequent explosion.[64][65][66]

Substitutes for asbestos in construction

Fiberglass insulation was invented in 1938 and is now the most commonly used type of insulation material.

Many companies that produced asbestos-cement products that were reinforced with asbestos fibres have developed products incorporating organic fibres. One such product was known as Eternit and another Everite now use Nutec fibres which consist of organic fibres, portland cement and silica.

Another potential fiber is Polybenzimidazole or PBI fiber. Polybenzimidazole fiber is a synthetic fiber with no melting point that also does not ignite. Due to its exceptional thermal and chemical stability, it is often used by fire departments and space agencies.

See also

Mineralogy

Other

References

  1. American Cancer Society
  2. 2.0 2.1 Wisconson Department of Natural Resources
  3. American Cancer Society
  4. WA Deer, RA Howie, J Zussman (1992). An Introduction to the Rock-Forming Minerals, 2nd Edition, Longman. 
  5. EPA clarification statement on asbestos (PDF format)
  6. World Mineral Production 2001-2005. British Geological Survey. Retrieved on 2007-08-03.
  7. History of Asbestos
  8. 8.0 8.1 8.2 Asbestos Resource Center
  9. Time Magazine
  10. 10.0 10.1 10.2 Mesothelioma Center
  11. 11.0 11.1 11.2 Understanding Asbestos Mesothelioma Applied Research Center
  12. Dehkhoda Persian Dictionary
  13. 13.0 13.1 University of Calgary
  14. A Brief History of Asbestos Use and Associated Health Risks EnvironmentalChemistry.com website
  15. 15.0 15.1 History of science This article incorporates content from the 1728 Cyclopaedia, a publication in the public domain.
  16. 16.0 16.1 16.2 Shipyards, a Crucible for Tragedy
  17. Horrible Toll Could Have Been Avoided
  18. Cancer Research
  19. American Cancer Society
  20. Asbestos in Japan
  21. Australian prohibition on use of chrysotile asbestos
  22. 22.0 22.1 Asbestos deaths just the tip of the iceberg Japan Times Online
  23. P. Brodeur, "Annals of Law, The Asbestos Industry on Trial, 1-A Failure to Warn, The New Yorker, June 10, 1985, pp 57
  24. Chief Inspector of Factories and Workshops, "Annual Report of the Chief Inspector of Factories and Workshops for the Year 1898", 1899, cited in Tweedale referenced below
  25. D. Auribault, "Note sur l'Hygiène et la Sécurité des Ouvriers dans les Filatures et Tissages d'Amianté (On hygiene and security of the workers in the spinning and weaving of asbestos)" in Le Bulletin de l'Inspection du Travail, 1906, pp 120 - 132. This summary was given by Broduer and roughly confirmed by Merewether & Price in the report cited below.
  26. H. M. Murray, testimony before the Departmental Committee on Compensation for Industrial Diseases "Minutes of Evidence, Appendices and Index", 1907. pg 127 cited and summarized in Merewether & Price referenced below
  27. F. L. Hoffman, "Mortality from Respiratory Diseases in Dusty Trades", Bulletin of the US Bureau of Labor Statistics, Vol. 231, pp 176 - 180. Mr. Hoffman was a professional statistician, employed by Prudential with an international reputation on public health matters
  28. W. E. Cooke, "Fibrosis of the Lungs Due to the Inhalation of Asbestos Dust," British Medical Journal, 1927, pg. 487
  29. W. E. Cooke, "Pulmonary Asbestosis," British Medical Journal, 1927, pp. 1024 - 1025, cited in G. Peters & B. Peters, Sourcebook on Asbestos Diseases, Volume 1, 1980, pg. G1
  30. E.R.A. Merewether & C. W. Price, "Report on Effects of Asbestos Dust on the Lung" H.M. Stationery Office, 1930
  31. G. Tweedale, "Magic Mineral to Killer Dust, Turner & Newall and the Asbestos Hazard", Oxford University Press, 2001, page 21
  32. Broduer, pp 59 - 60
  33. R. G. Mills, "Pulmonary Asbestosis: Report of a Case", Minnesota Medicine, July 1930, pp 495 - 499
  34. Cite error: Invalid <ref> tag; no text was provided for refs named Castleman
  35. 35.0 35.1 35.2 35.3 Paul Brodeur (1985). Outrageous Misconduct: The Asbestos Industry on Trial, 1st Edition, Pantheon Books. ISBN 0-394-53320-8. 
  36. Barry I. Castleman, Asbestos: Medical and Legal Aspects, 4th edition, Aspen Law and Business, Englewood Cliffs, NJ 1996, p.195
  37. Testimony of Charles H. Roemer, Deposition taken April 25, 1984, Johns-Manville Corp., et al v. the United States of America, U.S. Claims Court Civ. No. 465-83C, cited in Barry I. Castleman, Asbestos: Medical and Legal Aspects, 4th edition, Aspen Law and Business, Englewood Cliffs, NJ 1996, p.581
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Additional reading

External links

Regulatory and government links

Mineral and mining links

Health and the environment


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