Asbestos

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Asbestos is a naturally occurring mineral, distinguished from other minerals by the fact that its crystals form long, thin fibers. it is also gay

The Greeks termed asbestos the "miracle mineral" because they admired it for its soft and pliant properties, as well as its ability to withstand heat (the word asbestos' is derived from a Greek adjective meaning "inextinguishable"). 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 because of 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.

Deposits of asbestos are found throughout the world. The primary sites of commercial production are: the Commonwealth of Independent States, Canada, Brazil, Zimbabwe, South Africa, and Russia.

Contents 1 Types 1.1 White asbestos 1.2 Brown asbestos 1.3 Blue asbestos 1.4 Other asbestos 2 Production trends 3 Uses 3.1 Ancient history 3.2 Eighteenth and nineteenth centuries 3.3 Modern usage 3.3.1 Serpentine group 3.3.2 Amphibole group 4 Health issues 4.1 Early corporate research 4.2 Asbestos as a contaminant 4.3 Naturally occurring asbestos 4.4 Asbestos in the environment 4.5 Asbestos construction in developing countries 4.6 Other asbestos-related diseases 5 Litigation 6 Critics of safety regulations 7 Substitutes for asbestos in construction 8 See also 8.1 Mineralogy 8.2 Other 9 Notes 10 References 11 External links 11.1 Regulatory and government 11.2 Mineral and mining 11.3 Health and the environment

[edit] Types

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

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, 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 sheetlike crystalline structure. Serpentine (chrysotile) has a stringlike crystalline structure.^[1] Tremolite often comtaminates chrysotile asbestos, thus creating an additional hazard.

[edit] 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.^[2] 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.^[3] 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.^[4]

[edit] 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.^[3]

[edit] 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. One formula given for crocidolite is Na₂Fe²⁺₃Fe³⁺₂Si₈O₂₂(OH)₂.

[edit] 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 visit the EPA's clarification statement.^[5]

[edit] Production trends

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.^[6]

[edit] Uses

[edit] Ancient history

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] Charlemagne, the first Holy Roman Emperor, had a tablecloth made of asbestos.^[8][9] Wealthy Persians, who bought asbestos imported over the Hindu Kush, amazed guests by cleaning the cloth simply by exposing it to fire. The Persians believed the fiber was fur from an animal that lived in fire and died when exposed to water.^[10][11] 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.^[12]

Others assert that the ancients used asbestos to make perpetual wicks for sepulchral or other lamps.^[9][10] 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.^[12]

[edit] Eighteenth and nineteenth centuries

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 in Quebec.^[13] 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.^[9]

Approximately 100,000 people have or will die from asbestos exposure related to ship building. In Hampton Roads, a shipbuilding town, mesothelioma occurrence is seven times the national rate.^[14] Thousands of metric tons of asbestos were used in WWII 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.^[13]

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.

Kent, the first filtered cigarette on the market, used crocidolite asbestos in its "Micronite" filter from 1952 to 1956.^[15]

The first documented death related to asbestos was in 1906.^[8] In the early 1900's 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.^[7] By the 1930s England regulated ventilation and made asbestos an excusable work related disease.^[7][16] The term mesothelioma was not used in medical literature until 1931 and was not associated with asbestos until sometime in the 1940s.^[8]

The United States government and asbestos industry have been criticized for not acting quickly enough to inform the public of dangers, and reduce public exposure. In the late 1970s court documents proved that asbestos industry officials knew of asbestos dangers and tried to conceal them.^[13]

In Japan, particularly after World War II, asbestos was used in the manufacture of ammonium sulfate, which was used for rice production and was sprayed upon the ceilings, steel framing, and walls of railroad cars and buildings (during the 1960s), and was 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.^[17]

[edit] Modern usage

[edit] 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 :

In the European Union and Australia it has recently been banned as a potential health hazard^[18] 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.^[19] 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.^[19]

[edit] 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

This article or section deals primarily with the United States and Canada and does not represent a worldwide view of the subject. Please improve this article or discuss the issue on the talk page.

[edit] Health issues

The first signs of health related concerns associated with asbestos fibers was likely around the beginning of the 20th century. Asbestos diseases can be seen as early as 10 years after exposure. As such, with widespread asbestos mining, manufacturing and installation in the nineteenth century, it is likely that asbestos related sickness/illness was present and diagnosed, though not named until later in the twentieth century.

In 1918, a Prudential Insurance Company official noted that life insurance companies would not cover asbestos workers, because of the "health-injurious conditions of the industry".^[20]

[edit] Early corporate research

In 1930, the major asbestos company Johns-Manville produced a report, for internal company use only, about medical reports of asbestos worker fatalities.^[20] A 1932 letter from U.S. Bureau of Mines to asbestos manufacturer Eagle-Picher states, "It is now known that asbestos dust is one of the most dangerous dusts to which man is exposed".^[21] In 1933, Metropolitan Life Insurance Co. doctors found that 29% of workers in a Johns-Manville plant had asbestosis.^[20] Likewise, in 1933, Johns-Manville officials settled 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."^[21] In 1934, officials of two large asbestos companies, Johns-Manville and Raybestos-Manhattan, edited an article about the diseases of asbestos workers written by a Metropolitan Life Insurance Company doctor. The changes minimized the danger of asbestos dust.^[21] In 1935, officials of Johns-Manville and Raybestos-Manhattan instructed the editor of Asbestos magazine to publish nothing about asbestosis.^[21] In 1936, a group of asbestos companies agreed to sponsor research on the health effects of asbestos dust but require that the companies maintain complete control over the disclosure of the results.^[20]

In 1942, an internal Owens-Corning corporate memo referred to "medical literature on asbestosis . . . . scores of publications in which the lung and skin hazards of asbestos are discussed."^[22]. Either in 1942 or 1943, the president of Johns-Manville stated that the managers of another asbestos company were "a bunch of fools for notifying employees who had asbestosis." When one of the managers asked, "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."^[23]. In 1944, a Metropolitan Life Insurance Company report found 42 cases of asbestosis among 195 asbestos miners.^[24].

In 1951, asbestos companies remove all references to cancer before allowing publication of research they sponsored.^[25]. In 1952, Dr. Kenneth Smith, Johns-Manville medical director, recommended (unsuccessfully) that warning labels be attached to products containing asbestos. Later Smith testified: "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."^[26]. In 1953, National Gypsum's safety director wrote 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 noted that the letter was "full of dynamite," and urged 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."^[27].

[edit] 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.)^[28] 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 asbestos, 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 become more easily 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 because of 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.

[edit] 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 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% for every 10 kilometers that an individual lived from a likely asbestos source.^[29]

Portions of El Dorado County, California, are known to contain natural asbestos formations near the surface.^[29] 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".^[30]

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.^[29]

[edit] Asbestos in the environment

Asbestos is in the air we breathe and some of the water we drink, including water from natural sources.^[31] Studies have shown that asbestos workers (not the general population) with lung cancer 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.^[32]

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). 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.^[33]

[edit] 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.

[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 are seen, but if extensive it can cause lung impairment.

[edit] Litigation

The examples and perspective in this article or section may not represent a worldwide view of the subject. Please improve this article or discuss the issue on the talk page.

Main article: Asbestos and the law

Asbestos litigation is the longest, most expensive mass tort in U.S. history, involving more than 6,000 defendants and 600,000 claimants.^[34] Current trends indicate that the rate at which people are diagnosed with the disease will likely increase through the next decade. Analysts have estimated that the total costs of asbestos litigation in the U.S. is over $250 billion.^[35] 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 innocent purchaser defense. In some instances, the U.S. EPA includes asbestos contaminated facilities on the NPL (Superfund). Buyers should be careful not to purchase facilites, 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.

The volume of the asbestos liability has alarmed the manufacturers and insurance industry. 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.

Arguably the most notorious environmental polluter in history, W.R. Grace (A Civil Action), failed to make public an internal study conducted by W.R. Grace, subsequent to its purchase of the Libby, MT Asbestos Mine in 1963. The study, W.R. Grace/Zonolite: Confidential Study of Zonolite/Libby Employees (1969), stated "Although 17% of our 1 to 5 years service group have or are suspect of lung disease, there is a marked rise (45%) beginning with the 11 year of service, climbing to 92% in the 21 to 25 years service group. This suggests that chances of getting lung disease increases as years of exposure increase." (see Exhibit 130.4).

[edit] Critics of safety regulations

The neutrality of this section is disputed. Please see the discussion on the talk page.

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".^[36] In May 1998, Canada requested consultations with the European Commission concerning France's 1996 prohibition of the importation and sale of asbestos.^[37]

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.^[37]

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.^[37]

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^[38]

Asbestos regulation critics include the controversial Junkscience.com author and Fox News columnist Steve Milloy and the asbestos industry.^[39] 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.^[40][41] 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.^[42][41]

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.^[43] 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.^[44] 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.^[45][46][47]

[edit] 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 is a synthetic fiber with no melting point that also does not ignite. Because of its exceptional thermal and chemical stability, it is often used by fire departments and space agencies.