Asbestos 2 by sexychiic

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									Definition of Asbestos



       Asbestos (from the Greek for inextinguishable) is a general term covering two

distinct groups of fibrous minerals. From Serpentine rock is derived Chrysotile or White

Asbestos, a magnesium silicate. From Amphiboles rock are derived Amosite or Brown

Asbestos and Crocidolite or Blue Asbestos, and of a lesser commercial significance,

Anthophyllite, Tremolite and Actinolite. There are in fact at least 30 types of asbestiform

minerals but only the above mentioned are of any industrial significance. All asbestos

types have a number of properties that have made them invaluable in many industrial

applications such as, Chrysotile has a very good resistance to alkalis,    Amosite has a

very good resistance to high temperature, Crocidolite has a very good resistance to acids.

The main sources of Chrysotile asbestos, the commonest fiber in industrial use, were

mined in Quebec, British Columbia, South Africa, Russia, Italy, America, Greece, and

Cyprus. Crocidolite was mined in South Africa and Australia and Amosite was mined in

Australia and South Africa (The name Amosite is derived from AMOSA (Asbestos

Mines Of South Africa).



Types of Asbestos



Serpentine



       Serpentine are rock forming minerals that are found in Val Antigorio, Italy;

Russia; Rhodesia Switzerland; North Carolina, California, Rhode Island and Arizona,
USA and Quebec, Canada and Cyprus. Serpentine is actually a general name applied to

several members of a polymorphic group which have the same chemistry but different

structures. Their structure is composed of layers of silicate tetrahedrons linked into sheets

and in between these there are layers of Mg(OH)2 which are called brucite layers. In

Chrysotile asbestos, the brucite layers and silicate layers bend into tubes that produce the

fibres.



Amphibole

          The amphiboles are large group of common rock forming minerals and are

present in most metamorphic and many igneous rocks. There are over 60 recognized

members mostly because of their chemical differences. Amphiboles are formed at lower

temperatures with the presence of water.



Chrysotile (Mg,Fe)3Si2O5(OH)4



          The name chrysotile in Greek means golden fibers. The physical characteristics

of Chrysotile are: the color is olive green, yellow or golden, brown, or black, luster is

greasy, waxy or silky, transparency crystals are translucent and masses are opaque,

crystal system is variable, crystal Habits: never in large individual crystals, usually

compact masses or fibrous. Veins of viberous serpentine can be found inside of massive

serpentine or other rocks, the fracture is splintery.* Hardness is 3 - 4.5, and streak white.

Other Characteristic are: serpentine in the rough has a silky feel to the touch and fibers

are very flexible, notable occurrences Val Antigorio, Italy; Russia; Rhodesia Switzerland;
North Carolina, California, Rhode Island and Arizona, USA and Quebec, Canada and

Cyprus. Best Field Indicators softness, color, silky feel and luster, asbestos if present and

its flexibility.



Crocidolite



        The typically dark blue mineral was named after a famous eighteenth century

German explorer and mineralogist, Emil Riebeck.Some forms of riebeckite are

asbestiform "Crocidolite", the largest deposit of Crocidolite occurs in South Africa and

Australia and is still productive. Crocidolite is also known as "blue asbestos" and

"riebeckite asbestos". The chemistry of riebeckite is odd in that it includes two different

iron atoms, one is ferric and one is ferrous.




Significance of Asbestos



        Asbestos is the term used to describe a group of naturally occurring minerals

whose characteristic feature is that they occur as fibres. The most common type of

asbestos used in Australia have been: Chrysotile (white asbestos), Amosite (brown

asbestos) and Crocidolite (blue asbestos).       The fibres of asbestos can be split by

mechanical energy into progressively finer fibres and eventually into fibrils of

microscopic size. Respirable fibres longer than about 5 µm are considered responsible

for adverse health affects caused by asbestos. To be respirable, a fibre needs to have a
diameter of less than about 5 µm, though those of the diameter less than about 1 µm are

considered most hazardous.



         Over 3000 uses of Asbestos have been described among the most common are:

asbestos-cement building products e.g. “fibro” boards, pipes and roofing materials,

electrical, thermal and acoustic insulation e.g. lagging asbestos rope and asbestos cloth

and fire resistant insulation e.g. sprayed limpet asbestos in buildings. The term asbestos

is used for a group of fibrous, naturally occurring silicate minerals that exhibit properties

rendering them useful in commerce.



         Asbestos in water again affirmed by the World Health Organization as not be a

health hazard. The 1993 second edition of the World Health Organization’s Guidelines

for Drinking Water Quality has recently been published and ,once again WHO affirms

that asbestos in water is not a hazard to health. After years of study, WHO clearly states

its position on this issue: There is therefore no consistent evidence that ingested asbestos

is hazardous to health and this it was concluded that there was no need to establish a

health     based     guideline     value     for     asbestos     in    drinking     water.

Further this respected international body , in its revised guidelines , identifies asbestos

among a short list three chemicals that are not of health significance at concentrations

normally found in drinking water. This latest pronouncement by WHO is consistent with

the conclusions of other authorities and should remove any remaining doubts about

asbestos in water presenting a potential hazard to health. For example, the U.S.

Environmental Protection Agency has stated as follows: Asbestos is not classified as
carcinogen in the regulations because EPA has determined it is carcinogenic only when

inhaled, not ingested. (EPA News release dated January 7,1991 on Drinking Water

Contaminants Rule).



       Falling production levels and rising demand affected asbestos prices during 1996;

even some Russian producers, notorious for their discounting policies, responded to

changing market conditions by raising their prices. Sales to Thailand, Korea and

Indonesia were buoyant while the construction of three asbestos cement plants fuelled

demand in India. One expert feels that “some sort of renaissance may be seen”

throughout Asia and predicts that “at the very least, consumption will remain steady into

the next millennium.” Despite a sizeable decrease in asbestos imports, Japan remained

one of the world’s most important markets absorbing 180,000 metric tons annually.

Demand from Latin American countries remained firm; however, adverse exchange rates

and other economic factors discouraged the import of fiber and favored the use of local

product. British Geological statistics for global production of asbestos show a drop of

nearly thirty per cent between 1992 (3.5 million tons) and 1996 (2.5 million tons).

Production fell in Swaziland, Canada and India. By the end of 1996, South Africa’s two

principal asbestos producers, Griqualand Exploration and Finance Co. (Gefco) and

Msauli Asbestos, were both suffering from falling production levels. At the beginning of

1997, Gefco announced that it would cease production of amphibole fiber. Problems with

mining and milling operations in the former Soviet Union and Kazakstan adversely

affected their production levels. In 1996, just three countries accounted for sixty-five per

cent of global output: Russia, Canada and China. Production levels actually rose
substantially in China, Brazil, Zimbabwe and Greece. In China, some asbestos is mined

at the Laogai, forced labor camps: the Xinkang mine at Simian LR General Brigade

prison produces one sixth of China’s asbestos. Canadian and Russian producers remain

firmly committed to the asbestos industry. Two Quebec-based companies are expanding

their operations: JM Asbestos Inc. is developing a new chrysotile mine in a three-year

$C125 million project which will guarantee supplies until 2018 and in 1996 LAB

Chrysotile rehired 75% of its former workforce. Russian commitment to asbestos is

evinced not only by its mining interests but also by two dozen asbestos-cement plants,

numerous asbestos textiles facilities and even two asbestos cardboard factories.



       Throughout 1997 asbestos interests kept up the pressure on national governments

and international bodies in an effort to stave off further bans on the use of chrysotile.

Canadian representatives, in particular, have been active in lobbying ministers and civil

servants in the UK, France and European Union. Last year Canada, the world’s second

largest producer of asbestos, also continued to press for a reversal of the French ban on

chrysotile at the World Trade Organization (WTO). Over the last three years, the WTO

has emerged as a convenient forum in which occupational and environmental health

regulations of member states can be contested. With the globalization of trade and

information, the scope of the WTO is likely to expand. Simultaneously, pronouncements

by international health organizations such as the International Labour Office (ILO) take

on added significance as ammunition in future disputes. Recent developments have

forced the ILO to consider the threat posed to its credibility and reputation by business

interests. The efforts of Canadian government officials are continually being reinforced
by asbestos industry personnel, including staff and consultants of the Asbestos Institute, a

body which was formed in the mid-1980’s to “maximise the use of existing resources in a

concerted effort to defend and promote the safe use of asbestos on a global scale." During

the past century, asbestos has been mined, processed, and used in thousands of products.

Because of the exceptionally effective insulating, fire-resistant, and reinforcing properties

of asbestos-containing materials (ACM), they have been utilized widely as surface-

applied finishes (for acoustical, decorative, and fire-retardant purposes), and as thermal

insulation in the construction of buildings, as well as in equipment used in buildings.

Although chrysotile is estimated to constitute approximately 95 percent of the asbestos

used in the United States, building surveys have shown amosite and, to a lesser extent,

Crocidolite, to have been used with greater frequency in buildings than the total

consumption figures would suggest. At least one common form of asbestos, chrysotile is

present naturally in the atmosphere.



       For instance, in European Communities - Measures Affecting Asbestos and

Asbestos -Containing Products, Canada complained about the French import ban of

asbestos, a measure which was an aspect of France's general prohibition of the sale, use,

and manufacture of asbestos in France.28 Although this French measure does not purport

to change the Canadian environmental policy, it causes harmful effects on the Canadian

export of asbestos. Also included in this category of ETM are most of the sanitary and

technical measures which fall under the scope of the Agreement on Technical Barriers to

Trade (hereinafter the TBT Agreement)29 and the Agreement on the Application of


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Sanitary and Phytosanitary Measures (the SPS Agreement).30 These agreements came

into force when the WTO was established and aim at preventing technical regulations and

sanitary measures of the members from "creating unnecessary obstacles to international

trade".31 Even though these agreements attempt to "minimize... the negative effects [of

sanitary and technical regulations] on trade“32, it is crystal clear that they do not intend to

deprive the sovereign right of the WTO members to enact sanitary and technical

regulations in order to protect human health. Therefore, when we analyze this type of

ETM (i.e., measures aimed at preserving the environment without intending to change

other countries' environmental policies), it does not make sense to discuss whether this

kind of ETM should be allowed under the WTO. Rather, the concern of this is that ETM-

imposing countries tend to choose measures which impose a heavy burden on

international trade because they do not have an incentive to take into account the trade

harms on other countries.




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Reference

Definition of Asbestos. Available at [www.asbestos-ace.co.uk/asbestos/]. Accessed on
        [11/05/2004]

Significance of Asbestos. Available at [www.newcastle.edu.au/discipline/
        geology/research/ro/woodsrf.htm]. Accessed on [03/2000].

EPA does not believe that installed A/C pipe should be replaced or that its use should be
discontinued.(U.S.Fedral Register dated July 12, 1989, page 29497)

								
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