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Asbestos

DESIGNATIONS

CAS No.: 1332-21-4

Registry name: Asbestos

Chemical name: Asbestos

Synonyms, Trade names: Serpentine asbestos, amphibole asbestos, fibre asbestos, blue asbestos

Chemical name (German): Asbest

Chemical name (French): Amiante

Appearance: fibrous, impure minerals whose colour varies between pure white and green, brown or grey depending on the iron-oxide content; crocidolite is blue (blue asbestos); the fibres are between 20 and 25 nm long; asbestos fibres are smooth and greasy to the touch.

BASIC CHEMICAL AND PHYSICAL DATA

Asbestos is not a chemical element, but rather an umbrella term for two groups of minerals (serpentine and amphibole asbestos)

  Serpentine

Amphibole

Chrysotile Crocidolite Amosite Anthophyllite Tremolite Actinolite
Empirical formula: Mg3 Si205(OH)4 Na2Fe2(Fe,Mg)3 Si8O22 (OH)2 (Fe,Mg)7 Si8O22(OH)2 Mg7 Si8O22(OH)2 Ca2Mg5 Si8O22(OH)2 Ca2(Mg,Fe)5 Si8O22(OH)2
Rel. molecul. mass: 277.13 g 1,008.82 g 1,171.83 g 780.88 g 812.42 g 1,091.67 g
Density: 2.2-2.6 g/cm3 2.8-3.6 g/cm3 2.9-3.3 g/cm3 2.8-3.2 g/cm3 2.9-3.2 g/cm3 3.0-3.21 g/cm3
Melting point: 1,500C 1,200C 1,400C 1,450C 1,315C 1,400C

Flash point: asbestos is non-combustible, resistant to heat and features a low conductivity in water: insoluble

ORIGIN AND USE

Usage:
Because of its heat-resistance and suppleness and its capacity for being incorporated into inorganic and organic binders, asbestos is used in industry for thermal insulation, fireproofing and sealing in addition to acting as a filler in the production of countless composites (more than 3000). Economic exploitation is centred on chrysotile asbestos from the serpentine group (95 %). 5 % of amphibole asbestos is used for asbestos-fibre production.

Spun asbestos is used for fireproof, chemical-resistant clothing. When mixed with cement, asbestos is cast to form panels and pipes (70 - 90 % of the world production is used in the construction industry in Western Europe; acc. WHO, 1987). Asbestos has also been used as a filter material in the drinks and pharmaceutical industry and for the manufacture of brake and clutch linings for motor vehicles.

Origin/derivation:
Asbestos is extremely widespread in nature. The most important deposits are to be found in the former Soviet Union, Canada and South Africa. Natural emissions are produced for example by the weathering of serpentine rocks.

Production figures:
Worldwide production in 1983 was in excess of 4 million tons (WHO, 1987). The main producers are as follows (WHO, 1986):

USSR 1983: 2,250,000 t/a
Canada 1983: 820,000 t/a
South Africa 1983: 221,111 t/a
Brazil 1983: 158,855 t/a
Zimbabwe 1983: 153,221 t/a
Italy 1983: 139,054 t/a
China 1983: 110,000 t/a

Toxicity

Humans: TCLo 2.8 fibres/cm3/5 years acc. UBA, 1986
TCLo 1.2 fibres/cm3/19 years without interruption acc. UBA, 1986
Mammals:
Rat TDLo 100 mg/kg, intrapleural acc. UBA, 1986

As yet there are no known characteristic toxicology data (DVGW, 1988).

Characteristic effects:

Humans/mammals: Various asbestos-induced illnesses are known from the industrial-medicine sector in which the size of the fibres plays a crucial role. Generally speaking, fibres with a diameter of less than 2 m m and a length of more than 5 m m are considered to be hazardous to health (diameter : length = 1 : 3). Such a fibre size is capable of entering the lungs, gathering there and becoming encapsulated. Fibres have also been found to have a certain migration capability in the organism and the cell metabolism. Accumulation in the lungs causes sclerosis of the pulmonary alveoli and thus impairs the oxygen exchange.

The inhalation of large quantities of fibre can cause asbestosis which increases the risk of bronchial cancer. In particular, dusts < 200 m m are highly toxic and suspected of being a direct cause of tumours.

Exposure to asbestos irritates the eyes and the respiratory tract. Direct penetration into damaged skin produces excessive hornification. Fibres in the lungs bring about chronic bronchitis, irritation of the pleura and pleurisy. Distension of the lungs can result in lung cancer. Workplace exposure may produce periods of latency in the gastro-intestinal tract lasting up to 40 years.

ENVIRONMENTAL BEHAVIOUR

Water:
Asbestos fibres cause water to become turbid, but are not soluble in water.

Air:
The dwell time in the atmosphere is dependent on the fibre size. Asbestos fibres can be transported over hundreds of kilometres in the atmosphere. Weathering produces short and thin asbestos fibres from the coarse dust.

Soil:
If asbestos fibres get into the soil, they accumulate on the surface and may be scattered again at any time. Particles in excess of 2 m m are not washed into the soil pores. In the soil itself and in sediments, asbestos is considered to be harmless (DVGW, 1988). Asbestos dusts in refuse or on dumps must be covered or moistened during transportation to stop them ingressing into the air. Soils and sediments in general are considered as accumulation sites.

Half-life:
The half-life of fibres on mucous membranes is a matter of minutes - hours or days - years after penetration into the tissue (HORN, 1989).

Food chain:
Asbestos fibres penetrate into organisms via drinking water. The pollution of drinking water is caused by fibres in asbestos-cement pipes. The impact is a function of the calcium-carbonate saturation of the water and depends on the number of iron-oxide deposits in the pipes. There is as yet no proof of oral asbestos intake causing cancer.

ENVIRONMENTAL STANDARDS

Medium/ acceptor Sector Country/ organ.

Status

Value Cat. Remarks Source
Air: Workp A

L

250,000 f/m3   chrysotile [1991] acc. Albracht, 1991
Workp B

L

150,000 f/m3   crocidolite [1987] acc. Albracht, 1991
Workp B

L

1,000,000 f/m3   other asbestos [1987] acc. Albracht, 1991
Workp CH

L

1,000,000 f/m3   dusts [1988] acc. Albracht, 1991
Workp DK

L

300,000 f/m3   crocidolite, ceiling value (15min) [1988] acc. Albracht, 1991
Workp DK

L

300,000 f/m3   other asbestos [1988] acc. Albracht, 1991
Workp F

L

500,000 f/m3   crocidolite [1987] acc. Albracht, 1991
Workp F

L

1,000,000 f/m3   other asbestos [1987] acc. Albracht, 1991
Workp D

L

250,000 f/m3 TRK chrysotile [1990] acc. Albracht, 1991
Workp D

G

50,000 f/m3 TRK crocidolite, remediation [1990] acc. Albracht, 1991
Workp GB

L

200,000 f/m3   crocidolite, 4h [1984] acc. Albracht, 1991
Workp GB

L

500,000 f/m3   other asbestos, 4h, [1984] acc. Albracht, 1991
Workp DDR

L

1,000,000 f/m3   dusts [1983] acc. Albracht, 1991
Workp DDR

L

2,000,000 f/m3   short time value (30 min) [1983] acc. Albracht, 1991
Workp GR

L

500,000 f/m3   crocidolite [1988] acc. Albracht, 1991
Workp GR

L

1,000,000 f/m3   other asbestos [1988] acc. Albracht, 1991
Workp IRL

L

500,000 f/m3   crocidolite [1989] acc. Albracht, 1991
Workp IRL

L

1,000,000 f/m3   other asbestos [1989] acc. Albracht, 1991
Workp NL

L

200,000 f/m3   crocidolite, ceiling value (10 min) [1989] acc. Albracht, 1991
Workp NL

L

2,000,000 f/m3   Other asbestos, 4h [1989] acc. Albracht, 1991
Workp S

L

200,000 f/m3   asbestos (except chrysotile) [1987] acc. Albracht, 1991
Workp USA

L

200,000 f/m3   asbestos [1986] acc. Albracht, 1991
Workp USA

G

200,000 f/m3   amosite ACGIH, 1988
Workp USA

G

500,000 f/m3   crocidolite ACGIH, 1988
Workp USA

G

2,000,000 f/m3   chrysotile, other asbestos ACGIH, 1988
Air F

(L)

0.1 mg/m3   Emission (dust) acc. MEEK et al, 1985
Emiss. D

L

0.1 mg/m3 TA-L fine dust, mass flow 0.5g/h acc. TA Luft, 1986
  DDR

L

0.005 mg/m3 MIKk   acc. HORN, 1989
Foodstuffs: Drinkw USA

L

7,100 fibres/lx103   Average and long fibres acc. DVGW, 1988

Note: There is virtually a complete ban in Denmark on materials containing asbestos for production, import and utilization. Norway, Sweden and Holland control the asbestos content of insulating materials and consumer goods in supplementary legislation.

Comparison/reference values

Medium/origin Country Value Source
Surface water:
Northern Lake Constance (1981) D < 5 fibres/l x 103 1) acc. DVGW, 1988
Southern Lake Constance (1981) D 10-20 fibres/l x 103 1) acc. DVGW, 1988
Franconian Forest (1981) D 10-50 fibres/l x 103 1) acc. DVGW, 1988
Bavarian Forest (1981) D < 5-30 fibres/l x 103 1) acc. DVGW, 1988
Groundwater:
Northern Germany (1981) D 4-100 fibres/l x 103 1) acc. DVGW, 1988
Franconian Forest (1981) D < 5-60 fibres/l x 103 1) acc. DVGW, 1988
Drinking water:
10 utility companies (1981) D 5-1,000 fibres/l x 103 2) acc. DVGW, 1988
Montreal (1971) CDN 2,000-9,500 fibres/l x 103 acc. DVGW, 1988
Toronto (1974) CDN 700-4,100 fibres/l x 103 acc. DVGW, 1988
Duluth (1974) USA 20,000-75,000 fibres/l x 103 acc. DVGW, 1988
Chicago (1977) USA 80-2,300 fibres/l x 103 acc. DVGW, 1988

Note:
1) Asbestos fibres more than 5 m m long
2) Utility companies with asbestos-cement pipes and a negative saturation index > 0.2 at tapping point

Assessment/comments

Asbestos fibres are released into the environment by natural and anthropogenic processes. The liberation of asbestos during the manufacture and processing of materials containing asbestos must be significantly reduced especially in confined areas and at workplaces because of the great hazard to the respiratory organs and in particular the lungs. There is increasing speculation that the oral intake of asbestos can cause tumours. Therefore, there is no justification for the further use of asbestos cement in drinking water pipes. Numerous products containing substitute materials are now making it possible to dispense with the use of substances containing asbestos.


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