Properties and Uses

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Synthetic mineral fibres (SMF), also known as man made mineral fibres (MMMF), synthetic vitreous fibres (SVF) and man made vitreous fibres (MMVF), is a term used to describe a number of fibrous materials made from natural or synthetic minerals and metal oxides and includes glass fibre, rock wool and ceramic fibre. The major use of SMF is in thermal and acoustic insulation and for reinforcement of other materials. Glass wool, fibre glass, and rock wool were commonly used in Australia as insulation materials in residential and commercial buildings.

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There are four main categories of SMF:

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1. continuous glass filament, used in textiles and for reinforcement purposes;
    

2. insulation wools, used mainly in building applications as acoustic and thermal insulation;
    

3. special purpose fibres used for high temperature applications and filtration; and
    

4. refractory fibres, used for high temperature insulation.

 

Health Effects

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Experience with asbestos fibres has raised concerns about the health effects from exposure to SMF. The similarity in shape of asbestos fibres and synthetic mineral fibres has led to investigation of the carcinogenicity of, and other health effects arising from, exposure to SMF.

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Synthetic mineral fibres, including ceramic fibres, glasswool, superfine glassfibre and rockwool, are not currently assigned to any carcinogen category by the Safe Work Australia has classified synthetic mineral fibres as follows:

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• mineral wool, with the exception of those specified elsewhere in the Hazardous Substance Information System [Synthetic mineral fibres (SMF); Glasswool]. Note: Man-made vitreous (silicate) fibres with random orientation with alkaline oxide and alkali earth oxide (Na2O+K2O+CaO+MgO+BaO) content greater than 18 % by weight are classified in carcinogen category 3 – Substances suspected of having carcinogenic potential; and
   

• refractory Ceramic Fibres, Special Purpose Fibres, with the exception of those specified elsewhere in HSIS [Synthetic mineral fibres (SMF)]. Note: Man-made vitreous (silicate) fibres with random orientation with alkaline oxide and alkali earth oxide (Na2O+K2O+CaO+ MgO+BaO) content less or equal to 18 % by weight are classified in carcinogen category 2 – Probable human carcinogen.

 

Substances suspected of having carcinogenic potential are those substances which have possible carcinogenic effects on humans but the available information is not adequate for making a satisfactory assessment. There is some evidence of carcinogenicity from appropriate animal or epidemiological studies, but this is insufficient to place the substance in Category 2.

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Probable human carcinogens are those substances for which there is sufficient evidence to presume that human exposure might result in the development of cancer. This evidence is generally based on appropriate long term animal studies, limited epidemiological evidence or other relevant information.

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Health effects, based on available animal experiments and epidemiological evidence, are summarised as follows:

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• available evidence from animal and human studies demonstrates that all forms of SMF covered in the National Code of Practice for the Safe Use of Synthetic Mineral Fibres [NOHSC:2006(1990)] are significantly less potent as a health hazard than chrysotile asbestos fibres;
   

• animal experiments and evidence from human studies have resulted in the International Agency for Research on Cancer (IARC) classifying SMF materials as follows:
   

  • insulation glass wool, continuous glass filament, rock wool and slag wool in Group 3: The agent is not classifiable as to its carcinogenicity to humans;
     

  • refractory ceramic fibres and ppecial-purpose glass fibres such as E-glass and ‘475’ glass fibres in Group 2B: The agent is possibly carcinogenic to humans; and
     

  • no evaluation was made of newly developed man made vitreous fibres (such as the alkaline earth silicate or high alumina, low-silica wools), which were designed to be more biosoluble, due to lack of available human data;
     

• irritation of the skin, eyes and upper respiratory tract may occur with certain SMF materials;
   

• there is no risk of lung fibrosis based on existing animal and human studies;
   

• human studies of SMF other than ceramic fibres (see above) indicate there is no risk of mesothelioma, although animal experiments have induced mesothelioma; and
   

• a slightly increased risk of lung cancer has been shown to be associated with employment in the early rockwool and slagwool manufacturing industry. A suggestive increase (non-statistically significant) in the glasswool sector has also been found. The increased risk of lung cancer has not been associated with duration or intensity of exposure. No risk has been found in the reinforcing glass filament industry.

 

The National Code of Practice concludes that provided SMF work is carried out in accordance with the national code of practice and compliance is maintained with the exposure standards, there is a negligible health risk associated with exposure to SMF under present day manufacturing and usage patterns.