Refractory Ceramic Fibre Survey And Lab Testing

Towards the end of 1998 certain types of man-made mineral fibres (MMMFs) will be classified as carcinogens. This OC and ID give information and guidance on hazards and precautions in the use of refractory ceramic fibre, one widely used type of MMMF.

Refractory ceramic fibre (RCF) comprises a group of several types of man-made vitreous (silicate) fibres, used as insulation material in high temperature applications particularly in the following industries, listed in decreasing order of usage:

  • ceramics;
  • secondary metal treatment (including foundries);
  • petrochemical industry;
  • steel and non-ferrous metals (primary treatment);
  • chemical processing (general); and
  • automotive industry.

On 10 November 1997, a European Technical Progress Committee decided that the evidence was sufficient to warrant RCF being classified as a category 2 carcinogen (ie a substance to be regarded as if it were carcinogenic to humans) and the risk phase R49 ('may cause cancer by inhalation') will apply. The Directive approved by this committee (Directive 97/69/EC of 5 December 1997) and now ratified by the European Commission will be implemented in the UK by an amendment to the Chemicals (Hazard Information and Packaging for Supply) Regulations 1994 (CHIP Regulations) as amended, coming into force no later than 16 December 1998. Further information is contained in OM 1997/123.

It has also been agreed that risk phrase R38 ('irritating to the skin') will apply to RCFs.

The classification as a category 2 carcinogen will apply to fibres of a certain size only (those less than 6mm length weighted geometric mean diameter). Most RCF products currently marketed in the UK will fall into this category. The main implication is that the Control of Substances Hazardous to Health Regulations 1994 (COSHH) Carcinogens ACOP (file 273) will apply to all work with RCF. Information notes explaining the position in more detail as far as the ceramics industry is concerned were produced by the Ceramics and Heavy Clay NIG and circulated widely in November/December 1997 (see SIM03/2003/52). The information they contain may also be relevant to other industries.

An additional problem for users is that after being exposed to high temperatures (greater than 1000oC) for prolonged periods as can happen in kilns and furnaces, it is known that RCF at the surface of the lining devitrifies to crystalline phases including cristobalite, a form of crystalline silica which can cause silicosis. Exposure to simulated 'after-service' fibres did not produce significant excess tumours in animal studies.

The new Directive also classifies certain types of mineral wool as category 3 carcinogens. Although mineral wools are used in the above industries they have much wider application, particularly for domestic loft insulation, and are therefore not covered in this OC.

As exposure to RCF must be reduced to the lowest level reasonably practicable, appropriate respiratory protective equipment (RPE) will need to be used when maintenance, wrecking, or any other job likely to result in significant levels of dust is being carried out (this will be the case despite the above precautions being taken). Respiratory protective equipment must either be CE marked or HSE approved. HSE approval of RPE ceased on 30 June 1995 but HSE approved equipment made before 1 July 1995 can continue to be used, as long as it is suitable and maintained to perform correctly. HSE guidance booklet HS(G)53 The selection, use and maintenance of respiratory protective equipment5 provides further guidance.

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