The Health and Safety Commission has agreed a new occupational exposure limit for refractory ceramic fibres. The limit will not formally come into force until later this year (2004), but manufacturers and users of these fibres are advised that they should take appropriate steps to ensure that the exposure of their workforces is reduced accordingly.
Refractory Ceramic Fibres (RCFs) are alumino-silicate fibres that are used mainly in the ceramic, steel and metal treatment industries, as a lining for furnaces and kilns. Until now, the workplace exposure to RCFs has been covered by a generic limit covering all machine-made mineral fibres (MMMF).
In 1997 the European Commission determined that RCFs and Special Purpose Fibres (SPFs) should be classified as Category 2 carcinogens. These are substances that should be regarded as if they are carcinogenic to humans, and where there is sufficient evidence to provide a strong presumption that exposure to them may result in the development of a cancer. Other MMMF do not fall under this classification.
* - 1 fibre/millilitre (8-hour TWA)
*defined as 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.
The gravimetric limit of 5 mg.m-3, based on the weight of the substance in the air remains unchanged.
Manufacturers and users of RCFs and SPFs, including those who dismantle furnace and kiln insulation should ensure that workplace exposures are reduced as low as is reasonably practicable, and do not exceed this limit.
Because of this new limit, the existing occupational exposure limit for MMMF has also been redefined as follows:
* - 2 fibres/millilitre (8-hour TWA)
It is anticipated that the new limit will come into force formally towards the end of 2004 with the introduction of the new framework for occupational exposure limits.
1. The HSC's proposals for a new limit for RCFs were contained in Consultative Document CD187 which was published in June 2003.
2. The HSC's proposals for a new framework for occupational exposure limits were contained in Consultative Document CD189 which was published in October 2003.