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Man Made Mineral Fibres

Asbestos Knowledge Base

MMMF are synthetic mineral fibres. Produced since the 1950's, common forms are inorganic vitreous fibres. The main types are;

  • Mineral wools - glass wool, rock wool, slag wool
  • Continuous filament - glass or textile fibre
  • Refractory fibres - ceramic and special purpose fibres

MMMF are generally coarser than asbestos fibres and exhibit good resistance to heat and chemicals, can be woven and formed into insulation blankets, and can be used as a reinforcing agent.

Although synthetic, MMMF should not be considered 'safe'. Some fibres are fine enough to be breathed in but few will reach deep into the lung and those that do will not persist as they are generally much more soluble than asbestos. There is some evidence of increased lung cancer risk in workers producing mineral wool insulation in the early days of the industry. Remember it takes many years for the related diseases to become evident, so evidence is only available since the 1950s.

Reference to the DETR's Asbestos and MMMF document will give you more information on the issues associated with MMMF including all the above and some answers to commonly asked questions.

The advice continues to be to avoid working with MMMF if possible. If you have to work with MMMF then ensure you have an appropriate face mask and avoid skin contact wherever possible.

MMMF products are not currently included in the CAW.