Machine made mineral fibre MMMF

44 Silica, Amorphous Total Inhalable Dust 6 mg.m -3 8 hour Time Weighted Average Respirable Dust 2.4 mg.m -3 8 hour Time Weighted Average Silica, Fused Respirable Dust 0.08 mg.m -3 8 hour Time Weighted Average Crystalline Silica Cristobalite, Tridymite Respirable Dust 0.1 mg.m -3 8 hour Time Weighted Average

4.2 Machine made mineral fibre MMMF

Machine Made Mineral Fibres MMMF includes ceramic fibers, special purpose fibers and continuous filament fibers. The material is normally made from molten glass, rock or slag. The material exhibits good resistance to heat and chemicals and can be woven. It is therefore widely used in thermal and acoustic insulation of buildings and process plant and as structural fire protection in the form of rolls, slabs, blown cavity wall filling, plasterboard laminates and pipe insulation. Use of MMMF has accelerated as asbestos materials have been phased out. Since their introduction in the late 1800s it has been recognised that mineral wools cause irritations of the skin and eyes, and that at excessively dusty conditions they lead to irritation of the upper respiratory tract. The irritation of skin and eyes is caused by coarse fibres. While most skin becomes resistant after a transitory period, some people need to take precautions to protect their skin and a small number need to move to other work. Studies in which non-asbestos mineral fibres were implanted into the chests of laboratory animals have shown that mesothelioma tumours result, but other experiments in which animals inhaled high concentrations of mineral wool fibres have not indicated an association with excess occurrence of lung tumours. Inhalation studies on animals have not led to clinically significant fibrosis. A large American industry mortality study showed no cases of mesothelioma. In 45 this study an excess of lung cancer was observed in small groups of workers with more than 30 years since first exposure to mineral wool, but there was no correlation between either the intensity or length of exposure and the excess of lung cancer. In fact, X-ray and lung function studies on current workers have not shown exposure to mineral wool to be associated with lung abnormality.

4.3 Welding Fume