IARC monographs programme:
Carcinogenic risks from airborne man-made vitreous fibres [glass wool, rock wool, and slag wool]
Man-made vitreous fibres in the form of wools are widely used in thermal and acoustic insulation and in other manufactured products in Europe and North America. These products, including glass wool, rock (stone) wool, and slag wool, have been in use for decades and have been extensively studied to establish whether fibres that are released during manufacture, use, or removal of these products present a risk of cancer when inhaled.
Andrew Auty prepared a report for ABI in 1999 and concluded that the case for carcinogenicity had not been made, but that these wools should be classed as irritants. [A small proportion of people in physical contact with these wools have a strong, short-term inflammatory reaction].
An earlier IARC review (1988) provide no evidence of increased risks of lung cancer or of mesothelioma from occupational exposures during manufacture of these materials, and inadequate evidence overall of any cancer risk. The recent review (reported here) was stimulated by the completion of extensive, high quality international research. It seems unlikely that further research could significantly alter the current findings. If any risk remains, it seems to us that this would be in relation to unusual predisposition.
Foreseeability would be very difficult to establish.
The more bio-persistent materials will remain classified by IARC as possible human carcinogens (Group 2B) at least for the time being. These include refractory ceramic fibres, which are used industrially as insulation in high-temperature environments such as blast furnaces, and certain special-purpose glass wools not used as insulating materials. In contrast, the more commonly used vitreous fibre wools including insulation glass wool, rock (stone) wool and slag wool are now considered not classifiable as to carcinogenicity to humans (Group 3). Continuous glass filaments, which are used principally to reinforce plastics, are also considered not classifiable as to carcinogenicity to humans.
This topic has been unusually closely examined. In our view the position is unlikely to change, save for further discoveries about predisposition.
GM Marsh et al. J Occup Environ Med. Sep (2001) Vol. 43 (9) p 757.
A study of mortality from malignant mesothelioma among 1011 rock/slag wool workers and 9060 fibreglass workers. A manual search of death certificates revealed 10 death certificates with any mention of the word “mesothelioma.” A subsequent review of medical records and pathology specimens for 3 of the 10 workers deemed two deaths as definitely not due to mesothelioma and one as having a 50% chance of being caused by mesothelioma. Two other deaths, for which only medical records were available, were given less than a 50% chance of being due to mesothelioma. Eight of the 10 decedents had potential occupational asbestos exposure inside or outside the MMVF industry.
The authors conclude that the overall mortality risk from malignant mesothelioma does not seem to be elevated in the US MMVF cohort.
An inconclusive study but supportive of the IARC findings.
Death certificates can be unreliable/ misinterpreted.