A: Airborne continuous filament can be inhaled. However, the potential for inhaled glass fibre to cause any health hazard depends on its “respirability”, i.e. its potential to enter the lower regions of the lung. Indeed, the essential feature of a health and safety assessment for the product is to determine whether it is possible for the product to cause lung disease through respiration.
Fibres with diameters greater than 3 microns, which is the case for continuous filament glass fibre, do not reach the lower respiratory tract and, therefore have no possibility of causing serious pulmonary disease.
According to the WHO definition, respirable fibres have a diameter (d) smaller than 3 microns, a length (l) larger than 5 microns and a l/d- ratio larger than or equal to 3. Continuous filament glass fibres do not possess cleavage planes which would allow them to split length-wise into fibres with smaller diameters, rather they break across the fibre, resulting in fibres which are of the same diameter as the original fibre with a shorter length and a small amount of dust.
In 1987 IARC (The International Agency for Research on Cancer, a division of the World Health Organisation (WHO)) classified continuous filament fibreglass as not classifiable as to human carcinogenicity (Group 3).
In recent years, several major reviews have been undertaken by various expert international organizations on the health and safety aspects of glass fibres. The first of these was conducted by the International Agency for Research on Cancer (IARC) in 1987. The purpose of the IARC review was to determine whether these fibres are carcinogenic to humans. At that time, IARC concluded that continuous filament glass fibres are not classifiable as to their carcinogenicity to humans (IARC classification Group 3). In October 2001, after a comprehensive review of more recent human epidemiology and animal toxicity data, IARC concluded that the classification of continuous filament glass fibres in Group 3 is appropriate, confirming that there is currently no evidence for the carcinogenicity of continuous filament glass fibres to humans (IARC Monograph Man-Made Vitreous Fibres Vol. 81, 2002).