TR 069 – Toxicology of Man-Made Organic Fibres

TR 069 : Toxicology of Man-Made Organic Fibres | April 1996

The established relationship between inhalation of asbestos fibres of respirable size and disease has led to a belief that all similarly sized and shaped particles of other materials are equally dangerous to human health.  Organic fibres, man-made or natural, produce small numbers of respirable fibre-shaped particulates.

This report briefly describes the nature of man-made organic fibres and the release of respirable fibre-shaped particulates, reviews the available data on occupational exposure, health effects and the toxicology of man-made organic fibres, compares organic and mineral fibres and indicates data gaps and areas of research which could contribute most to risk assessment.

Little is known about the generation of respirable fibre-shaped particulates during production, use and disposal of man-made organic fibres but available data on industrial exposure indicate that the exposure potential is low, typically between 0.01 and 0.1 fibres/cm³ for commodity fibres and below 0.5 fibres/cm³ for p-aramids.

Much is known about the health hazards of natural organic fibres, but none of this is related or has been ascribed to fibre-shaped respirable-sized particulates.  Two case reports suggest a relationship with fibre shape is uncertain in these cases.  The health effects described were different from those induced by exposure to asbestos. The few epidemiological studies on health risks from occupational exposures in the man-made organic fibre industry are inadequate to exclude or to establish a human health risk from exposure to respirable fibre-shaped particulates from man-made organic fibres.

Man-made organic fibres differ from natural and man-made mineral fibres in several characteristics that determine toxicity, e.g. chemical composition, surface structure, physical characteristics of respirable fibre-shaped particulates and biodegradability.

The limited toxicological database indicates that the biological activity of respirable fibre-shaped particles derived from man-made organic fibres and from natural and man-made mineral materials are quantitatively and qualitatively different.

Future research should focus primarily on man-made organic fibres with more than a trivial exposure potential. Toxicological test systems, currently in use for screening and/or classification of fibres, need to be re-evaluated for their relevance to man-made organic fibres before test results can be extrapolated to any hazard. A combination of tests for cytoxicity and genotoxicity with acute inhalation, sub-chronic inhalation and biodegradability studies will provide useful information. Epidemiological studies are unlikely to contribute significantly to future risk assessments, because of the apparent impossibility to establish significant differences in exposure levels and/or finding non-exposed controls; exposure in industry being of the same magnitude as in the general population.