Wednesday, May 18, 2005

An Older Review of Rat to Man extrapolation of fibers

BrooklynDodger warns that this review may have been included in the later review by the germans. It may be that crocidolite and amosite pose a higher unit risk, fiber for fiber than chrysotile in people, although that at best makes chrysotile not as bad as the worst thing in the world.

The excess risk of tumours exposed to asbestos were previously compared with the results of rat inhalation experiments. It could be demonstrated that humans at the workplace suffer from a tumour risk at fibre concentrations which are 300 times lower than those needed in the rat inhalation model to produce the same risk. On comparing the risk of lung cancer in this study with the risk of lung cancer for chrysotile textile workers, it can be concluded, that the risk of lung cancer and mesothelioma from crocidolite and amosite was higher than in the chrysotile textile factory. Carcinogenic response was observed at a fibre concentration 6000 times higher in animal inhalation experiments with crocidolite asbestos (SEM analysis of WHO fibres). As a result of these findings, it has been concluded that inhalation studies in rats are not sufficiently sensitive for the detection of hazards and risks to humans exposed to man-made fibres.

Ann Occup Hyg. 1995 Oct;39(5):715-25.

Airborne fibre concentrations and lung burden compared to the tumour response in rats and humans exposed to asbestos.

Rodelsperger K, Woitowitz HJ.Institute and Outpatient Clinic of Occupational and Social Medicine, Justus-Liebig-University, Giessen, Germany.

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