A comparison of the pathological effects in rats of the UICC reference samples of amosite and chrysotile with those of amosite and chrysotile collected from the factory environment (1980)

In this animal inhalation experiment, the authors compared standard UICC reference samples of amosite and chrysotile with amosite and chrysotile dust collected from the bag filters of factories that each used only one asbestos type. The factory dusts contained considerable non-asbestos material, which was not characterized. Groups of 48 rats breathed one dust at 10 mg per cubic metre of air for 12 months, and most were then allowed to live out their lifespan. The UICC chrysotile cloud had more long fibres than factory chrysotile. Factory amosite had more long fibres than UICC amosite. Factory fibres were thicker in both cases. After 12 months, the rats' lungs held more asbestos with the factory dusts. The two chrysotile samples produced similar fibrosis. Factory chrysotile produced 3 malignant lung tumours among 42 rats, against 8 among 43 with UICC chrysotile, a difference that was not statistically significant. Factory amosite produced much more fibrosis than UICC amosite, but neither amosite produced malignant lung tumours. The authors suggested that fibrosis and tumours depend on different fibre lengths, with tumours requiring the longest fibres.

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From J-M's medical library

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