A study by electron microscopy of the effects of chrysotile and man-made mineral fibres on rat lungs (1980)

This was an animal experiment using transmission electron microscopy, reported by the authors as preliminary. It examined changes in rat lungs after inhaling man-made mineral fibres and compared them with chrysotile. Twelve adult Fischer rats were used. Two rats each breathed UICC chrysotile B, glass fibre (Johns Manville Code 100), rock wool, resin-coated glass wool or uncoated glass wool at 10 mg per cubic metre, seven hours a day, five days a week, for 50 weeks, followed by four months without dust. Two rats were kept dust-free. All exposed animals showed, to varying degrees, focal fibrosis, increased type II alveolar cells, debris in the air spaces and hyperplasia (cell overgrowth). Fibrosis was more marked with chrysotile. Five of the ten exposed rats had discrete areas of hyperplastic cells, and both chrysotile-exposed rats had nodules of Kulschitzky-type cells. The authors' overall impression was that chrysotile was the most reactive material and that uncoated glass wool was more reactive than coated. They noted that the chrysotile's respirable fraction contained considerably more fibres, which may partly account for the fibrosis pattern.

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From J-M's medical library

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