Experimental Studies on Biological Effects of Tremolite Talc on Hamsters (1974)

This is a statement by the author with an attached grant progress report. In the experiments, hamsters received a single injection of mineral dust into the pleural space. Talc sample FD-14 contained 50% fibrous tremolite and 35% talc. At 25 mg, the tremolite talc group, which started with about 50 hamsters, had no mesotheliomas through 700 days; 15 animals were alive at 650 days. Three separate chrysotile groups at the same dose, each starting with about 50 hamsters, had final totals of 8, 9 and 10 hamsters with mesotheliomas by 650 days. Tremolite talc left small deposits with very little fibrous tissue, while chrysotile caused thick fibrous pleural adhesions. In groups of 50 hamsters per sample, chrysotile caused mesotheliomas in 9 of 50 at 25 mg, 4 of 50 at 10 mg and none at 1 mg, and crocidolite caused them in 2 of 50 at 1 mg. Milling the three tumor-causing chrysotile preparations to mostly submicroscopic but still fibrous particles eliminated their carcinogenic effect in these tests. The author concluded that the experiments showed profound differences between the biologic effects of tremolite talc and chrysotile asbestos.

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From J-M's medical library

This copy comes from the Johns-Manville medical library. J-M listed it in its medical library index as no. 003423.

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