The Porosity of Amosite and Chrysotile Asbestos (1976)

This laboratory study measured pore size distribution and total porosity in two kinds of asbestos. It did not study people or disease. The authors tested South African amosite and Canadian chrysotile as received, mechanically dispersed in water, and impact milled under liquid nitrogen cooling. Samples were preconditioned for at least 16 hours under vacuum pumping at 25, 250 or 400°C. Pore sizes were then calculated from nitrogen adsorption measurements with a computer program the authors wrote. Chrysotile was considerably more porous than amosite. For untreated amosite, mechanical dispersion increased total pore volume about three times and impact milling about seven times. For chrysotile, dispersion roughly doubled it. Milling produced more pores larger than 100 angstroms in amosite and 150 angstroms in chrysotile. A higher preconditioning temperature changed total pore volume little in dispersed samples but increased it in unground samples. The authors noted reports from NIOSH and other laboratories that finely ground asbestos lost much of its fibrogenicity (ability to cause fibrosis). They suggested the milling-related pore changes may have some effect on this. Toxicity was not tested here. The scanned text is badly damaged and incomplete.

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From J-M's medical library

This copy comes from the Johns-Manville medical library. It was among the papers J-M kept in its medical library without an index entry.