Mesotheliomas in rats following inoculation with acid-leached chrysotile asbestos and other mineral fibres

Abstract

The carcinogenicity of untreated UICC chrysotile A, of acid (oxalic and hydrochloric)-leached UICC chrysotile A, of crocidolite and of JM 104 glass fibers was studied by intrapleural injection into 304 rats. When > 80% of the Mg had been leached from chrysotile fibers by hydrochloric or oxalic acid, the proportion of pleural mesotheliomas was nil or dramatically < that obtained with untreated chrysotile. The carcinogenic effect of crocidolite was > that of 43.7% oxalic acid-leached chrysotile. The proportion of mesotheliomas observed in animals injected with JM 104 glass fibers was similar to that in animals injected with fibers from which 63.8% had been leached with oxalic acid. With regard to the induction of pleural carcinogenicity by chrysotile fibers, not only size characteristics, but also parameters (such as chemical composition and physicochemical properties), must intervene.