You are here:
RELATIVE MESOTHELIOMA INDUCTION IN RATS BY MINERAL FIBERS: COMPARISON WITH RESIDUAL PULMONARY MINERAL FIBER NUMBER AND EPIDEMIOLOGY
Citation:
Coffin, D., P. Cook, AND J. Creason. RELATIVE MESOTHELIOMA INDUCTION IN RATS BY MINERAL FIBERS: COMPARISON WITH RESIDUAL PULMONARY MINERAL FIBER NUMBER AND EPIDEMIOLOGY. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-92/339.
Description:
Experiments were performed in Fischer 344 rats comparing relative tumorigeneses of chrysotile, krokidolite asbestos, erionite and attapulgite by intrapleural injection and chrysotile, krokidolite and erionite by intratracheal instillation. Tumor fiber ratios were computed employing the number of mineral fibers in tie injection dose for the intrapleural experiments or the number of residual mineral fibers in the whole lung averaged over one year for the intratracheal experiments. Although the fibers in many categories were quantified, comparisons shown in the paper are based an the category L greater than or equal to 8um x W less than or equal to O.25um (RF). Data shows that on the basis of percent tumor induction versus number of fibers x10-6, the relative potency to induce mesothelioma was as follows; intrapleural Injection; erionite; 530 or 378, krokidolite; 68, chrysotile 1.0. ntratracheal Instillation: erionite! 818, krokidolite 35, chrysotile 1.0. umor fiber ratios for amosite and ferroactinolite were similar to krokidolite in intrapleural experiments. his data, indicates that a potency factor linked to but not governed by length/width ratios of the fiber appears to be the chief determinant of mesothelioma induction. e, term this factor intrinsic fiber potency. his is most potent in erionite and least potent in chrysotile. rokidolite and probably the other amphiboles are intermediate. imilar mechanisms appear to operate for mesothelioma induction in humans since epidemiological data ranks similarly.