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Cytotoxicity of Respirable Dusts Fron Industrial Hinerals: Comparison of Two Naturally Occurring and Two Man-Made Silicates

1987; Taylor & Francis; Volume: 10; Issue: 1-2 Linguagem: Inglês

10.3109/01480548709042583

1525-6014

Denis Nadeau, Louise Fouquette-couture, Daniel Paradis, Jaleh Khorani, Denis Lane, Jacques Dunnigan,

Occupational and environmental lung diseases

ABSTRACTThe membranolytic and cytotoxic properties of two naturally occurring (chrysotile asbestos; attapulgite clay) and two man-made (Fiberfrax™, an aluminium-silicate, and xonotlite, a calcium silicate) industrial minerals were compared. »Short« fiber fractions of chrysotile and Fiberfrax were obtained by sedimentation in demineralized water, while the attapulgite and xonotlite samples were used as obtained. The aluminium silicate fibers were found to be non- hemolytic, while for the other three silicates, chrysotile had the strongest hemolysis potential, followed very closely by xonotlite; attapulgite was less hemolytic than the former two silicates, but was nevertheless highly hemolytic to the rat erythrocytes.Using rat pulmonary alveolar macrophages, the in vitro cytotoxicity assays showed that with fresh cell monolayers, all four silicates were equivalent in causing cell damages at a dose of 250 μg; at a lower dose (50 μg), the intensity of the cytotoxic effect was in the decreasing order: Fiberfrax > attapulgite > chrysotile > xonotlite. With one day-old cultured cell monolayers, a dose of 250 μg of the silicates fibers was less cytotoxic, with the exception of the attapulgite fibers which remained essentially as cytotoxic as with the fresh cell monolayers. The reduced cytotoxic response was especially noticeable with the chrysotile fibers. At 50 μg, the cytotoxicity scale of the mineral dusts with one day-old cell monolayers was essentially the same as the one obtained with the fresh cell monolayers, that is: Fiberfrax ≊ attapulgite > chrysotile ≥ xonotlite. Overall, these in vitro tests imply: 1) that all four industrial silicates tested can be considered to be »biologically active« 2) that on the basis of their different reactivities with the two types of cell culture conditions used, their biological reactivity in vivo might be quite distinct. This might be especially true for at least the chrysotile, attapulgite and xonotlite short fibers, considering that these three types of silicate dusts have very similar dimensions. Moreover, for the chrysotile and attapulgite samples, fiber numbers is probably not an important factor, since the density of the two silicates is roughly the same. The unaltered cytotoxic responses of the American attapulgite fibers in the two macrophage assays correlate well with the fact that short attapulgite fibers seems to have a stronger in vivo reactivity than short chrysotile fibers. In fact, it might be the strongest of the four industrial silicates tested. On that basis, it is concluded that the combined use of fresh and cultured PAM for an in vitro assay may be useful1 to extrapolate the pathogenicity of »respirable» dusts, more so if the comparison is done with particles with similar morphologies.