COMPARISON OF CYTOTOXICITY OF MAN-MADE VITREOUS FIBERS

The purpose of the study was to compare the cytotoxicity of man-made v itreous fibres (MMVFs): four refractory ceramic fibres (RCFs 1-4), two glasswool fibres (MMVF 10 and 11), a rockwool fibre (MMVF 21) and a s lagwool fibre (MMVF 22). The ability of the fibres to induce haemolysi s in sheep erythrocytes, to release lactate dehydrogenase (LDH) from r at alveolar macrophages (AM) and to increase the production of reactiv e oxygen metabolites (ROMs) in human polymorphonuclear leukocytes (PML ) was studied. To assess the relative cytotoxicity of MMVFs, their tox icity was compared with that induced by quartz, chrysotile or titanium dioxide. MMVFs induced a modest, but dose-dependent, increase of haem olysis at doses of 0.5, 2.5 and 5.0 mg ml(-1). The amount of haemolysi s and LDH release induced by MMVFs was generally similar to that induc ed by titanium dioxide. Glasswool fibre MMVF 10 induced less LDH relea se from rat AM than rockwool MMVF 21 or slagwool MMVF 22 fibres, where as glasswool fibre MMVF 11 induced less LDH release than slagwool fibr e MMVF 22 (P<0.05). All fibres also dose-dependently increased the pro duction of ROMs at doses between 25 and 500 mu g ml(-1). The shapes of the time-courses of MMVF-induced production of ROMs suggest that the mechanisms whereby the different fibres induce ROM production may exhi bit similar features. There are clear-cut differences in the potency o f various MMVFs to induce cytotoxicity and oxidative burst. The presen t results also emphasize the importance of using several measures of t oxicity when assessing the biological activity of various fibres in vi tro. (C) 1997 British Occupational Hygiene Society.