title: Absence of genotoxic effects of nonasbestos mineral fibers.
abstract: The biological activity of natural and synthetic mineral fibers has been examined. Natural attapulgite [(Mg, Al)2Si4O10(OH).4H2O], synthetic xonotlite [Ca3Si3O8(OH)2] and natural sepiolite [Mg2Si3O8.2H2O] were selected. Genotoxic effects were investigated by means of a well established cellular model based upon the measurement of unscheduled DNA synthesis (UDS) in rat hepatocytes in primary culture. The intrinsic capacity of the fibers (1 and 10 micrograms/ml) to induce UDS was first tested. None of the fiber types showed detectable UDS-eliciting activity. Also, the possible modulation of the cellular response to genotoxic agents by the materials was examined by exposing the cells to mixtures of 2-acetylaminofluorene (AAF) (0.05 and 0.25 micrograms/ml) and fibers (1 and 10 micrograms/ml). In these experiments, the UDS response was significantly diminished in the presence of xonotlite. This phenomenon may reflect changes in the uptake and/or metabolism of AAF or may result from an inhibition of DNA repair processes, the latter suggesting a possible cocarcinogenic potential for this synthetic silicate. These results point to the immediate necessity of studying more extensively the biological effects of fibrous materials that can be used as substitutes for asbestos.
authors.affiliation: Département de chimie, Université du Québec a Montréal, Canada.
authors.forename: F
authors.initials: F
authors.lastname: Denizeau
authors.forename: M
authors.initials: M
authors.lastname: Marion
authors.forename: G
authors.initials: G
authors.lastname: Chevalier
authors.forename: M G
authors.initials: MG
authors.lastname: Cote
mesh_terms: D000818:Animals; D017610:Calcium Compounds; D008099:Liver / Q000187:drug effects; D008274:Magnesium / Q000009:adverse effects*; D017616:Magnesium Compounds; D017633:Magnesium Silicates; D008297:Male; D008903:Minerals / Q000009:adverse effects*; D009153:Mutagens; D051381:Rats; D011919:Rats, Inbred Strains; D017640:Silicates; D012824:Silicic Acid / Q000009:adverse effects*; D012825:Silicon / Q000009:adverse effects*; D017655:Silicon Compounds; D012822:Silicon Dioxide / Q000009:adverse effects*
chemical_list: D017610:Calcium Compounds; D017616:Magnesium Compounds; D017633:Magnesium Silicates; D008903:Minerals; D009153:Mutagens; D017640:Silicates; D017655:Silicon Compounds; D012824:Silicic Acid; D012822:Silicon Dioxide; C001671:magnesium trisilicate; D008274:Magnesium; C031293:calcium silicate; C026325:attapulgite; D012825:Silicon