title: Does the crystal habit modulate the genotoxic potential of silica particles? A cytogenetic evaluation in human and murine cell lines.
abstract: Crystalline silica inhaled from occupational sources has been classified by IARC as carcinogenic to humans; in contrast, for amorphous silica, epidemiological and experimental evidence remains insufficient. The genotoxicity of crystalline silica is still debated because of the inconsistency of experimental results ("variability of silica hazard"), often related to the features of the particle surfaces. We have assessed the role of crystal habit in the genotoxicity of silica powders. Pure quartz (crystalline) and vitreous silica (amorphous), sharing the same surface features, were used in an in vitro study with human pulmonary epithelial (A549) and murine macrophage (RAW264.7) cell lines, representative of occupational and environmental exposures. Genotoxicity was evaluated by the comet and micronucleus assays, and cytotoxicity by the trypan blue method. Cells were treated with silica powders for 4 and 24h. Quartz but not vitreous silica caused cell death and DNA damage in RAW264.7 cells. A549 cells were relatively resistant to both powders. Our results support the view that crystal habit per se plays a pivotal role in modulating the biological responses to silica particles.
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Via Volta 4, 56126 Pisa, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Guidi
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Via Volta 4, 56126 Pisa, Italy. Electronic address: marco.nigro@med.unipi.it.
authors.forename: M
authors.initials: M
authors.lastname: Nigro
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Via Volta 4, 56126 Pisa, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Bernardeschi
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Via Volta 4, 56126 Pisa, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Lucchesi
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Via Volta 4, 56126 Pisa, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Scarcelli
authors.affiliation: Department of Clinical and Experimental Medicine, University of Pisa, Via Volta 4, 56126 Pisa, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Frenzilli
mesh_terms: D000818:Animals; D002273:Carcinogens / Q000737:chemistry; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival; D020552:Comet Assay; D004249:DNA Damage; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D008168:Lung / Q000473:pathology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects*; D051379:Mice; D015162:Micronucleus Tests; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D011208:Powders; D011791:Quartz / Q000633:toxicity; D000067996:RAW 264.7 Cells; D012822:Silicon Dioxide / Q000633:toxicity*; D014343:Trypan Blue / Q000737:chemistry
chemical_list: D002273:Carcinogens; D011208:Powders; D011791:Quartz; D012822:Silicon Dioxide; D014343:Trypan Blue
keywords: A549; Amorphous silica; DNA damage; Micronucleus; Murine macrophages; Quartz