Potential toxicity of nonregulated asbestiform minerals: balangeroite from the western Alps. Part 2: Oxidant activity of the fibers.
The asbestiform mineral balangeroite [(Mg,Fe2+,Fe3+,Mn2+)42Si16O54(OH)36], whose toxic potential is unknown, is associated with chrysotile asbestos in the western Alps (Balangero mine, Piedmont, Italy). In order to examine whether such fibers may contribute to the oxidative damage produced by local asbestos dusts when inhaled, balangeroite was studied by means of both cell-free and cellular tests, comparing the results with those concerning the most pathogenic asbestos form, crocidolite. Similarly to the crocidolite surface, iron was mobilized from balangeroite by chelators, to a different extent: deferoxamine > ascorbic acid > ferrozine. Poorly coordinated surface ions, as evaluated from the adsorption of NO as a probe molecule (by both calorimetry and infrared spectroscopy), are even more abundant on balangeroite than on crocidolite. The spin trapping technique shows that surface iron-derived Fenton activity (HO* from H2O2) is similar for the two fiber types, while a pretreatment in ascorbic acid, by reducing previously oxidized surface iron, activates the potential to cleave a C-H bond (yielding *CO2- from formate anion). Balangeroite, like crocidolite, produces nitrite accumulation, lipid peroxidation, and NO synthase activation in a human lung epithelial cell line (A549). All these findings, regarded as features related to the toxic potential of asbestos, suggest that balangeroite may be a potentially hazardous fiber per se and could be partly responsible for lung diseases reported in epidemiological studies in exposed miners.
Turci
Francesco
F
Interdepartmental Center G. Scansetti for Studies on Asbestos and Other Toxic Particulates, Department of Chemistry IFM, University of Torino, Torino, Italy.
Tomatis
Maura
M
Gazzano
Elena
E
Riganti
Chiara
C
Martra
Gianmario
G
Bosia
Amalia
A
Ghigo
Dario
D
Fubini
Bice
B
D000327:Adsorption; D017638:Asbestos, Crocidolite / Q000633:toxicity; D017632:Asbestos, Serpentine / Q000633:toxicity*; D002151:Calorimetry; D002614:Chelating Agents / Q000737:chemistry / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005609:Free Radicals / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D007202:Indicators and Reagents; D007501:Iron / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008315:Malondialdehyde / Q000378:metabolism; D019016:Mineral Fibers / Q000633:toxicity*; D009569:Nitric Oxide / Q000096:biosynthesis / Q000737:chemistry; D019001:Nitric Oxide Synthase / Q000378:metabolism; D016877:Oxidants / Q000633:toxicity*; D018384:Oxidative Stress / Q000187:drug effects; D017550:Spectroscopy, Fourier Transform Infrared; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
D017632:Asbestos, Serpentine; D002614:Chelating Agents; D005609:Free Radicals; D007202:Indicators and Reagents; D019016:Mineral Fibers; D016877:Oxidants; D017392:Thiobarbituric Acid Reactive Substances; C497700:balangeroite; D017638:Asbestos, Crocidolite; D009569:Nitric Oxide; D008315:Malondialdehyde; D006861:Hydrogen Peroxide; D007501:Iron; D019001:Nitric Oxide Synthase