title: Free-radical chemistry as a means to evaluate lunar dust health hazard in view of future missions to the moon.
abstract: Lunar dust toxicity has to be evaluated in view of future manned missions to the Moon. Previous studies on lunar specimens and simulated dusts have revealed an oxidant activity assigned to HO· release. However, the mechanisms behind the reactivity of lunar dust are still quite unclear at the molecular level. In the present study, a complementary set of tests--including terephthalate (TA) hydroxylation, free radical release as measured by means of the spin-trapping/electron paramagnetic resonance (EPR) technique, and cell-free lipoperoxidation--is proposed to investigate the reactions induced by the fine fraction of a lunar dust analogue (JSC-1A-vf) in biologically relevant experimental environments. Our study proved that JSC-1A-vf is able to hydroxylate TA also in anaerobic conditions, which indicates that molecular oxygen is not involved in such a reaction. Spin-trapping/EPR measures showed that the HO· radical is not the reactive intermediate involved in the oxidative potential of JSC-1A-vf. A surface reactivity implying a redox cycle of phosphate-complexed iron via a Fe(IV) state is proposed. The role of this iron species was investigated by assessing the reactivity of JSC-1A-vf toward hydrogen peroxide (Fenton-like activity), formate ions (homolytic rupture of C-H bond), and linoleic acid (cell-free lipoperoxidation). JSC-1A-vf was active in all tests, confirming that redox centers of transition metal ions on the surface of the dust may be responsible for dust reactivity and that the TA assay may be a useful field probe to monitor the surface oxidative potential of lunar dust.
authors.affiliation: 1Dipartimento di Chimica, University of Torino, Torino, Italy.|2"G. Scansetti" Interdepartmental Center, University of Torino, Torino, Italy.|3NIS Excellence Center, University of Torino, Torino, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Turci
authors.affiliation: 1Dipartimento di Chimica, University of Torino, Torino, Italy.|2"G. Scansetti" Interdepartmental Center, University of Torino, Torino, Italy.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Corazzari
authors.affiliation: 1Dipartimento di Chimica, University of Torino, Torino, Italy.|3NIS Excellence Center, University of Torino, Torino, Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Alberto
authors.affiliation: 1Dipartimento di Chimica, University of Torino, Torino, Italy.|2"G. Scansetti" Interdepartmental Center, University of Torino, Torino, Italy.|3NIS Excellence Center, University of Torino, Torino, Italy.
authors.forename: Gianmario
authors.initials: G
authors.lastname: Martra
authors.affiliation: 1Dipartimento di Chimica, University of Torino, Torino, Italy.|2"G. Scansetti" Interdepartmental Center, University of Torino, Torino, Italy.|3NIS Excellence Center, University of Torino, Torino, Italy.
authors.forename: Bice
authors.initials: B
authors.lastname: Fubini
mesh_terms: D001205:Ascorbic Acid / Q000737:chemistry; D004391:Dust / Q000032:analysis; D005609:Free Radicals / Q000737:chemistry*; D006262:Health; D006861:Hydrogen Peroxide / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D006900:Hydroxylation; D007501:Iron / Q000737:chemistry; D019787:Linoleic Acid / Q000737:chemistry; D015227:Lipid Peroxidation; D016081:Moon; D010100:Oxygen / Q000032:analysis; D010795:Phthalic Acids / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000737:chemistry; D013026:Space Flight; D013535:Suspensions
chemical_list: D004391:Dust; C045076:Fenton's reagent; D005609:Free Radicals; D010795:Phthalic Acids; D017382:Reactive Oxygen Species; D013535:Suspensions; D017665:Hydroxyl Radical; C011363:terephthalic acid; D019787:Linoleic Acid; D006861:Hydrogen Peroxide; D007501:Iron; D001205:Ascorbic Acid; D010100:Oxygen