Toxic and mutagenic effects of chromium(VI). A review

Activation of Molecular Oxygen during the Reactions of Chromium(VI/V/IV) with Biological Reductants: Implications for Chromium-Induced Genotoxicities1

“…Implications to the Roles of O 2 in Cr - Induced Genotoxicities. The lack of significant H 2 O 2 accumulation as a result of O 2 consumption during the Cr(VI/V/IV) + Red reactions (Table ) supports the suggestion of Kortenkamp et al 3b, that Fenton-like reactions (eq 34) do not play a significant role in the systems Cr(VI) + Red + O 2 in the absence of added H 2 O 2 : …”

Activation of Molecular Oxygen during the Reactions of Chromium(VI/V/IV) with Biological Reductants: Implications for Chromium-Induced Genotoxicities1

“…Implications to the Roles of O 2 in Cr - Induced Genotoxicities. The lack of significant H 2 O 2 accumulation as a result of O 2 consumption during the Cr(VI/V/IV) + Red reactions (Table ) supports the suggestion of Kortenkamp et al 3b, that Fenton-like reactions (eq 34) do not play a significant role in the systems Cr(VI) + Red + O 2 in the absence of added H 2 O 2 : …”

Reaction pathways in the decomposition of hydrogen peroxide catalyzed by copper(II)☆

“…(8) and (12) are both thermodynamically favorable under standard conditions, the more favorable one being Eq. (12). This is coherent with the kinetic evidence shown above that rate constant k VIII is much higher than k V , and with the fact that O À 2 is known to react very rapidly with Cu(II) [37,38].…”

Evidence for the involvement of CrII and free radicals as intermediates in the reduction of HCrO 4

“…In O 2 -saturated solutions (1.26 mM) and [Cr VI ] 0 6 0.01 mM, reactions (9) and (11) can be neglected and Cr II and S Å intermediates formed in reactions (7) and (8) should be rapidly trapped by O 2 [27]. The proposed mechanism is in accordance with the previous observation that O 2 has not kinetic effect on this reaction [1][2][3][4], because when [Cr VI ] 0 P 0.1 mM (as usually employed in the kinetic measurements), both Cr II and S Å react with HCrO À 4 faster than they do with O 2 [6,27,28].…”

Activation of Molecular Oxygen during the Reactions of Chromium(VI/V/IV) with Biological Reductants: Implications for Chromium-Induced Genotoxicities1

“…Implications to the Roles of O 2 in Cr - Induced Genotoxicities. The lack of significant H 2 O 2 accumulation as a result of O 2 consumption during the Cr(VI/V/IV) + Red reactions (Table ) supports the suggestion of Kortenkamp et al 3b, that Fenton-like reactions (eq 34) do not play a significant role in the systems Cr(VI) + Red + O 2 in the absence of added H 2 O 2 : …”

Reaction pathways in the decomposition of hydrogen peroxide catalyzed by copper(II)☆

“…(8) and (12) are both thermodynamically favorable under standard conditions, the more favorable one being Eq. (12). This is coherent with the kinetic evidence shown above that rate constant k VIII is much higher than k V , and with the fact that O À 2 is known to react very rapidly with Cu(II) [37,38].…”

Evidence for the involvement of CrII and free radicals as intermediates in the reduction of HCrO 4

“…In O 2 -saturated solutions (1.26 mM) and [Cr VI ] 0 6 0.01 mM, reactions (9) and (11) can be neglected and Cr II and S Å intermediates formed in reactions (7) and (8) should be rapidly trapped by O 2 [27]. The proposed mechanism is in accordance with the previous observation that O 2 has not kinetic effect on this reaction [1][2][3][4], because when [Cr VI ] 0 P 0.1 mM (as usually employed in the kinetic measurements), both Cr II and S Å react with HCrO À 4 faster than they do with O 2 [6,27,28].…”

Activation of Molecular Oxygen during the Reactions of Chromium(VI/V/IV) with Biological Reductants: Implications for Chromium-Induced Genotoxicities1

“…Implications to the Roles of O 2 in Cr - Induced Genotoxicities. The lack of significant H 2 O 2 accumulation as a result of O 2 consumption during the Cr(VI/V/IV) + Red reactions (Table ) supports the suggestion of Kortenkamp et al 3b, that Fenton-like reactions (eq 34) do not play a significant role in the systems Cr(VI) + Red + O 2 in the absence of added H 2 O 2 : …”

Reaction pathways in the decomposition of hydrogen peroxide catalyzed by copper(II)☆

“…(8) and (12) are both thermodynamically favorable under standard conditions, the more favorable one being Eq. (12). This is coherent with the kinetic evidence shown above that rate constant k VIII is much higher than k V , and with the fact that O À 2 is known to react very rapidly with Cu(II) [37,38].…”

Evidence for the involvement of CrII and free radicals as intermediates in the reduction of HCrO 4

“…In O 2 -saturated solutions (1.26 mM) and [Cr VI ] 0 6 0.01 mM, reactions (9) and (11) can be neglected and Cr II and S Å intermediates formed in reactions (7) and (8) should be rapidly trapped by O 2 [27]. The proposed mechanism is in accordance with the previous observation that O 2 has not kinetic effect on this reaction [1][2][3][4], because when [Cr VI ] 0 P 0.1 mM (as usually employed in the kinetic measurements), both Cr II and S Å react with HCrO À 4 faster than they do with O 2 [6,27,28].…”