Combining Drosophila melanogaster somatic-mutation-recombination and electron-spin-resonance-spectroscopy data to interpret epidemiologic observations on chromium carcinogenicity.
Lung cancers are significantly increased among workers exposed to chromate (Cr6+, Cr3+), chromium pigments (Cr6+) and chromium plating (Cr6+). Chromium lung burdens and cancer risk increase proportionately with duration of employment at long latencies. However, this epidemiologic information alone is insufficient in determining whether Cr6+ or Cr3+ are equally important in causing cancer. We have attempted to combine epidemiologic data with data from the Drosophila melanogaster somatic-mutation-recombination-test and from the in vitro electron-spin-resonance spectroscopy study to demonstrate that following somatic recombination plays a more important role than somatic mutation in chromium carcinogenesis. Cr4+ is more important than Cr5+ or Cr6+ in inducing somatic recombination while Cr6+ produces more and bigger clones than Cr4+ in somatic mutation. Cr3+ produces negative results in this fruit-fly wing-spot-assay. When the larvae and flies exposed to Cr6+ and Cr4+ are examined by ESR, only Cr5+ and Cr3+ are found. Thermodynamic parameters deltaE, deltaH, and deltaS are also estimated from these latter experiments to explain the relative importance of Cr6+, Cr4+, Cr3+ in chromium carcinogenesis among exposed industrial workers.
Katz
A J
AJ
Department of Biological Sciences, Illinois State University, Normal, USA.
Chiu
A
A
Beaubier
J
J
Shi
X
X
D000818:Animals; D015197:Carcinogenicity Tests; D002273:Carcinogens / Q000633:toxicity*; D002712:Chlorides / Q000633:toxicity; D002857:Chromium / Q000633:toxicity*; D017608:Chromium Compounds / Q000633:toxicity; D004331:Drosophila melanogaster / Q000187:drug effects / Q000235:genetics; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D006801:Humans; D007814:Larva / Q000187:drug effects / Q000235:genetics; D019656:Loss of Heterozygosity / Q000187:drug effects; D008175:Lung Neoplasms / Q000139:chemically induced* / Q000453:epidemiology; D009154:Mutation / Q000187:drug effects*; D011995:Recombination, Genetic; D013816:Thermodynamics
D002273:Carcinogens; D002712:Chlorides; D017608:Chromium Compounds; D002857:Chromium; C074702:chromium hexavalent ion; C022990:chromic chloride