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Comparison of two particulate hexavalent chromium compounds: Barium chromate is more genotoxic than lead chromate in human lung cells
Author(s) -
Wise Sandra S.,
Schuler Julie H.C.,
Holmes Amie L.,
Katsifis Spiros P.,
Ketterer Michael E.,
Hartsock Wendy J.,
Zheng Tongzhang,
Wise John Pierce
Publication year - 2004
Publication title -
environmental and molecular mutagenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1
H-Index - 87
eISSN - 1098-2280
pISSN - 0893-6692
DOI - 10.1002/em.20044
Subject(s) - hexavalent chromium , chromate conversion coating , clastogen , chemistry , chromium , carcinogen , micronucleus , toxicity , micronucleus test , genotoxicity , toxicology , environmental chemistry , biochemistry , biology , organic chemistry
Abstract Particulate hexavalent chromium [Cr(VI)] compounds are well‐established human lung carcinogens. However, their carcinogenic mechanisms are poorly understood as most investigators have used soluble Cr(VI) compounds. Recent work from our laboratory has found that barium chromate (BC) is also cytotoxic and clastogenic. To understand how BC relates to existing data on other particulate Cr(VI) compounds, we compared its cytotoxicity and clastogenicity with lead chromate (LC), which has been used as a prototypical particulate Cr(VI) compound, in WTHBF‐6 cells, a near‐normal human lung cell line. We found that BC is a more potent cytotoxicant, inducing 67%, 12%, 3%, and 0% relative survival at concentrations of 0.1, 0.5, 1, and 5 μg/cm 2 , respectively, while LC induced 90%, 71%, 43%, and 15% survival at these same concentrations. We found that BC was also more clastogenic, damaging 22% and 49% of metaphase cells at 0.1 and 0.5 μg/cm 2 , and causing complete cell cycle arrest at 1 and 5 μg/cm 2 . By contrast, 0.1, 0.5, and 1.0 μg/cm 2 LC damaged 10%, 27%, and 37% of metaphase cells, respectively, and complete cell cycle arrest was not observed until a concentration of 5 μg/cm 2 was reached. We found that BC and LC both partially dissolved in complete medium in the presence of cells, producing similar extracellular concentrations. Both compounds were also comparable with respect to particle uptake and the amount of intracellular Cr ions. Considering previous reports showing that lead ions were inactive and that sodium chromate and LC have similar clastogenic potencies, these data suggest that BC genotoxicity may not be solely mediated by Cr ions, but also involve some clastogenic activity of barium ions. Environ. Mol. Mutagen. 44:156–162, 2004. © 2004 Wiley‐Liss, Inc.