Genotoxic Effects of Chromium(III) and Cobalt(II) and Their Mixtures on the Selected Cell Lines

Cr(III) and Co(II) can be potentially toxic to cells and induce a number of morphological and biochemical changes. These metals are widely used in many industries and can cause environmental pollution. They are the components of dietary supplements, vitamin and mineral products, and energy drinks. Moreover, these metals are used in dentistry and orthopedics as components of implants. Data about the mechanism of genotoxic effects of Cr(III) and Co(II) are still incomplete. The aim of this study was to analyze the genotoxic effects of chromium(III) and cobalt(II) and their mixtures on two cell lines: mouse embryo fibroblast cell line BALB/3T3 and human hepatocellular carcinoma cell line G2 (HepG2). The BALB/3T3 and HepG2 cell lines were exposed to chromium chloride and cobalt chloride at concentrations ranging from 100 to 1400 µM. The genotoxicity assays used were the comet and micronucleus assays. On the basis of the results obtained from the first stage of the research, the concentrations of elements were selected in order to determine the interactions between them. The tested cell lines were treated with mixtures of the following compounds: chromium chloride at the concentration of 200 μM and cobalt chloride at the concentration of 1000 μM or chromium chloride at the concentration of 1000 μM and cobalt chloride at the concentration of 200 μM in the genotoxicity assays. This study shows that both cobalt(II) and chromium(III) cause genotoxic effects in the BALB/3T3 and HepG2 cell lines. A statistically significant increase in the percentage of comets was observed with increasing concentrations of Co(II) and Cr(III) compared to the control. A statistically significant induction of chromosomal aberrations was also observed in the micronucleus test. Moreover, chromium(III) at a concentration of 200 µM had a protective effect against the toxic concentration of cobalt(II) at a concentration of 1000 µM. The toxic effect of cobalt chloride and chromium chloride was confirmed in this study. Further research is needed on the genotoxic effects of cobalt(II) and chromium(III), especially due to the growing popularity of dietary supplements containing compounds of these metals and doubts as to the safety of their use.