Detecting genotoxic effects of heavy metal ions on human lymphocytes by micronucleus technique

Recently, the concentration of heavy metals in our environment has increasingly been on the rise as a result of industrialization, modernization and the use of many heavy metals in production of materials that we use in our everyday lives. Although many metal ions are essential to human metabolism, many scientific studies have demonstrated the toxicological character of heavy metals at higher concentrations. Some of the toxic effects may be observed at the tissue, cellular and molecular levels. Heavy metals are elements and are present in natural composition of Earth's crust. For this reason; as opposed to many toxic organic or inorganic impurities, they cannot be destroyed, eliminated, or reduced to less harmful derivatives. Hence, recycling programs have been developed especially for those heavy metals that are routinely used in our daily lives. However, the heavy metal pollution has still been a big issue because these recycling programs have either not adequately been applied to; even not at all implemented for some of the metals, or consumption of them have increased. The cytotoxic and genotoxic effects of heavy metals may be showing differences based on each element but toxicity mechanism essentially may be classified as direct and indirect. The indirect effects can be listed as inhibition of DNA repair mechanisms, triggering the formation of oxidative stress and deregulating the cell division mechanisms. In this study, in which the interactions of aluminum (Al) and cadmium (Cd) elements with human lymphocyte cells were examined, the water-soluble salt forms of aluminum sulfate (Al2(SO4)3) and cadmium chloride (CdCl2) were used. The reason why water is used as a carrier solvent is to prevent the possibility of special toxic effects of other solutions that may have a negative impact to the experimental results. As for the method used in this study; the peripheral blood lymphocytes drawn from non-smoking three healthy volunteers treated with the salts of the metals intended to be investigated and micronucleus technique was used for the evaluation of the samples obtained. This technique was preferred because the application and the evaluation stages were simple, fast, and reliable. After the peripheral blood samples cultured, they were treated with "Phytohaemagglutinin" (PHA) to undergo a mitotic division. Then, metals were added to the cultures, and at the last stage; the chromosome damage in binucleate cells, the division of which was stopped at metaphase stage by adding "Cytochalasin-B" (CytoB), were evaluated by scoring of observed micronuclei (MN). In this study where 1000 binucleate cells were evaluated per dose, each dose was compared with its own control group by applying chi-square test. For both metals, at certain doses an increase of 1.5 to 2 times micronucleus as the control group was observed but the results obtained were not found to be statistically meaningful. Besides, when the obtained results of the same metal are compared with each other between the donor groups using the one-way anova test, there have been a meaningful difference between micronucleus increases in different individuals (p < 0.0001). The proliferation index (PI) values for both metals and the donors were also evaluated. The cell survival graphs were drawn based on doses by using the calculated values from the all scored cell samples and compared with each other by using the regression analysis. For both metals, the PI values have shown a meaningful decrease based on the dose (p < 0.01, R2 > 0.7). In addition, despite the PI values show differences for each individual, when the curves of lines drawn in regression graph are compared, a meaningful parallelism is observed (p > 0.5) for the response to doses for the same metal.