Cellular pathologies and genotoxic effects arising secondary to heavy metal exposure: A review

Environmental pollution is significant and oftentimes hazardous in the areas, where mining, foundries and smelters and other metallurgical operations are located. Systematic research on the chronic effects of metals started during the past century; nevertheless, it is evident that even today, there are large gaps in knowledge regarding the assessment of the health effects caused by environmental and occupational exposures to these metals. Heavy metals induce the production of reactive oxygen species (ROS) causing oxidative stress, make several repair-inhibiting cellular changes and alter the DNA repair processes. They favour the 'false' repairing of double-strand breaks (DSBs), propagate DNA mutations and induce carcinogenesis. A detailed literature search was performed using the MedLine/PubMed database. Depending on the mechanism of action, arsenicals can act as genotoxins, non-genotoxic agents and carcinogens. Cadmium can bind to proteins, reduce DNA repair, activate protein degradation, up-regulate cytokines and proto-oncogenes (c-fos, c-jun and c-myc), induce the expression of metallothionein, haeme-oxygenases, glutathione transferases, heat-shock proteins, acute-phase reactants and DNA polymerase β at lower concentrations. Inorganic mercury damages oxidative phosphorylation and electron transport pathways at the ubiquinone-cytochrome b5 locus and thus induces ROS production. Abandoned mining areas generate environmentally persistent waste. These specific sites urgently require maximally efficient and cheap remediation. This bears the need for methodologies employing green and sustainable remediation. Phytoremediation is important in that it is a prevalent in situ remediation technique. Its advantages include the use of solar energy, cost-effectiveness, easy operation, reduction in secondary contaminants, the use of biomass for biofuel production and low-cost adsorbents.