Chronic Arsenic Toxicity and Cancer
Kunal Kanti Majumdar
Arsenic pollution in ground water has been envisaged as a problem of Global concern. Chronic arsenic toxicity (arsenicosis) due to drinking of arsenic contaminated ground water is a major environmental health hazard throughout the world including India and Bangladesh. Chronic exposure to arsenic in drinking water can cause increased risk of skin, lung, kidney, bladder cancer, liver disease and chronic respiratory problems. The exact molecular mechanism of arsenic induced carcinogenesis is still less understood. Both arsenite and its metabolites can have a variety of genotoxic effects, which may be mediated by oxidants or free radical species. All of these species also have effects on signaling pathways leading to proliferative responses. There are interesting differences in the activities of inorganic and organic species both in terms of target organ carcinogenicity and genotoxic and toxic mechanisms. A scientific consensus has not yet been reached on the many suggested modes of arsenic carcinogenesis that exist in the literature. These include modes that are predominately genotoxic (i.e.,chromosomal abnormalities, oxidative stress, and gene amplification) vs. more nongenotoxic (i.e., altered growth factors, enhanced cell proliferation and promotion of carcinogenesis, and altered DNA repair). Likewise, the doseresponse relationship at low arsenic concentrations for any of these suggested modes is not known.
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