Arsenic Exposure and its Health Effects and Risk of Cancer in Developing Countries: Micronutrients as Host Defence


Arsenic (As) is a ubiquitous metalloid found in several forms in food and the environment, such as the soil,air and water. The predominant form is inorganic arsenic in drinking water, which is both highly toxic andcarcinogenic and rapidly bioavailable. As is currently one of the most important environmental globalcontaminants and toxicants, particularly in the developing countries. For decades, very large populations havebeen and are currently still exposed to inorganic As through geogenically contaminated drinking water. Anincreased incidence of disease mediated by this toxicant is the consequence of long-term exposure. In humans,chronic ingestion of inorganic arsenic (>500mg/L As) has been associated with cardiovascular, nervous, hepaticand renal diseases and diabetes mellitus as well as cancer of the skin, bladder, lung, liver and prostate. Contraryto the earlier view that methylated compounds are innocuous, the methylated metabolites are now recognized tobe both toxic and carcinogenic, possibly due to genotoxicity, inhibition of antioxidative enzyme functions, orother mechanisms. As inhibits indirectly sulfhydryl containing enzymes and interferes with cellular metabolism.Effects involve such phenomena as cytotoxicity, genotoxicity and inhibition of enzymes with antioxidant function.These are all related to nutritional factors directly or indirectly. Nutritional studies both in experimental andepidemiological studies provide convincing evidence that nutritional intervention, including chemoprevention,offers a pragmatic approach to mitigate the health effects of arsenic exposure, particularly cancer, in the relativelyresource-poor developing countries. Nutritional intervention, especially with micronutrients, many of whichare antioxidants and share the same pathway with As, appears a host defence against the health effects ofarsenic contamination in developing countries and should be embraced as it is pragmatic and inexpensive.