Humans can be exposed to Arsenic (As) through the intake of air, food and water. Although food is usually the major source of arsenic exposure for people, most adverse effects are seen after arsenic exposure from drinking water. The two main reasons for this situation are that most food arsenicals are organic and have little or no toxicity, and in many cases, Arsenic exposures from drinking water sources are to the more toxic inorganic form and occur at relatively high doses, e.g., hundreds of micrograms per day. In various parts of the world, Arsenic in drinking water is associated with such effects as gastroenteritis, neurological manifestations, vascular changes, diabetes and cancers (bladder, lung, liver, kidney and prostate). After reviewing the Arsenic database, the U.S. Environmental Protection Agency promulgated a maximum contaminant level for Arsenic in drinking water of 10μg/L.
Arsenic and many of its compounds are especially potent poisons. Arsenic disrupts intracellular energy transfer through several mechanisms, inhibits lipoid acid which leads to insufficient cellular and mitochondrial respiration. These metabolic interferences lead to death from multi-system organ failure, probably from necrotic cell death. Although arsenic causes toxicity, it can also play a protective role in leukemia treatment.