Chapter 2 - Delineation of a Major Worldwide Problem of Arsenic-Contaminated Groundwater

Abstract

Groundwater contamination of arsenic can occur from various anthropogenic sources such as pesticides, wood preservatives, glass manufacture, and other miscellaneous arsenic uses. These sources can be monitored and controlled. Arsenic contamination was reported as early as 1938; however, skin lesions and cancers attributable to arsenic were rare and ignored until new evidence emerged from Taiwan in 1977. The serious health effects of arsenic exposure that include lung, liver, and bladder cancers were confirmed shortly thereafter by studies of exposed populations in Argentina, Chile, and China. Of the various countries affected by this contamination, Bangladesh and India are experiencing the most serious groundwater arsenic problem. The relative toxicity of arsenic depends mainly on its chemical form and is dictated in part by the valence state. Recently, a great deal of support has been found in the role of microbes in the release of arsenic into groundwater. A brief review of high arsenic concentrations in groundwater and also mechanisms proposed for the release of arsenic into groundwater systems, with particular significance to the possible role of metal reducing bacteria in arsenic mobilization into the shallow aquifers of the Ganges delta, is provided here.