Scientists of abroad debate over the processes of arsenic contamination but no one can show with latest investigations particular formation that was responsible for arsenic contamination about 18 thousands years ago. Generally naturally occurring arsenic evolves with volcanic rocks. And last stage of magma crystallization, and occurs with other minerals
DFID (British Development Help) have funded numerous initiatives on the arsenic issue. These include a two phased approach by DPHE / British Geological Survey (BGS) / Mott MacDonald Ltd. Phase one included the compilation review and database of existing groundwater and sediment arsenic data from Bangladesh; a systematic groundwater quality survey using laboratory analysis for the 41 districts then believed to be worst affected in Bangladesh; a detailed geochemical investigation in three special study areas; modelling the movement of groundwater and arsenic in a typical Bangladesh situation. Phase two continued from Phase one and extended the survey to the remaining districts of Bangladesh excluding the three districts of the Chittagong Hill Tracts.
There are two main theories as to how arsenic is released into the groundwater