From what I could tell on wikipedia[1][2], it's natural and the wells hold water in a way to allow As to collect in higher concentrations [1] http://en.wikiped

From what I could tell on wikipedia[1][2], it's natural and the wells hold water in a way to allow As to collect in higher concentrations [1] http://en.wikipedia.org/wiki/Arsenic_contamination_of_groundwater http://en.wikipedia.org/wiki/Arsenic_contamination_of_ground... [2] http://en.wikipedia.org/wiki/Arsenic_poisoning http://en.wikipedia.org/wiki/Arsenic_poisoning