Geologists from Stanford University, Columbia University and University of Delaware study environment and water sources in Bangladesh, Nepal, India, Myanmar, Cambodia and Vietnam; finds that wells in gray-colored sands have high levels of arsenic and suggest that wells be dug in orange-colored sands instead; research, which is published in journal Science, notes that holes dug for crop irrigation should not extend to deep aquifers; say that doing so could endanger safety of drinking water in re...