For more than a decade it has been known that shallow tube wells in Bangladesh are frequently contaminated with arsenic concentrations at a level that is harmful to human health. By now it is clear that a disaster of an unheard magnitude is going on: the World Health Organization has estimated that long-term exposure to arsenic in groundwater. at concentrations over 500 μg L&lt... https://www.rxkaitori.com/product-category/harvard-coolled-drivers/