Arsenic, a well-known poison, can be taken out of drinking water using sophisticated treatment methods. But in places that lack the equipment or technical know-how required to remove it, it still laces drinking water and makes people sick. To tackle this problem, scientists have come up with a new low-cost, simple way to remove arsenic using leftovers from another known health threat — cigarettes. They report their method in ACS' journal Industrial & Engineering Chemistry Research.