If you've seen the 1940s cinematic black comedy "Arsenic and Old Lace," in which a couple of well-meaning spinsters take it upon themselves to put lonely old men out of their misery by giving them elderberry wine laced with arsenic, you know that the latter substance is pretty bad stuff. When it contaminates drinking water, arsenic can cause bladder, lung and skin cancer, as well as harm the nervous system, heart and blood vessels [source: National Resources Defense Council].
Unfortunately, almost 100 million people in developing countries today are exposed to dangerously high levels of arsenic in their water, and they can't afford the complex, expensive purification methods used in the U.S. to get rid of it. However, a new technology may offer a solution. Monmouth University (N. J.) chemistry professor Tsanangurayi Tongesayi has developed an inexpensive arsenic-removing system in which chopped-up pieces of ordinary plastic beverage bottles are coated with cysteine, an amino acid. When the plastic pieces are added to water, the cysteine binds to the arsenic, removing it and rendering the water drinkable. In tests, he's been able to take water containing dangerous arsenic levels of 20 parts per billion, and reduce it to 0.2 parts per billion, which meets the U.S. Environmental Protection Agency's standard [source: Science Daily]