Arsenic has been long known as a poison. Exposure to arsenic via drinking water initially causes skin diseases such as pigmentation (dark and light spots on the skin) and arsenicosis (hardening of skin on hands and feets). Later, cancer of the skin, lungs, bladder, and kidney may occur . Unfortunately, there is no cure for these diseases. Both the World Health Organization (WHO) and the U.S. Environmental Protection Agency (USEPA) have classified arsenic as a carcinogen. In some parts of Bangladesh, West Bengal, and Nepal, the arsenic level in the groundwater can be over 100 times higher than the WHO and EPA guidelines of 10 ug/L.