Toxins contained in California tap water could help cause to around 15,500 cancer cases there over the course of a lifetime, a shocking new study has claimed. Researchers from the Environmental Working Group [EWG] say chemicals such as arsenic and hexavalent chromium, as well as radioactive elements such as uranium and radium, have been found in their analysis of the state's drinking water. For an article published today in the journal Environmental Health, EWG scientists say carcinogens and other toxic contaminants were detected in more than 2,700 California community water systems. They estimated that 7,251 cancer cases will be caused over a lifetime in California solely due to the amount of arsenic found in the water. Statewide, nearly two-thirds of drinking water systems contained at least two cancer-causing contaminants, according to the research.