Radioactive iodine found in Tokyo water --Radiation above national safety level found in spinach and milk 19 Mar 2011 As looming nuclear crisis threatens Japan, the government says small amounts of radioactive iodine have been detected in tap water in Tokyo and five other areas. On Saturday, the Japanese government said a sample of tap water from the Japanese capital contained 1.5 becquerals per kg of iodine 131, well below the 'tolerable' limit for food and drink of 300 becquerals per kg.