Police in China have detained four people after radioactive material being used in a construction project went missing, state media reported on Monday. A tiny piece of irridium-192, used to locate flaws in pieces of metal, vanished on Wednesday from a construction site in the eastern city of Nanjing and was not recovered until Saturday afternoon, the official China Daily reported. It was found in bushes 1km from the construction site wrapped in a plastic bag, put in a lead container and then taken away, the newspaper said. Police have detained four people deemed responsible for its loss from an engineering company, the paper added. More