SERGEI ARDZINBA paws his white laboratory coat and gestures at the tumbledown building. “There’s nothing harmful in there now,” he says. “It was all taken away after the break-in.” Scrawled in chalk on the rusting steel doors of the disused laboratory, messages in Russian tell a less reassuring story: “Radiation! Danger! Stop! Cancer! Do not enter! You will regret it!” Staff at the primate research institute where Ardzinba is director say they wrote the warnings to scare off inquisitive children. “Just in case”, they have welded the doors shut. The reason: inside this decaying laboratory are the remains of a lethal irradiation device used to induce leukaemia in monkeys. Two years ago, thieves broke into the abandoned building on the edge of the institute, which…