A small amount of radioactive material has mysteriously disappeared from a Toronto research facility. The Sunnybrook Research Institute (SRI) announced Wednesday evening that a locked, lead-lined cabinet containing radioactive material went missing some time after June or July of last year. The working theory is that the cabinet was mistakenly sent to a scrapyard, said Michael Julius, the institute's vice-president of research. Although SRI is located at Sunnybrook hospital, Dr. Julius said the missing cabinet is not a threat to patients. "There is no impact on patient safety. I really do want to underscore that," he said. Staff at SRI first noticed the cabinet was missing during a routine audit on March 21. The cabinet, a heavy 75-cubic-centimetre object, was clearly labelled as containing radioactive material. Inside were 14 radioactive items, only one of which poses a potential health risk, Dr. Julius said. That item, about half the size of a dime and used to calibrate X-ray machines, contains the radioactive isotope Americium-241, commonly found in smoke detectors. It was encased in its own locked, lead-and-steel box inside the cabinet. "If you managed to get it out of the smaller box - which would be a feat, I have to tell you - if you were to put it in your pocket, for example, and left it in your pocket for a day or two, you could get a radiation burn," Dr. Julius said.