Abstract: On July 18, 1990, Employees #1 through #3 were potentially exposed during an unexpected and unmanned release of ethylene oxide (EtO). Employee #3 heard the ethylene oxide alarm ring. He turned off the sterilizer and turned it on again, as per standard operating procedure. He then left the area and notified engineering, noting that the sterilizer was in the purge cycle. The employer later ran a complete check on the ethylene oxide system. It was determined that the EtO capture box was not designed properly and a firm was contracted to correct this. The system has been shut down since July 18, 1990. The employer was cited for inadequate engineering controls.