At least 115 Panamanians died after drinking toxic cough syrup in 2006, investigators said on Thursday, as the slow probe into the health disaster turned up more cases. Jose Oro, a spokesman for the Ministry of Public Affairs, said recent clinical tests had shown at least 115 people died after taking cough syrup that was adulterated with diethylene glycol, a poisonous substance normally used in engine coolant. The Chinese-made toxin was mistaken for a sweetener by government drug manufacturers, who made low-cost medicines for Panama's poorest people. Investigators previously estimated the drug had killed 94 people, mainly from kidney failure or related ailments. Investigations are only slowly turning up new cases because of the number of people involved. Only around 20 percent of the 763 people tested to date have actually shown traces of the deadly drug, according to a government study. (Reporting by Andrew Beatty, editing by Todd Eastham) REUTERS NEWS SERVICE