Back in August, six Harvard University medical researchers were poisoned after they drank coffee spiked with sodium azide, reports the Associated Press this week. Sodium azide is a common preservative. The researchers, who worked in the pathology department, complained of dizziness and ringing ears and one person passed out. They were all sent to the emergency room and were eventually released. Matteo Iannacone tells ABC News that the toxicology results reported that the coffee had a "very high concentration" of sodium azide. "I can not think it would be an accident," Iannacone says. According to NPR, Harvard has removed the suspect coffee machine and increased video surveillance in the area.