sodium azide
Late last summer, six researchers at Harvard University's medical school fell into a poisoner's trap. Each poured a cup of coffee from a communal coffee maker in the school's pathology department. All of them ended up in the hospital; some had fainted, others were dizzy and nauseated, most couldn't hear over the ringing in their ears.
Investigators quickly discovered that the coffee machine's water tank had been laced with laboratory preservative called sodium azide, used to keep bacteria from growing in chemical solutions. This offered up an almost limitless pool of suspects - anyone…