Officials at the Health Sciences Centre say 50 gallons of formalin, a liquid similar to formaldehyde, spilled on the fourth floor of the Thorlakson building on Thursday.
The entire building was evacuated as a Hazmat team and other emergency crews arrived to contain the situation.
A construction worker accidentally broke a feeder pipe, which caused the leak.
He was the only person directly exposed to the formalin. He was treated, decontaminated and allowed to go home.
Several surgeries were cancelled although officials expect to have them rescheduled soon.