1.1 Definition of Biohazard

A biohazard can be defined as any organism, and/or its toxin, that is 
known or suspected to cause human or animal disease. Biohazardous/infectious
material falls under Class D, Division 3 of the Workplace Hazardous Materials 
Information System (WHMIS). Exposure to biohazardous microorganisms (which 
include viruses, bacteria, fungi, and parasites) or to their toxic metabolites 
may occur via puncture wounds or as a result of absorption through the 
respiratory tract, digestive system, skin and mucous membranes: such exposures 
may result while handling animals, cell cultures and tissues or diagnostic specimens.

-Copyright McGill Laboratory Biosafety Manual - First edition, 1995--