A human pathogen is a micro-organism, nucleic acid or protein capable of causing disease in a human. This includes animal or plant pathogens that can cause disease in humans. Toxins are substances that are produced by or derived from a microorganism which are able to cause disease in a human.

Under this Act, human pathogens are divided into risk groups, as defined in Section 3. These definitions outline the criteria to be used in assessing which risk group a human pathogen may fall into. These criteria include the level of risk to the health of a person or to public health, as well as the likelihood that the human pathogen will cause disease in a human, and whether or not treatment and preventative measures are available.  Examples of human pathogens that fall into each Risk Group are provided in Schedules 2 to 4. Toxins are those listed in Schedule 1.

The Public Health Agency of Canada will establish an advisory committee to advise the Minister on the risk group classification of human pathogens and toxins and what should be in Schedules 1 to 5.  The advice of this committee will be made public.