Epidemiology: The branch of medicine that deals with the study of the causes, distribution, and control of disease in populations 1Most definitions are drawn from the American Heritage Dictionary of the English Language, Fourth ed. [...] Toxicology: The study of the nature, effects, and detection of poisons and the treatment of poisoning. [...] It mandates standards of ambient air quality based on exposure patterns of children to ambient air pollutants, the special susceptibility of infants and children to these pollutants, and the interaction of multiple air pollutants on the health of infants and children. [...] This is particularly relevant in the promotion of the health of the foetus and young child. [...] Two of those are particularly relevant to children’s environmental health: the defence of the Charter of Rights and Freedoms and the assurance of equality of opportunity so all Canadians can share in prosperity.