Assessing the health risks of priority substances under the Canadian environmental protection act

The Canadian Environmental Protection Act (CEPA) came into force in June 1988. This legislation provides the federal government with broad powers to deal with health and environmental problems posed by chemicals and the products of biotechnology throughout their life cycle. Responsibility for administering CEPA is shared between the Department of the Environment and the Department of National Health and Welfare. Part II of the Act, the "toxic substances" provisions, enables the federal government to impose controls on substances new to Canadian commerce and to address the health and environmental risks posed by existing substances. Part II of CEPA also delineates the manner in which existing substances are to be selected for assessment (priority substances) and controlled. The first Priority Substances List was published in February 1989. The 44 entries on this list include discrete chemicals, classes of chemicals, and complex mixtures of chemicals; the Department of the Environment and the Department of National Health and Welfare must ascertain whether these substances pose a risk (are "toxic" as defined in CEPA) to the environment or to human health by February 1994. This paper outlines the administrative arrangements for conducting risk assessments and the requirements for ascertaining whether a substance is "toxic" with respect to human health under CEPA. The rationale for deeming dioxins and furans, the first two priority substances to be assessed, as "toxic" with respect to human health is also described.