Abstract

  Ecosystem health is a key principle which underlies the Canadian Environmental Protection Act (CEPA). This act is designed to protect human health and the environment from harmful and/or irreversible effects by providing a cradle-to-grave regulation of toxic substances.
  As an example of the application of this act, this contribution considers the most toxic dioxins and furans which are generally associated with Kraft pulp mill effluents. These are some of the first substances to come under the CEPA legislation. The proposed CEPA regulations for dioxins and furans ate based on 'end-of-pipe' control, which would effectively limit their concentrations in effluent to something close to measurable levels. Depending on sample matrix and methodology, however, measurable levels may differ considerably.
  Evidence presented at the Alberta-Pacific (ALPAC) pulp mill hearings in Alberta and the Northwest Territories during 1989 demonstrated that total loadings are particularly important in dealing with the far-field effects of these extremely toxic, persistent, and bioaccumulating substances. Further, it was reported that there might be no threshold of effect for tetrachlorodibenzo-para-dioxin (2, 3. 7, 8 TCDD) or the companion furan. If such evidence is correct, the CEPA regulations should be designed to achieve zero discharge of these contaminants. Measurable levels, as presently defined in the CEPA regulations, maybe in excess of zero discharge requirements.
  Clearly, such in consistency may cause problems and should be addressed directly. Unfortunately, the first draft of the CEPA regulations represents a piecemeal approach. In this, it is unfair to industry, it is scientifically inadequate, and it may not be enforceable. The application of CEPA regulations for the pulp and paper industry will set a new precedent for Canada's approach to ecosystem health. It is therefore essential to base decisions on a good understanding of the dynamics and effects of chemicals in ecosystems and to re-evaluate, carefully, the toxicities of key contaminants. Interim measures are likely appropriate.

Keywords: ecosystem health, Canadian Environmental Protection Act, Kraft mill effluent, toxic substances