Environmental Risk Assessment for Uranium Mines and Mills in Canada

Abstract

In the past, the concern with radiation exposures arising from human activities has been with the protection of human health. The concept was that, if humans were adequately protected, then 'other living things are also likely to be sufficiently protected' (ICRP 1977) or 'other species are not put at risk' (ICRP 1991). In recent years, the general validity of this view has been challenged (e.g., IAEA 1999), in part, because of increased worldwide concern over sustainability of the environment, including maintaining biodiversity and protecting habitats, rather than because of actual observation of biological effects in non-human species. With the passing of the new Nuclear Safety and Control Act of May 2000, the Canadian Nuclear Safety Commission (CNSC) was required to regulate nuclear facilities in such a way as '…to prevent unreasonable risk to the environment.' This was a new challenge for both the CNSC and the industries which it regulates, especially the uranium mining industry. The former Advisory Committee on Radiological Protection (ACRP) was a group of experts whose role was to provide the CNSC with independent advice on matters relating to health or environmental aspects of ionizing radiation. In view of the new importance of the environment to the CNSC's regulatory framework, the ACRP established a Working Group to report on current scientific matters pertaining to the potential risks to non-human biota from ionizing radiation and on possible frameworks for the protection of non-human biota. The findings of the ACRP are described in INFO 0703 (ACRP 2002). A key Canadian regulatory initiative was the inclusion of releases of radionuclides from nuclear facilities (impact on non-human biota) in the second Priority Substances List (PSL-2). A draft report released in July 2001 (EC/HC 2001) generated considerable dialogue among the various stakeholders. The final report of May 2003 concluded that there is little evidence to suggest that current releases of radionuclides from nuclear facilities are harmful to the environment and that it is in fact the chemical properties of uranium that are the issue. While a great deal of debate over the findings of the PSL-2 report remains, the PSL-2 report concluded that 'releases of uranium and uranium compounds contained in effluent from uranium mines and mills are entering the environment in quantities or concentrations that may have a harmful effect on the environment and its biological diversity'. Nevertheless, it is still important to evaluate the potential adverse effects on non- human biota exposed to ionizing radiation. In considering how to assess the potential effects of ionizing radiation on the environment, it should be remembered that the ultimate goal of environmental protection is to ensure that communities and populations of organisms can reproduce and survive and that all higher organisms in the food-chain will be self- sustaining. Thus, the focus of a strategy for environmental protection must be on the collective response of the population or the community rather than the response of a single individual within the community. It is also important to understand that in assessing risks to the environment, there are many sources of uncertainty, which need to be addressed, or as a minimum acknowledged. Some of these sources of uncertainty include identifying the population at risk, defining what adverse effect is to be assessed, spatial and temporal averaging of exposures, the dose calculatio n procedure, and the role of natural background variability, among other factors. Each of these aspects introduces uncertainty into the assessment of environmental risk. The presence of such uncertainties is an important consideration in deciding whether or not a true environmental risk is present and how to use the results of the environmental assessments which encompasses uncertainty as part of a risk (- informed) management strategy, consistent with the federal government initiatives in Smart Regulation (www.pco-bcp.gc.ca/smartreg-regint/en/index.html). Since the passing of the new Nuclear Safety and Control Act in 2000, environmental risk assessments have been carried out at various nuclear sites across the country, including uranium mining sites, resulting in extensive dialogue between the CNSC and industry. This dialogue has helped the Canadian process to evolve. At the same time, there have been, and continue to be, several important international initiatives in the area of environmental risk assessment. A continuing challenge to both regulators and practitioners is to participate in, or at least to monitor, such international initiatives and to incorporate relevant information and procedures into the Canadian approach. Thus, this paper attempts to provide an overview of key international initiatives and how these and other initiatives as considered within the Canadian regulatory framework.