Between science and politics: assessing the risks of dioxins in Canada and the United States

Conclusions The history of U.S. and Canadian risk assessments for dioxin is an increasingly familiar tale of debates within the scientific community played out in the political arena. Uncertainty among scientists creates the possibility of large disparities between different governments' policies. However, the pattern of differences that emerges reflects the context in which science policy decisions are made within each agency and within each country. The political environment has implications not just for how mandated science is received, but for how it is conducted.Many features of the dioxin case are consistent with observations by others. In the cases of formaldehyde, alachlor, alar, and amaranth, EPA relied on mathematical models to assess the risks of potential carcinogens, while Health and Welfare Canada relied on the more traditional safety factor approach.³⁵ This body of evidence is suggestive of national styles of transscience. Features of the U.S. style include explicit rationales for regulatory decisions, reliance on consistent and explicit risk assessment principles, and public debate over scientific aspects of public policy. The Canadian style is exemplified by closed decisionmaking, case-by-case review, and the absence of public discussion of the scientific basis for government decisions.The differences between FDA and EPA in this case study suggest an important caveat, however. The U.S. style is most clearly reflected in the implementation of the non-discretionary environmental, health and safety statutes passed by the U.S. Congress since 1970. More closed and traditional styles of regulatory decisionmaking may survive within the U.S. as vestiges of a more deferential past.Even less than pure science, trans-science is not a universal enterprise. When scientists do reach agreement, it can be a powerful force that can even overcome political and national differences (Haas, 1989). However, when science is uncertain, as is typically the case in assessing the risks of toxic chemicals, there is more room for political factors to shape the way different countries interpret science in making policy decisions.