Why different regulatory decisions when the scientific information base is similar?--Human risk assessment.

The main objective of this analysis has been to characterize the role of science, in a broad sense, in relation to social, economical, political, and other factors in explaining why regulatory decisions vary in different countries, although they are based on more or less identical scientific data. Eleven countries from different geographical areas and with varying cultural background have provided information in response to an extensive questionnaire aimed at identifying procedures for registration, restricting, or banning registration for certain selected pesticides. Although many of these responses lacked sufficient detail in certain aspects, together with other documentary sources they nonetheless provided insight with respect to some of the main concerns among and between nations regarding decisions in pesticide management. Among the main conclusions presented in this analysis, the following deserves particular emphasis: The underlying reasons for introducing restrictions on pesticide use on the national level will have to be more explicitly stated and openly declared by regulatory bodies of all nations. Although more pronounced in some countries, there is a strong influence of nonscientific considerations in pesticide management, that is not always based on rational considerations. In the field of hazard and risk assessment differences in scientific opinion have primarily, but not exclusively been identified regarding the evaluation of carcinogenic effects in experimental animals. In this area debated issues are the interpretation of the significance for man of certain types of tumors, methods for dose-response extrapolation, genotoxic versus nongenotoxic carcinogens, the use of MTD in long-term studies, mechanistic approaches to interpret cancer induction, and others. Another area identified to cause divergence is exposure assessment. Evaluation of pesticides on the national level for the purpose of regulation involves a tremendous duplication of efforts that could be substantially reduced by effective cooperation on the international level.