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Issues in Risk Assessment A similar presumption of hazard is used by the U.S. Department of Agriculture in evaluating proposed species introductions for biological control purposes. The polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin study did not explicitly discuss hazard identification. Regulatory actions on both substances are strongly influenced by human health risks, so it is not clear that any explicit ecological hazard identification was needed or performed. For the spotted owl study, hazard identification occurred through environmental impact studies undertaken by federal agencies to comply with National Environmental Policy Act that identified this species as being vulnerable to loss of habitat due to old-growth forest clearing. In fisheries management, it might be assumed that fishing is by definition a hazard. Within limits, fishing confers no greater risk to a population than does predation or even the killing of small numbers of fish by toxic chemical spills. Detailed assessments, such as those described in the case study, appear to be triggered by observations of declining catch or by other evidence (e.g., from modeling studies) that suggests that sustainable yields are being exceeded. The case studies demonstrate that ecological hazard identification can take many forms and can involve both scientific data and policy decisions. The group discussed two possible modifications of the Red Book paradigm to accommodate the clear influence of policy on the conduct of ecological risk assessment: addition of a ''scoping" component before hazard identification and expansion of the definition of hazard identification to include management inputs. No consensus was achieved on which alternative is preferable, but the group agreed that flexibility is important, the separation between risk assessment and risk management must be retained, a distinction is needed between socially relevant and biologically relevant end points for assessment, a social consensus as to which environmental values should be protected is needed, and scientists should communicate knowledge, not policy. DOSE-RESPONSE ASSESSMENT J. Bailar and J. Meyer Discussion in this session focused first on the need to generalize the