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596 Commentaries

continue to be injured. To persuade scientists andregulatory officials of these predictions and of thebenefits that would thereby accrue to society, aquality of synthesis of the evidence is required thatcan only be provided using this framework to inferscientifically-defensible causal relationships. I in­vite Dr. EI-Shaarawi and other Great Lakes scien­tists and regulatory officials to read the proceedingsof the two Cause-Effect Linkages Workshops and todecide whether the methodology and papers canserve as the basis to change the quality of scientificadvice to regulatory officials for this extraordinarygroup of substances.

REFERENCESEI-Shaarawi, A.H. 1994. Proving causality is not always

necessary and sufficient for regulatory action. J.Great Lakes Research 20(3):593-594.

Fox, G.A. 1991. Practical causal inference for ecoepi-

demiologists. Journal of Toxicology and Environmen­tal Health 33:359-373.

Great Lakes Water Quality Agreement. 1990. StandardMethods (1989) and Annex I lists of substances(1989). Papers presented to the Parties by the Bina­tional Objective Development Committee.

Great Lakes Water Quality Board. 1993. Legislative andRegulatory Considerations for Virtual Elimination ofPersistent Toxic Substances. Report to the VirtualElimination Task Force and the International JointCommission. Windsor, Ontario.

International Joint Commission. 1993. A Strategy forVirtual Elimination of Persistent Toxic Substances.Volumes 1 and 2. Windsor, Ontario.

Susser, M. 1986. The logic of Sir Karl Popper and thepractice of epidemiology. American Journal of Epi­demiology 124:711-718.

Michael GilbertsonInternational Joint Commission

Windsor, Ontario N9A 6T3

Erratum

Allele IDH-2*83 should read IDH-2*120 in Table 3 (p. 304) in C.C. Krueger, D.L. Perkins,R.J. Everett, D.R. Schreiner, and B. May. 1994. Genetic variation in naturalized rainbow trout(Oncorhynchus mykiss) from Minnesota tributaries to Lake Superior. J. Great Lakes Res. 20:299-316.