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U-SHAPED DOSE-RESPONSE CURVES: THEIR OCCURRENCE AND IMPLICATIONS FOR RISK ASSESSMENT
Citation:
Davis, J. AND D. Svendsgaard. U-SHAPED DOSE-RESPONSE CURVES: THEIR OCCURRENCE AND IMPLICATIONS FOR RISK ASSESSMENT. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-90/171 (NTIS PB91115808), 1990.
Description:
A class of curvilinear dose-response relationships in toxicological and epidemiological studies may be roughly described by "U-shaped curves. uch curves reflect an apparent reversal or inversion in the effect of an otherwise toxic agent at a low or intermediate region of the dose continuum. everal examples of U-shaped dose response functions are presented to illustrate the variety of agents and end points that can follow this form. uch findings are not thought to represent a unitary phenomenon, but may be explained through numerous possible principles or mechanisms, some of which are illustrated and discussed in general terms. -shaped dose-response curves raise important issues for toxicological and environmental health risk assessments, particularly in the identification of no-observed-effect levels and in the evaluation of multiple outcomes and trade-offs between potential risks and benefits of a given agent. t is especially important to avoid focusing exclusively on an apparent improvement in one end point and failing to consider other, possibly deleterious effects of the same agent.