Dynamic measures for ecotoxicity

Kooijman, S.A.L.M., Bedaux, J.J.M., Gerritsen, A.A.M., Oldersma, H. and Hanstveit, A.O. 1998. Dynamic measures for ecotoxicity. In: Newman, M.C. and Strojan, C. Risk Assessment: Logic and Measurement Ann Arbor Press, pp 187 - 224.


We review the problems with the No Observed Effect Concentration (NOEC) to identify a concentration of test chemical that has no effect on test organisms and conclude that effect models are required to solve the problems. We then argue that the logit and probit models are not suitable as effect models and identify three required components of dynamic models for toxic effects: toxico kinetics, effects on a target parameter coupled to the internal concentration and the physiological component. The Dynamic Energy Budget (DEB) model, which is used to model the latter component, relates a change in a target parameter of a particular physiological process, such as the specific costs for growth, to an output variable, such as the cumulative number of offspring. We compare the logit/probit and the DEB-based models conceptually and numerically and conclude that the DEB-based model is more effective as an effect model. Contrary to the logit model, the DEB-based model provides the required information to evaluate the consequences of effects on individuals for population dynamics. Quantitative Structure Activity Relationships are easier to derive on the basis of the DEB-based model.

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