190:, mortality, feeding, growth and reproduction (Kooijman 1997). This type of approach starts with the description of the uptake and elimination of a compound by an organism, as an effect can only be expected if the compound is inside the organism, and where the no-effect-concentration is one of the modeling parameters. As the approach is biologically based it is also possible by using the
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phenomena, etc.). The effects of these multiple stressors are excluded in the standard test procedures by keeping the local environment in the test constant. It is also possible to use these parameter values to predict effects at longer exposure times, or effects when the concentration in the medium
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other than zero may give the impression that an effect is accepted, and this is in conflict with the aim of maximally protecting the environment. In addition ECx values do depend on the exposure time. ECx values for survival decrease for increasing exposure time, until equilibrium has been
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established. This is because effects depend on internal concentrations, and that it takes time for the compound to penetrate the body of test organisms. However, sub-lethal endpoints (e.g., body size, reproductive output) may reveal less predictable effect patterns in time.
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Péry A.R.R., Flammarion P., Vollat B., Bedaux J.J.M., Kooijman S.A.L.M. and Garric J. (2002) - Using a biology-based model (DEBtox) to analyse bioassays in ecotoxicology: Opportunities & recommendations. Environ. Toxicol. & Chem., 21 (11):
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Heugens, E. H. W., Hendriks, A. J., Dekker, T., Straalen, N. M. van and
Admiraal, W. (2001) - A review of the effects of multiple stressors on aquatic organisms and analysis of uncertainty factors of use in risk assessment. Crit. Rev Toxicol. 31:
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Heugens, E. H. W., Jager, T., Creyghton, R., Kraak, M. H. S., Hendriks, A. J., Straalen, N. M. van and
Admiraal. W. (2003) - Temperature-dependent effects of cadmium on Daphnia magna: accumulation versus sensitivity. Environ. Sci. Technol. 37:
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There is not much debate on the existence of an NEC, but the assignment of a value is another matter. Current practice consists of the use of standard tests. In the standard tests groups of animals are exposed to different concentrations of
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in a survival experiment indicates the concentration where 50% of the test animals would die in that experiment). ECx concentrations also have their problems in applying them to risk assessment. Any other value for
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Hoeven N. van der, Noppert, F. and
Leopold A. (1997) – How to measure no effect. Part I: Towards a new measure of chronic toxicity in ecotoxicology. Introduction and workshop results. Environmetrics, 8: 241 –
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Hallam T.G., Lassiter R.R. and
Kooijman S.A.L.M. (1989) - Effects of toxicants on aquatic populations. In: Levin, S. A., Hallam, T. G. and Gross, L. F. (Eds), Mathematical Ecology. Springer, London: 352 –
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The shape of the effect patterns over time depends on properties of the test compound, properties of the organism, the endpoint considered and the dimensions in which the endpoint is expressed (e.g., body
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is not constant. If the observed effects include those on survival and reproduction of individuals, these parameters can also be used to predict effects on growing populations in the field.
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Kooijman S.A.L.M. (1997) - Process-oriented descriptions of toxic effects. In: Schüürmann, G. and
Markert, B. (Eds) Ecotoxicology. Spektrum Akademischer Verlag, 483 - 519
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Bruijn J.H.M. and Hof M. (1997) – How to measure no effect. Part IV: how acceptable is the ECx from an environmental policy point of view? Environmetrics, 8: 263 – 267.
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T. Jager, Heugens E. H. W. and
Kooijman S. A. L. M. (2006) Making sense of ecotoxicological test results: towards process-based models. Ecotoxicology, 15:305-314,
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OECD, Document No 54 of "Series on
Testing Assessment", 2006. Current approaches in the statistical analysis of ecotoxicity data: a guidance to application
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Alda
Alvarez, O., Jager, T., Nunez Coloa, B. and Kammenga, J.E. (2006). Temporal dynamics of effect concentrations. Environ. Sci. Technol. 40:2478-2484.
133:, or NOEL). This NOEC has been severely criticized on statistical grounds by several authors and it was concluded that the NOEC should be abandoned.
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Crane M. and Newman M.C. (2000) – What level of effect is a no observed effect? Environmental
Toxicology and Chemistry, vol 19, no 2, 516 – 519
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Suter G.W. (1996) – Abuse of hypothesis testing statistics in ecological risk assessment, Human and ecological risk assessment 2 (2): 331-347
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Laskowski R. (1995) - Some good reasons to ban the use of NOEC, LOEC and related concepts in ecotoxicology. OIKOS 73:1, pp. 140–144
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Sibly R.M. and Calow P. (1989)- A life cycle theory of responses to stress. Biological
Journal of the Linnean Society 37 (1-2): 101-116
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Biology-based methods not only aim to describe observed effects, but also to understand them in terms of underlying processes such as
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Chen C.W. and Selleck R.E. (1969) - A kinetic model of fish toxicity threshold. Res. J. Water Pollut. Control Feder. 41: 294 – 308.
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Straalen N.M. (1997) – How to measure no effect II: Threshold effects in ecotoxicology. Environmetrics, 8: 249 – 253.
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198:(e.g. effects of food restriction, temperature, etc.) and processes that are active under field conditions (e.g.
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44:. Risk assessment is nowadays considered essential for making these decisions on a scientifically sound basis.
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Kooijman S.A.L.M. (2000) - Dynamic Energy and Mass Budgets in Biological Systems. Cambridge University Press
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Kooijman S.A.L.M. (1981) - Parametric analyses of mortality rates in bioassays. Water Res. 15: 107 – 119
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69:lowest-observed-adverse-effect level
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230:Retrieved on June 19, 2009
228:thefreedictionary.com/AOEL
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194:to incorporate multiple
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105:that will not harm the
91:No-effect concentration
86:No-effect concentration
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19:are used to determine
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129:(NOEC, also called a
56:(NOAEL), also called
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