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Extrapolation concepts for dealing with multiple contamination in environmental risk assessment.
Rolf Altenburger1, William R Greco
1UFZ Helmholtz Centre for Environmental Research, Department of Bioanalytical Ecotoxicology, PermoserstraBe, 15, 04318 Leipzig, Germany. rolf.altenburger@ufz.de
Integrated Environmental Assessment and Management
|May 12, 2009
Summary
Organisms face complex mixture exposures. Predictive modeling effectively estimates combined effects for simultaneous or sequential exposures without recovery, but challenges remain for pulsed exposures or nonchemical stressors.
Area of Science:
- Ecotoxicology
- Environmental Chemistry
- Risk Assessment
Background:
- Organisms frequently encounter multiple environmental stressors simultaneously.
- Assessing individual chemical risks is standard, but inadequate for complex mixture exposures.
- The vast number of potential mixtures makes experimental evaluation impractical.
Purpose of the Study:
- To review current consensus on modeling techniques for predicting ecotoxicological mixture effects.
- To identify exposure scenarios where mixture effect prediction is reliable.
- To highlight areas requiring further research in ecotoxicological mixture assessment.
Main Methods:
- Literature review of established extrapolation techniques for mixture toxicity.
- Analysis of consensus on modeling approaches for predicting combined effects.
- Identification of specific exposure patterns (simultaneous, sequential, pulsed) and interfering factors (nonchemical stressors).
Main Results:
- Predictive modeling shows reasonable accuracy for simultaneous and sequential (no recovery) mixture exposures.
- Extrapolation techniques are well-established for these specific exposure scenarios.
- Predicting effects for pulsed exposures with recovery or nonchemical stressor interactions remains an open research area.
Conclusions:
- Modeling approaches offer a viable alternative to experimental testing for many mixture exposure situations.
- Current models reliably predict combined effects for continuous or immediate sequential exposures.
- Further research is needed to develop robust models for intermittent exposures and nonchemical stressor interactions in ecotoxicology.
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