Ecological response analyses

The combining of exposure analysis with ecological effects data results in a stressor-response profile. This profile is an attempt to match ecosystem impacts at the levels of the stressor concentration under study. Relationships between the xenobiotic and the measurement endpoint are evaluated with a consideration of how this interaction affects the assessment endpoint. Rarely is this process straightforward. Often some model is used to specifically state the relationship between the measurement and assessment endpoint. When this relationship is not specifically stated it is then left to professional judgment. 

The EPA framework lists the relationships between assessment and measurement endpoints  

Phylogentic extrapolation states the relationship of toxicity data from one species to another or, perhaps more often, class to class. Often only 

Response extrapolation presents the relationship between two toxicity endpoints such as the NOAEL and the EC50. 

Laboratory-to-field extrapolation examines the relationship of the estimate of toxicity gathered in the laboratory to the effects expected in the field situation. Laboratory situations are purposefully kept simple compared to the reality of the field and are designed to rank toxicity rather than to mimic the field situation. Laboratory tests have limited the route of exposure and behavior. In the field these restrictions are not in place, often leading to unexpected results. 

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Analysis. Although separated into different sides of the analysis box, exposure and ecological responses are intimately connected. Often the biological response to a toxicant alters the exposure for a different compartment of the ecosystem. 

Risk assessment Some participants suggested that further development and validation of appropriate methods to assess the ecological risks of chemical agents are required. Dose-response curves should be established at the community and ecosystem levels. Several participants suggested that when applying for an exemption of chemicals according to the Stockholm Convention, China might need to support its application with risk-based analysis. 

Hartmann T (1999) Chemical ecology of pyrrohzidine alkaloids. Planta 207 483-495 Kessler A, Baldwin IT (2002) Plant responses to insect herbivory the emerging molecular analysis. Annu Rev Plant Biol 53 299-328... 

Participants, stakeholders, and practitioners interact in the stakeholder process. Each group is inclusive of the other, and each group is responsible for applying, interpreting, and reviewing the ecological assessments and the uncertainty analysis methods where they are used. 

LaForest, S Wu, W. and Lofstedt, C. (1997). A genetic analysis of population differences in pheromone production and response between two populations of the turnip moth, Agrotis segetum. Journal of Chemical Ecology 23 1487-1503. 

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