Problem formulation
The problem formulation, the most critical phase, is a process for evaluating and generating preliminary hypotheses about why ecological effects have occurred, or may occur, due to human activities. During this phase, management goals are evaluated to help establish objectives for the risk assessment; the ecological problem (i.e. the affected environmental resource and the stressors of concern) is defined; and the plan for analyzing data and characterizing risk is developed. The objective of this step is to develop:
- assessment endpoints (e.g., hatching success of a species) that adequately reflect management goals and the ecosystem they represent. These assessment endpoints are explicit expressionsof the actual environmental value that must be protected and they link the risk assessment to management concerns. Assessment endpoints include both a key or valued ecological entity and an attribute of that entity of concern that is important to protect and is potentially at risk. The scientific basis for a risk assessment is enhanced when assessment endpoints are both ecologically relevant and susceptible to the stressors of concern. Assessment endpoints that also logically represent societal values and management goals will increase the likelihood that the risk assessment will be understood and used in management decisions.
Definition of ecological entity:
In ecological risk assessment, is a general term referring to a species, a functional group of species, an ecosystem function or characteristic, or a specific valued habitat or biome.
Ecologically relevant endpoints:
Reflect important attributes of the ecosystem and can be functionally related to other components of the ecosystem. They help sustain the structure, function, and biodiversity of an ecosystem.
- conceptual models that describe critical relationships between a stressor or several stressors and assessment endpoint(s). More specifically, these models link anthropogenic activities with stressors and evaluate the relationships among exposure pathways, ecological effects, and ecological receptors. The models may also describe natural processes that influence these relationships. Conceptual models include a set of risk hypotheses that describe predicted relationships between stressor, exposure, and assessment endpoint response, along with the rationale for their selection.
Ecological receptors:
Include any living organisms other than humans, the habitat which supports such organisms, or natural resources which could be adversely affected by environmental contaminations resulting by a release at or migration from a site.
For more information:
http://www.eugris.info/FurtherDescription.asp?Ca=2&Cy=0&T=Receptor:%20Ecological&e=34
The assessment endpoints and the conceptual models are then integrated to develop a plan or proposal for risk analysis (see analysis plan in fig. 1) that identifies measures (of effect, exposure and ecosystem and receptor characteristics) to evaluate each risk hypothesis and that describes the assessment design, data needs, extrapolations, assumptions, and specific methods for conducting the analysis.
Measures of effect: are used to evaluate the response of the assessment endpoint when exposed to a stressor.
Measures of exposure: are measures of how exposure may be occurring, including how a stressor moves through the environment and how it may co-occur with the assessment endpoint.
Measures of ecosystem and receptor characteristics: include ecosystem characteristics that influence the behaviour and location of assessment endpoints, the distribution of a stressor, and the life history characteristics of the assessment endpoint that may affect exposure or response to the stressor.
