Ecological risk assessment definition

The link between the ecological/ecotoxicological risk assessment and the risk management frameworks is demonstrated. The ecological risk assessment consists of seven interactive elements (Fig. 17). The quantitative and descriptive science used to conduct ERA (Table 5) does not answer, in a direct way, the question of what should be done to manage the risk. Science determines adversity, but the public determines acceptability (Fig. 18). But acceptable risk is a highly subjective and relative term. It is time and space-specific and depends upon definitions of quality of life and robustness of the environment. 

It is evident that some techniques do not have conceptually similar equivalents with various levels of complexity. Hence, tiering is not (yet) possible for all problem definitions. Moreover, it is clear that human risk assessment can sometimes operate on a higher conceptual tier than ecological risk assessment, for example, when BRN modeling and PBPK models are used. On the other hand, ecological risk assessment approaches may be sometimes more diverse, and can be better tailored to a risk assessment problem and its context. 

There are many concepts in use for the assessment of risks or impacts of chemical mixtures, both for human and ecological risk assessment. Many of these concepts are identical or similar in both disciplines, for example, whole mixture tests, (partial) mixture characterization, mixture fractionation, and the concepts of CA and RA (or I A). The regulatory application and implementation of bioassays for uncharacterized whole mixtures is typical for the field of ecological risk assessment. The human field is leading in the development and application of process-based mixture models such as PBTK and BRN models and qualitative binary weight-of-evidence (BINWOE) methods. Mixture assessment methods from human and ecological problem definition contexts should be further compared, and the comparison results should be used to improve methods. 

Perhaps the easiest definition of ecological risk assessment is the probability of an effect occurring to an ecological system. Note that the word "probability" is key here. Important components of a risk assessment are the estimations of hazard and exposure due to a stressor. 

This introductory section describes the purpose, scope, and intended audience for this report discusses the definition and application of ecological risk assessment outlines the basic elements of the proposed framework and describes the organization of this report. 

At the time of writing, English Nature has yet to produce any definitive guidance in connection with the regime. As a result, the review that follows is based mainly on best practice in ecological risk assessment and work performed recently by the Environment Agency. 

If ecological modeling is to become a standard tool for risk assessments of pesticides, all stakeholders involved need to understand what models are and how they are developed. It is important to realize that models by definition ignore many, if not most, aspects of real systems in order to identify key factors of the system s internal organization. Models are based on assumptions that are implemented, tested, and revised. Model development is iterative and ends when certain acceptance criteria are fulfilled. To assess or evaluate a model, we need to know its purpose. 

An important similarity between human and ecological assessment of mixtures is the structure of the assessment procedure. Both procedures are often organized along a series of consecutive steps, that is, problem definition, hazard identification, exposure assessment, effect- or dose-response assessment, and risk characterization... 

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