Ecosystem endpoints

Criteria 1) Relevance to human health endpoints. 2) Sensitivity to change in loadings. 3) Overall historical data quality. 4) Data collection infrastructure. 5) Feasibility of data collection and analysis. 6) Ability to adjust for confounding factors. 7) Understanding of linkages with rest of ecosystem. 8) Broad geographic distribution. 9) Well-known life history (for fauna). 10) Nonintrusive sampling. 

CLL approach and ecosystem, risk analysis. This approach provides insights on assessment and measurement endpoints for ecosystem-level EcoRA since it has a set of environmental criteria to detect the state of ecosystems critical load itself can be treated as a criterion for ecosystem sustainability (Bashkin, 2002). Moreover, one can derive spatial ecosystem risk estimates based on the percentage of ecosystems protected/potentially at risk under the current and predicted level of pollutant loads. 

There are a number of approaches to measuring risks depending on assessment and measurement endpoints selected. At ecosystem level, one can propose a percentage of the affected area with CLs exceeded as an acceptable quantitative parameter for ecosystem risk magnitude. In pristine areas, actual state of the environment may be taken as a reference point for risk characterization. 

At present, the calculation and mapping of critical loads for heavy metals is only at the beginning and in Europe there are only a few examples of application of methods described in Section 3.2. We will refer to case studies from Germany and Russia as the most characteristic research in this direction. The typical endpoints in these calculations refer to critical concentrations of different heavy metals in the ecosystems. The determination of the given critical concentrations is still uncertain and the relevant risk assessment calculated as an exceedance of critical loads should be based on selecting values of critical concentrations (see 3.2.2). 

Critical Loads of Heavy Metals Depending on ERA Endpoints The ecosystem characteristics of case study plots in various natural forests of the European part of Russia are shown in Table 4. Critical loads in an occasion of human health and ecotoxicological effects on biota (endpoints) have been accounted. Corresponding critical limits of HM concentration in soil drainage waters are presented in Table 1. 

Table 4. Percentage of various endpoints contribution to total environmental risk assessment of ecosystem sensitivity to acid deposition in Northern Asia (Bashkin, 1998).

Ecosystem-forming soils Endpoint assessment method Endpoints ... 

CNcrit, included in the calculation of critical nitrogen leaching, Ni(crit), values, the input of this endpoint parameter into the uncertainty of CL(N) is expressed in a lesser degree. Furthermore, the runoff processes are practically not significant for ecosystems of Luvic Phaeozems, Chernozems and Kashtanozems due to low P PE ratio. During the calculations of CL(N) for ecosystems of North East Asia, the values of critical immobilization and denitrification from N depositions as the endpoints both in relative and absolute meanings played a subordinate role that obviously reflects their minor contribution into uncertainty and sensitivity analysis of the computed output values of ecosystem sensitivity to acidic deposition. 

Thus, the ERA estimates shown in Table 4 characterize the significance of the endpoints, such as nitrogen content in plant issues and surface waters for many ecosystems... 

According to USEPA, the key aspect of the ERA is the problem formulation phase. This phase is characterized by USEPA as the identification of ecosystem components at risk and specification of the endpoints used to assess and measure that risk [13]. Assessment endpoints are an expression of the valued resources to be considered in an ERA, whereas measurement endpoints are the actual measures of data used to evaluate the assessment endpoint. 

In recent years, concern that chemicals might inadvertently be disrupting the endocrine system of humans and wildlife has increased. The concerns regarding exposure to these endocrine disrupters are based on adverse effects observed in certain wildlife, fish, and ecosystems increased incidences of certain endocrine-related human diseases and adverse effects observed in laboratory animals exposed to certain chemicals. The main effects reported in both wildlife and humans concern reproductive and sexual development and function altered immune system, nervous system, and thyroid function and hormone-related cancers. Endocrine dismption is not considered a toxicological endpoint in its own right, but a functional change or toxicological mode(s) of action that may lead to adverse effects. Endocrine dismpters are addressed further in Section 4.11. 

Assessment endpoints are measurable ecosystem characteristics that represent management goals (USEPA 1998). They should define... 

It is essential to define the assessment scenario within which the assessment endpoint will be assessed. The assessment scenario should specify the spatial, temporal, and ecological boundaries within which the endpoint is assessed, since these have substantial implications for the structure of the assessment model and the scope of the input data. The assessment scenario should also describe those aspects of the ecosystem that are relevant to the assessment, that is, those aspects that have an influence on the mechanisms of exposure and effects that will be assessed. This step is important in all ecological risk assessments it places the assessment activity into the real context of an ecosystem, helps to prevent construction of inappropriate models, and helps with interpretation and communication of results. 

For pesticide risk assessments, it may often be necessary to assess impacts of the same pesticide used in different crops, in different seasons, in different geographic regions, and on different species and ecosystems. This will require the use of multiple scenarios and possibly multiple assessment endpoints. 

Once protection goals have been chosen, the selection of appropriate entities to protect in the environment (assessment endpoints) is important in assessing risk. Poorly selected assessment endpoints have resulted in more failures in the risk assessment process than any other possible errors in the process [14]. Assessment endpoints are explicit expressions of the actual valued ecosystem components (organisms, populations, or communities) or ecosystem functions that are to be... 

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