Ecosystem risk assessment

Although none of the three laws or their implementing regulations directly addressed the reuse of waste materials, they necessitate a series of evaluations in the reuse program of solid waste, which include the preparation of an environmental assessment, a human health risk assessment, or an ecosystem risk assessment. 

The first section explains the concepts of EIA and RA and the existing approaches to their integration. This is followed by an analysis of the current situation with ecological input into EIA and discussion on how the formal EcoRA framework provides for site-specific ecosystem risk assessment. The subsequent section reviews the CLL approach and its applicability for assessing ecological effects in EIA. Finally, a model for assessment of ecosystem risks within EIA using the CLL approach is proposed. 

However, applicability of the bottom-up approach is limited primarily by cost implications to conduct ecosystem risk assessment following accurately the formal U.S. EPA procedure, an assessor must spent huge amounts of time and money on collecting necessary input data, data processing and interpreting the outputs. Of importance, very specific data are often required that cannot be easily obtained with the help of standard environmental monitoring studies. 

The top-down approach to ecosystem assessment that considers an elementary ecosystem as a receptor for evaluating toxic effects is currently in the making and remains difficult to carry out. One can identify the following key problem spots in methodology for ecosystem risk assessment ... 

Due to lack of established, user-friendly, and cost effective quantitative approaches to ecosystem risk assessment inEcoR A, in the current El A practice of project appraisal ecosystem risk assessment (if conducted) is usually comparative or qualitative (see, e.g., Lohani et al. (1997) for in-depth discussion). 

Qualitative findings of ecosystem risk assessments are of low utility for risk management. They cannot be compared with quantitative estimates of other risks this compromises the ability of risk ranking to provide insights to setting priorities. It is particularly difficult to convert them into a format applicable for cost-benefit analysis, which is a key tool that any proponent uses in decision-making on a proposed project. 

Scope of the CLL approach. Critical loads and levels can be calculated for various specified sensitive elements of the environment (UNECE CLRTAP 2004, V-l). However, terrestrial and aquatic ecosystems are most frequently referred to as receptors in this effect-based approach. In addition, specific parts of ecosystems (e.g., populations of most valuable species) or ecosystem characteristics can be defined as receptors as well (UNECE CLRTAP, 2004). Such flexibility and established provisions for ecosystem assessment makes the CLL concept a promising solution for ecosystem risk assessment and a potential substitute for site-specific chemical RA following the bottom-up approach. 

In the authors opinion, even if imperfect, the CLL approach is preferable to apply for ecosystem risk assessment than a qualitative EcoRA based mainly on expert judgment. 

Risk assessment of chemicals is an organized process that aims to describe and estimate the likelihood of adverse outcomes from environmental exposure to chemicals (US PCCRARM 1997), and is applied for both humans and ecosystems. Risk assessment traditionally focuses on single chemicals. However, awareness is growing that exposure to single substances is the exception rather than the rule. In practice, humans and ecological receptors are often exposed to multiple chemicals that may or may not interact, that is, influence each other by physical, chemical, or biological means before or after reaching the molecular site of toxic action. 

The approaches described in this chapter are of interest to several audiences in both human health and ecosystem risk assessments, particularly 1) research scientists who are actively involved in developing methods and expanding the knowledge base on how to conduct risk assessments of mixtures, 2) risk assessors who are charged with conducting risk assessments of mixtures, and 3) regulators who are involved in the development of risk assessment procedures and standards for mixtures. 

A risk estimate indicates Uie likelihood of occurrence of the different types of health or enviroinnental effects in exposed populations. Risk assessment should include both liuimn health and environmental evaluations (i.c., impacts on ecosystems). Ecological impacts include actual or potential effects on plants and animals (other than domesticated species). The number produced from the risk characleriznlion, representing the probability of adi crse... 

Herbicides constitute a large and diverse class of pesticides that, with a few exceptions, have very low mammalian toxicity and have received relatively little attention as environmental pollutants. Much of the work in the held of ecotoxicology and much environmental risk assessment has focused on animals, especially vertebrate animals. There has perhaps been a tendency to overlook the importance of plants in the natural world. Most plants belong to the lowest trophic levels of ecosystems, and animals in higher trophic levels are absolutely dependent on them for their survival. 

Ecotoxicology is primarily concerned with effects of chemicals on populations, communities, and ecosystems, but the trouble is that field studies are expensive and difficult to perform and can only be employed to a limited extent. In the main, environmental risk assessment of pesticides and certain other chemicals has to be... 

Data collected in drift studies may later be interpreted in risk assessments in conjunction with toxicity data for specific sensitive areas. Eor example, a risk assessment for determination of appropriate mitigation (if necessary) may include field study data on exposure risk from drift, along with information on other routes of exposure (e.g., dislodgable residues, runoff, etc.) and toxicity data from laboratory and/or field study models. The results of such an assessment may be used to estimate whether a given exposure represents a hazard to any specific entity or ecosystem. 

Additionally, the integration of geographic information system (GIS) with analytical data is an effective procedure in addressing the problem of spatial and temporal variability of the different parameters involved in the environmental fate of chemicals. Based on accurate local estimations, GIS-based models would then also allow deriving realistic and representative spatially averaged regional PECs. Table 4 shows some studies that have used GIS-based methodologies to perform a site-specific risk assessment of PECs in different exposed ecosystems. 

EcoFate EcoFate is a software package for conducting ecosystem based environmental and ecological risk assessments of chemical emissions by point and non-point sources in freshwater and marine aquatic ecosystems, including lakes, rivers and marine inlets... 

Bioavailability of Metals, Nonmetals and Xenobiotics Immobilized on Soil Components, (4) Distribution and Activity of Biomolecules in Terrestrial Systems, (5) Interactions between Soil Microbial Biomass and Organic Matter/Nutrient Transformations, and (6) Impact of Interactions among Soil Mineral Colloids, Organic Matter and Biota on Risk Assessment and Restoration of Terrestrial Ecosystems. There were 2 plenary lectures, 9 invited speakers, 36 oral presentations and 45 posters. Dr. N. Senesi from University of Bari, Italy, presented an IUPAC lecture entitled Metal-Humic... 

Keywords Ecosystem services, European river basins, Risk assessment, Risk management, River basin management plans, Water framework directive... 

To identify the key toxicants impacting marine and freshwater ecosystems on a site and basin scale as a crucial basis for scientifically sound risk assessment and decision support on risk management, remedial action strategies and preventive policies for the mitigation of harmful effects. 

The methodology for conducting aquatic model ecosystem studies was well established by the late 1990s. However, the use of the data in risk assessments raised a number of uncertainties regarding their interpretation and implementation [32]. Four of the uncertainties that were identified were the extent to which aquatic model ecosystem data generated in one location could be applied to another situation, the potential influence of mixtures of chemicals or stressors, whether the timing (season) of application would influence the outcome of the study, and whether differences in ecosystem properties (e.g., trophic status) might influence the results. 

Giddings JM, Solomon KR, Maund SJ (2001) Probabilistic risk assessment of cotton pyrethroids in aquatic ecosystems 2. Aquatic mesocosm and field studies observed effects and their ecological significance. Environ Toxicol Chem 20 660-668... 

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