Ecological Risk Assessment Process Research Articles

Integrating climate model projections into environmental risk assessment: A probabilistic modeling approach.

The Society of Environmental Toxicology and Chemistry (SETAC) convened a Pellston workshop in 2022 to examine how information on climate change could be better incorporated into the ecological risk assessment (ERA) process for chemicals as well as other environmental stressors. A major impetus for this workshop is that climate change can affect components of ecological risks in multiple direct and indirect ways, including the use patterns and environmental exposure pathways of chemical stressors such as pesticides, the toxicity of chemicals in receiving environments, and the vulnerability of species of concern related to habitat quality and use. This article explores a modeling approach for integrating climate model projections into the assessment of near- and long-term ecological risks, developed in collaboration with climate scientists. State-of-the-art global climate modeling and downscaling techniques may enable climate projections at scales appropriate for the study area. It is, however, also important to realize the limitations of individual global climate models and make use of climate model ensembles represented by statistical properties. Here, we present a probabilistic modeling approach aiming to combine projected climatic variables as well as the associated uncertainties from climate model ensembles in conjunction with ERA pathways. We draw upon three examples of ERA that utilized Bayesian networks for this purpose and that also represent methodological advancements for better prediction of future risks to ecosystems. We envision that the modeling approach developed from this international collaboration will contribute to better assessment and management of risks from chemical stressors in a changing climate. Integr Environ Assess Manag 2024;20:367-383. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Absent ecology in the terrestrial ecological risk assessment process and an absent need for assessment

While the U.S. Environmental Protection Agency’s ecological risk assessment process was devised with the best of intentions, including fashioning it to be isomorphic with the human health risk assessment process, longtime existing biological information demonstrating ecological receptors to be irrelevant for evaluation, was evidently overlooked. Owing to the spatial dynamics of density and home range, birds and mammals as the only terrestrial species routinely evaluated, occur in numbers far too small to legitimize their inclusion in assessments. These receptors would also not be expected to sufficiently contact contaminated media, principally soil, to trigger the development of concerning toxicological effects. The ecotoxicological manifestation of brief lifespans constitutes yet another reality not considered in applied ecological risk assessment. The decades-old nature of sites obviates any need for assessment; were toxicological effects to be elicited, they would have necessarily already arisen, yet they have consistently failed to appear. The analysis presented argues that in the haste to develop an ecological assessment process, the interplay of contaminated sites being relatively small, and species of seeming interest traveling over relatively vast spaces, has been ignored. The data assembled and reviewed demonstrate Superfund-type sites to house insufficient ecological resources to warrant a risk assessment process altogether.

A unified approach for protecting listed species and ecosystem services in isolated wetlands using community-level protection goals

The protection of listed species through the Ecological Risk Assessment (ERA) process is encumbered by the number and diversity of species that need protection and the limited data available to inform assessments. Ecological communities within isolated ecosystems often contain a number of biologically diverse endemic, endangered, and threatened species, as well as providing numerous ecosystem services (ES). We propose an approach that develops community-level protection goals using isolated wetlands that includes both listed species and Service Providing Units (SPUs) that drive ES for ecological risk assessments (ERAs). Community-level protection goals are achieved by developing a protection community and weighing lines of evidence to determine a set of focal species within that community upon which to base the assessment. Lines of evidence include chemical mechanism of action, likely routes of exposure, and taxa susceptibility, as well as relationships among species, and other ecological factors. We demonstrate the process using case studies of chlorpyrifos in California vernal pools and coal ash effluent in Carolina bays. In the California vernal pool case study, listed species were the primary SPUs for the ES provided by the critical habitat. The weight of evidence demonstrated the honey bee as the focal species for the terrestrial environment and the vernal pool fairy shrimp as the focal species for the aquatic environment. The protection community within the Carolina bay case study was more taxonomically diverse than vernal pools for both listed species and SPUs, with amphibians identified as the focal species for which to target mitigation goals and hazard levels. The approach presented here will reduce the time and resource investment required for assessment of risk to listed species and adds an ES perspective to demonstrate value of assessments beyond listed species concerns.

Heavy Metal Pollution and Ecological Risk Assessment of the Agriculture Soil in Xunyang Mining Area, Shaanxi Province, Northwestern China.

Mining is considered to be one of the most significant sources of environmental pollution with regard to heavy metals. Mineral mining causes large quantities of mercury, cadmium, and other elements to be released into the environment and naturally poses a serious threat to environment. This paper will analyze the pollution status of agricultural soil caused by the mining of heavy metals in various mining areas in the Xunyang County in the Shaanxi Province of China, an area in famous for its resource mining. Equally, it will look at the potential ecological risk assessment process that is used to analyze the ecological risks of mining heavy metals in agricultural soil located in the surrounding areas. Based on the soil investigation, As pose a moderate ecological risk on the Au mining area. In addition, the Hg metals pose a significantly high potential ecological risk and Cd metals pose a considerable potential ecological risk on the Hg mining area. In the Pb-Zn mining area, a significantly high potential ecological risk was mainly posed by Cd. These results suggest that many heavy metals pose a high potential ecological risk on the agricultural soil in these three mining areas in the Xunyang County, and may cause elevated heavy metal contents in crops, eventually jeopardizing the health of local residents who consume food grown in polluted soil.

Empirically-based modeling and mapping to consider the co-occurrence of ecological receptors and stressors

Part of the ecological risk assessment process involves examining the potential for environmental stressors and ecological receptors to co-occur across a landscape. In this study, we introduce a Bayesian joint modeling framework for use in evaluating and mapping the co-occurrence of stressors and receptors using empirical data, open-source statistical software, and Geographic Information Systems tools and data. To illustrate the approach, we apply the framework to bioassessment data on stream fishes and nutrients collected from a watershed in southwestern Ohio. The results highlighted the joint model's ability to parse and exploit statistical dependencies in order to provide empirical insight into the potential environmental and ecotoxicological interactions influencing co-occurrence. We also demonstrate how probabilistic predictions can be generated and mapped to visualize spatial patterns in co-occurrences. For practitioners, we believe that this data-driven approach to modeling and mapping co-occurrence can lead to more quantitatively transparent and robust assessments of ecological risk.

Incorporating the joint toxicity of co‐applied pesticides into the ecological risk assessment process

Pesticides are frequently formulated as mixtures of active ingredients. Although traditionally ecological risk assessments (ERAs) have focused on individual active ingredients, there is an ongoing effort in many jurisdictions to more formally include assessment of mixtures. The overall goal of this project was to describe an approach for conducting ERA of jointly applied pesticides. We suggest that standard testing of formulation mixtures is not warranted due to the low probability of synergy occurring at a high-enough magnitude to be measurable above experimental variability. Thus, empirical testing should focus on formulations for which there is a greater likelihood of synergy due to known toxicological interactions of the pesticide class or a priori knowledge of synergy, such as intellectual property claims. Additionally, empirical testing should focus on species that are above levels of concern and limit testing on species for which it is unlikely that synergy would significantly change the outcome of the ERA. If empirical testing is warranted, we suggest that results be compared to the concentration addition model (CA). If the empirical data deviates from the model by a factor of greater than 5, then synergy is considered likely and the ERA is based on the empirical data. Otherwise, the ERA may use CA to calculate risk quotients or be based on the most toxic active ingredient. To evaluate the approach, we reviewed formulation mixtures for which data were available. Only 3 of 24 mixture studies were found to deviate from CA by more than 5. The majority of the studies had a single component that dominated toxicity, suggesting that the ERA for these formulations will not be meaningfully different if based on the most toxic active ingredient. Overall, this approach balances risk assessment conservatism and reduces testing that would likely not result in improvement of the ERA. Integr Environ Assess Manag 2018;14:79-91. © 2017 SETAC.

The Role of Omics in the Application of Adverse Outcome Pathways for Chemical Risk Assessment.

In conjunction with the second International Environmental Omics Symposium (iEOS) conference, held at the University of Liverpool (United Kingdom) in September 2014, a workshop was held to bring together experts in toxicology and regulatory science from academia, government and industry. The purpose of the workshop was to review the specific roles that high-content omics datasets (eg, transcriptomics, metabolomics, lipidomics, and proteomics) can hold within the adverse outcome pathway (AOP) framework for supporting ecological and human health risk assessments. In light of the growing number of examples of the application of omics data in the context of ecological risk assessment, we considered how omics datasets might continue to support the AOP framework. In particular, the role of omics in identifying potential AOP molecular initiating events and providing supportive evidence of key events at different levels of biological organization and across taxonomic groups was discussed. Areas with potential for short and medium-term breakthroughs were also discussed, such as providing mechanistic evidence to support chemical read-across, providing weight of evidence information for mode of action assignment, understanding biological networks, and developing robust extrapolations of species-sensitivity. Key challenges that need to be addressed were considered, including the need for a cohesive approach towards experimental design, the lack of a mutually agreed framework to quantitatively link genes and pathways to key events, and the need for better interpretation of chemically induced changes at the molecular level. This article was developed to provide an overview of ecological risk assessment process and a perspective on how high content molecular-level datasets can support the future of assessment procedures through the AOP framework.

Predator Preference for Bt-Fed Spodoptera frugiperda (Lepidoptera: Noctuidae) Prey: Implications for Insect Resistance Management in Bt Maize Seed Blends.

Understanding indirect, trophic-level effects of genetically engineered plants, expressing insecticidal proteins derived from the bacterium, Bacillus thuringiensis (Bt), is essential to the ecological risk assessment process. In this study, we examine potential indirect, trophic-level effects of Bt-sensitive prey using the predator, Harmonia axyridis (Pallas), feeding upon Spodoptera frugiperda (J.E. Smith) larvae, which had delayed development (lower body mass) following ingestion of Cry1Ab maize leaves. We found no adverse effects on development and survival when H. axyridis larvae were fed S. frugiperda larvae that had fed on Cry1Ab maize tissue. Presence of Cry1Ab in H. axyridis decreased considerably after switching to another diet within 48 h. In a no-choice assay, H. axyridis larvae consumed more Bt-fed S. frugiperda than non-Bt-fed larvae. Preference for S.frugiperda feeding on Bt maize was confirmed in subsequent choice assays with H. axyridis predation on Bt-fed, 1-5-d-old S. frugiperda larvae. We suggest that H. axyridis preferred prey, not based on whether it had fed on Bt or non-Bt maize, but rather on larval mass, and they compensated for the nutritional deficiency of lighter larvae through increased consumption. Pest larvae with variable levels of resistance developing on Bt diet are often stunted versus sensitive larvae developing on non-Bt diet. It is possible that such larvae may be preferentially removed from local field populations. These results may have implications for insect resistance management and may be played out under field conditions where seed blends of Bt and non-Bt hybrids are planted.

A method for estimating watershed restoration feasibility under different treatment levels

The restoration of watershed health can be influenced by ecological, technical and socio-economic factors. The paper presents a conceptual framework and typology to assess watershed ecological restoration based on the properties and processes of sustainable watershed development. According to multiple life stages, habitat properties and existing legal frameworks and applicable valuation approaches, the bio-indicator that integrates natural, political and socio-economic dimensions is proposed. With existing assessment results and official web-pages as references, evaluation systems concerning human impacts on aquatic systems are set forth. Suitable aquatic bio-indicators can standardize the monitoring methodology with respect to water quality, organic pollutants and pesticides, generation time, migration ability, saprobic status, taxonomic composition and diversity. A large number of fish-based indexes have been developed to monitor and manage river ecosystems. Biophysical and statistical models are being used to identify influential stream variables that correlate with macroinvertebrate indices. A probabilistic fuzzy hybrid model to assess river water quality is proposed. The method and process of ecological risk assessment are provided based on adaptive management principles. The environmental sustainability index (ESI) is used to estimate the degree of environmental restoration sustainability with the emergy triangle as a reference.

Increased ecological risk due to the hyperaccumulation of As in Pteris cretica during the phytoremediation of an As-contaminated site

Ecological risk due to the hyperaccumulation of As in Pteris cretica during phytoremediation was evaluated at an abandoned As-contaminated site. Five receptor groups representing terrestrial invertebrates, avian insectivores, small mammals, herbivores, and omnivores were selected as potentially affected ecological receptors. Soil and food ingestion were considered as major exposure pathways. Phytoremediation was performed with P.cretica only and with both P.cretica and siderophores to enhance plant uptake of As. Ecological hazard index (EHI) values for the small mammal greatly exceeded 1.0 even after three weeks of growth regardless of siderophore application, probably due to its limited home range. For the mammalian herbivore, which mainly consumes plant foliage, the EHI values were greater than 5.73 after seven weeks without siderophore application, but the value increased sharply to 29.3 at seven weeks when siderophores were applied. This increased risk could be attributed to the facilitated translocation of As from roots to stems and leaves in P.cretica. Our results suggest that, when a phytoremediation strategy is considered for metals remediation, its ecological consequences should be taken into account to prevent the spread of hyperaccumulated heavy metals throughout the food chain of ecological receptors. Uncertainties involved in the ecological risk assessment process were also discussed.

Ecological risk assessment of wetland ecosystems using Multi Criteria Decision Making and Geographic Information System

Nowadays, wetlands are at risk from a wide range of stress factors. Practical application of wetland ecological risk assessment will result in a better understanding of how physical, chemical, and biological stressors impinge on wetlands and will provide a framework for prudent wetland management. An important aspect of wetland management is to identify ecological risks affecting the area and to develop a wetland-zoning map based on those risks. This study uses a process of ecological risk assessment (ERA) to identify stress factors and responses within the framework of an ecosystem-based approach. All potential environmental factors, physical, chemical and biological need to be examined in context. This study aims to present a systematic methodology for risk assessment and zoning of wetland ecosystems. Initially, the most important risks threatening wetlands are identified in an ecosystem-based approach. Endpoint assessments are defined according to values and functions of the wetland and the ecological risks associated with these endpoints are identified. In the characteristics step, risks are analyzed according to severity, probability and a range of consequences. A Multi Criteria Decision Making (MCDM) method is used to prioritize these risks on the basis of experts’ opinions. Geographic Information System (GIS) is used to develop a zoning map with a combination of risk layers according to importance. Finally, management strategies are proposed to deal with the risks. The proposed methodology was applied to Shadegan International Wetland, located in southwestern Iran. This wetland is in the Montero list and is currently threatened by various risks. According to the results, high-ranking potential risks and areas with different levels of risk and management strategies were proposed for this wetland.

Identification of chemicals of potential concern (COPECs) in anthropogenic wetlands of the Colorado River delta

An early step in an Ecological Risk Assessment (ERA) process is the screening of chemicals to identify those that constitute a potential risk by comparing concentrations to levels that are believed to be nonhazardous or “benchmarks”. In the present study we analyzed concentrations of metals and metalloids (mercury, arsenic, selenium, and copper) as well as organochlorine pesticides in samples of water, sediment, and fish from the Cienega de Santa Clara wetland, Rio Hardy wetland, and the Upper Gulf of California-estuary. These wetlands are located in northwestern Mexico in the Colorado River delta. All contaminants analyzed were retained as Chemicals of Potential Ecological Concern (COPECs). Mercury was identified as a priority COPEC due to its potential negative effects in freshwater biota, benthic invertebrates and fish eating birds in all three study areas. Copper posed a potential high risk to Rio Hardy aquatic biota. Arsenic represented a risk to aquatic plants and to benthic invertebrates of the three areas with special concern at the Upper Gulf of California-estuary. Selenium was found at levels that could cause a slight (5.6%) reduction in avian reproductive success at the Cienega de Santa Clara and Rio Hardy, similar to the effects found at the Salton Sea. For organochlorine pesticides, DDT represented a potential high risk for aquatic biota at the Cienega de Santa Clara and Rio Hardy, DDD posed a risk for fish eating birds at the Cienega de Santa Clara, and DDE represented a high risk for fish eating birds at the Rio Hardy. In addition to these contaminants, other published studies in the area have identified chromium, lead, boron, PCBs, organophosphorous pesticides and contaminants of emergent concern (CECs) as toxic or potentially toxic for aquatic biota, benthic invertebrates, and wildlife. We recommend to follow-up with an ERA process where the actual effects of COPECs in species and plants of concern (i.e. endangered, rare, keystone species) are evaluated.

Enhanced growth reduces precocial male maturation in Atlantic salmon

Summary1. Understanding the proximate and ultimate mechanisms shaping the expression of alternative reproductive phenotypes is a fundamental question in life‐history evolution. Precocial maturation in fishes, one such alternative phenotype, has been thought to reflect rapid growth and/or energy accumulation; however, mechanistically linking these specific traits to discrete life‐history patterns is complex and poorly understood.2. Here, we use growth hormone (GH) transgenic Atlantic salmon to elucidate the effects of intrinsically fast growth on precocial male maturation as parr (freshwater life stage). Despite facilitating growth to sizes typical of mature wild‐type parr, transgenesis did not influence maturation in the first year of life. In the second year, the number of maturing transgenic parr was only half that of non‐transgenic individuals.3. By manipulating intrinsic growth and controlling for both environment and genetic background, this study provides direct empirical evidence suggesting that the physiological mechanisms promoting growth do not play a causative role in precocial male maturation in fishes.4. In addition, this study provides the first empirical data on the relative incidence of precocial male maturation in GH transgenic and non‐transgenic Atlantic salmon and, therefore, provides valuable information for the ecological risk assessment process.

A Screening Level Ecological Risk Assessment and ranking method for liquid radioactive and chemical mixtures released by nuclear facilities under normal operating conditions

Ecological Risk Assessment is used to evaluate the potential hazards to the environment that are attributable to emissions of pollutants from industries. There is guidance available regarding the general ecological risk assessment process including problem formulation, exposure and effect analyses, and risk characterization. In a first step, the Screening-Level Ecological Risk Assessment (SLERA) is used to evaluate whether the emissions can put the receptor ecosystems at risk or not. Concerning releases from nuclear facilities under authorization, any SLERA is a challenging task because of (1) the large number of substances, (2) the various quantities that may be emitted to the aquatic ecosystems and (3) the various environmental situations to be considered. This task must be performed for two categories of pollutants, radionuclides and chemicals, each exhibiting specificities in terms of concentration in media or dose-effect relationships. Since these relationships for radioactive substances are based on the tissue-absorbed dose in Gray, the first step is to express critical exposure values to radionuclides in a consistent way with the critical concentration used for chemicals. We describe here the screening and ranking method that was developed and an application to the electronuclear sites along the Rhône River.

Enhancing the ecological risk assessment process

The Ecological Processes and Effects Committee of the US Environmental Protection Agency Science Advisory Board conducted a self-initiated study and convened a public workshop to characterize the state of the ecological risk assessment (ERA), with a view toward advancing the science and application of the process. That survey and analysis of ERA in decision making shows that such assessments have been most effective when clear management goals were included in the problem formulation; translated into information needs; and developed in collaboration with decision makers, assessors, scientists, and stakeholders. This process is best facilitated when risk managers, risk assessors, and stakeholders are engaged in an ongoing dialogue about problem formulation. Identification and acknowledgment of uncertainties that have the potential to profoundly affect the results and outcome of risk assessments also improves assessment effectiveness. Thus we suggest 1) through peer review of ERAs be conducted at the problem formulation stage and 2) the predictive power of risk-based decision making be expanded to reduce uncertainties through analytical and methodological approaches like life cycle analysis. Risk assessment and monitoring programs need better integration to reduce uncertainty and to evaluate risk management decision outcomes. Postdecision audit programs should be initiated to evaluate the environmental outcomes of risk-based decisions. In addition, a process should be developed to demonstrate how monitoring data can be used to reduce uncertainties. Ecological risk assessments should include the effects of chemical and nonchemical stressors at multiple levels of biological organization and spatial scale, and the extent and resolution of the pertinent scales and levels of organization should be explicitly considered during problem formulation. An approach to interpreting lines of evidence and weight of evidence is critically needed for complex assessments, and it would be useful to develop case studies and/or standards of practice for interpreting lines of evidence. In addition, tools for cumulative risk assessment should be developed because contaminants are often released into stressed environments.

The strengths of the ecological risk assessment process: linking science to decision making

Twenty-five years ago, ecological assessments were being performed by different organizations, using different principles and methods, with little or no communication between different groups and no means for reconciling conflicts and inconsistencies between assessment methodologies. The recognition by practitioners of environmental assessment of the need for a unifying conceptual framework stimulated the development of today's Framework and Guidelines for Ecological Risk Assessment (ERA). This paper discusses the success of ERA as a process for linking environmental science to decision making, using 3 recently published case studies involving establishment of baseline ecological risks at a contaminated site, probabilistic assessment of regional risks of pesticide use, and regulation of pharmaceutical product manufacture. Some promising future directions in ERA are briefly discussed, and 3 critical challenges to future success are identified.

Testing the Limits of Rodent Sperm Analysis: Azoospermia in an Otherwise Healthy Wild Rodent Population

By comparing the sperm parameters of small rodents trapped at contaminated terrestrial sites and nearby habitat-matched noncontaminated locations, the patent-pending Rodent Sperm Analysis (RSA) method provides a direct health status appraisal for the maximally chemical-exposed mammalian ecological receptor in the wild. RSA outcomes have consistently allowed for as definitive determinations of receptor health as are possible at the present time, thereby streamlining the ecological risk assessment (ERA) process. Here, we describe the unanticipated discovery, at a contaminated US EPA Superfund National Priorities List site, of a population of Hispid cotton rats (Sigmodon hispidus), with a high percentage of adult males lacking sperm entirely (azoospermia). In light of the RSA method's role in streamlining ERAs and in bringing contaminated Superfund-type site investigations to closure, we consider the consequences of the discovery. The two matters specifically discussed are (1) the computation of a population's average sperm count where azoospermia is present and (2) the merits of the RSA method and its sperm parameter thresholds-for-effect when azoospermia is masked in an otherwise apparently healthy rodent population.

The strengths of the ecological risk assessment process: linking science to decision making

The strengths of the ecological risk assessment process: linking science to decision making

Ecological risk assessment of contaminated soil

AbstractThe basis for an ecological risk assessment based on meeting the needs of recent UK and EU legislation is described. The background to the framework and the legislative driver and relevant definitions of harm are provided, prior to an overview of the proposed ecological risk assessment process, which has been broken down into a Tiered approach. Tier 0 requires the establishment of a conceptual site model, where potential contaminant-pathway-receptor linkages are sought and, assuming they are identified, lead on to higher Tier assessments. Tier 1 relies largely on chemical analysis of soil contaminant levels and comparison with soil quality guideline values to assess the likelihood of harm. In some cases biological screening assays may also be undertaken within this Tier. Based on a weight of evidence approach, should data from Tier 1 indicate harm or leave uncertainty, then Tier 2 biological testing is undertaken using assays relevant to the site of interest. In situations where harm is identified under Tier 2 then Tier 3 is reserved for establishing the extent of harm within the ecosystem. Finally the use of the 'weight-of-evidence' approach to generate scientifically robust conclusions regarding the harm (or potential for harm) within the ecosystem is briefly outlined. The framework discussed is currently being adopted by the UK Environment Agency, with implementation expected in 2005. The UK scheme compares favourably with comparative schemes operating in other countries possessing the merits of being iterative, tiered, flexible with agreed exit points subject to satisfying defined criteria and so speeding the decision-making process.

Risk analysis and management decisions for weed biological control agents: Ecological theory and modeling results

Biologically based control methods offer many advantages for the control of invasive plant species; however, these methods are not without risks to native species. Thus, there is a need for more effective and efficient methods of risk analysis for biological control agents. We show how the process of ecological risk assessment established by the United States’ Environmental Protection Agency may be adapted to improve assessment of the risks of proposed biological control agents. We discuss the risks posed by weed biological control agents, and present a simple individual-based model of herbivorous insect movement and oviposition on two species of host plant, a target invasive plant species and a non-target native species, in simulated landscapes. The model shows that risks of non-target impacts may be influenced by the details of the movement behavior of biological control agents in heterogeneous landscapes. The specific details of insect movement that appear to be relevant are readily measured in field trials and the general modeling approach is readily adapted to real landscapes. Current biological control risk assessments typically emphasize effects analysis at the expense of exposure analysis; the modeling approach presented here provides a simple and feasible way to incorporate exposure analyses. We conclude that models such as ours should be given serious consideration as part of a comprehensive strategy of risk assessment for proposed weed biological control agents.