Harnessing Modeling for Assessing the Population Relevance of Exposure to Endocrine-Active Chemicals.

The presence of endocrine-active chemicals (EACs) in the environment continues to cause concern for wildlife given their potential for adverse effects on organisms. However, there is a significant lack of understanding about the potential effects of EACs on populations. This has real-world limitations for EAC management and regulation, where the aim in environmental risk assessment is to protect populations. We propose a methodological approach for the application of modeling in addressing the population relevance of EAC exposure in fish. We provide a case study with the fungicide prochloraz to illustrate how this approach could be applied. We used two population models, one for brown trout (Salmo trutta; inSTREAM) and the other for three-spined stickleback (Gasterosteus aculeatus) that met regulatory requirements for development and validation. Effects data extracted from the literature were combined with environmentally realistic exposure profiles generated with the FOCUS SW software. Population-level effects for prochloraz were observed in some modeling scenarios (hazard-threshold [HT]) but not others (dose-response), demonstrating the repercussions of making different decisions on implementation of exposure and effects. The population responses, defined through changes in abundance and biomass, of both trout and stickleback exposed to prochloraz were similar, indicating that the use of conservative effects/exposure decisions in model parameterization may be of greater significance in determining population-level adverse effects to EAC exposure than life-history characteristics. Our study supports the use of models as an effective approach to evaluate the adverse effects of EACs on fish populations. In particular, our HT parameterization is proposed for the use of population modeling in a regulatory context in accordance with Commission Regulation (EU) 2018/605. Environ Toxicol Chem 2023;42:1624-1640. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

The food-water quality nexus in periurban aquacultures downstream of Bangkok, Thailand.

Peri-urban aquacultures produce nutritious food in proximity to markets, but poor surface water quality in rapidly expanding megacities threatens their success in emerging economies. Our study compared, for a wide range of parameters, water quality downstream of Bangkok with aquaculture regulations and standards. For parameters not meeting those requirements, we sought to establish whether aquaculture practice or external factors were responsible. We applied conventional and advanced methods, including micropollutant analysis, genetic markers, and 16S rRNA amplicon sequencing, to investigate three family-owned aquacultures spanning extensive, semi-intensive and intensive practices. Canals draining the city of Bangkok did not meet quality standards for water to be used in aquaculture, and were sources for faecal coliforms, Bacteriodes, Prevotella, Human E. coli, tetracycline resistance genes, and nitrogen into the aquaculture ponds. Because of these inputs, aquacultures suffered algae blooms, with and without fertilizer and feed addition to the ponds. The aquacultures were sources of salinity and the herbicide diuron into the canals. Diuron was detectable in shrimp, but not at a level of concern to human health. Given the extent and nature of pollution, peri-urban water policy should prioritize charging for urban wastewater treatment over water fees for small-scale agricultural users. The extensive aquaculture attenuated per year an estimated twenty population equivalents of nitrogen pollution and trillions of faecal coliform bacteria inputs from the canal. Extensive aquacultures could thus contribute to peri-urban blue-green infrastructures providing ecosystem services to the urban population such as flood risk management, food production and water pollution attenuation.

Assessing and managing multiple risks in a changing world-The Roskilde recommendations.

Roskilde University (Denmark) hosted a November 2015 workshop, Environmental Risk-Assessing and Managing Multiple Risks in a Changing World. This Focus article presents the consensus recommendations of 30 attendees from 9 countries regarding implementation of a common currency (ecosystem services) for holistic environmental risk assessment and management; improvements to risk assessment and management in a complex, human-modified, and changing world; appropriate development of protection goals in a 2-stage process; dealing with societal issues; risk-management information needs; conducting risk assessment of risk management; and development of adaptive and flexible regulatory systems. The authors encourage both cross-disciplinary and interdisciplinary approaches to address their 10 recommendations: 1) adopt ecosystem services as a common currency for risk assessment and management; 2) consider cumulative stressors (chemical and nonchemical) and determine which dominate to best manage and restore ecosystem services; 3) fully integrate risk managers and communities of interest into the risk-assessment process; 4) fully integrate risk assessors and communities of interest into the risk-management process; 5) consider socioeconomics and increased transparency in both risk assessment and risk management; 6) recognize the ethical rights of humans and ecosystems to an adequate level of protection; 7) determine relevant reference conditions and the proper ecological context for assessments in human-modified systems; 8) assess risks and benefits to humans and the ecosystem and consider unintended consequences of management actions; 9) avoid excessive conservatism or possible underprotection resulting from sole reliance on binary, numerical benchmarks; and 10) develop adaptive risk-management and regulatory goals based on ranges of uncertainty. Environ Toxicol Chem 2017;36:7-16. © 2016 SETAC.

Density-dependent processes in the life history of fishes: evidence from laboratory populations of zebrafish Danio rerio.

Population regulation is fundamental to the long-term persistence of populations and their responses to harvesting, habitat modification, and exposure to toxic chemicals. In fish and other organisms with complex life histories, regulation may involve density dependence in different life-stages and vital rates. We studied density dependence in body growth and mortality through the life-cycle of laboratory populations of zebrafish Danio rerio. When feed input was held constant at population-level (leading to resource limitation), body growth was strongly density-dependent in the late juvenile and adult phases of the life-cycle. Density dependence in mortality was strong during the early juvenile phase but declined thereafter and virtually ceased prior to maturation. Provision of feed in proportion to individual requirements (easing resource limitation) removed density dependence in growth and substantially reduced density dependence in mortality, thus indicating that 'bottom-up' effects act on growth as well as mortality, but most strongly on growth. Both growth and mortality played an important role in population regulation, with density-dependent growth having the greater impact on population biomass while mortality had the greatest impact on numbers. We demonstrate a clear ontogenic pattern of change in density-dependent processes within populations of a very small (maximum length 5 mm) fish, maintained in constant homogeneous laboratory conditions. The patterns are consistent with those distilled from studies on wild fish populations, indicating the presence of broad ontogenic patterns in density-dependent processes that are invariant to maximum body size and hold in homogeneous laboratory, as well as complex natural environments.

Multi-criteria decision analysis of test endpoints for detecting the effects of endocrine active substances in fish full life cycle tests.

Fish full life cycle (FFLC) tests are increasingly required in the ecotoxicological assessment of endocrine active substances. However, FFLC tests have not been internationally standardized or validated, and it is currently unclear how such tests should best be designed to provide statistically sound and ecologically relevant results. This study describes how the technique of multi-criteria decision analysis (MCDA) was used to elicit the views of fish ecologists, aquatic ecotoxicologists and statisticians on optimal experimental designs for assessing the effects of endocrine active chemicals on fish. In MCDA qualitative criteria (that can be valued, but not quantified) and quantitative criteria can be used in a structured decision-making process. The aim of the present application of MCDA is to present a logical means of collating both data and expert opinions on the best way to focus FFLC tests on endocrine active substances. The analyses are presented to demonstrate how MCDA can be used in this context. Each of 3 workgroups focused on 1 of 3 species: fathead minnow (Pimephales promelas), Japanese medaka (Oryzias latipes), and zebrafish (Danio rerio). Test endpoints (e.g., fecundity, growth, gonadal histopathology) were scored for each species for various desirable features such as statistical power and ecological relevance, with the importance of these features determined by assigning weights to them, using a swing weighting procedure. The endpoint F1 fertilization success consistently emerged as a preferred option for all species. In addition, some endpoints scored highly in particular species, such as development of secondary sexual characteristics (fathead minnow) and sex ratio (zebrafish). Other endpoints such as hatching success ranked relatively highly and should be considered as useful endpoints to measure in tests with any of the fish species. MCDA also indicated relatively less preferred endpoints in fish life cycle tests. For example, intensive histopathology consistently ranked low, as did measurement of diagnostic biomarkers, such as vitellogenin, most likely due to the high costs of these methods or their limited ecological relevance. Life cycle tests typically do not focus on identifying toxic modes and/or mechanisms of action, but rather, single chemical concentration-response relationships for endpoints (e.g., survival, growth, reproduction) that can be translated into evaluation of risk. It is, therefore, likely to be an inefficient use of limited resources to measure these mechanism-specific endpoints in life cycle tests, unless the value of such endpoints for answering particular questions justifies their integration in specific case studies.