Toward harmonizing ecotoxicity characterization in life cycle impact assessment

Characterizing Freshwater Ecotoxicity of More Than 9000 Chemicals by Combining Different Levels of Available Measured Test Data with In Silico Predictions

Ecotoxicological impacts of chemicals released into the environment are characterized by combining fate, exposure, and effects. For characterizing effects, species sensitivity distributions (SSDs) estimate toxic pressures of chemicals as the potentially affected fraction of species. Life cycle assessment (LCA) uses SSDs to identify products with lowest ecotoxicological impacts. To reflect ambient concentrations, the Global Life Cycle Impact Assessment Method (GLAM) ecotoxicity task force recently recommended deriving SSDs for LCA based on chronic EC10s (10% effect concentration, for a life-history trait) and using the 20th percentile of an EC10-based SSD as a working point. However, because we lacked measured effect concentrations, impacts of only few chemicals were assessed, underlining data limitations for decision support. The aims of this paper were therefore to derive and validate freshwater SSDs by combining measured effect concentrations with in silico methods. Freshwater effect factors (EFs) and uncertainty estimates for use in GLAM-consistent life cycle impact assessment were then derived by combining three elements: (1) using intraspecies extrapolating effect data to estimate EC10s, (2) using interspecies quantitative structure-activity relationships, or (3) assuming a constant slope of 0.7 to derive SSDs. Species sensitivity distributions, associated EFs, and EF confidence intervals for 9862 chemicals, including data-poor ones, were estimated based on these elements. Intraspecies extrapolations and the fixed slope approach were most often applied. The resulting EFs were consistent with EFs derived from SSD-EC50 models, implying a similar chemical ecotoxicity rank order and method robustness. Our approach is an important step toward considering the potential ecotoxic impacts of chemicals currently neglected in assessment frameworks due to limited test data. Environ Toxicol Chem 2024;43:1914-1927. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Industrial ecotoxicology in focus: The unexplored environmental impacts of pilot-scale advanced filtration in Sc recovery

The demand within the European Union (EU) for the crucial raw material Scandium (Sc), coupled with the lack of sufficient recovery strategies, has gravitated research into exploiting alternative secondary sources. Utilizing residues from ore-production processes has proven to be a successful attempt for advanced Sc recovery. Despite the emergence of new technologies for Sc recovery from such residues, the potential environmental impacts of byproducts and technology wastes are often disregarded. Our study aimed to assess the environmental efficiency of a pilot-scale Sc recovery technology that relies solely on filtration. We employed a problem-specific ecotoxicity toolkit based on the approach of Direct Toxicity Assessment (DTA). The results of DTA provide an indication of the scale of the adverse effect of (contaminated) samples without the necessity of translating the results into chemical concentration. Standardized test methods (Aliivibrio fischeri bioluminescence inhibition, Daphnia magna lethality and Sinapis al b a root and shoot elongation inhibition) were applied, supplemented by a bioconcentration assessment with the D. magna bioaccumulation test method to gain insight on the bioaccumulation potential of different metals in the case of all samples from the filtration technology. Comprehensive genotoxicity evaluations were also implemented using three distinct test methods (Ames test, Ames MPF test, SOS Chromotest). We conducted a comparative direct toxicity assessment to anticipate the potential environmental impacts of residues generated at each filtration step on the aquatic ecosystem. Our findings indicate that the environmental impact of the generated intermediate and final residues was alleviated by the consecutive filtration steps employed. The pilot-scale application of the Sc recovery technology achieved a high and statistically significant reduction in toxicity according to each test organism during the filtration processes. Specifically, toxicity decreased by 73 %, 86 % and 87 % according to the Aliivibrio fischeri bioluminescence inhibition assay, the Sinapis alba shoot elongation inhibition test, and the Daphnia magna lethality test, respectively. The toolbox of industrial ecotoxicology is recommended to predict the environmental performance of metal recovery technologies related to potential ecosystem effects.

Freshwater ecotoxicity characterization factors for PMT/vPvM substances

This study addresses the gap in freshwater ecotoxicological characterization factors (CFs) for Persistent, Mobile, and Toxic (PMT) and Very Persistent and Very Mobile (vPvM) substances. These CFs are vital for integrating the ecotoxicity impacts of these chemicals into life cycle assessments. Our goals are twofold: first, to calculate experimental freshwater CFs for PMT/vPvM substances listed by the German Environment Agency (UBA); second, to compare these CFs with those from the USEtox database. The expanded UBA list includes 343 PMT/vPvM substances, each representing a unique chemical structure, and linked to 474 REACH-registered substances. This study successfully computed CFs for 244 substances, with 107 overlapping the USEtox database and 137 being new. However, ecotoxicity data limitations prevented CF determination for 97 substances. This research enhances our understanding of freshwater CFs for PMT/vPvM substances, covering 72% of UBA's 343 PMT/vPvM substances. Data scarcity remains a significant challenge, which invariably impedes CF calculations. Notably, the disparities observed between CF values in the USEtox database and those derived in this research largely stem from variations in ecotoxicity data. Consequently, this research underscores the dynamic nature of CFs for substances, emphasizing the need for regular updates to ensure their accuracy and relevance.

Quantifying pesticide emissions for drift deposition in comparative risk and impact assessment

Estimating emissions of chemical pesticides used in agriculture is an essential component in evaluating the potential toxicity-related impacts on humans and ecosystems in various comparative risk and impact assessment frameworks, such as life cycle assessment, environmental footprinting, absolute environmental sustainability assessment, chemical substitution, and risk prioritization. Emissions related to drift deposition-usually derived from drift experiments-can reach non-target areas, and vary as a function of crop characteristics and application technique. We derive cumulative drift deposition fractions for a wide range of experimental drift functions for use in comparative and mass-balanced approaches. We clarify that cumulative drift deposition fractions require to integrate the underlying drift functions over the relevant deposition area and to correct for the ratio of deposition area to treated field area to arrive at overall mass deposited per unit mass of applied pesticide. Our results show that for most crops, drift deposition fractions from pesticide application are below 0.03 (i.e. 3% of applied mass), except for grapes and fruit trees, where drift fractions can reach 5% when using canon or air blast sprayers. Notably, aerial applications on soybeans can result in significantly higher drift deposition fractions, ranging from 20% to 60%. Additionally, varying the nozzle position can lead to a factor of five differences in pesticide deposition, and establishing buffer zones can effectively reduce drift deposition. To address remaining limitations in deriving cumulative drift deposition fractions, we discuss possible alternative modelling approaches. Our proposed approach can be implemented in different quantitative and comparative assessment frameworks that require emission estimates of agricultural pesticides, in support of reducing chemical pollution and related impacts on human health and the environment.

Consideration of unmeasured micropollutants released from WWTP for potential impact estimations

During wastewater treatment, micropollutants are only partly eliminated and may present a risk for human health and aquatic ecosystems. The potential impacts these substances may have are currently underestimated due to the lack in available concentrations that lie below the limit of quantification (LOQ) for an important set of micropollutants. Here, the potential impacts due to 261 organic micropollutants on human health and aquatic environments were investigated at the scale of France. Even with concentrations below the LOQ, certain micropollutants were found to have a significant potential impact. For unmeasured concentrations, a global concentration distribution built from several datasets with different LOQ was used. By disregarding the unmeasured micropollutants, the potential impacts have been underestimated by >300 % on both human health and aquatic environments. Certain substances, such as hydrazine, endrin, or 2,3,7,8-TetraCDD, could lead to very strong potential impacts, even with unmeasured concentration levels. Moreover, the usual convention of LOQ/2 to replace unmeasured concentrations also appeared to overestimate the potential impact. The present work can be adapted to any other compartment or geographical context.

Micro- and nanoplastics in soil: Linking sources to damage on soil ecosystem services in life cycle assessment

Soil ecosystems are crucial for providing vital ecosystem services (ES), and are increasingly pressured by the intensification and expansion of human activities, leading to potentially harmful consequences for their related ES provision. Micro- and nanoplastics (MNPs), associated with releases from various human activities, have become prevalent in various soil ecosystems and pose a global threat. Life Cycle Assessment (LCA), a tool for evaluating environmental performance of product and technology life cycles, has yet to adequately include MNPs-related damage to soil ES, owing to factors like uncertainties in MNPs environmental fate and ecotoxicological effects, and characterizing related damage on soil species loss, functional diversity, and ES. This study aims to address this gap by providing as a first step an overview of the current understanding of MNPs in soil ecosystems and proposing a conceptual approach to link MNPs impacts to soil ES damage. We find that MNPs pervade soil ecosystems worldwide, introduced through various pathways, including wastewater discharge, urban runoff, atmospheric deposition, and degradation of larger plastic debris. MNPs can inflict a range of ecotoxicity effects on soil species, including physical harm, chemical toxicity, and pollutants bioaccumulation. Methods to translate these impacts into damage on ES are under development and typically focus on discrete, yet not fully integrated aspects along the impact-to-damage pathway. We propose a conceptual framework for linking different MNPs effects on soil organisms to damage on soil species loss, functional diversity loss and loss of ES, and elaborate on each link. Proposed underlying approaches include the Threshold Indicator Taxa Analysis (TITAN) for translating ecotoxicological effects associated with MNPs into quantitative measures of soil species diversity damage; trait-based approaches for linking soil species loss to functional diversity loss; and ecological networks and Bayesian Belief Networks for linking functional diversity loss to soil ES damage. With the proposed conceptual framework, our study constitutes a starting point for including the characterization of MNPs-related damage on soil ES in LCA.

To Split or Not to Split: Characterizing Chemical Pollution Impacts in Aquatic Ecosystems with Species Sensitivity Distributions for Specific Taxonomic Groups

Bridging applied ecology and ecotoxicology is key to protect ecosystems. These disciplines show a mismatch, especially when evaluating pressures. Contrasting to applied ecology, ecotoxicological impacts are often characterized for whole species assemblages based on Species Sensitivity Distributions (SSDs). SSDs are statistical models describing per chemical across-species sensitivity variation based on laboratory toxicity tests. To assist in the aligning of the disciplines and improve decision-support uses of SSDs, we investigate taxonomic-group-specific SSDs for algae/cyanobacteria/aquatic plants, invertebrates, and vertebrates for 180 chemicals with sufficient test data. We show that splitting improves pollution impact assessments for chemicals with a specific mode of action and, surprisingly, for narcotic chemicals. We provide a framework for splitting SSDs that can be applied to serve in environmental protection, life cycle assessment, and management of freshwater ecosystems. We illustrate that using split SSDs has potentially large implications for the decision-support of SSD-based outputs around the globe.

A methodology to screen priority toxins in pollutant release inventories

Pollutant release inventories are used for environmental policy making to reduce toxic pollutants, even though the quantity-based inventory analysis does not take into account the relative toxicity of pollutants. To overcome this limit, life cycle impact assessment (LCIA)-based inventory analysis was developed but still has a high uncertainty from modelling the site- and time-specific fates and transports of pollutants. Thus, this study develops a methodology to evaluate toxicity potentials based on the concentration of pollutants in the exposure to humans in order to circumvent the uncertainty and subsequently screen priority toxins in pollutant release inventories. This methodology combines (i) analytical measurement of the concentration of the pollutants exposed to humans; (ii) application of toxicity effect characterization factors for pollutants; and (iii) identification of priority toxins and industries based on the toxicity potential evaluation results. To demonstrate the methodology, a case study is considered, evaluating toxicity potentials from the ingestion of heavy metals in seafood organisms and then identifying priority toxins and industry sectors in a pollutant release inventory. The results of the case study show that the methodology-based priority pollutant is different from the quantity- and LCIA-based ones. Therefore, the methodology can contribute to making effective environmental policy.

Environmental performance of phytosanitary control techniques on soybean crop estimated by life cycle assessment (LCA)

Phytosanitary control is essential to ensure agricultural productivity and quality. However, approaches based on scheduled use of pesticides, overuse of harmful molecules produce impacts on different types of living organisms. Integrated Pest and Disease Management (IPM-IDM) may significantly reduce the burden of pesticides in the environment. Plant resistance may also be included in the IPM-IDM and even in conventional management due to little requirement of additional knowledge and changes in agricultural practices. Robust environmental assessments using methodology of universal use, life cycle assessment (LCA), may estimate the impacts of specific pesticides that cause major damages, including remarkable category impacts. Therefore the objective of this study was to determine the impacts and (eco)toxicological effects of phytosanitary strategies (IPM-IDM including or not lepidopteran resistant transgenic cultivars) vs. the scheduled approach. Two inventory modeling methods were also applied to gather information on the use and applicability of these methods. Life cycle assessment (LCA) was applied using two inventory modeling methods: 100%Soil and PestLCI (Consensus) using data from Brazilian croplands under tropical conditions, by combining phytosanitary approaches (IPM-IDM, IPM-IDM + transgenic cultivar, conventional, conventional + transgenic cultivar) and modeling methods. Hence, eight soybean production scenarios were established. The IPM-IDM was efficient to reduce the (eco)toxicity impacts of soybean production mainly for freshwater ecotoxicity category. Due to the dynamic character of IPM-IDM approaches, the inclusion of recently introduced strategies (plant resistant and biological control to stink bugs and plant fungal diseases) may diminish even more the principal impacting substances throughout the Brazilian croplands. The PestLCI Consensus method, although its development is yet in progress, to date can be suggested to estimate the agriculture environmental impacts more properly under tropical conditions.

Probabilistic Points of Departure and Reference Doses for Characterizing Human Noncancer and Developmental/Reproductive Effects for 10,145 Chemicals

BACKGROUND

Regulatory toxicity values used to assess and manage chemical risks rely on the determination of the point of departure (POD) for a critical effect, which results from a comprehensive and systematic assessment of available toxicity studies. However, regulatory assessments are only available for a small fraction of chemicals.

OBJECTIVES

Using in vivo experimental animal data from the U.S. Environmental Protection Agency's Toxicity Value Database, we developed a semiautomated approach to determine surrogate oral route PODs, and corresponding toxicity values where regulatory assessments are unavailable.

METHODS

We developed a curated data set restricted to effect levels, exposure routes, study designs, and species relevant for deriving toxicity values. Effect levels were adjusted to chronic human equivalent benchmark doses (BMDh). We hypothesized that a quantile of the BMDh distribution could serve as a surrogate POD and determined the appropriate quantile by calibration to regulatory PODs. Finally, we characterized uncertainties around the surrogate PODs from intra- and interstudy variability and derived probabilistic toxicity values using a standardized workflow.

RESULTS

The BMDh distribution for each chemical was adequately fit by a lognormal distribution, and the 25th percentile best predicted the available regulatory PODs [R2≥0.78, residual standard error (RSE)≤0.53 log10 units]. We derived surrogate PODs for 10,145 chemicals from the curated data set, differentiating between general noncancer and reproductive/developmental effects, with typical uncertainties (at 95% confidence) of a factor of 10 and 12, respectively. From these PODs, probabilistic reference doses (1% incidence at 95% confidence), as well as human population effect doses (10% incidence), were derived.

DISCUSSION

In providing surrogate PODs calibrated to regulatory values and deriving corresponding toxicity values, we have substantially expanded the coverage of chemicals from 744 to 8,023 for general noncancer effects, and from 41 to 6,697 for reproductive/developmental effects. These results can be used across various risk assessment and risk management contexts, from hazardous site and life cycle impact assessments to chemical prioritization and substitution. https://doi.org/10.1289/EHP11524.

Generating environmental sampling and testing data for micro- and nanoplastics for use in life cycle impact assessment

Ongoing efforts focus on quantifying plastic pollution and describing and estimating the related magnitude of exposure and impacts on human and environmental health. Data gathered during such work usually follows a receptor perspective. However, Life Cycle Assessment (LCA) represents an emitter perspective. This study examines existing data gathering and reporting approaches for field and laboratory studies on micro- and nanoplastics (MNPs) exposure and effects relevant to LCA data inputs. The outcomes indicate that receptor perspective approaches do not typically provide suitable or sufficiently harmonised data. Improved design is needed in the sampling, testing and recording of results using harmonised, validated and comparable methods, with more comprehensive reporting of relevant data. We propose a three-level set of requirements for data recording and reporting to increase the potential for LCA studies and models to utilise data gathered in receptor-oriented studies. We show for which purpose such data can be used as inputs to LCA, particularly in life cycle impact assessment (LCIA) methods. Implementing these requirements will facilitate proper integration of the potential environmental impacts of plastic losses from human activity (e.g. litter) into LCA. Then, the impacts of plastic emissions can eventually be connected and compared with other environmental issues related to anthropogenic activities.

Comparative selective pressure potential of antibiotics in the environment

To guide both environmental and public health policy, it is important to assess the degree of antibiotic resistance selection pressure under measured environmental concentrations (MECs), and to compare the efficacy of different mitigation strategies to minimize the spread of resistance. To this end, the resistance selection and enrichment potential due to antibiotic emissions into the environment must be analysed from a life cycle perspective, for a wide range of antibiotics, and considering variations in the underlying fitness costs between different resistance mutations and genes. The aim of this study is to consistently derive fitness cost-dependent minimum selective concentrations (MSCs) from readily available bacterial inhibition data and to build MSC-based species sensitivity distributions (SSDs). These are then used to determine antibiotic-specific resistance selection concentrations predicted to promote resistance in 5% of exposed bacterial species (RSC₅). Using a previously developed competition model, we provide estimated MSC₁₀ endpoints for 2,984 antibiotic and bacterial species combinations; the largest set of modelled MSCs available to date. Based on constructed SSDs, we derive RSC₅ for 128 antibiotics with four orders of magnitude difference in their 'selective pressure potential' in the environment. By comparing our RSC₅ to MECs, we highlight specific environmental compartments (e.g. hospital and wastewater effluents, lakes and rivers), as well as several antibiotics (e.g. ciprofloxacin, norfloxacin, enrofloxacin, and tetracycline), to be scrutinized for their potential role in resistance selection and dissemination. In addition to enabling comparative risk screening of the selective pressure potential of multiple antibiotics, our SSD-derived RSC₅ provide the point of departure for calculating new life cycle-based characterization factors for antibiotics to compare mitigation strategies, thereby contributing towards a 'One-Health' approach to tackling the global antibiotic resistance crisis.

Linking freshwater ecotoxicity to damage on ecosystem services in life cycle assessment

Freshwater ecosystems provide major benefits to human wellbeing-so-called ecosystem services (ES)-but are currently threatened among others by ecotoxicological pressure from chemicals reaching the environment. There is an increased motivation to incorporate ES in quantification tools that support decision-making, such as life cycle assessment (LCA). However, mechanistic models and frameworks that can systematically translate ecotoxicity effect data from chemical tests into eventual damage on species diversity, functional diversity, and ES in the field are still missing. While current approaches focus on translating predicted ecotoxicity impacts to damage in terms of species loss, no approaches are available in LCA and other comparative assessment frameworks for linking ecotoxicity to damage on ecosystem functioning or ES. To overcome this challenge, we propose a way forward based on evaluating available approaches to characterize damage of chemical pollution on freshwater ES. We first outline an overall framework for linking freshwater ecotoxicity effects to damage on related ES in compliance with the boundary conditions of quantitative, comparative assessments. Second, within the proposed framework, we present possible approaches for stepwise linking ecotoxicity effects to species loss, functional diversity loss, and damage on ES. Finally, we discuss strengths, limitations, and data availability of possible approaches for each step. Although most approaches for directly deriving damage on ES from either species loss or damage to functional diversity have not been operationalized, there are some promising ways forward. The Threshold Indicator Taxa ANalysis (TITAN) seems suitable to translate predicted ecotoxicity effects to a metric of quantitative damage on species diversity. A Trait Probability Density Framework (TPD) approach that incorporates various functional diversity components and functional groups could be adapted to link species loss to functional diversity loss. An Ecological Production Function (EPF) approach seems most promising for further linking functional diversity loss to damage on ES flows for human wellbeing. However, in order to integrate the entire pathway from predicted freshwater ecotoxicity to damage on ES into LCA and other comparative frameworks, the approaches adopted for each step need to be harmonized in terms of assumptions, boundary conditions and consistent interfaces with each other.

Ecotoxicity characterization of chemicals: Global recommendations and implementation in USEtox

Chemicals emitted to the environment affect ecosystem health from local to global scale, and reducing chemical impacts has become an important element of European and global sustainability efforts. The present work advances ecotoxicity characterization of chemicals in life cycle impact assessment by proposing recommendations resulting from international expert workshops and work conducted under the umbrella of the UNEP-SETAC Life Cycle Initiative in the GLAM project (Global guidance on environmental life cycle impact assessment indicators). We include specific recommendations for broadening the assessment scope through proposing to introduce additional environmental compartments beyond freshwater and related ecotoxicity indicators, as well as for adapting the ecotoxicity effect modelling approach to better reflect environmentally relevant exposure levels and including to a larger extent chronic test data. As result, we (1) propose a consistent mathematical framework for calculating freshwater ecotoxicity characterization factors and their underlying fate, exposure and effect parameters; (2) implement the framework into the USEtox scientific consensus model; (3) calculate characterization factors for chemicals reported in an inventory of a life cycle assessment case study on rice production and consumption; and (4) investigate the influence of effect data selection criteria on resulting indicator scores. Our results highlight the need for careful interpretation of life cycle assessment impact scores in light of robustness of underlying species sensitivity distributions. Next steps are to apply the recommended characterization framework in additional case studies, and to adapt it to soil, sediment and the marine environment. Our framework is applicable for evaluating chemicals in life cycle assessment, chemical and environmental footprinting, chemical substitution, risk screening, chemical prioritization, and comparison with environmental sustainability targets.

Semi-automated harmonization and selection of chemical data for risk and impact assessment

Chemical data for thousands of substances are available for safety, risk, life cycle and substitution assessments, as submitted for example under the European Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Regulation. However, to widely disseminate reported physicochemical properties as well as human and ecological exposure and toxicological data for use in various science and policy fields, systematic methods for data harmonization and selection are necessary. In response to this need, we developed a semi-automated method for deriving appropriate substance property values as input for various assessment frameworks with different requirements for resolution and data quality. Starting with data reported for a given substance and property, we propose a set of aligned data selection and harmonization criteria to obtain a representative mean value and related confidence intervals per chemical-property combination. The proposed method was tested on a set of octanol-water partition coefficients (K_ow) for an illustrative set of 20 substances, reported under the REACH regulation as example data source. Our method is generally applicable to any set of substances, and can assess specific distributions in quality and variability across reported data. Further research can likely extend our method for mining information from text fields and adapt it to available data reported or collected from other sources and other substance properties to improve the reliability of input data for risk and impact assessments.

Life Cycle Thinking for the environmental and financial assessment of rice management systems in the Senegal River Valley

Rice is a staple food in Senegal, which however imports more than 70% of the rice consumed annually to meet its domestic demand. Despite governmental efforts to increase rice self-sufficiency, both rice supply and yields remain low. Senegalese farmers face challenges related to irrigation infrastructure and fertiliser access, besides those derived from climate change. This study applies Life Cycle Assessment (LCA) combined with financial Life Cycle Costing (LCC) to evaluate alternative scenarios for rice management in the Senegal River Valley and identify sustainability hotspots and potential improvements. Specifically, rice cultivation in Ross Béthio (Saint Louis, Senegal) is assessed based on the observed agricultural practices during the dry seasons of 2016 and 2017. Two scenarios capturing conventional (CONV) and intensive (INT) practices are compared to two reference scenarios (SAED scenarios) according to the recommendations of the official agricultural advisory service. The INT scenario generates the lowest impacts per kg of paddy rice in seven out of thirteen impact categories, including climate change, freshwater and marine eutrophication, ozone depletion and water scarcity. This is due to the higher yields (7.4 t ha^-1) relative to CONV (4.8 t ha^-1) and the two reference SAED scenarios (6.0 t ha^-1). The two latter scenarios show the lowest values in the remaining categories, although they also generate slightly lower profits than INT (138 € t^-1 vs. 149 € t^-1) due to increased labour costs for additional fertilisation treatments. The results from both LCA and LCC underline the importance of increasing yields to decrease environmental impacts and production costs of rice when estimated per kg of product. Well-designed fertiliser application doses and timing and increased mechanisation can deliver further environmental benefits. Additional improvements (e.g. in irrigation, crop rotations, straw management) could be considered to promote the long-term sustainability and profitability of rice production in Senegal. LCA in combination with financial LCC is identified as a decision-support tool for evaluating the sustainability of alternative crop management practices. Life Cycle Thinking can still benefit from experiential learning based on information exchange between farmers, researchers and extension agents to contribute to a sustainable agriculture and ultimately to food security in Africa.

Towards a more comprehensive life cycle assessment framework for assessing toxicity-related impacts for livestock products: The case of Danish pork

In life cycle assessments of livestock systems, toxicity-related impacts are not commonly considered or only specific aspects (such as pesticides, manufacturing of inputs) are assessed. In this context, the aim of this study was to define a framework for assessing toxicity-related impacts and to characterize human toxicity and freshwater ecotoxicity for a livestock product based on applying the state-of-the-art models PestLCI Consensus and USEtox. Furthermore, methodological gaps were discussed and ways forward were suggested. The case study focused on Danish pork production and the toxicity results were reported per kg 'meat' (the parts of pig used for human consumption) leaving the slaughterhouse. The assessment framework included the use of pesticides and heavy metals in feed production, the use of veterinary pharmaceuticals in pig production, and the manufacturing of inputs. The use of cleaning agents could not be assessed with the currently available methods. New characterization factors were calculated for 35 chemicals not available in USEtox. For Danish pork production, feed production was the main contributor to the analyzed toxicity impacts. The use of pesticides was the main driver for organic substances while heavy metal emissions related to the application of pig manure to fields were the hotspot for metal-based substances. The use of veterinary pharmaceuticals contributed only to freshwater ecotoxicity by 3%. PestLCI Consensus estimates were compared with different approaches. The impact of metabolites of pesticides and veterinary pharmaceuticals was assessed and discussed. Methodological gaps and research needs were identified regarding the assessment of pesticides, veterinary pharmaceuticals, metal-based substances, inorganic substances, and combined exposure to multiple chemicals. Better data related to the use and chemical properties of substances are needed to reduce uncertainty in toxicity modeling.

Toward harmonizing global pesticide regulations for surface freshwaters in support of protecting human health

To promote international collaboration on environmental pollution management and human health protection, we conducted a global-level study on the management of pesticides for surface freshwater quality. Prior to actions being taken in terms of water treatment or remediation, it is essential that clear and definite regulations be disseminated. In our study, 3094 surface freshwater quality standards for 184 different pesticides were recorded from 53 countries and categorized according to pesticide types and standard types, as well as diverse use of freshwater by humans, and compared water quality standards related to human health. Our results indicate large variations in pesticide regulations, standard types (i.e., long- or short-term water quality standards), and related numerical values. With regard to the protection of human health, the 10 most frequently regulated pesticides account for approximately 47% of the total number of standards across 184 considered pesticides. The average occurrence-weighted variations of standard values (i.e., numerical values provided in a standard in terms of residue limits of a given pesticide in water) for the 20 most regulated persistent organic pollutants (POPs) and other phase-out pesticides (i.e., pesticides not currently-approved for use in agriculture across various countries) are 4.1 and 2.6 orders of magnitude, respectively, with human-exposure related standard values for some pesticides varying with over 3 orders of magnitude (e.g., lindane). In addition, variations in water quality standard values occurred across standard types (e.g., maximum and average), water use types (e.g., unspecified waters and human consumption), and standard values (e.g., pesticide individuals and groups). We conclude that regulatory inconsistencies emphasize the need for international collaboration on domestic water treatment, environmental management as well as specific water quality standards for the wider range of current-use pesticides, thereby improving global harmonization in support of protecting human health.

Introducing ground cover management in pesticide emission modeling

Ground cover management (GCM) is an important agricultural practice used to reduce weed growth, erosion and runoff, and improve soil fertility. In the present study, an approach to account for GCM is proposed in the modeling of pesticide emissions to evaluate the environmental sustainability of agricultural practices. As a starting point, we include a cover crop compartment in the mass balance of calculating initial (within minutes after application) and secondary (including additional processes) pesticide emission fractions. The following parameters were considered: (i) cover crop occupation between the rows of main field crops, (ii) cover crop canopy density, and (iii) cover crop family. Two modalities of cover crop occupation and cover crop canopy density were tested for two crop growth stages, using scenarios without cover crops as control. From that, emission fractions and related ecotoxicity impacts were estimated for pesticides applied to tomato production in Martinique (French West Indies) and to grapevine cultivation in the Loire Valley (France). Our results demonstrate that, on average, the presence of a cover crop reduced the pesticide emission fraction reaching field soil by a factor of 3 compared with bare soil, independently of field crop and its growth stage, and cover crop occupation and density. When considering cover exported from the field, ecotoxicity impacts were reduced by approximately 65% and 90%, compared with bare soil for grapevine and tomato, respectively, regardless of the emission distribution used. Because additional processes may influence emission distributions under GCM, such as runoff, leaching, or preferential flow, further research is required to incorporate these processes consistently in our proposed GCM approach. Considering GCM in pesticide emission modeling highlights the potential of soil cover to reduce pesticide emissions to field soil and related freshwater ecotoxicity. Furthermore, the consideration of GCM as common farming practice allows the modeling of pesticide emissions in intercropping systems. Integr Environ Assess Manag 2022;18:274-288. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Developing Conversion Factors of LCIA Methods for Comparison of LCA Results in the Construction Sector

The inconsistency caused by different life cycle impact assessment (LCIA) methods is a long-term challenge for the life cycle assessment (LCA) community. It is necessary to systematically analyze the differences caused by LCIA methods and facilitate the fair comparison of LCA results. This study proposes an effective method of conversion factors (CFs) for converting the results of 8 LCIA methods for 14 impact categories and then demonstrates its application in the construction sector. Correlation analyses of the datasets of construction materials are conducted to develop CFs for the impact categories. A set of conversion cards are devised to present the CFs and the associated correlation information for the LCIA methods. It is revealed that the differences between LCIA methods are largely caused by the characterization methods, rather than due to the metrics. A comparison based only on the same metrics but ignoring the underlying LCIA mechanisms is misleading. High correlations are observed for the impact categories of climate change, acidification, eutrophication, and resource depletion. The developed CFs and conversion cards can greatly help LCA practitioners in the fair comparison of LCA results from different LCIA methods. Case studies are conducted, and verify that by applying the CFs the seemingly incomparable results from different LCIA methods become comparable. The CF method addresses the inconsistency problem of LCIA methods in a practical manner and helps improve the comparability and reliability of LCA studies in the construction sector. Suggestions are provided for the further development of LCIA conversion factors.

Exposure and Toxicity Characterization of Chemical Emissions and Chemicals in Products: Global Recommendations and Implementation in USEtox

PURPOSE

Reducing chemical pressure on human and environmental health is an integral part of the global sustainability agenda. Guidelines for deriving globally applicable, life cycle based indicators are required to consistently quantify toxicity impacts from chemical emissions as well as from chemicals in consumer products. In response, we elaborate the methodological framework and present recommendations for advancing near-field/far-field exposure and toxicity characterization, and for implementing these recommendations in the scientific consensus model USEtox.

METHODS

An expert taskforce was convened by the Life Cycle Initiative hosted by UN Environment to expand existing guidance for evaluating human toxicity impacts from exposure to chemical substances. This taskforce evaluated advances since the original release of USEtox. Based on these advances, the taskforce identified two major aspects that required refinement, namely integrating near-field and far-field exposure and improving human dose-response modeling. Dedicated efforts have led to a set of recommendations to address these aspects in an update of USEtox, while ensuring consistency with the boundary conditions for characterizing life cycle toxicity impacts and being aligned with recommendations from agencies that regulate chemical exposure. The proposed framework was finally tested in an illustrative rice production and consumption case study.

RESULTS AND DISCUSSION

On the exposure side, a matrix system is proposed and recommended to integrate far-field exposure from environmental emissions with near-field exposure from chemicals in various consumer product types. Consumer exposure is addressed via submodels for each product type to account for product characteristics and exposure settings. Case study results illustrate that product-use related exposure dominates overall life cycle exposure. On the effect side, a probabilistic dose-response approach combined with a decision tree for identifying reliable points of departure is proposed for non-cancer effects, following recent guidance from the World Health Organization. This approach allows for explicitly considering both uncertainty and human variability in effect factors. Factors reflecting disease severity are proposed to distinguish cancer from non-cancer effects, and within the latter discriminate reproductive/developmental and other non-cancer effects. All proposed aspects have been consistently implemented into the original USEtox framework.

CONCLUSIONS

The recommended methodological advancements address several key limitations in earlier approaches. Next steps are to test the new characterization framework in additional case studies and to close remaining research gaps. Our framework is applicable for evaluating chemical emissions and product-related exposure in life cycle assessment, chemical alternatives assessment and chemical substitution, consumer exposure and risk screening, and high-throughput chemical prioritization.

A Critical Review of Organic Ultraviolet Filter Exposure, Hazard, and Risk to Corals

There has been a rapid increase in public, political, and scientific interest regarding the impact of organic ultraviolet (UV) filters to coral reefs. Such filters are found in sunscreens and other consumer products and enter the aquatic environment via direct (i.e., recreational activities, effluents) or indirect (i.e., land runoff) pathways. This review summarizes the current state of the science regarding the concentration of organic UV filters in seawater and sediment near coral reef ecosystems and in coral tissues, toxicological data from early and adult life stages of coral species, and preliminary environmental risk characterizations. Up to 14 different organic UV filters in seawater near coral reefs have been reported across 12 studies, with the majority of concentrations in the nanograms per liter range. Nine papers report toxicological findings from no response to a variety of biological effects occurring in the micrograms per liter to milligrams per liter range, in part given the wide variations in experimental design and coral species and/or life stage used. This review presents key findings; scientific data gaps; flaws in assumptions, practice, and inference; and a number of recommendations for future studies to assess the environmental risk of organic UV filters to coral reef ecosystems. Environ Toxicol Chem 2021;40:967-988. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Addressing temporal considerations in life cycle assessment

In life cycle assessment (LCA), temporal considerations are usually lost during the life cycle inventory calculation, resulting in an aggregated "snapshot" of potential impacts. Disregarding such temporal considerations has previously been underlined as an important source of uncertainty, but a growing number of approaches have been developed to tackle this issue. Nevertheless, their adoption by LCA practitioners is still uncommon, which raises concerns about the representativeness of current LCA results. Furthermore, a lack of consistency can be observed in the used terms for discussions on temporal considerations. The purpose of this review is thus to search for common ground and to identify the current implementation challenges while also proposing development pathways. This paper introduces a glossary of the most frequently used terms related to temporal considerations in LCA to build a common understanding of key concepts and to facilitate discussions. A review is also performed on current solutions for temporal considerations in different LCA phases (goal and scope definition, life cycle inventory analysis and life cycle impact assessment), analysing each temporal consideration for its relevant conceptual developments in LCA and its level of operationalisation. We then present a potential stepwise approach and development pathways to address the current challenges of implementation for dynamic LCA (DLCA). Three key focal areas for integrating temporal considerations within the LCA framework are discussed: i) define the temporal scope over which temporal distributions of emissions are occurring, ii) use calendar-specific information to model systems and associated impacts, and iii) select the appropriate level of temporal resolution to describe the variations of flows and characterisation factors. Addressing more temporal considerations within a DLCA framework is expected to reduce uncertainties and increase the representativeness of results, but possible trade-offs between additional data collection efforts and the increased value of results from DLCAs should be kept in mind.

Building a European exposure science strategy

Exposure information is a critical element in various regulatory and non-regulatory frameworks in Europe and elsewhere. Exposure science supports to ensure safe environments, reduce human health risks, and foster a sustainable future. However, increasing diversity in regulations and the lack of a professional identity as exposure scientists currently hamper developing the field and uptake into European policy. In response, we discuss trends, and identify three key needs for advancing and harmonizing exposure science and its application in Europe. We provide overarching building blocks and define six long-term activities to address the identified key needs, and to iteratively improve guidelines, tools, data, and education. More specifically, we propose creating European networks to maximize synergies with adjacent fields and identify funding opportunities, building common exposure assessment approaches across regulations, providing tiered education and training programmes, developing an aligned and integrated exposure assessment framework, offering best practices guidance, and launching an exposure information exchange platform. Dedicated working groups will further specify these activities in a consistent action plan. Together, these elements form the foundation for establishing goals and an action roadmap for successfully developing and implementing a 'European Exposure Science Strategy' 2020-2030, which is aligned with advances in science and technology.

A biological characteristic extrapolation of compound toxicity for different developmental stage species with toxicokinetic-toxicodynamic model

Intraspecific difference in toxicity brings uncertainty to ecological risk assessment (ERA) and water quality criteria (WQC) of chemicals. Here, we compared intraspecies sensitivity to toxicants for Mesocyclops leuckarti of which toxicity data was obtained from published literatures, and zebrafish Danio rerio of which toxicity data was done in this study). Due to the internal concentration of chemicals not measured, simplified toxicokinetic-toxicodynamic (TK-TD) models were used, and we investigated whether TK-TD parameters estimated by Bayesian method might represent the differences in sensitivity between life-stages of 2 species. The results demonstrated that the difference in TK-TD parameters (background mortality m₀, no effect concentration NEC, the killing rate k_s, and the dominant rate k_d) could represent the toxicity difference between life-stages of individual species. The TK-TD model could predict toxicity in individual species (Cyprinus carpio L., Enchytraeus crypticus, Folsomia candida, Hyalella Azteca) exposed to different chemical concentrations and successfully extrapolate toxicity between different life stages of Mesocyclops leuckarti and Danio rerio by scaling several TK-TD parameters. The modified TK-TD model on the extrapolation toxicity of chemicals between life stages for species could be useful for the ERA and for deriving and revising WQC for chemicals.

Influence of metal speciation on soil ecotoxicity impacts in life cycle assessment

It is unknown whether metallic elements remain important contributors to terrestrial ecotoxicity impact scores in life cycle assessment (LCA) when solid- and liquid-phase speciation are considered in environmental fate, exposure and effects. Here, a new speciation-based method for calculating comparative toxicity potentials (CTP) of 23 metallic elements in soils was compared with two other widely used methods which do not consider speciation (i.e., IMPACT, 2002+ and ReCiPe 2008) for nearly 13,000 life cycles of unit processes taken from different sectors. Differences in impact scores between method were driven either by differences in characterization models (ReCiPe 2008) or both by differences in characterization models and substance coverage (IMPACT, 2002+). Strong correlations (r > 0.98) and seemingly constant shifts in impact scores were found for those processes where one or few substances (usually metals) contributed most to total impact and there were large differences in CTPs between methods for these substances. Weaker correlations but often better agreement in impact scores were found for those processes where organic substances were dominant contributors to total impact. Our results suggest that metals are expected to remain important contributors to soil ecotoxicity impacts in LCA when speciation is considered.

An (Eco)Toxicity Life Cycle Impact Assessment Framework for Per- And Polyfluoroalkyl Substances

A framework for characterizing per- and polyfluoroalkyl substances (PFASs) in life cycle impact assessment (LCIA) is proposed. Thousands of PFASs are used worldwide, with special properties imparted by the fluorinated alkyl chain. Our framework makes it possible to characterize a large part of the family of PFASs by introducing transformation fractions that translate emissions of primary emitted PFASs into the highly persistent terminal degradation products: the perfluoroalkyl acids (PFAAs). Using a PFAA-adapted characterization model, human toxicity as well as marine and freshwater aquatic ecotoxicity characterization factors are calculated for three PFAAs, namely perfluorooctanoic acid (PFOA) perfluorohexanoic acid (PFHxA) and perfluorobutanesulfonic acid (PFBS). The model is evaluated to adequately capture long-term fate, where PFAAs are predicted to accumulate in open oceans. The characterization factors of the three PFAAs are ranked among the top 5% for marine ecotoxicity, when compared to 3104 chemicals in the existing USEtox results databases. Uncertainty analysis indicates potential for equally high ranks for human health impacts. Data availability constitutes an important limitation creating uncertainties. Even so, a life cycle assessment (LCA) case study illustrates practical application of our proposed framework, demonstrating that even low emissions of PFASs can have large effects on LCA results.

Characterizing honey bee exposure and effects from pesticides for chemical prioritization and life cycle assessment

Agricultural pesticides are key contributors to pollinator decline worldwide. However, methods for quantifying impacts associated with pollinator exposure to pesticides are currently missing in comparative risk screening, chemical substitution and prioritization, and life cycle impact assessment methods. To address this gap, we developed a method for quantifying pesticide field exposure and ecotoxicity effects of honey bees as most economically important pollinator species worldwide. We defined bee intake and dermal contact fractions representing respectively oral and dermal exposure per unit mass applied, and tested our model on two pesticides applied to oilseed rape. Our results show that exposure varies between types of forager bees, with highest dermal contact fraction of 59 ppm in nectar foragers for lambda-cyhalothrin (insecticide), and highest oral intake fractions of 32 and 190 ppm in nectar foragers for boscalid (fungicide) and lambda-cyhalothrin, respectively. Hive oral exposure is up to 115 times higher than forager oral exposure. Combining exposure with effect estimates yields impacts, which are three orders of magnitude higher for the insecticide. Overall, nectar foragers are the most affected forager type for both pesticides, dominated by oral exposure. Our framework constitutes an important step toward integrating pollinator impacts in chemical substitution and life cycle impact assessment, and should be expanded to cover all relevant pesticide-crop combinations.

Estimate ecotoxicity characterization factors for chemicals in life cycle assessment using machine learning models

In life cycle assessment, characterization factors are used to convert the amount of the chemicals and other pollutants generated in a product's life cycle to the standard unit of an impact category, such as ecotoxicity. However, as a widely used impact assessment method, USEtox (version 2.11) only has ecotoxicity characterization factors for a small portion of chemicals due to the lack of laboratory experiment data. Here we develop machine learning models to estimate ecotoxicity hazardous concentrations 50% (HC₅₀) in USEtox to calculate characterization factors for chemicals based on their physical-chemical properties in EPA's CompTox Chemical Dashborad and the classification of their mode of action. The model is validated by ten randomly selected test sets that are not used for training. The results show that the random forest model has the best predictive performance. The average root mean squared error of the estimated HC₅₀ on the test sets is 0.761. The average coefficient of determination (R²) on the test set is 0.630, meaning 63% of the variability of HC₅₀ in USEtox can be explained by the predicted HC₅₀ from the random forest model. Our model outperforms a traditional quantitative structure-activity relationship (QSAR) model (ECOSAR) and linear regression models. We also provide estimates of missing ecotoxicity characterization factors for 552 chemicals in USEtox using the validated random forest model.

Reliable and representative in silico predictions of freshwater ecotoxicological hazardous concentrations

A reliable quantification of the potential effects of chemicals on freshwater ecosystems requires ecotoxicological response data for a large set of species which is typically not available in practice. In this study, we propose a method to estimate hazardous concentrations (HCs) of chemicals on freshwater ecosystems by combining two in silico approaches: quantitative structure activity relationships (QSARs) and interspecies correlation estimation (ICE) models. We illustrate the principle of our QSAR-ICE method by quantifying the HCs of 51 chemicals at which 50% and 5% of all species are exposed above the concentration causing acute effects. We assessed the bias of the HCs, defined as the ratio of the HC based on measured ecotoxicity data and the HC based on in silico data, as well as the statistical uncertainty, defined as the ratio of the 95th and 5th percentile of the HC. Our QSAR-ICE method resulted in a bias that was comparable to the use of measured data for three species, as commonly used in effect assessments: the average bias of the QSAR-ICE HC50 was 1.2 and of the HC5 2.3 compared to 1.2 when measured data for three species were used for both HCs. We also found that extreme statistical uncertainties (>10⁵) are commonly avoided in the HCs derived with the QSAR-ICE method compared to the use of three measurements with statistical uncertainties up to 10¹². We demonstrated the applicability of our QSAR-ICE approach by deriving HC50s for 1,223 out of the 3,077 organic chemicals of the USEtox database. We conclude that our QSAR-ICE method can be used to determine HCs without the need for additional in vivo testing to help prioritise which chemicals with no or few ecotoxicity data require more thorough assessment.

Extrapolation Factors for Characterizing Freshwater Ecotoxicity Effects

Various environmental and chemical assessment frameworks including ecological risk assessment and life cycle impact assessment aim at evaluating long-term ecotoxicity effects. Chronic test data are reported under the European Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) regulation for various chemicals. However, chronic data are missing for a large fraction of marketed chemicals, for which acute test results are often available. Utilizing acute data requires robust extrapolation factors across effect endpoints, exposure durations, and species groups. We propose a decision tree based on strict criteria for curating and selecting high-quality aquatic ecotoxicity information available in REACH for organic chemicals, to derive a consistent set of generic and species group-specific extrapolation factors. Where ecotoxicity effect data are not available at all, we alternatively provide extrapolations from octanol-water partitioning coefficients as suitable predictor for chemicals with nonpolar narcosis as mode of action. Extrapolation factors range from 0.2 to 7 and are higher when simultaneously extrapolating across effect endpoints and exposure durations. Our results are consistent with previously reported values, while considering more endpoints, providing species group-specific factors, and characterizing uncertainty. Our proposed decision tree can be adapted to curate information from additional data sources as well as data for other environments, such as sediment ecotoxicity. Our approach and robust extrapolation factors help to increase the substance coverage for characterizing ecotoxicity effects across chemical and environmental assessment frameworks. Environ Toxicol Chem 2019;38:2568-2582. © 2019 SETAC.

Towards integrating toxicity characterization into environmental studies: case study of bromine in soils

AbstractPollution from bromine and some of its related compounds is currently unregulated in soil from Russia and other countries, and tools for sound assessment of environmental impacts of bromine contamination are largely missing. Hence, assessing potential implications for humans and ecosystems of bromine soil contamination is urgently needed, which requires the combination of measured soil concentrations from environmental studies and quantified potential toxicity impacts. To address this need, we used data from an experimental study assessing bromine in soils (384 samples) of Tomsk oblast, Russia, starting from measured concentrations obtained by Instrumental Neutron Activation Analysis in an earlier study. From these data, we calculated the bromine mass in soils and used these as starting point to characterize related cumulative impacts on human health and ecosystems in the Tomsk region, using a global scientific consensus model for screening-level comparative toxicity characterization of chemical emissions. Results show that the combination of sampling methodology with toxicity characterization techniques presents a new approach to be used in environmental studies aimed at environmental assessment and analysis of a territory. Our results indicate that it is important to account for substance-specific chemical reaction pathways and transfer processes, as well as to consider region-specific environmental characteristics. Our approach will help complement environmental assessment results with environmental sustainability elements, to consider potential tradeoffs in impacts, related to soil pollution, in support of improved emission and pollution reduction strategies.

Improving the Life Cycle Impact Assessment of Metal Ecotoxicity: Importance of Chromium Speciation, Water Chemistry, and Metal Release

Investigations of metal ecotoxicity in life cycle assessment (LCA) and life cycle impact assessment (LCIA) are becoming important tools for evaluating the environmental impact of a product or process. There is, however, improvement needed for LCIA of metal ecotoxicity in order to make this assessment more relevant and robust. In this work, three issues within the LCIA of metal ecotoxicity are investigated, mainly focusing on topics related to stainless steel manufacturing. The first issue is the importance of considering regional water chemistry when constructing the characterization factor (CF). A model freshwater of relevance for stainless steel manufacturing in a region of Sweden was created with chemistry different from available options. The second issue is related to the lack of consideration on changes in speciation of Cr(VI) in freshwater for a given emission, as Cr(VI) to some extent will be reduced to Cr(III). Two new options are suggested based on relationships between the Cr(VI)–total Cr ratio as a way to improve the relevancy of LCIA for Cr(VI) in freshwater. The last issue is how to treat metal release from slags in LCIA. Metal release from slags was shown to vary significantly between different ways of modelling slag emissions (differences in total metal content, slag leaching tests, estimated emissions to groundwater).

Advancements in Life Cycle Human Exposure and Toxicity Characterization

BACKGROUND

The Life Cycle Initiative, hosted at the United Nations Environment Programme, selected human toxicity impacts from exposure to chemical substances as an impact category that requires global guidance to overcome current assessment challenges. The initiative leadership established the Human Toxicity Task Force to develop guidance on assessing human exposure and toxicity impacts. Based on input gathered at three workshops addressing the main current scientific challenges and questions, the task force built a roadmap for advancing human toxicity characterization, primarily for use in life cycle impact assessment (LCIA).

OBJECTIVES

The present paper aims at reporting on the outcomes of the task force workshops along with interpretation of how these outcomes will impact the practice and reliability of toxicity characterization. The task force thereby focuses on two major issues that emerged from the workshops, namely considering near-field exposures and improving dose–response modeling.

DISCUSSION

The task force recommended approaches to improve the assessment of human exposure, including capturing missing exposure settings and human receptor pathways by coupling additional fate and exposure processes in consumer and occupational environments (near field) with existing processes in outdoor environments (far field). To quantify overall aggregate exposure, the task force suggested that environments be coupled using a consistent set of quantified chemical mass fractions transferred among environmental compartments. With respect to dose–response, the task force was concerned about the way LCIA currently characterizes human toxicity effects, and discussed several potential solutions. A specific concern is the use of a (linear) dose–response extrapolation to zero. Another concern addresses the challenge of identifying a metric for human toxicity impacts that is aligned with the spatiotemporal resolution of present LCIA methodology, yet is adequate to indicate health impact potential.

CONCLUSIONS

Further research efforts are required based on our proposed set of recommendations for improving the characterization of human exposure and toxicity impacts in LCIA and other comparative assessment frameworks. https://doi.org/10.1289/EHP3871.

Terrestrial Ecotoxic Impacts Stemming from Emissions of Cd, Cu, Ni, Pb and Zn from Manure: A Spatially Differentiated Assessment in Europe

Metallic elements present in livestock manure as co-contaminants have the potential to cause terrestrial ecotoxic impacts when the manure is used as fertilizer on agricultural soils. The magnitude of this impact at country scale in Europe has, to date, not been quantified. Here, we address this knowledge gap by combining recently developed national emission inventories of Cd, Cu, Ni, Pb and Zn releases from manure with metal- and soil-specific comparative toxicity potentials (CTP) calculated for cropland grid cells at 1 × 1 km resolution for 33 European countries. The CTPs account for speciation in environmental fate, exposure and effects, including reduction in the solid-phase reactivity of a metal when it is associated with organic carbon present in the manure. Given the scarcity of inventory data at sub-national level, it was assumed that each unit area of cropland within a given country has the same probability to receive manure. The resulting CTPs span a range of several orders of magnitude reflecting the influence of soil type and properties on the speciation patterns and resulting CTP values. However, when combined with the use of manure in each European country, the resulting national impact scores were mainly explained by the total mass input of metal released to soil rather than by geographic variability in the CTP values. Simple linear regression is then sufficient to predict terrestrial ecotoxic impacts from input mass. Although some changes in ranking of metals and countries were observed, both mass- and impact-based comparisons between metals agreed that Zn and Cu are dominant contributors to total impacts, and that top contributing countries were those emitting the largest amounts of metals. Our findings show that spatially differentiated impact assessment is important for ranking of countries when differences in national emission inventories between countries are smaller than a factor of two (Ni), a factor of three (Cd, Cu, Zn) or a factor of four (Pb). In other cases, ranking of countries can be based on national emission inventories.