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Ecotoxicological data are highly important for risk assessment processes and are used for deriving environmental quality criteria, which are enacted for assuring the good quality of waters, soils or sediments and achieving desirable environmental quality objectives. Therefore, it is of significant importance the evaluation of the reliability and relevance of available data for analysing their possible use in the aforementioned processes. In this context, a new methodology which has been developed based on Multi-Criteria Decision Analysis (MCDA) techniques, is being used, demonstrated and tested for analysing the reliability and relevance of ecotoxicological data of cyanide (which are produced through laboratory biotests for individual effects). The proposed methodology is also used for the production of Weighted by Data Quality Species Sensitivity Distributions (SSD-WDQ), as a component of the Ecological Risk Assessment of chemicals in aquatic systems. The SSD-WDQ production resulted in the estimation of environmental quality criteria (hazard concentration affecting 5% and 50% of the species). The proposed work is part of the development of the AMORE Decision Support System (DSS) for the application of probabilistic Ecological Risk Assessment (ERA), presented in the companion paper (Isigonis et al., 2019). The DSS has been tested through a case study on ERA of cyanide in the watershed of river Selune in France. The paper presents the ‘Effect Assessment’ of cyanide, based on the aforementioned methodologies. The main results presented in the paper are the probabilistic analysis of the estimated species sensitivity on cyanide (Effect Assessment) and the calculation of Hazardous Concentration (HCx) of the same contaminant in the Selune river area, based on the functionalities of the DSS. The results are described and discussed in detail, with the use of various graphs and indices. The indices are calculated for all the available ecotoxicological data, as well as for the data on trophic levels or taxonomic groups separately. An effect comparison is presented between the innovative methodologies included in the DSS and the currently existing methodologies.

International audience; PurposeDam reservoirs sometimes need to be fully drawn down, an operation that induces sediment resuspension. In the case of contaminated sediments, such resuspension may promote the remobilization of trace metals from the solid to the dissolved phase, threatening the water quality. The objective of this study is to evaluate the kinetic release and removal processes of trace metals during the resuspension of polluted sediments from a dam reservoir.Materials and methodsTotal contents of trace elements were analyzed in the surface sediments collected in the dam. Ascorbate and sequential extractions were used to assess the trace metal fractionation. Aliquots of wet sediments were resuspended during a week using a 3-L glass reactor. Three solid/solution ratios (2.7, 5.0, and 9.4 g L−1) were tested. The pH, Eh, dissolved oxygen, and temperature were continuously measured, and water samples were collected through a small pipe inserted into the reactor. Evolution of dissolved organic carbon, alkalinity, major ions, and trace element concentrations were measured in the water over the resuspension experiments. Another resuspension experiment was carried out to determine the quantity of elements that could be adsorbed onto the glass wall of the reactor.Results and discussionHigh levels of As, Cd, Pb, and Zn were measured in the reservoir sediments, compared to the quality guidelines. The temporal evolutions of the dissolved elements were similar during the resuspension experiments, regardless of the mass of sediment used. Depending on the elements, different trends can be highlighted: (1) Cd, Cr, Cu, Ni, V, and Zn were not remobilized; (2) Al, Mo, As, Ba, and Sr continuously increased during the experiments; and (3) Mn, Co, Fe, and Pb increased at the beginning of the experiments and then were removed from the dissolved phase. Co was likely adsorbed onto Mn oxyhydroxides, whereas Pb appeared to be regulated by the Fe oxyhydroxides. The results from sequential extractions did not allow to relate these groups to specific distributions in the solid phase.ConclusionsThe greater risk of water quality degradation for this reservoir would be posed by the remobilization of As, which showed the greatest and the most prolonged release during resuspension, because it could not be removed onto particles due to its speciation. Dissolved As reached a maximum of 30 μg L−1 at the conclusion of the experiments, a concentration above the drinking water standard but well below the acute toxicity levels reported in the literature for fishes.

The objective of this paper is to present a model simulating and predicting the exchange kinetics of lead (Pb) between contaminated sediments and water during resuspension events potentially occurring in reservoirs. We developed an innovative model that combines thermodynamic speciation of particulate surfaces (oxides and Particulate Organic Carbon (POC)), thermodynamic Pb speciation in water, and kinetic modelling of exchanges between free Pb and particulate sites (i.e., dissolution of a carbonate carrier phase, adsorption/coprecipitation and desorption/dissolution to/from oxides, and adsorption and desorption/degradation to/from particulate organic particles). We used results from laboratory resuspension experiments performed on sediments from three contaminated dam reservoirs to calibrate a new chemical speciation model. Uptake and release processes to/from sediments were found to be controlled by at least two successive reactions that are associated with two particulate pools (here oxides and POC). Kinetic adsorption and desorption rates were calibrated for seven experimental conditions. Variability in kinetic rates allowed evaluation of the effect of the solid-to-liquid ratio and sediment origin on exchange kinetics at the water-particle interface. The kinetic release of dissolved Pb by desorption or dissolution from the oxides was reproduced almost identically between the experiments, regardless of the solid-to-liquid ratio or sediment origin. Long-term readsorption on POC sites is more variable, even if ranges of variation in the adsorption and desorption kinetic rates related to POC remain limited, considering that tested sediments vary significantly. CAPSULE: A kinetic model simulating the dynamics of lead (Pb) during sediment resuspension was developed and calibrated to laboratory experiments performed on three contaminated sediments.

Industrial and urban emissions over several decades left a legacy of contamination by persistent organic pollutants in the sediments of Venice lagoon (Italy), which might still represent a hazard for the health of ecosystems and population. A new modelling tool for integrated exposure assessment, MERLIN-Expo, was applied to simulate integrated ecological and human exposure to PCBs and dioxins. MERLIN-Expo library provides a set of environmental fate models that can be easily combined to create several scenarios, and coupled to a human intake and a physiologically-based pharmaco-kinetic (PBPK) model to simulate human internal exposure. The Phytoplankton, Invertebrate and Fish models implemented in MERLIN-Expo library were combined to create an aquatic food web and to dynamically simulate bioaccumulation and biomagnification of dioxins and PCBs. Concentrations of PCB and dioxins in water, reconstructed from concentrations in dated sediment cores, were used as time-series inputs to run long term simulations. Estimated concentrations in edible aquatic species were used to estimate daily human intake through the consumption of local seafood. Finally, the application of the PBPK model allowed to explore the accumulation of 2,3,7,8-TCDD and PCB126 in human tissues for several decades. Simulated chemical concentrations in biota were evaluated against monitoring data for four aquatic species, finding an appreciable agreement, with some differences depending on the species and target chemicals. Estimated chemical concentrations in blood were compared to real human biomonitoring data measured in adult men. Despite several assumptions included in the assessment framework, simulated concentrations resulted close to measured data (the same order of magnitude or one order of difference). The results allowed performing a preliminary ecological and human health risk assessment for the selected chemicals by evaluating the exposure estimates against benchmark values available in literature. The study provided useful insights for supporting the verification of MERLIN-Expo in a real complex exposure scenario.

MERLIN-Expo merges and integrates advanced exposure assessment methodologies, allowing the building of complex scenarios involving several pollution sources and targets. The assessment of exposure and risks to human health from chemicals is of major concern for policy and ultimately benefits all citizens. The development and operational fusion of the advanced exposure assessment methodologies envisaged in the MERLIN-Expo tool will have a significant impact in the long term on several policies dealing with chemical safety management. There are more than 30 agencies in Europe related to exposure and risk evaluation of chemicals, which have an important role in implementing EU policies, having especially tasks of technical, scientific, operational and/or regulatory nature. The main purpose of the present paper is to introduce MERLIN-Expo and to highlight its potential for being effectively integrated within the group of tools available to assess the risk and exposure of chemicals for EU policy. The main results show that the tool is highly suitable for use in site-specific or local impact assessment, with minor modifications it can also be used for Plant Protection Products (PPPs), biocides and REACH, while major additions would be required for a comprehensive application in the field of consumer and worker exposure assessment.

Ecological Risk Assessment of chemicals in fluvial systems is a highly researched topic, but its importance for the environmental protection of our planet is vital. Thus, new developments and improvements to existing methodologies are proposed constantly, for providing more advanced tools and more accurate results to researchers and other interested parties. In the field of probabilistic Ecological Risk Assessment, a new Decision Support System is proposed, developed, tested and evaluated. The AMORE DSS is a modular DSS, which incorporates a series of new methodologies, and is built upon the notions of 'Exposure Assessment', 'Effect Assessment' and 'Risk Assessment'. The AMORE Decision Support System has been developed as part of the AMORE research project (French National Research Agency project). The DSS provides a set of tools for analysing and integrating both exposure and effect information in order to evaluate the risk for species living on a given contaminated aquatic system in terms of the Potentially Affected Fraction. The DSS has been tested through a case study on ERA of cyanide in the watershed of river Selune in France. The paper presents the 'Exposure Assessment' and 'Risk Assessment' of the cyanide case study, as well as the complete functionalities of the AMORE DSS. The main results presented in the paper are the statistical analysis of the measured environmental concentrations of cyanide (Exposure Assessment) and the probabilistic 'Risk assessment' of the same contaminant in the area of interest, based on the functionalities of the DSS. The results are described and discussed in detail with the use of various graphs and risk indices. The risk indices are calculated for all the available ecotoxicological data, as well as for the data on trophic levels or taxonomic groups separately. A risk comparison is presented between the innovative methodologies included in the DSS and the currently existing methodologies.

The assessment of bioaccumulation processes plays a significant role in the evaluation of chemical risks. The awareness of long-lasting and often irreversible effects of bioaccumulative chemicals on ecological and human targets encouraged the inclusion of bioaccumulation assessment in many national and international legislative frameworks. At the same time, various experimental and modelling approaches have been developed to estimate bioaccumulation metrics such as the bioaccumulation factor (BAF) or the biomagnification factor (BMF). In this chapter, the main processes governing bioaccumulation phenomena in selected aquatic organisms (phytoplankton, invertebrate and fish) and in terrestrial mammals are described, in particular those implemented in the corresponding models available in MERLIN-Expo tool for exposure assessment. The main objective is to describe the development of bioaccumulation models for organic and inorganic contaminants which takes into account recent progresses and which satisfactorily describes bioaccumulation of contaminants along food webs including phytoplankton, invertebrate and fish species for surface waters, and mammals for terrestrial systems, and also allowing dynamic and stochastic assessment according to MERLIN-Expo modelling features. The coupling of different aquatic biota models allows to recreate aquatic food web of different dimensions and complexity, while the coupling of terrestrial mammal model with plant models available in MERLIN-Expo permits to simulate the transfer of contaminants along simplified terrestrial food chains.

Human Health Risk Assessment (HHRA) and Environmental Risk Assessment (ERA) are well-established regulatory and scientific research fields that support regulatory decision-making in the European Union (EU) and are undergoing constant development. HHRA and ERA are crucial steps for reaching the objectives of Europe 2020, a strategy put forward by the Commission that sets out a vision of Europe’s social market economy for the twenty-first century. This chapter aims to describe the basic principles, the evolution and the future challenges of HHRA and ERA.

Atmosphere is an important component of the whole ecosystem because it directly interacts with all the other media, i.e. soil, surface waters, vegetation and biota. This chapter describes the processes that should be considered in models simulating the fate of chemicals in the atmosphere. The first section describes model approaches able to simulate the long-range transport of chemicals in the atmosphere. The second section describes the partition of chemicals between gaseous and particulate phases in the atmosphere. Two approaches, respectively, based on liquid vapour pressure and octanol-air partition coefficient are presented. The third section describes chemical reactions occurring in the atmosphere, driven by photolysis and reactions with photooxidants like the hydroxyl radical OH. The forth section describes dry deposition of both gaseous and particulate chemicals on the earth surface. Dry deposition is driven by aerodynamic, quasi-laminar sublayer and canopy resistances. The calculation of these latter is presented here in detail. The fifth section describes wet deposition of both gaseous and particulate chemicals on the earth surface, driven by rainout (in-cloud) and washout (below-cloud) scavenging.

A good knowledge and modelling of the fate of chemicals in surface waters is essential for achieving a holistic risk assessment approach. This chapter describes the processes that should be considered in models simulating the fate of chemicals in natural waters. The first section describes the exchange of chemicals between the dissolved and particulate phases in water and sediments, as well as the simulation of suspended particulate matter concentration. The second section describes mechanistic modelling of chemical exchange between the overlying water column and bottom sediments that results from deposition and/or resuspension of contaminated particles. The third section describes the diffusion of chemical at the interface between surface water and sediment porewater that is classically based on a two-film diffusion description. The fourth section describes absorption and volatilization of semi-volatile substances at the air-water interface that are generally modelled according to the stagnant boundary theory. The fifth section describes processes responsible for degradation (i.e. hydrolysis, photolysis, biodegradation) that are generally aggregated in a global loss rate.

Consumption of contaminated fruits, vegetables and/or cereals may be a significant exposure route for human exposure to chemicals. This chapter describes the processes that should be considered in models simulating the fate of chemicals in plants. The first section describes modelling approaches able to simulate the uptake of chemicals from soil to root and their subsequent transport through the xylem flow. This process is governed by the transpiration stream, driving the movement of dissolved chemicals in the continuum soil-root-stem-leaves/storage organs. Section 2 describes the transport of chemicals in the phloem system, which is responsible for distributing the products of photosynthesis from the leaves to the rest of the plant. Section 3 describes diffusion of chemicals from soil to tubers, which are botanically seen as a part of the stem. The transport of chemicals inside the tuber is driven by partition coefficients, water and gas contents, and diffusion coefficients in water/gas pores. Section 4 describes diffusive exchanges between leaves and air through both the stomata and cuticle pathways. Diffusion is driven by several permeabilities in series and/or in parallel within the leaf structure. Section 5 describes processes responsible for deposition and interception of chemicals on above-ground plant. Wet particle deposition is driven by rain events while dry deposition is driven by gravitational deposition of aerosols. Both the fractions of dry and wet deposits intercepted by leaf can be related to the interception fraction and the above-ground biomass (or leaf area index). Section 6 describes partition of chemicals between plant and plant water. Section 7 describes specific electrodiffusive processes for electrolytes. Such processes have to account for the distribution of the chemical among neutral and dissociated species and for electrical potential across the membrane. Section 8 describes data available for bioaccumulation of metals in plants.

The MERLIN-Expo tool was evaluated using a SWOT analysis, which was based on expert judgement and literature review. A list of criteria was set up containing the major model characteristics, which were divided in general model criteria and relevance model criteria. Relevance model criteria were defined as criteria, which are highly depending on the regulatory framework the model is used in. From the analysis presented above, it appeared that certain regulatory chemical frameworks (e.g. REACH, biocides) are stricter towards their requirements compared to others (e.g. site-specific/local regulatory frameworks). Based on expert judgement, the MERLIN-Expo tool was evaluated using the general and relevance criteria. MERLIN-Expo has many advanced functionalities (such as uncertainty analysis, modular approach, dynamic model, combines environmental fate with pharmacokinetics) and models (many fate processes and environmental compartments, different human populations). At the same time, the threat is that current (regulatory) applicability frameworks do not always require these advanced assessment functionalities. The MERLIN-Expo tool appeared to be most suitable for the site-specific assessment as this is the most flexible framework. Based on this analysis, weaknesses of the MERLIN-Expo tool for its use in a certain regulatory framework could also be identified. These weaknesses are at the same time further development opportunities for MERLIN-Expo. On general model characteristics, MERLIN-Expo was identified as a highly documented (both for novice and expert level), transparent, user-friendly tool with regular trainings. Its main treat now is to ensure continuing support and mechanisms for future developmental work and updates.

At the example of the MERLIN-Expo case study, important aspects of the documentation and of standardisation of chemical exposure models are discussed. A key challenge faced by developers of large or complex chemical exposure models is limited transparency leading to loss of confidence in the applicability of results of the model and other inefficiencies such as lacking interoperability. These inefficiencies can be addressed by standardisation which is explained as a process leading to improved common definitions, transparency and reliability in application. A review of available frameworks on the documentation of exposure models as well other complex models is conducted. The process of arriving at consensus on recommended documentation of exposure models via a workshop process is described, involving representatives from different stakeholders such as scientists, regulators, manufacturers or consultants. Key components of the documentation of chemical exposure models are presented, and a way to structure the communication of the information is proposed. The role of standardisation in supporting research and innovation projects is illustrated.

International audience; Radiation protection goals for ecological resources are focussed on ecological structures and functions at population-, community-, and ecosystem-levels. The current approach to radiation safety for non-human biota relies on organism-level endpoints, and as such is not aligned with the stated overarching protection goals of international agencies. Exposure to stressors can trigger non-linear changes in ecosystem structure and function that cannot be predicted from effects on individual organisms. From the ecological sciences, we know that important interactive dynamics related to such emergent properties determine the flows of goods and services in ecological systems that human societies rely upon. A previous Task Group of the IUR (International Union of Radioecology) has presented the rationale for adding an Ecosystem Approach to the suite of tools available to manage radiation safety. In this paper, we summarize the arguments for an Ecosystem Approach and identify next steps and challenges ahead pertaining to developing and implementing a practical Ecosystem Approach to complement organism-level endpoints currently used in radiation safety. © 2014 Elsevier Ltd.

The assessment of the potentially harmful effects of metals on biota depends on the speciation and bioavailability of the metals. In this study, we investigated copper accumulation and toxicity in the aquatic plant Myriophyllum aquaticum after exposure to artificial sediments varying in peat and/or ferric hydroxide content and spiked with Cu (5 to 200 mg.kg-1). Modeling of the kinetic DGT (diffusive gradient in thin film) measurements revealed fast and slow copper resupply from the solid phase for sediment formulated with and without peat, respectively. M. aquaticum proved to be sensitive to copper, as the copper accumulation and growth differed depending on the sediment composition and copper concentration. Comparing the copper accumulation in M. aquaticum to total dissolved, free and CDGT (concentration in solution derived from DGT measurements) copper concentrations revealed that CDGT concentrations were a better predictor of the accumulation than the others. However, the relatively weak correlation observed (r2=0.6) and the fact that plant uptake does not increase proportionally to fluxes to DGT suggest that copper uptake in plants was not diffusion limited. Thus, the free copper concentrations near the root surface were sufficient to meet the plant's demand during the experiment. Furthermore, labile complexes that continuously resupply the Cu2+ pool may also contribute to the Environmental Toxicology and Chemistry

The biotic ligand model (BLM) theoretically enables the derivation of environmental quality standards that are based on true bioavailable fractions of metals. Several physicochemical variables (especially pH, major cations, dissolved organic carbon, and dissolved metal concentrations) must, however, be assigned to run the BLM, but they are highly variable in time and space in natural systems. This article describes probabilistic approaches for integrating such variability during the derivation of risk indexes. To describe each variable using a probability density function (PDF), several methods were combined to 1) treat censored data (i.e., data below the limit of detection), 2) incorporate the uncertainty of the solid-to-liquid partitioning of metals, and 3) detect outliers. From a probabilistic perspective, 2 alternative approaches that are based on log-normal and Γ distributions were tested to estimate the probability of the predicted environmental concentration (PEC) exceeding the predicted non-effect concentration (PNEC), i.e., . The probabilistic approach was tested on 4 real-case studies based on Cu-related data collected from stations on the Loire and Moselle rivers. The approach described in this article is based on BLM tools that are freely available for end-users (i.e., the Bio-Met software) and on accessible statistical data treatments. This approach could be used by stakeholders who are involved in risk assessments of metals for improving site-specific studies. Integr Environ Assess Manag 2013;9:508–516. © 2013 SETAC

MERLIN-Expo is a library of models that was developed in the frame of the FP7 EU project 4FUN in order to provide an integrated assessment tool for state-of-the-art exposure assessment for environment, biota and humans, allowing the detection of scientific uncertainties at each step of the exposure process. This paper describes the main features of the MERLIN-Expo tool. The main challenges in exposure modelling that MERLIN-Expo has tackled are: (i) the integration of multimedia (MM) models simulating the fate of chemicals in environmental media, and of physiologically based pharmacokinetic (PBPK) models simulating the fate of chemicals in human body. MERLIN-Expo thus allows the determination of internal effective chemical concentrations; (ii) the incorporation of a set of functionalities for uncertainty/sensitivity analysis, from screening to variance-based approaches. The availability of such tools for uncertainty and sensitivity analysis aimed to facilitate the incorporation of such issues in future decision making; (iii) the integration of human and wildlife biota targets with common fate modelling in the environment. MERLIN-Expo is composed of a library of fate models dedicated to non biological receptor media (surface waters, soils, outdoor air), biological media of concern for humans (several cultivated crops, mammals, milk, fish), as well as wildlife biota (primary producers in rivers, invertebrates, fish) and humans. These models can be linked together to create flexible scenarios relevant for both human and wildlife biota exposure. Standardized documentation for each model and training material were prepared to support an accurate use of the tool by end-users. One of the objectives of the 4FUN project was also to increase the confidence in the applicability of the MERLIN-Expo tool through targeted realistic case studies. In particular, we aimed at demonstrating the feasibility of building complex realistic exposure scenarios and the accuracy of the modelling predictions through a comparison with actual measurements.

This paper reports on a case study - conducted within the European FP7 project "4FUN" - focusing on exposure of pre-school children to lead resulting from past emissions by non-ferrous smelters in Belgium (Northern Campine area). Exposure scenarios were constructed and simulated with the MERLIN-Expo tool to estimate external Pb exposure as well as the Pb body burden in children living in the vicinity of the former industrial sites as compared to children living in adjacent areas and a reference area. Simulations were run for several scenarios ranging from very simple to rather complex in order to study the effect of different simulation approaches (e.g., deterministic vs. probabilistic, individual vs. aggregated population exposure) and different exposure scenarios (e.g., with vs. without considering local food consumption or time activity patterns) on the model outcomes (predicted concentrations of Pb in environmental and human matrices). This paper discusses the two most complex scenarios, namely exposure at the aggregated population level and at the individual level for a random sub-sample of subjects, respectively. In the final and most realistic exposure scenario, simulating individual lead exposure, model predictions were shown to be higher than the biomonitoring data. Blood Pb levels in children, irrespective of the area they lived in, were overpredicted by MERLIN-Expo with a factor of about 2 on average. The model predictions for individual children overlap with the prediction interval calculated by MERLIN-Expo based on population averages, demonstrating the use of probabilistic approaches in risk assessment. While these results constitute a first verification of the model performance of MERLIN-Expo dealing with inorganic pollutants in a complex real-world exposure scenario and a demonstration of the robustness of the modelling tool, further validation and benchmarking efforts are required for a larger number of inorganic pollutants and different exposure settings.

In this study, we report on model simulations performed using the newly developed exposure tool, MERLIN-Expo, in order to assess inorganic arsenic (iAs) exposure to adults resulting from past emissions by non-ferrous smelters in Belgium (Northern Campine area). Exposure scenarios were constructed to estimate external iAs exposure as well as the toxicologically relevant As (tAs, i.e., iAs, MMA and DMA) body burden in adults living in the vicinity of the former industrial sites as compared to adults living in adjacent areas and a reference area. Two scenarios are discussed: a first scenario studying exposure to iAs at the aggregated population level and a second scenario studying exposure at the individual level for a random sub-sample of subjects in each of the three different study areas. These two scenarios only differ in the type of human related input data (i.e., time-activity data, ingestion rates and consumption patterns) that were used, namely averages (incl. probability density functions, PDFs) in the simulation at population level and subject-specific values in the simulation at individual level. The model predictions are shown to be lower than the corresponding biomonitoring data from the monitoring campaign. Urinary tAs levels in adults, irrespective of the area they lived in, were under-predicted by MERLIN-Expo by 40% on average. The model predictions for individual adults, by contrast, under-predict the biomonitoring data by 7% on average, but with more important under-predictions for subjects at the upper end of exposure. Still, average predicted urinary tAs levels from the simulations at population level and at individual level overlap, and, at least for the current case, lead to similar conclusions. These results constitute a first and partial verification of the model performance of MERLIN-Expo when dealing with iAs in a complex site-specific exposure scenario, and demonstrate the robustness of the modelling tool for these situations.

International audience; An important step in building a computational model is its documentation; a comprehensive and structured documentation can improve the model applicability and transparency in science/research and for regulatory purposes. This is particularly crucial and challenging for environmental and/or human exposure models that aim to establish quantitative relationships between personal exposure levels and their determinants. Exposure models simulate the transport and fate of a contaminant from the source to the receptor and may involve a large set of entities (e.g. all the media the contaminants may pass though). Such complex models are difficult to be described in a comprehensive, unambiguous and accessible way. Bad communication of assumptions, theory, structure and/or parameterization can lead to lack of confidence by the user and it may be source of errors. The goal of this paper is to propose a standard documentation protocol (SDP) for exposure models, i.e. a generic format and a standard structure by which all exposure models could be documented. For this purpose, a CEN (European Committee for Standardisation) workshop was set up with objective to agree on minimum requirements for the amount and type of information to be provided on exposure models documentation along with guidelines for the structure and presentation of the information. The resulting CEN workshop agreement (CWA) was expected to facilitate a more rigorous formulation of exposure models description and the understanding by users. This paper intends to describe the process followed for defining the SDP, the standardisation approach, as well as the main components of the SDP resulting from a wide consultation of interested stakeholders. The main outcome is a CEN CWA which establishes terms and definitions for exposure models and their elements, specifies minimum requirements for the amount and type of information to be documented, and proposes a structure for communicating the documentation to different users. © 2016 Elsevier B.V.

The study is focused on applying uncertainty and sensitivity analysis to support the application and evaluation of large exposure models where a significant number of parameters and complex exposure scenarios might be involved. The recently developed MERLIN-Expo exposure modelling tool was applied to probabilistically assess the ecological and human exposure to PCB 126 and 2,3,7,8-TCDD in the Venice lagoon (Italy). The 'Phytoplankton', 'Aquatic Invertebrate', 'Fish', 'Human intake' and PBPK models available in MERLIN-Expo library were integrated to create a specific food web to dynamically simulate bioaccumulation in various aquatic species and in the human body over individual lifetimes from 1932 until 1998. MERLIN-Expo is a high tier exposure modelling tool allowing propagation of uncertainty on the model predictions through Monte Carlo simulation. Uncertainty in model output can be further apportioned between parameters by applying built-in sensitivity analysis tools. In this study, uncertainty has been extensively addressed in the distribution functions to describe the data input and the effect on model results by applying sensitivity analysis techniques (screening Morris method, regression analysis, and variance-based method EFAST). In the exposure scenario developed for the Lagoon of Venice, the concentrations of 2,3,7,8-TCDD and PCB 126 in human blood turned out to be mainly influenced by a combination of parameters (half-lives of the chemicals, body weight variability, lipid fraction, food assimilation efficiency), physiological processes (uptake/elimination rates), environmental exposure concentrations (sediment, water, food) and eating behaviours (amount of food eaten). In conclusion, this case study demonstrated feasibility of MERLIN-Expo to be successfully employed in integrated, high tier exposure assessment.

International audience; In the present study, we demonstrate an integrated modeling approach for predicting internal tissue concentrations of chemicals by coupling a multimedia environmental model and a generic physiologically based pharmacokinetic (PBPK) model. A case study was designed for a region situated on the Seine river watershed, downstream of the Paris megacity, and for benzo(a)pyrene emitted from industrial zones in the region. In this case study, these two models are linked only by water intake from riverine system for the multimedia model into human body for the PBPK model. The limited monitoring data sets of B(a)P concentrations in bottom sediment and in raw river water, obtained at the downstream of Paris, were used to re-construct long-term daily concentrations of B(a)P in river water. The re-construction of long-term series of B(a)P level played a key role for the intermediate model calibration (conducted in multimedia model) and thus for improving model input to PBPK model. In order to take into account the parametric uncertainty in the model inputs, some input parameters relevant for the multimedia model were given by probability density functions (PDFs); some generic PDFs were updated with site-specific measurements by a Bayesian approach. The results of this study showed that the multimedia model fits well with actual annual measurements in sediments over one decade. No accumulation of B(a)P in the organs was observed. In conclusion, this case study demonstrated the feasibility of a full-chain assessment combining multimedia environmental predictions and PBPK modeling, including uncertainty and sensitivity analyses.

In the framework of environmental multimedia modeling studies dedicated to environmental and health risk assessments of chemicals, the bioconcentration factor (BCF) is a parameter commonly used, especially for fish. As for neutral lipophilic substances, it is assumed that BCF is independent of exposure levels of the substances. However, for metals some studies found the inverse relationship between BCF values and aquatic exposure concentrations for various aquatic species and metals, and also high variability in BCF data. To deal with the factors determining BCF for metals, we conducted regression analyses to evaluate the inverse relationships and introduce the concept of probability density function (PDF) for Cd, Cu, Zn, Pb, and As. In the present study, for building the regression model and derive the PDF of fish BCF, two statistical approaches are applied: ordinary regression analysis to estimate a regression model that does not consider the variation in data across different fish family groups; and hierarchical Bayesian regression analysis to estimate fish group-specific regression models. The results show that the BCF ranges and PDFs estimated for metals by both statistical approaches have less uncertainty than the variation of collected BCF data (the uncertainty is reduced by 9%–61%), and thus such PDFs proved to be useful to obtain accurate model predictions for environmental and health risk assessment concerning metals. Environ. Toxicol. Chem. 2010;29:2417–2425. © 2010 SETAC

Two advanced models that respectively simulate the transport of heavy metals in the atmosphere at continental and regional scale, as well as the transfer of contaminants in the air–soil–plant system, were used to study the potential accumulation of lead and cadmium in vegetables in a French region submitted to global and local industrial releases. The dynamics of lead and cadmium in the atmosphere, the soil and two types of plants (leaf and fruit vegetables respectively) were simulated over 40 years. Kinetic best estimate calculations were conducted to simulate the potential accumulation of lead and cadmium in soils and plants. An uncertainty analysis was also performed to provide confidence intervals for the maximum contamination levels of leaf and fruit vegetables. A sensitivity analysis allowed to identify the most sensitive parameters of the modeling system. For this purpose, Probability Density Functions were proposed for the main parameters included in the air-soil-plant model. Different results were obtained for lead and cadmium respectively, lead being more sensitive to aerial processes (interception of deposits by leaves eventually followed by translocation to edible organs).

Integrated Risk Assessment (IRA) has been defined by the EU FP7 HEROIC Coordination action as “the mutual exploitation of Environmental Risk Assessment for Human Health Risk Assessment and vice versa in order to coherently and more efficiently characterize an overall risk to humans and the environment for better informing the risk analysis process” (Wilks et al., 2015). Since exposure assessment and hazard characterization are the pillars of risk assessment, integrating Environmental Exposure assessment (EEA) and Human Exposure assessment (HEA) is a major component of an IRA framework. EEA and HEA typically pursue different targets, protection goals and timeframe. However, human and wildlife species also share the same environment and they similarly inhale air and ingest water and food through often similar overlapping pathways of exposure. Fate models used in EEA and HEA to predict the chemicals distribution among physical and biological media are essentially based on common properties of chemicals, and internal concentration estimations are largely based on inter-species (i.e. biota-to-human) extrapolations. Also, both EEA and HEA are challenged by increasing scientific complexity and resources constraints. Altogether, these points create the need for a better exploitation of all currently existing data, experimental approaches and modeling tools and it is assumed that a more integrated approach of both EEA and HEA may be part of the solution. Based on the outcome of an Expert Workshop on Extrapolations in Integrated Exposure Assessment organized by the HEROIC project in January 2014, this paper identifies perspectives and recommendations to better harmonize and extrapolate exposure assessment data, models and methods between Human Health and Environmental Risk Assessments to support the further development and promotion of the concept of IRA. Ultimately, these recommendations may feed into guidance showing when and how to apply IRA in the regulatory decision-making process for chemicals.

Ecotoxicological data are highly important for risk assessment processes and are used for deriving environmental quality criteria, which are enacted for assuring the good quality of waters, soils or sediments and achieving desirable environmental quality objectives. Therefore, it is of significant importance the evaluation of the reliability of available data for analysing their possible use in the aforementioned processes. The thorough analysis of currently available frameworks for the assessment of ecotoxicological data has led to the identification of significant flaws but at the same time various opportunities for improvement. In this context, a new methodology, based on Multi-Criteria Decision Analysis (MCDA) techniques, has been developed with the aim of analysing the reliability and relevance of ecotoxicological data (which are produced through laboratory biotests for individual effects), in a transparent quantitative way, through the use of expert knowledge, multiple criteria and fuzzy logic. The proposed methodology can be used for the production of weighted Species Sensitivity Weighted Distributions (SSWD), as a component of the ecological risk assessment of chemicals in aquatic systems. The MCDA aggregation methodology is described in detail and demonstrated through examples in the article and the hierarchically structured framework that is used for the evaluation and classification of ecotoxicological data is shortly discussed. The methodology is demonstrated for the aquatic compartment but it can be easily tailored to other environmental compartments (soil, air, sediments).

The influence of two types of colloids (natural organic matter, NOM), a colloid with high affinity for radionuclides (RN(s)), and hydrophilic synthetic latex (SHL), a colloid with low affinity for RN(s) on the transfer of 60Co and 85Sr in a silica sand column was studied under different physicochemical conditions : pH (4.9), ionic strength (10-3 M and 10-2 M), concentration of colloids (100 mg l-1, 10 mg l-1), flow velocity (12.4 cm h-1 and 3.7 cm h-1), water saturation of the column (100% and 70%). In the absence of colloids, the transfer of 60Co and 85Sr was retarded compared to the transfer of the conservative tracer. In the presence of colloids and according to the specific physicochemical conditions, an acceleration or retardation of 60Co and 85Sr transfer was observed compared to their transfer in the absence of colloids. Our results evidenced that any colloids even with low reactivity could significantly modify the RN transfer. However, the extent to which the transfer was influenced differs according to the colloid type; the NOM exhibiting higher impact than SHL. Batch experiments helped in interpreting of the interactions between the colloids, RN(s) and solid phase observed in column. © 2006 Elsevier Ltd. All rights reserved.

The desorption kinetic of trace elements (Cd, Zn, Co, Mn, Fe, Ag, and Cs) associated with Loire river natural suspended particulate matter (SPM; 0.4–63 Am) was followed up on times varying from 0.5 h to 30 days, from SPM previously contaminated during 1 h, 24 h and 30 days. Long term sorption kinetics indicated that the difference between sorption occurring during the period 0–30 days (time investigated in this study) and the period 0–48 h (time often used for sorption experiments) ranges from few to 25% according to the element. Desorption kinetics show that, whatever the age of the complex formed during the sorption step, the release tends to equilibrium between complexed and dissolved elements equivalent to the equilibrium obtained for sorption after a given time. However, the time to get this equilibrium depends on the aging of the complex and on the element. All the above features indicate different types of complexes formation and strength of the binding according to the age of the complex and according to the element. Using a multi-compartmental model, simulating the transfer of metals between water and different types of particulate sites, the relationships between the parameters describing slow and rapid processes helped in explaining the bagingQ effect observed. D 2005 Elsevier B.V. All rights reserved.

Carbon-14 is a particularly interesting radionuclide from the perspective of dose estimation. Many nuclear facilities, including power reactors, release 14 C into the environment, and much of this is as 14 CO 2 . This mixes readily with stable CO 2 , and hence enters the food chain as fundamental biomolecules. This isotopic mixing is often used as the basis for dose assessment models. The present model was developed for the situation of 14 C releases to surface waters, where there are distinct changes in the water 14 C activity concentrations throughout the year. Complete isotopic mixing (equilibrium) cannot be assumed. The model computes the specific activity (activity of 14 C per mass of total C) in water, phytoplankton, fish, crops, meat, milk and air, following a typical irrigation-based food-chain scenario. For most of the biotic compartments, the specific activity is a function of the specific activity in the previous time step, the specific activity of the substrate media, and the C turnover rate in the tissue. The turnover rate is taken to include biochemical turnover, growth dilution and mortality, recognizing that it is turnover of C in the population, not a tissue or an individual, that is relevant. Attention is paid to the incorporation of 14 C into the surface water biota and the loss of any remaining 14 CO 2 from the surface water–air interface under its own activity concentration gradient. For certain pathways, variants in the conceptual model are presented, in order to fully discuss the possibilities. As an example, a new model of the soil-to-plant specific activity relationship is proposed, where the degassing of both 14 C and stable C from the soil is considered. Selection of parameter values to represent the turnover rates as modeled is important, and is dealt with in a companion paper.

Seeking to make greater use of available data for risk assessment of substances, we constructed, for the situation in which chronic data are limited or even nonexistent but acute data are relatively large, an acute to chronic transformation (ACT) methodology based on the concept of species sensitivity distributions (SSDs). This ACT methodology uses a comparison of acute and chronic SSDs, separately for vertebrate data (with 22 substances) and for invertebrate data (with 15 substances). Rather than comparing an acute toxicity value with a chronic value, as when calculating an acute to chronic ratio (ACR), samples of acute and chronic data corresponding to the same category of species were compared. Starting from a sample of acute data, the ACT methodology showed relationships that enable the creation of a sample of predicted chronic values. This sample can then be used to calculate a predicted chronic hazardous concentration potentially affecting 5% of species (HC5%), just as with a sample of real chronic toxicity values. This ACT approach was tested on I I substances. For each substance, the real chronic HC5% and the predicted chronic HC5% were calculated and compared. The ratio between chronic HC5% and ACT HC5% was, on average, 1.6 and did not exceed 4.4 for the I I substances studied.

To simulate the behavior of radionuclides along a salinity gradient, in vitro sorption and desorption kinetics of Co, Mn, Cs, Fe, Ag, Zn and Cd were studied in Loire river water and the macrotidal Loire estuarine water over two different seasons. Partitioning between the dissolved phase and suspended solids were followed up over 100 h after adding radioactive tracers to freshly collected freshwater (sorption stage); this stage was followed by desorption in fresh and estuarine waters. A kinetic model describing the interactions between trace metals and particles under a salinity gradient was developed and calibrated. Among parameters and/or processes that control the fate and behavior of contaminated particles during their transfer in estuarine systems, this study shows that the speciation of trace metals is controlled by: (i) the chemical water composition: for all the elements except for Fe, desorption increased with salinity; however, the amplitude of such an effect strongly depended on the element and/or on the composition of the particulate phase (and consequently on the season); (ii) the possibility for a given element to form (or not) stable surface particle moieties such as oxides or inner-sphere complexes; (iii) the distribution of a given element among different types of sites characterised by different binding forces that can lead (or not) to re-adsorption processes after mixing of contaminated particles with uncontaminated water. Our model enabled the quantification of the contribution and the characteristic time of reactions that took place over short and long periods on the global partitioning between particulate and dissolved phases during sorption and desorption and to determine the extent to which these reactions were modified by the salinity.

Low level radioactive liquid discharges have been carried out in the Loire river since 1963. Since then, the number of power plants located on the Loire river and its tributaries has been steadily increasing to reach, in the year 2000, 14 reactors operating on 5 different sites. The question arose to evaluate to what extent the addition of several nuclear power plants on the same river system could increase the concentrations in radionuclides in the environment and affect the dose to the public. To address this issue, EDF initiated in 1998 the “Loire river and estuary radioecology” program with the focus on assessing possible accumulation of radionuclide in river bottom sediments or on river shores. The following radionuclides were considered because of their importance in power plant liquid discharges: tritium, 14 C, 58 Co, 60 Co, Ag, 134 Cs, 137 Cs, 54 Mn, 124 Sb, and 131 I. Radionuclide concentrations in the dissolved, particulate and sedimentary forms were evaluated using the CRESCENDO model. The development and validation of this model required a multi-step process. The first step was to design a 350-km long 1D hydraulic and water transport based on currently available tools and data. Next, daily tritium concentrations measured in Angers, at the downstream limit of the river, were compared with computed values. The following step was to calibrate the sediment transport model. Areas where fine particles settled (dams and river shores) were monitored to improve our understanding of sediment dynamics. Then equations representing radionuclide exchange between water and particles were derived from laboratory experiments and included in the model. After each step the computed values were compared to measure data sets to ensure the model adequately described the processes involved. In the final step, the CALVADOS model was used to calculate dose to the public at different locations along the Loire river.

Anthropogenic radionuclide inputs in the Loire estuary (French Atlantic coast) consist of radioactive releases from 14 nuclear reactors located along the Loire river basin, and of fallout from nuclear weapon tests and from the Tchernobyl accident. To estimate to what extent radionuclides associated with sediment accumulate in the estuary, three complementary approaches were used: field surveys, laboratory experiments and numerical modelling. Sampling of bottom sediments, water and suspended solids was carried out at 8 different dates over a 15 month-period . Analysis covered I4 C, 90 Sr ,3H, the naturally occurring gamma-emitters (uranium and thorium decay chains, 7 Be and 40 K), and the artificial gamma emitters (mainly cobalt and cesium isotopes). To gain information on the contamination history of the estuary, sediment cores were also collected at different locations inside and outside the estuarine zone. Processes of radionuclide transport and exchange between dissolved and particulate phases were included in a previously developed estuary specific 2D-hydrodynamic model. Equations of sorption and desorption kinetics were derived from laboratory experiments conducted at different salinities. Simulations carried out for two river discharge conditions (low summer flow, high winter flow) allowed to follow radionuclide desorption in the estuary. For long term simulations, a simplified model was developed. It provided estimates of the amount of radionuclides expelled out of the estuary under dissolved and particulate forms, of the transit time for both forms and of the variations in radionuclides concentrations in the fluid mud. Based on computed results and observations, contributions from different origins (natural, military, industrial, marine, continental) to the inventory of radioactivity in the estuary are presented.

Semi-volatile organic compounds (SVOCs) are subject to Long-Range Atmospheric Transport because of transport–deposition–reemission successive processes. Several experimental data available in the literature suggest that soil is a non-negligible contributor of SVOCs to atmosphere. Then coupling soil and atmosphere in integrated coupled models and simulating reemission processes can be essential for estimating atmospheric concentration of several pollutants. However, the sources of uncertainty and variability are multiple (soil properties, meteorological conditions, chemical-specific parameters) and can significantly influence the determination of reemissions. In order to identify the key parameters in reemission modeling and their effect on global modeling uncertainty, we conducted a sensitivity analysis targeted on the ‘reemission’ output variable. Different parameters were tested, including soil properties, partition coefficients and meteorological conditions. We performed EFAST sensitivity analysis for four chemicals (benzo-a-pyrene, hexachlorobenzene, PCB-28 and lindane) and different spatial scenari (regional and continental scales). Partition coefficients between air, solid and water phases are influent, depending on the precision of data and global behavior of the chemical. Reemissions showed a lower variability to soil parameters (soil organic matter and water contents at field capacity and wilting point). A mapping of these parameters at a regional scale is sufficient to correctly estimate reemissions when compared to other sources of uncertainty.

Using tagged river suspended matter with trace elements (Mn, Fe, Co, Zn, Ag, Cd, and Cs), the kinetic binding of these elements onto particles as well as the kinetics of the speciation within the filterable phase (

[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA; International audience; The present report is the companion study of our previous study in which we investigated the impact of the dissolved organic matter, water cationic composition and pH on the bioavailability and the bioaccumulation of copper (Cu) in aquatic mosses (Fontinalis antipyretica). The impact had been assessed under laboratory controlled conditions and modelled using a two-compartment model calibrated under a wide range of water compositions (Ferreira et al., 2008, 2009). Herein are reported the validation stage of the abovementioned approach for contrasted geochemical field conditions. Experiments were performed with aquatic mosses that were exposed for 7 d to two nominal Cu concentrations (5 and 15 mu g L-1) in a flow-through field microcosm supplied with four contrasting natural waters. At the end of the exposure period, a 6-fold difference in the bioaccumulated Cu contamination levels was found among the four deployment sites, suggesting a significant control of the water quality on the metal bioaccumulation by aquatic mosses. In parallel, the so-called `labile' Cu concentration for the same four field conditions was determined using a DGT device (Diffusive Gradient in Thin film). By coupling these DGT measurements and a cation competition model involving Ca2+, Mg2+, Na+ and H+, the time-dependent Cu concentrations in aquatic mosses were predicted; these simulation results were compared to the actual bioaccumulation of Cu in mosses. We found that any bioaccumulation model that ignores water characteristics is not suitable to predict the Cu accumulation by aquatic mosses under various water quality conditions. Instead, we found that our approach integrating DGT measurements and cationic composition was able to reproduce the Cu bioaccumulation kinetics by aquatic mosses for a wide range of water quality conditions. In conclusion, the DGT approach was demonstrated to be a dynamic in situ measuring technique that can be used as a surrogate of bioindicators if the cationic correction is taken into account. (C) 2012 Elsevier Ltd. All rights reserved.

The assessment of the potentially harmful effects of metals on biota depends on the speciation and bioavailability of the metals. In the present study, the authors investigated Cu accumulation and toxicity in the aquatic plant Myriophyllum aquaticum after exposure to artificial sediments varying in peat or ferric hydroxide content and spiked with Cu (5-200 mg kg(-1)). Modeling of the kinetic diffusive gradient in thin film (DGT) measurements revealed fast and slow Cu resupply from the solid phase for sediment formulated with and without peat, respectively. Myriophyllum aquaticum proved to be sensitive to Cu, as the Cu accumulation and growth differed depending on the sediment composition and Cu concentration. Comparing the Cu accumulation in M. aquaticum with total dissolved concentration, free concentration, and concentration in solution derived from DGT measurements (CDGT), Cu concentrations revealed that CDGT concentrations were a better predictor of accumulation than the others. However, the relatively weak correlation observed (r(2) = 0.6) and the fact that plant uptake does not increase proportionally to DGT fluxes suggest that Cu uptake in plants was not diffusion limited. Thus, the free Cu concentrations near the root surface were sufficient to meet the plant's demand during the experiment. Furthermore, labile complexes that continuously resupply the Cu(2+) pool may also contribute to the concentrations available for plant uptake. In the range of Cu concentrations investigated in the present study, saturation of uptake processes as well as toxicity are considered responsible for the poor DGT prediction of plant uptake.

International audience; For more than a decade, the integration of human and environmental risk assessment (RA) has become an attractive vision. At the same time, existing European regulations of chemical substances such as REACH (EC Regulation No. 1907/2006), the Plant Protection Products Regulation (EC regulation 1107/2009) and Biocide Regulation (EC Regulation 528/2012) continue to ask for sector-specific RAs, each of which have their individual information requirements regarding exposure and hazard data, and also use different methodologies for the ultimate risk quantification. In response to this difference between the vision for integration and the current scientific and regulatory practice, the present paper outlines five medium-term opportunities for integrating human and environmental RA, followed by detailed discussions of the associated major components and their state of the art. Current hazard assessment approaches are analyzed in terms of data availability and quality, and covering non-test tools, the integrated testing strategy (ITS) approach, the adverse outcome pathway (AOP) concept, methods for assessing uncertainty, and the issue of explicitly treating mixture toxicity. With respect to exposure, opportunities for integrating exposure assessment are discussed, taking into account the uncertainty, standardization and validation of exposure modeling as well as the availability of exposure data. A further focus is on ways to complement RA by a socio-economic assessment (SEA) in order to better inform about risk management options. In this way, the present analysis, developed as part of the EU FP7 project HEROIC, may contribute to paving the way for integrating, where useful and possible, human and environmental RA in a manner suitable for its coupling with SEA.

International audience; Biological and chemical measurements were performed in mesocosms to investigate the bioavailability of cop-per, with a greater emphasis on the effects of competing ions and copper speciation. Measurements were achieved in three different natural waters for two aquatic species (Gammarus pulex and Fontinalis antipyretica) along a copper gradient concentration: natural concentration, spiked at 5 and 15 μg L −1 . Aquatic mosses exhibited high enrichment rates that were above the background levels compared to gammarids. The accumu-lation of copper in F. antipyretica is better correlated to the weakly complexed copper concentrations measured using differential pulse anodic stripping voltammetry (DPASV) and diffusive gradient in thin film (DGT) than to the free copper concentration measured using an ion selective electrode (ISE). In unspiked natural waters, the presence of dissolved organic ligands strongly controls the metal speciation and consequently largely minimised the impact of competing cations on the accumulation of Cu in mosses. Furthermore, the BioMet Biotic Ligand Model (BLM) successfully describes the site-specific copper bioaccumulation for the freshwater mosses studied. However, the comparison of the results with a previous study appears to indicate that the adsorption/desorption of Cu in mosses is impacted by seasons. This highlights a limit of the BioMet model in which the physiological state of aquatic organisms is not considered. No toxic effect of Cu exposure on lipid peroxidation was observed in the mosses and gammarids regardless of the site and the concentration considered. However, the oxidative stress measured in the mosses via their guaiacol peroxidase (GPX) activity increased in the case where internalised Cu reached maximal values, which suggests a threshold effect on the GPX activity.

The species sensitivity distribution (SSD) approach is recommended for assessing chemical risk. In practice, however, it can be used only for the few substances for which large-scale ecotoxicological results are available. Indeed, the statistical frequentist approaches used for building SSDs and for deriving hazardous concentrations (HC5) inherently require extensive data to guarantee goodness-of-fit. An alternative Bayesian approach to estimating HC5 from small data sets was developed. In contrast to the noninformative Bayesian approaches that have been tested to date, the authors' method used informative priors related to the expected species sensitivity variance. This method was tested on actual ecotoxicological data for 21 well-informed substances. A cross-validation compared the HC5 values calculated using frequentist approaches with the results of our Bayesian approach, using both complete and truncated data samples. The authors' informative Bayesian approach was compared with noninformative Bayesian methods published in the past, including those incorporating loss functions. The authors found that even for the truncated sample the HC5 values derived from the informative Bayesian approach were generally close to those obtained using the frequentist approach, which requires more data. In addition, the probability of overestimating an HC5 is rather limited. More robust HC5 estimates can be practically obtained from additional data without impairing regulatory protection levels, which will encourage collecting new ecotoxicological data. In conclusion, the Bayesian informative approach was shown to be relatively robust and could be a good surrogate approach for deriving HC5 values from small data sets. Environ. Toxicol. Chem. 2013;32:602–611. © 2012 SETAC

International audience; Polychlorinated biphenyls (PCBs) are persistent contaminants suspected to cause adverse health effects in humans. As PCBs levels in food have not been monitored frequently in the past, modeling approaches based on environmental data have been proposed to predict the human dietary intake. In this work, we propose to improve these approaches by taking into account internal levels of PCBs in humans. This methodology is based on the analysis of biomonitoring data using exposure and physiologically based pharmacokinetic (PBPK) modeling to determine the most probable scenario of exposure. Breast milk concentrations were measured in Italian women for PCB-138, PCB-153 and PCB-180. For each congener, three exposure scenarios were derived and a PBPK model was used to relate the lifetime exposure to the breast milk levels. For the three PCBs, we determined the most probable scenario of exposure. Our results support the adequacy of the exposure and the PBPK models for PCB-180 and PCB-153, whereas we observed discrepancies between the models and the biomonitoring data for PCB-138. Our intake estimates are in good agreement with previous exposure assessments based solely on food contamination demonstrating the relevance of our approach to reconstruct accurately the exposure and to fill in data gaps on exposure.

Background and aims: Human exposure to chemicals through multiple pathways is classically estimated by the so-called ‘multimedia models’, calculating the distribution of contaminants among products...

International audience; Extensive research has been performed on the use of the DIPS (DGT-Induced Fluxes in Soils and Sediments) model to interpret diffusive gradients in thin-film, or DGT, measurements in soils and sediments. The current report identifies some areas where the DIFS model has been shown to yield poor results and proposes a model to address weaknesses. In particular, two major flaws in the current approaches are considered: (i) many studies of accumulation kinetics in DGT exhibit multiple kinetic stages and (ii) several combinations of the two fitted DIFS parameters can yield identical results, leaving the question of how to select the `best' combination. Previously, problem (i) has been addressed by separating the experimental data sets into distinct time segments. To overcome these problems, a model considering two types of particulate binding sites is proposed, instead of the DIES model which assumed one single particulate pool. A probabilistic approach is proposed to fit experimental data and to determine the range of possible physical parameters using Probability Distribution Functions (PDFs), as opposed to single values without any indication of their uncertainty. The new probabilistic model, called DGT-PROFS, was tested on three different formulated sediments which mainly differ in the presence or absence of iron oxides. It was shown that a good fit can be obtained for the complete set of data (instead of DIFS-2D) and that a range of uncertainty values for each modeling parameter can be obtained. The interpretation of parameter PDFs allows one to distinguish between a variety of geochemical behaviors, providing useful information on metal dynamics in sediments.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA; International audience; The diffusive gradients technique in thin films (DGT) was used to investigate the kinetic resupply of Cd and Cu to pore water from the solid phase. For the sake of simplification, experiments were performed using formulated sediments that differed in the presence or absence of humic acids (HA) and/or of iron hydroxides (i.e., goethite and ferrihydrite). The effects of the time after the contamination of the solid phase (aging effect) on formulated sediments that were coated with goethite and HA and spiked with Cd were also evaluated. Kinetic DGT results were interpreted using the newly developed, multi-compartmental model DGT-PROFS. Due to Cu humate formation, the addition of HA slightly increased the Cu concentration in the pore water independent of the effect of the iron hydroxide coating on the formulated sediments and slightly decreased that of Cd. The impact of 8-190d of aging resulted in a significant decrease in the Cd concentration of the pore water over an increasing incubation time. Modeling our results with DGT-PROFS led to the following conclusions concerning the impact of HA and iron hydroxides on Cd and Cu availability. First, in the presence of HA and absence of iron hydroxides, Cd is associated mainly with weak sites, while Cu is bound to strong sites. Similarly, in the presence of both iron hydroxides and HA, Cu appeared to be more heavily associated with the strong sites than did Cd. When the incubation time increased from 8 to 190d, a proportion of Cd initially adsorbed onto weak sites transferred to the strong sites, suggesting that the adsorption of Cd on sediments is controlled partially by slow kinetic processes.