LES ESCARGOTS BIO-INDICATEURS DE LA QUALITE DES SOLS - Snail watch : analyse en laboratoire ou in situ de la biodisponibilité des contaminants

http://www2.ademe.fr/servlet/KBaseShow?sort=-1&cid=96&m=3&catid=10143fiche outil 4 pagesCe document est une fiche outil présentant les possibilités d'utilisation des escargots pou analyse en laboratoire ou in situ de la biodisponibilité des contaminants. Cette fiche a été mise en ligne sur le site de l'ADEME/ sites pollués et sols/ outils méthodologiques: http://www2.ademe.fr/servlet/KBaseShow?sort=-1&cid=96&m=3&catid=1014

Chemical extractions and predicted free ion activities fail to estimate metal transfer from soil to field land snails.

International audienceThis study investigates the relevance of several soil chemical extractions (calcium chloride, acetic acid, citric acid and a four-step sequential procedure) and predicted free metal ion activities in the soil solution to characterise the transfer of trace metals (Cd, Pb, and Zn) from soil to snail soft tissues over a large smelter-impacted area (Metaleurop Nord, Nord-Pas-de-Calais, France). The study was first performed on six snail species together and then specifically on Cepaea sp. and Oxychilus draparnaudi. When the six species were considered together, the accumulation of metals depended mostly on the species. When significant, total or extractable metal concentrations, or the predicted free ion activities, accounted for less than 7% of the variation of the metal concentrations in the snail tissues. Species-specific analyses showed that extractable concentrations explained approximately 25% of the variation of the metal concentrations in O. draparnaudi, and up to 8% in Cepaea snails. When using total soil concentrations and soil properties as explanatory variables, the models were generally slightly better, explaining up to 42% of the variance. The soil extraction procedures and predicted free ion activities used in this study did not accurately estimate the metal transfer from soil to snails and could not be used in risk assessment

Determination of soil parameters modulating the biovailability and the accumulation of metals to the snai (cantareus aspersus)

[...] L’objectif decette thèse est l’étude des mécanismes modulant la biodisponibilité des métaux pour l’escargotCantareus aspersus (syn. Helix aspersa), invertébré vivant à l’interface sol‐plante‐air (maillonintermédiaire, saprophage, phytophage, de chaînes alimentaires). La biodisponibilité est principalementévaluée ici en mesurant l’accumulation (concentrations internes en métaux après 28 jours d’exposition) etles flux d’assimilation. L’influence de paramètres édaphiques sur la disponibilité et la biodisponibilité desmétaux des sols et la contribution des sources de contamination (sols/plantes) des escargots constituentles variables étudiées dans deux conditions d'exposition :[...] L’ensemble des résultats souligne la nécessité de prendre en compte les facteurs et lesmécanismes qui modulent la biodisponibilité des métaux pour modéliser au mieux leur accumulation etleur assimilation par les escargots. Aucune méthode chimique unique d’estimation de la biodisponibilitédes métaux n’ayant pu être déterminée, nous préconisons l’utilisation de mesures biologiques quireflètent mieux la réelle biodisponibilité.[...] The aim of this thesis is to study the mechanisms that modulate metal bioavailabilityfor the garden snail Cantareus aspersus (= Helix aspersa) a soil invertebrate living at the interfacesoil‐plant‐air (saprophagous and phytophagous intermediate link in the food chain).[...] These data underline the necessity to take into account the factors and mechanisms that modulate themetal bioavailability for snails to better model accumulation and assimilation of metal by snails. As nounique chemical method to assess metal bioavailability was determined, we recommend the use ofbiological measures that identify the real metal bioavailability rather than the use of chemical measures

Détermination des facteurs du sol modulant la biodisponibilité et l'accumulation des métaux pour l'escargot (cantareus aspersus)

[...] The aim of this thesis is to study the mechanisms that modulate metal bioavailabilityfor the garden snail Cantareus aspersus (= Helix aspersa) a soil invertebrate living at the interfacesoil‐plant‐air (saprophagous and phytophagous intermediate link in the food chain).[...] These data underline the necessity to take into account the factors and mechanisms that modulate themetal bioavailability for snails to better model accumulation and assimilation of metal by snails. As nounique chemical method to assess metal bioavailability was determined, we recommend the use ofbiological measures that identify the real metal bioavailability rather than the use of chemical measures.[...] L’objectif decette thèse est l’étude des mécanismes modulant la biodisponibilité des métaux pour l’escargotCantareus aspersus (syn. Helix aspersa), invertébré vivant à l’interface sol‐plante‐air (maillonintermédiaire, saprophage, phytophage, de chaînes alimentaires). La biodisponibilité est principalementévaluée ici en mesurant l’accumulation (concentrations internes en métaux après 28 jours d’exposition) etles flux d’assimilation. L’influence de paramètres édaphiques sur la disponibilité et la biodisponibilité desmétaux des sols et la contribution des sources de contamination (sols/plantes) des escargots constituentles variables étudiées dans deux conditions d'exposition :[...] L’ensemble des résultats souligne la nécessité de prendre en compte les facteurs et lesmécanismes qui modulent la biodisponibilité des métaux pour modéliser au mieux leur accumulation etleur assimilation par les escargots. Aucune méthode chimique unique d’estimation de la biodisponibilitédes métaux n’ayant pu être déterminée, nous préconisons l’utilisation de mesures biologiques quireflètent mieux la réelle biodisponibilité

The SET and ERITME indices: Integrative tools for the management of polluted sites.

International audienceTo address the lack of biological methods for assessing soil quality and its contaminant retention capacity and to provide a tool with which stakeholders can assess the risk of transfer of trace elements in the soil to the soil fauna, the Sum of the Excess of Transfers (SET) index from soil to the snail Cantareus aspersus has been broadened to include the internal concentrations of reference (CIRef) for 14 metals and metalloids (As, Cd, Co, Cu, Cr, Hg, Mo, Ni, Pb, Sb, Sn, Sr, Tl and Zn). The coefficient of determination of risk for these elements provides a new assessment tool for stakeholders: the ERITME (Evaluation of the Risk of the Transferred Metal Elements) tool. This upgraded tool has been used to highlight unsuspected risks and revise management priorities at an industrial site. Moreover, using the tool to determine the risk from metal trace elements allows for improved environmental risk assessment, as ERITME is an integrative tool based on the real bioavailability of metals rather than chemical measures that often lead to unsatisfactory assessments of transfer. The SET and ERITME integrative tools, using snails as indicators of trace element zooavailability, can be used in environmental risk assessment

Les bioindicateurs pour la gestion des sites contaminés - Evaluation des risques de transfert dans les chaînes trophiques terrestres : résultats sur sites ateliers.

International audienceCette présentation synthétise les résultats obtenus avec des bio-indicateurs d'accumulation (plantes, escargots) et d'effet (teneurs des feuilles en acides gras) par plusieurs équipes dans le cadre du programme Bioindicateur conduit sur 13 sites en France. Il est également montré que la biodisponibilité (évaluée avec des méthodes biologiques) ne peut être estimée par l'évaluation de la disponibilité (évaluée avec des méthodes chimiques)

Capacity of earthworm and land snail to reveal bioavailability of PCB and PCDD/F in contaminated soil

Given their stability, lipophilicity and high persistence, PCB and PCDD/F represent a group of anthropogenic substances that can easily accumulate into the food web. While the transfer and accumulation of these substances are well documented for the aquatic food web, only few studies focused on their transfer from soil to terrestrial organisms. The two projects TROPHé (INERIS) and TROPE (University of Bourgogne Franche-Comté) were undertaken to assess the PCB and PCDD/F transfer into terrestrial biota in order to further evaluate risks to terrestrial ecosystems. Thirty-five compounds were monitoring (6 indicator PCB, 12 dioxin-like PCB, 7 dioxins and 10 furans) from four soils contaminated by a former industrial fire and showing a wide range of concentrations (up to 246 ng I-TEQ.kg-1 for Ʃ17 PCDD/F+12 PCB-DL and up to 35 000 ng.kg-1 for indicator PCB). The transfer of these compounds was then studied in two soft-bodies soil-dwelling invertebrate species: the oligochaete (Eisenia fetida) and the gastropod (Cantareus aspersus). Oligochaetes are one of the most important biotic components in the soil and frequently represent the most abundant species in terms of biomass. They are exposed to soil contaminants by digestive and cutaneous routes. Snails are characteristics of the soil surface and exposed directly to soil contaminants by the same routes as earthworms and also indirectly by ingestion of plants. Their ability to accumulate PCB, PCDD/F is unknown. Worms and snails were exposed in controlled conditions to the soils up to 28 days. The concentrations of the 35 substances were measured after 14 and 28 days of exposure in worms and after 28 days in snails. Bioaccumulation factors (BAF) were calculated according to the concentrations recorded in each soil. The results clearly showed that PCB and PCDD/F were transferred into the worms and snails. A steady state was reach from 14 days of exposure of worms. For both organisms, PCB showed a higher transfer by comparison with PCDD/F as evident by higher concentrations and thus higher BAF (by factor 10) calculated. PCDF (especially 2,3,7,8 TCDF and 1,2,3,4,6,7,8,HpPCDF) were more accumulated than PCDD (OCDD was the most accumulated). Concerning, the PCDD/F the lower BAFworms were observed for the higher chlorinated compound. Such tendency was however not observed for PCB. Among iPCB, PCB153-138-101-180 reached the highest concentrations. Overall, similar tendencies were observed for both species but with higher BAF in worms. This could be the result of a specific ability of accumulation and/or of the way of exposure of these soil invertebrates to contaminants

Ex situ environmental risk assessment of polluted soils using threshold guide values for the land snail Cantareus aspersus

International audienceEnvironmental risk assessment of contaminated soils should ideally be carried out with complementary approaches (chemical and biological) conducted in situ and ex situ. While biological methods based on the assessment of effect and bioaccumulation in bioindicators exists for soil fauna organisms, such as land snails, the methodology is currently limited in the field to 14 metallic elements (MEs). To provide new relevant tools to the stakeholders polluted fields, the aim of this work is to determine ex situ threshold guide values (ex situ TGVs), for 15 MEs, 16 polycyclic aromatic hydrocarbons (PAHs) and 7 polychlorinated biphenyls (PCBs). These ex situ TGVs are the usual concentration of contaminants found in the viscera of the bioindicator Cantareus aspersus after 28 days of exposure to uncontaminated soils. The second objective was to assess and validate the relevance of these ex situ TGVs for the interpretation of contamination levels in various European contaminated soils based on global index calculations: i) The sum of the excess of transfers (SETs) and ii) the weighted SETs based on the general toxicity points of each contaminant used to evaluate the risk of transferred MEs, PAHs and PCBs (ERITMEs, ERITPAHs and ERITPCBs, respectively). In addition, the influence of soil physico-chemical properties on accumulation was modelled to better understand their roles in bioavailability. The presented ex situ TGV and the associated indicators (the global sum of the excess of transfers and global ecotoxicological risk) provide a basis by which stakeholders can prioritize the management of polluted soils depending on the risk they may represent. The determination of ex situ TGVs for organic and inorganic compounds provides new tools to characterize excess contaminant transfers, and it will also allow the use of snails for ERAs, notably for common pollutants, such as PAHs and PCBs for which guide values are not available

<i>In situ</i> assessment of phyto and zooavailability of trace elements: A complementary approach to chemical extraction procedures

International audienceFor an accurate risk assessment of sites contaminated by trace elements (TE), measurements of bioavailability must be performed. This is routinely achieved using the standardized 0.01 M CaCl2 method. However, the suitability of chemical extractions as proxies of bioavailability is questionable. We analyzed the correlations between chemically estimated TE bioavailability and TE actually accumulated by coupling plant and snails bioindicators. Results showed a better correlation between plant TE contents and CaCl2 fraction while total soil concentration better explained snail TE contents. However in both cases chemical measures were not suitable to predict TE accumulation and bioavailability. Considering the soil properties only improve the estimation of Cr, Ni and Pb accumulation by plants while for snails, TE contents in viscera were dependent both on soil and plant contents and soil properties. It highlights the complementarities of biomonitoring methods to assess bioavailability. This dual approach allows a “physiologically defined” evaluation of bioavailability

Telomere dynamic in humans and animals: Review and perspectives in environmental toxicology

International audienceTelomeres (TLs) play major roles in stabilizing the genome and are usually shortened with ageing. The maintenance of TLs is ensured by two mechanisms involving telomerase (TA) enzyme and alternative lengthening telomeres (ALT). TL shortening and/or TA inhibition have been related to health effects on organisms (leading to reduced reproductive lifespan and survival), suggesting that they could be key processes in toxicity mechanisms (at molecular and cellular levels) and relevant as an early warning of exposure and effect of chemicals on human health and animal population dynamics. Consequently, a critical analysis of knowledge about relationships between TL dynamic and environmental pollution is essential to highlight the relevance of TL measurement in environmental toxicology.The first objective of this review is to provide a survey on the basic knowledge about TL structure, roles, maintenance mechanisms and causes of shortening in both vertebrates (including humans) and invertebrates. Overall, TL length decreases with ageing but some unexpected exceptions are reported (e.g., in species with different lifespans, such as the nematode Caenorhabditis elegans or the crustacean Homarus americanus). Inconsistent results reported in various biological groups or even between species of the same genus (e.g., the microcrustacean Daphnia sp.) indicate that the relation usually proposed between TL shortening and a decrease in TA activity cannot be generalized and depends on the species, stage of development or lifespan. Although the scientific literature provides evidence of the effect of ageing on TL shortening, much less information on the relationships between shortening, maintenance of TLs, influence of other endogenous and environmental drivers, including exposure to chemical pollutants, is available, especially in invertebrates.The second objective of this review is to connect knowledge on TL dynamic and exposure to contaminants. Most of the studies published on humans rely on correlative epidemiological approaches and few in vitro experiments. They have shown TL attrition when exposed to contaminants, such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), pesticides and metallic elements (ME). In other vertebrates, the studies we found deals mainly with birds and, overall, report a disturbance of TL dynamic consecutively to exposure to chemicals, including metals and organic compounds. In invertebrates, no data are available and the potential of TL dynamic in environmental risk assessment remains to be explored.On the basis of the main gaps identified some research perspectives (e.g., impact of endogenous and environmental drivers, dose response effects, link between TL length, TA activity, longevity and ageing) are proposed to better understand the potential of TL and TA measurements in humans and animals in environmental toxicology