Applicability of the Caenorhabditis elegans survival, growth and reproduction test to assess the effects of biosolids used in agriculture

Modern high productivity agriculture has led to an impoverishment of nutrients and organic carbon in field soils, and as a consequence plants nutrition complements like fertilisers or wastes have to be used to keep high yield. These complex materials can also be a source of toxicants, depending on their origin, so there is a necessity to assess their environmental effects before field use. In this study, biosolids used in agriculture were tested as a mix with standard soil at different field dose through ecotoxicity test on the nematode Caenorhabditis elegans, endpoints for this organism being survival, growth and reproduction. In order to run these tests we first followed the standardized protocol for sediment and soil testing with C. elegans (ISO 10872, 2010). These results showed that the mixtures could be significantly different according to the type of soil (e.g. two phases system with overlaying water). Indeed, soil moistening in the standardized protocol is based on soil dry weight which means that the same amount of water is added for every soil, regardless of the water holding capacity (WHC) of the samples. Moreover, some biosolids can have a high WHC what increase humidity's differences among soil and soil mixed with biosolids when moistened as recommended by this protocol. To prevent this, improvements of the standardized protocol were developed, in which water addition is based on soil WHC instead of soil dry weight. Moreover, food volume added to the samples was lowered in order to be able to include it in the volume for soil moistening. In this context and in order to validate this new method, comparisons between standardized and optimized protocols were carried out for endpoints responses in five soils with different textures. This optimized protocol was used to assess the effect of different biosolids (limed sludge, manure ...) mixed with standard soil at different field rates and an example for a limed sludge is given. Regarding these results, improvements of the standardized protocol are adapted to assess the effects of these materials on C. elegans

Contribution of ecotoxicological tests in the evaluation of soil bioremediation efficiency

Clean-up of contaminated soils became a high priority only recently. Several techniques have been developed forthis purpose such as chemical, physical, thermic or microbiological methods. Efficiency of the remediation can be estimated using two approaches : a chemical specific approach and a toxicity-based approach. So far, the efficiency of the decontamination process was based essentially on chemical analyses which does not integrale the toxicity of all the soil contaminants and does not give a response on effects caused by the bioavailable fraction of these contaminants äs the toxicity-based approach. In the present study, bioremediation efficiency of a soil contaminated by 4-chlorobiphenyl was evaluated using chemical and biological analyses. Experiments were carried out in microcosms contaminated at a rate of 1 g/kg. Control microcosms without specific degrader were performed simultaneously. Acute toxicity to earthworms and inhibition of growth of barley roots were selected, from previous work, äs relevant ecotoxicological test

Effect of non-ageing and ageing ceria nanoparticles suspensions on fresh water micro-algae

When assessing the hazards properties of nanomaterials in the environment, the main research challenges are numerous. Firstly, determining if nanomaterials are more or less toxic than the bulk forms of the same materials and the extent to which toxicity is governed or influenced by the physico-chemicals properties of the nanoparticles. Secondly, it appears necessary to study the effect of nanomaterials and nanoparticles throughout their life cycle including both initial forms and physico-chemically modified form (i.e. aggregated or agglomerated forms) resulting from an ageing process. Our work focused on the effect of commercial ceria nanoparticle (nCeO2) suspensions, towards freshwater micro-algae assessing the effect nCeO2 suspensions with different agglomeration/aggregation state obtained by using an artificial ageing process. Both ageing and non-ageing nCeO2 suspensions were fully characterized using dynamic light scattering (ZetaSizer, Malvern Instruments) or laser diffraction (MasterSizer, Malvern Instruments) and transmission electron microscopy (TEM). In addition, the interaction between NPs and algae were investigated using flow-cytometry and environmental scanning electron microscope technique (E-SEM).The results obtained showed that the algae growth inhibition was similar after exposure to non-ageing or ageing nCeO2 suspensions. The results obtained from flow-cytometry and E-SEM proved that the ceria NPs are able to tightly entrap the algae cells, which could in part contribute to the effect recorded. Those results also support the fact that aggregation or agglomeration has a few influences when focusing on the standardized algae ecotoxicity test. Moreover by comparison to our previous studies performed with other ceria suspensions, it was shown that the primary particle size and consequently the particle surface area is a relevant parameter in assessing the ecotoxicity of nanoparticles

Evaluation of an in vitro hsp 70 induction test for toxicity assessment of complex mixtures : comparaison with chemical analyses and ecotoxicity tests

International audienceThe aim of this study was to assess the potential of a human cell line containing the hsp70 promoter linked to the chloramphenicol acetyltransferase reporter gene in evaluating the toxic potential of complex mixtures. Cells were exposed to eluates of industrial wastes and the cellular responses were compared with the metal contents of the samples and with standardized aquatic (microalgal growth inhibition, daphnia Immobilization, bacterial luminescence inhibition, Ceriodaphnia dubia reproduction inhibition) and terrestrial (earthworm lethality, plant growth inhibition) tests. The hsp70 promoter was significantly induced by 11 of 14 samples, with different dose-response patterns. Significant correlations of in vitro induction potency with aquatic ecotoxicity, especially with chronic tests, and with the metal contents of the samples were observed. Our study provides new information on the relevance of hsp70 gene induction as a criterion of toxicity and suggests its usefulness for the detection of toxicity associated with metallic pollution in complex mixtures

Physico-chemical and biological characterization of an aquifer polluted with ETBE

International audiencePetroleum compounds and among them, gasoline, is the most massively used chemicals worldwide and, as a consequence gasoline derives compounds are the most frequently found contaminants in groundwate

Adapting oecd aquatic toxicity tests for use with manufactured nanomaterials: key issues and consensus recommendations

The unique or enhanced properties of manufactured nanomaterials (MNs) suggest that their use in nanoenabled products will continue to increase. This will result in increased potential for human and environmental exposure to MNs during manufacturing, use, and disposal of nanoenabled products. Scientifically based risk assessment for MNs necessitates the development of reproducible, standardized hazard testing methods such as those provided by the Organisation of Economic Cooperation and Development (OECD). Currently, there is no comprehensive guidance on how best to address testing issues specific to MN particulate, fibrous, or colloidal properties. This paper summarizes the findings from an expert workshop convened to develop a guidance document that addresses the difficulties encountered when testing MNs using OECD aquatic and sediment test guidelines. Critical components were identified by workshop participants that require specific guidance for MN testing: preparation of dispersions, dose metrics, the importance and challenges associated with maintaining and monitoring exposure levels, and the need for reliable methods to quantify MNs in complex media. To facilitate a scientific advance in the consistency of nanoecotoxicology test results, we identify and discuss critical considerations where expert consensus recommendations were and were not achieved and provide specific research recommendations to resolve issues for which consensus was not reached. This process will enable the development of prescriptive testing guidance for MNs. Critically, we highlight the need to quantify and properly interpret and express exposure during the bioassays used to determine hazard values

Etude de biocapteurs, a algues immobilisees pour le controle des milieux hydriques

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 81418 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Utilisation d’une approche multicritère pour la sélection d’essais d’écotoxicité

Sensitivity of animal and plant communities to toxicants may vary significantly from one species to another. If testing is performed on one species, the high diversity in the sensitivity between species might result in a high level of uncertainty. It is therefore admitted that only a combination of several bioassays can give a clear view of the toxic effects of chemicals and/or environmental samples. The best approach is therefore to use a battery of tests with several species belonging to different taxonomic groups and trophic levels. Usually, two methods can be used for selecting bioassays in order to establish a test battery: i) an “a priori” method, in which the selection is made according to decision criteria such as standardization of the method, ecological relevance of test organisms, or cost, ii) an “a posteriori” method, in which the selection is made after performing multivariate analyses of test results obtained on a large series of bioassays. In the present study on soil quality, a methodological framework, based on the use of the multicriteria method SIRIS (System of Integration of Risk with Interaction of Scores) was applied to perform an “a priori ” selection of bioassays among 115 relevant ecotoxicity tests, selected from an extensive literature review.L’utilisation d’essais sur organismes biologiques est désormais reconnue comme l’un des éléments pertinents permettant de caractériser de façon satisfaisante la qualité des milieux. En effet, ces outils prennent en compte, à la fois la biodisponibilité - disponibilité pour les organismes vivants - des différentes substances chimiques présentes, mais également les effets de synergie ou d’antagonisme qui peuvent se produire entre ces dernières. Ces essais biologiques, initialement utilisés pour le contrôle des substances chimiques et des rejets en milieu aquatique, sont aujourd’hui appliqués à d’autres domaines tels que la caractérisation des sites et des sols pollués, la valorisation des boues en agriculture, la gestion des sédiments ainsi que la classifi cation des déchets