Cytotoxicity and genotoxicity of lanthanides for Vicia faba L. are mediated by their chemical speciation in different exposure media.

A comprehensive study of the toxicity of lanthanides (LN) in relation to the media composition will enhance the prediction of their potential adverse effects for living organisms. Here we examined the effect of different media on the V. faba root elongation and on the cytotoxic (mitotic index) and the genotoxic (micronucleated cell number) effects from toxicity tests with Ce, Gd and Lu (100, 800 and 6400 µg L-1). Three different exposure media were selected: the standard Hoagland media (SH); an alternative SH, without phosphates (SH-P); and distilled water (DW). In the SH no cyto-genotoxic effects were observed and even, for low LN content, potential root elongation stimulation was reported. The absence of toxic effects was explained by a drastic decrease of the total dissolved LN concentration due to the presence of phosphates causing LN precipitation. In SH-P, LN remained largely soluble and inhibition of root elongation was observed mainly for the highest treatments. While in the tests done in DW, toxic effects were obtained for all treatments. Our results showed that in absence of phosphorous, LN appear mainly as free form and complexed in carbonates and sulphates, and can cause toxic effects, whereas toxicity is not expected when phosphorous is available in aquatic media. The highest LN root contents were observed for the tests using distilled water, possibly due to the absence of competition by Ca2+ for uptake. The present work demonstrated that media composition has a great impact in assessing the ecotoxicology of lanthanides.

In situ assessment of phytotechnologies for multicontaminated soil management.

Due to human activities, large volumes of soils are contaminated with organic pollutants such as polycyclic aromatic hydrocarbons, and very often by metallic pollutants as well. Multipolluted soils are therefore a key concern for remediation. This work presents a long-term evaluation of the fate and environmental impact of the organic and metallic contaminants of an industrially polluted soil under natural and plant-assisted conditions. A field trial was followed for four years according to six treatments in four replicates: unplanted, planted with alfalfa with or without mycorrhizal inoculation, planted with Noccaea caerulescens, naturally colonized by indigenous plants, and thermally treated soil planted with alfalfa. Leaching water volumes and composition, PAH concentrations in soil and solutions, soil fauna and microbial diversity, soil and solution toxicity using standardized bioassays, plant biomass, mycorrhizal colonization, were monitored. Results showed that plant cover alone did not affect total contaminant concentrations in soil. However, it was most efficient in improving the contamination impact on the environment and in increasing the biological diversity. Leaching water quality remained an issue because of its high toxicity shown by micro-algae testing. In this matter, prior treatment of the soil by thermal desorption proved to be the only effective treatment.

Evaluation of the genotoxic, mutagenic and oxidant stress potentials of municipal solid waste incinerator bottom ash leachates.

Triplicate aqueous leachates of a municipal solid waste incineration bottom ash (MSWIBA) were produced according to a European standardised method. Leachates analysis showed relatively low concentrations (less than 1 mg.l(-1)) for four metals (iron, cadmium, lead and copper). No mutagenic activity was revealed after performing the Salmonella/microsome assay with and without microsomal activation. With the Vicia root tip micronucleus assay, a significant increase in micronucleated cells was observed between 3.4% and 100% leachate concentration. Significant and elevated antioxidant stress enzyme activities, e.g., superoxide dismutase (SOD), catalase (CAT), peroxidase (PER) and glutathione reductase (GR), were detected in Vicia root tissues even at the lowest tested leachate concentration (i.e., 0.3%), whereas this was not always the case in leaf tissues, which showed tissue specificity for the tested enzymes. At the lowest concentration (i.e., 0.3%), a higher increase was observed (respectively 197% and 45% compared to the control) for root glutathione reductase and peroxidase activities over those of other enzymes (superoxide dismutase and catalase). Our results suggest that MSWIBA aqueous leachates need to be formally tested with genotoxic sensitive tests before recycling and support the hypothesis that plant genotoxicity is related to the cellular production of reactive oxygen species (ROS).

Classical and biochemical endpoints in the evaluation of phytotoxic effects caused by the herbicide trichloroacetate.

Three terrestrial plant species, oat (Avena sativa ), Chinese cabbage (Brassica campestris cv. chinensis) and lettuce (Lactuca sativa), were exposed to different concentrations of herbicide TCA (sodium trichloroacetate) in a growth test according to guideline OECD # 208. Classical (i.e. germination and biomass) and biochemical (i.e., antioxydant enzyme activities) endpoints were investigated. Germination rate decreased significantly at 3.9 mg TCA kg dry soil(-1) (for oat and lettuce) and 62.5 mg TCA kg dry soil(-1) (for Chinese cabbage). Biomass decreased significantly only at 1.9 mg TCA kg dry soil(-1) (for oat and lettuce) and 15.6 mg TCA kg dry soil(-1) (for Chinese cabbage). The activities of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6), peroxidase (EC 1.11.1.7) and glutathione reductase (EC 1.6.4.2) increased significantly at the lowest concentration of TCA tested, i.e. 0.03 mg TCA kg dry soil(-1) (for oat and lettuce) and 0.48 mg TCA kg dry soil(-1) (for Chinese cabbage). Our results showed a ranking of sensitivity among the different endpoints for the three plant species: enzyme activities>biomass>germination rate. The increase in antioxidant enzyme activities observed in this study ensured the detoxification of increased levels of active oxygen species, and presumably prevented the plants from undergoing oxidative stress damage. Thus, the use of enzyme activities will permit the detection of early injury in plant growth testing.

Assessment of the genotoxicity of contaminated soil with the Allium/Vicia-micronucleus and the Tradescantia-micronucleus assays.

The present study concerns the genotoxicity of contaminated soil near Metz, France. Three plant bioassays, the Vicia faba (broad bean), the Allium cepa (white onion) and the Tradescantia (spiderwort) micronuclei tests were used to evaluate for genotoxicity. Two soil samples were tested: soil sample A (from an industrial waste site) and soil sample B (from a cokeworks waste site). Maleic hydrazide was used as the positive control. Aqueous extracts of the soil samples were used to treat the roots of Vicia and Allium, and plant cuttings of Tradescantia according to the standard protocol for these plant assays established by the International Program on Chemical Safety and the World Health Organization. The results of these tests showed differential sensitivity in the three different bioassays. Soil sample A was more toxic than soil sample B.

Comet assay in genetic ecotoxicology: a review.

The Comet assay, also called the single cell gel electrophoresis (SCGE) assay or microgel electrophoresis (MGE) assay, primarily measures DNA strand breakage in single cells. Since the protocol was published by Singh et al. [1988], its use has increased in different topic areas: clinical applications, human monitoring, radiation biology, genetic toxicology, and genetic ecotoxicology. This study is a review of the investigations that have involved the alkaline version of the Comet assay in genetic ecotoxicology. It focuses mainly on the type of organisms (plants, worms, molluscs, fish, amphibians, and mammalians) but also on the type of cells that have been used for ecotoxicological studies. In the 23 papers published since 1993 and presented here, the original test procedure may have been slightly modified according to the cell type. In vitro and in vivo experiments as well as in situ studies have been carried out in various environments (water, soil, and air). Although the Comet assay is able to detect genotoxic effects of chemical and physical agents, only chemical substances and environmental complex mixtures will be considered in this review.

Effects of algae frozen at different temperatures on chronic assessment endpoints observed with Daphnia magna.

The Daphnia magna 21-day juvenile production test is not yet fully standardized because of many sources of variation. One is the diet provided to daphnids: the ration must be sufficient and the quality of algal cells must be optimal for achieving the required number of offspring defined by the new OECD guidelines. The experiments reported herein first examined the effects of Raphidocelis subcapitata after it had been maintained under four different conditions of storage (4, -20, -80, and -196 degrees C) on the survival, reproductive performance (over 21 days), and growth (ascertained by dry weight) of individually held D. magna for three generations. Under all of the four regimes tested, daphnids survived and reproduced in a manner which fulfilled the current OECD guidelines for a valid test, but the best results were obtained with fresh algae and algae frozen at -80 degrees C. Second, although D. magna has been widely used to determine toxicity of chemical substances, there are no reports in the literature that describe a rigorous study of the nutritional quality of the algae given to daphnids. Therefore, cell number, optical density, amount of organic carbon, and esterasic activity (assessed by intracellular breakdown of FDA to fluorescein) of algae that have been preserved at 4, -20, -80, and -196 degrees C were investigated. This part of the study indicated that freezing had no effect on cell numbers, in contrast to optical density, amount of organic carbon, and esterasic activity. First, it was found that esterasic activity was closely correlated to the reproductive performance of daphnids. It appears important, therefore, to consider the inclusion of this enzymatic activity as part of the routine quality control given to this microinvertebrate chronic procedure.