An assessment of the embryotoxicity of cadmium in the terrestrial mollusk Cantareus aspersus: from bioaccumulation to impacts at different levels of biological organization.

This study aims to determine various parameters that allow the evaluation of the toxicity of chemicals to embryos of the ubiquitous land snail Cantareus aspersus. For this purpose, we investigated morphological and physiological endpoints in control embryos and in embryos exposed to a solution of 6mg Cd/L (CdCl2) in a liquid phase bioassay: size at days 3, 6 and 10, heart rate at 7 days, delay in hatching, states of development of non-hatched eggs after 17 days and the fresh mass of newly hatched embryos. The kinetics of Cd accumulation in eggs and DNA fragmentation were also measured. The first detectable sign of adverse effects appeared after 7 days of development, when the heart rate decreased in Cd-exposed embryos compared with the control. After 10 days of exposure, Cd-exposed hatchlings exhibited a lower fresh mass than control individuals. The majority (75 percent) of non-hatched embryos at 17 days was dead and presented signs of disaggregation or malformations. The hatching of Cd-exposed eggs was delayed 4 days, and DNA fragmentation was later detected after 20 days of Cd exposure. The measurement of Cd in the eggs showed that concentrations are relatively stable during the exposure period from 3 days (20-27µg Cd/g DW) to the end of exposure. The present study completes the range of endpoints that can be used to study the effects of contaminants and provides new parameters that are readily measured throughout the embryonic development of a terrestrial mollusk.

Hair as a noninvasive tool for risk assessment: do the concentrations of cadmium and lead in the hair of wood mice (Apodemus sylvaticus) reflect internal concentrations?

There is an increasing need for developing noninvasive markers of accumulation when studying the transfer of pollutants in wildlife, in response to problems caused by sacrifice of animals (disturbed population dynamics, respect of ethical protocols). Thus, the aim of this work was to determine whether trace metal (TM) concentrations in hair could be used as an accurate noninvasive estimator of internal and environmental concentrations. For that purpose, on a 40km² site surrounding an ancient smelter, 321 wood mice (Apodemus sylvaticus) were sampled on seven squares (500×500m) and 4 squares in fall 2010 and spring 2011, respectively. The relationships between the cadmium (Cd) and lead (Pb) concentrations in hair and those in the liver, kidneys, and soils were described. The results indicated that hair concentration was a relatively good predictor of Pb concentrations in organs (p<0.001, 0.46

Coupling of random amplified polymorphic DNA profiles analysis and high resolution capillary electrophoresis system for the assessment of chemical genotoxicity.

Cadmium (Cd) can be toxic to terrestrial snails, but few data are available about its genotoxic effects on early life stages (ELS). The aim of this study was to investigate the genotoxic potential of Cd in embryos of Helix aspersa using a new approach that couples Random Amplified Polymorphic DNA (RAPD) and a high-resolution capillary electrophoresis system (HRS). Clutches of H. aspersa were exposed to Cd solutions (2, 4, and 6 mg/L) from the beginning of their embryonic development. In addition to a dose-dependent effect of Cd on hatching rate, DNA fragmentation was observed in embryos that were exposed to 6 mg Cd/L. The analysis of RAPD products with HRS showed differences between the profiles of exposed and nonexposed embryos, starting at 2 mg Cd/L. In comparison to the profiles of the control samples, all profiles from the exposed snails exhibited an additional 270 bp DNA fragment and lacked a 450 bp DNA fragment. These profile modifications are related to the genotoxic effect of Cd on the ELS of H. aspersa . Our study demonstrates the efficacy of coupling RAPD and HRS for a rapid and efficient screening of the effects of chemicals on DNA.

How terrestrial snails can be used in risk assessment of soils.

Among soil invertebrates, terrestrial snails are herbivorous and detritivorous organisms exposed to polluted soils by both digestive and cutaneous routes. Using laboratory-reared snails (Helix aspersa aspersa), we describe how the effects of contaminants on survival and growth of snails can be evaluated in laboratory bioassays. A national ring test was performed to assess the effect of Cd added to the soil or to the food. The ecotoxicity of sewage sludge also was evaluated. The present results demonstrate that toxicity depends on both the pollutants and the exposure route. Cadmium was sixfold more toxic for snails exposed via food contamination (median effective concentration [EC50], 68-139 microg/g) than via soil contamination (EC50, 534-877 microg/g), whereas the opposite occurred with the sewage sludge (EC50, 55% of sludge in the food and 10% of waste in the soil). A logistic relationship linked growth inhibition and internal Cd concentrations, which can reach 2,000 microg/g in the viscera of snails exposed to 626 microg/g in the food. No clear trend was found between Cu, Zn, Pb, Cr, and Ni concentrations in the sludge and in snail tissues. These data enabled the development of an international standard, which should enhance the use of terrestrial gastropods for both fundamental research and routine risk assessment in the terrestrial environment.

Assessment of whole effluent toxicity on aquatic snails: bioaccumulation of Cr, Zn, and Fe, and individual effects in bioassays.

We used a freshwater gastropod, Lymnaea palustris, in chronic bioassays to assess the toxicity of an industrial effluent containing high levels of metals, particularly Cr, Zn, and Fe. Adult snails were exposed for four weeks to different concentrations of effluent sampled at three successive treatment steps (crude effluent, effluent after physicochemical treatment, and after biological treatment). Dose-dependent responses reflecting exposure (metal bioaccumulation) and effects on survival, fecundity, and malondialdehyde production (a proxy for oxidative stress) were investigated. We found that Cr and Zn were accumulated in snail tissues, whereas Fe was regulated. Body concentrations of Cr and Zn decreased along the effluent-treatment gradient, particularly after the physicochemical treatment. For controls versus treatments, no effect on malondialdehyde production was detected. Significant effects were noted for fecundity. The number of eggs per individual decreased for snails exposed to 20, 30, and 40% concentrations of physicochemically treated effluent and for snails exposed to an 80% concentration of the biologically treated effluent. A hormetic effect on the number of eggs per individual was observed for snails exposed to 10 and 20% concentrations of the effluent that had been biologically treated. Deleterious effects of the effluent on L. palustris fecundity were not correlated with high internal concentrations of metals in the snails, suggesting that toxicity resulted from other factors.