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(M/MF152) Cd transfer from soil to snail: involvment in bioaccumulation and toxic effects. Coeurdassier, Michael1, de Vaufleury, Annette1, 1 ABSTRACT- Terrestrial snails are well known to accumulate large quantities of metals in their tissues in a contaminated environment. They are considered as suitable indicators of metal pollution in the field where several routes of contamination act concurrently (digestive, epithelial and respiratory). To evaluate the relative involvement of the digestive and epithelial routes in the transfer of Cd from soil to snail, young lab-reared H. aspersa were exposed to artificial soil contaminated at 0, 100, 500 and 1000 ⋅Cd /g for four weeks. Two modes of exposure were used for each test concentration (i) the snails were in direct contact with the substrate (DC) or (ii) were separated from substrate with a pierced plate (NC) which avoided a direct cutaneous contact of the foot but allowed the ingestion of substrate. Cd bioaccumulation and the toxic effects on snail growth were analysed. Cd concentrations in foot and viscera of DC snails were twice those measured in NC tissues. The bioaccumulation factors for foot and viscera were respectively 0.22⋅ 0.06, 0.71⋅ 0.20 for DC snails and 0.11 ⋅ 0.03 and 0.36⋅ 0.07 for NC snails. Dose-dependent growth inhibition was noted in DC snails: EC50 and EC10 were respectively 540 and 112 ⋅/g. In NC snails, only the EC10 was evaluated to be 300⋅/g. Internal concentrations of Cd in DC and NC snails were linearly correlated with growth effect (r2 =0.95, p<0.01) which shows that internal Cd concentrations are linked with growth inhibition whatever the contamination route. The present results constitute a step towards establishing more precise relationships between "internal body residue" and toxic effects in snails. Key words: snail, exposure routes, metal, bioaccumulation |
