Growing snails used as sentinels to evaluate terrestrial environment contamination by trace elements.

Young garden snails (Helix aspersa) reared in standard conditions (aged two months, mean weight 4.6 +/- 0.5 g) set as sentinels in cages laid on the soil for four weeks, give data for biomonitoring the environmental impact of chemicals on soil ecosystems in the field. The survival and the growth of the snails are influenced by the nature of the biotope and the level of the pollutants. Assay of cadmium, copper, lead and zinc bioaccumulated in the tissues of the sentinel snails provides information on the bioavailability of metals in the environment. The encagement model, little used for terrestrial species, can be useful in monitoring (specific and global endpoints) metal pollution of the environment in reference to the trophic level of the primary consumers. Active biomonitoring is positively compared with the passive biomonitoring.