Dose-dependent effects of cadmium on the growth of snails in toxicity bioassays.

The effects on survival and growth of exposure to cadmium (Cd) in the food were analyzed in juvenile snails (age one month, mean weight 1 g) of the two subspecies Helix aspersa aspersa (H.a.a.) and H. aspersa maxima (H.a.m.). The experiments lasted for four weeks and the animals were fed with special snail food containing 0-, 50-, 100-, 200-, 400-, and 800 microg Cd/g of dry food. No significant adverse effect (NOEC) was noted at 50 microg/g for three weeks. A negative effect of Cd on growth was noted from 100 to 800 microg/g and plotting the growth coefficient variation against the Cd concentration led to an estimate of the EC75 at day 14 of 370 microg/g in H.a.a. and 470 microg/g in H.a.m. and at day 28 of 290 microg/g in H.a.a. and 330 microg/g in H.a.m. Juvenile snails are thus a suitable material for use as bioindicators in the assay of contamination of food.