Analysis of some factors that may modify the bioavailability of cadmium and lead by Biomphalaria glabrata

Laboratory acute bioassays (t = 96 h) were used to determine the uptake, distribution, and elimination of cadmium and lead by the freshwater gastropod Biomphalaria glabrata. Experiments were conducted on nonpigmented and pigmented organisms separately. The influence of food and different concentrations of humic acids were also investigated. The results showed that, after the treatments, the digestive gland presented the highest level of metal uptake for both elements. Food did not prove to induce significant changes in the pattern of accumulation and distribution within the different tissues. Instead, different concentrations of humic materials modified the pattern of accumulation and distribution of cadmium and lead but in a different way according to the metal. Elimination of cadmium from the soft tissues was considerably slow, presenting a redistribution over the time of depuration. Elimination of lead was faster in the digestive gland and gonads. After all the treatments, no significant differences were observed between nonpigmented and pigmented snails.