Hazardous exposure of ground-living small mammals to cadmium and lead in contaminated terrestrial ecosystems.

The dietary exposure to cadmium and lead of two ground-living species of small mammals, i.e., shrews Sorex araneus (Insectivora) and voles Microtus agrestis (Rodentia), was investigated and related to metal loads in target organs (kidneys and liver). The study was done in two natural areas polluted with cadmium and lead originating from urban and industrial metal sources. The average intake of cadmium by the herbivorous voles varied between 0.1 and 0.4 micrograms/g/day and of lead between 2 and 10 micrograms/g/day. The carnivorous shrews showed a considerably higher metal intake rates, i.e., cadmium 3 to 16 micrograms/g/day and lead 19 to 53 micrograms/g/day, which was largely due to the consumption of contaminated earthworms (Oligochaeta). An average cadmium intake of 15 micrograms/g/day or a lead intake of 20 micrograms/g/day corresponded with critical renal metal loads of 120 micrograms/g for cadmium and 25 micrograms/g for lead, which are indicative of adverse health effects. The renal metal loads in shrews reached the critical level, but they remained far below this level in voles. The results indicate a greater risk of toxic exposure to cadmium and lead in soricine shrews than in microtine rodents.