The transfer of lead (Pb) from earthworms to shrews (Myosorex varius)

Shrews (Myosorex varius) were bait-trapped close to Stellenbosch in the Western Cape, South Africa, and analyzed to determine the Pb content of the liver, kidneys, muscle tissue, brain, skull, and bone. Shrews were also fed in the laboratory on mince meat and Pb-contaminated live earthworms for 12-17 days and the Pb content compared with control shrews from the field. The Pb levels in the control shrews from the field were exceptionally high and exceeded levels generally considered to be critical for the onset of pathological symptoms in target organs. The shrews that were fed with Pb-contaminated earthworms had significantly higher Pb concentrations in their livers and kidneys than the control shrews. Given that Pb is bioaccumulated in earthworms, this study showed that predation on earthworms could constitute a major pathway for the entry of Pb into the food chain. M. varius could, similar to other species of shrews in other parts of the world, be a suitable biological monitor to study the environmental hazard of Pb pollution.