Heavy Metal Concentrations in Two Populations of Mopane Worms (Imbrasia belina) in the Kruger National Park Pose a Potential Human Health Risk

Metal concentrations in Mopane worms from Phalaborwa and Shangoni sites in the Kruger National Park were determined. Metal concentrations were evaluated by inductively coupled plasma optical emission spectroscopy (ICP-OES) and ICP-MS spectrometry after microwave digestion. The results indicate a substantial bioaccumulation of metals in Mopane worms. In Phalaborwa Cd concentrations were 15 times and Cu two times higher than the EU and UK recommended legal limits for human consumption, Zn levels were tolerable. Likewise, Cd, Cu and Zn concentrations at the Shangoni site were 26, 2.5 and 0.4 times over the EU and UK approved limits. Manganese concentrations were 20 and 67 times higher than FDA standards respectively. During the study the condition factor of the worms was determined. No significant difference between the condition factors indicated the worms at both sites are in similar condition. Potential sources of metals in the worms are either from the food they eat or pollution settling on the leaves.