Polonium-210 and Lead-210 in edible molluscs from near the Cape of Good Hope: Sources of variability in polonium-210 concentrations

Measurements of the natural radionuclides 210Po and 210Pb in mussels, squid and oysters from near the Cape of Good Hope are reported and compared with previously published 210Po and 210Pb data from Northern Hemisphere organisms in the same taxa. Emphasis is laid on discussing the causes of variability in the concentrations of 210Po in marine organisms. No systematic evidence is found for a ‘latitude’ effect, but allometric effects, intertaxon differences, change of diet with animal size and regional effects are all significant for 210Po. The consequences for human radiation dose calculations of variability of 210Po levels in seafoods are discussed briefly; particular reference is made to the case of a Stone Age mussel-eating community in South Africa.