The accumulation and retention of 95m Tc by the edible winkle ( Littorina littorea L.)

Abstract

The whole body equilibrium concentration factor for the direct accumulation of 95mTc from seawater by the edible winkle (Littorina littorea) was estimated to be 45 with a biological half-time of 115 days. Winkle shells accumulate 95mTc by adsorption only, there being no evidence for metabolic accumulation. About 98% of the 95mTc in the whole animal was in the flesh. The 95mTc was eliminated exponentially from winkles following accumulation from seawater, slowly in starved winkles, with a half-time of 347 days, and rapidly in fed winkles, with a half-time of 39 days. Residual 95mTc after depuration was, in both cases, present in the digestive-gland-kidney complex. A factorial experiment investigating the effects of two temperatures (10°C and 16°C), two winkle weight ranges (3±0·5 g and 8±0·5 g) and two feeding regimes (feeding ad libitum and starvation) on 95Tc elimination from winkles is described. The results indicate that the most significant factor in reducing elimination is starvation. Using the experimental data, equilibrium concentration factors for winkles accumulating 99Tc from food are calculated. The results obtained are discussed and comparison is made with the values found for winkles and other molluscs in the environment.