Accumulation and Retention of Ingested Cobalt-60 by the Common Goby

The accumulation and elimination of 60Co by the common goby, Acanthogobius flavimanus, were investigated with the ingestion of contaminated food. It was found that the elimination pattern of 60Co by the fish showed an initial rapid decrease followed thereafter by a slower elimination pattern. The absorption rate of 60Co (defined as the activity remaining 24 hours after a single administration) following a single administration was approximately 4% of the administered dose, and the biological half-life for 60Co in the fish was 69 days on an average. On the other hand, it was found that the accumulation of 6OCo by the fish on daily oral administration showed a gradual increasing tendency during the whole period, and the retained activity in the fish at the end of daily feeding experiment was about 6% of total administered doses. Using a single exponential model, the time to reach 90% and 50% of total body burden in the fish at the equilibrium state were estimated to be approximately 228 days and 69 days, respectively. The concentration of 60 Co by various organs of the fish due to ingestion of labelled food showed a decreasing tendency in the order of liver, other viscera (excluding liver and digestive tract), fins, gills, digestive tract, head, skin, and muscle.