Ingestion of Chernobyl 137Cs in Akita City, Japan

The ingestion of 137Cs during 1985-1988 in Akita City, Japan, has been studied. Samples of 13 separate food categories were collected and analyzed for Cs radioisotopes. The ingestion rate of 137Cs originating from the Chenobyl accident decreased exponentially with a practical half-life of 1.6 years. The total ingestion of Chernobyl 137Cs per capita is estimated to be 62 Bq. The relative contributions of various food categories to 137Cs ingestion after the accident were dissimilar to those from nuclear weapons testing. Thus, the contamination pattern for Chernobyl 137Cs was characterized by a higher contribution (42%) by dairy products to total 137Cs ingestion. The practical half-life for the decrease in the 137Cs ingestion rate from dairy products was found to be 0.75 years. The transfer coefficient from deposition to diet for 137Cs from the Chernobyl accident was found to be significantly lower than that describing transfer of 137Cs from nuclear weapons test. (author)