Concentration factors for 137Cs in Japanese coastal fish (1984-1990)

Concentration factors (CFs; Bq kg-1 in wet fish muscle/Bq kg-1 in filtered seawater) for 137Cs were determined in Japanese coastal fish collected from 1984 to 1990. 137Cs/Cs (stable) atom ratios were also examined to clarify the distribution equilibrium of 137Cs between marine fish and seawater. The geometric mean of CF in Japanese coastal fish was 52 +/- 4 (standard error of the mean), with values ranging from 14 to 133. 137Cs/Cs atom ratios both in marine fish and seawater indicate that the distribution of 137Cs was in equilibrium between fish muscle and seawater. Therefore, CF values obtained in the present study can be regarded as equilibrated. Our results show that the CFs for 137Cs in Japanese coastal fish were within the range of Japanese guidelines, but were below the recommended IAEA value.