Cesium-137 Accumulation in Marine Fish and Associated Dose Exposure: A Global Review

Establishing baseline data for natural radiation exposure and radioactivity levels is essential for radiological health and safety programs, particularly during the implementation and development of nuclear power initiatives. This review evaluates gamma radiation exposure and anthropogenic cesium-137 (137Cs) levels in the world’s oceans and marine fish, analyzing their radioecological impact. Data from 30 peer-reviewed publications indicate that 137Cs activity concentrations in seawater range from 0.07 Bq kg–1 to 6.4 kBq kg–1, with fish values between 0.01–3.50 kBq kg–1. Regression models developed from these studies predict the correlation between 137Cs levels in seawater and fish, providing insights into bioaccumulation patterns. Results reveal significant initial contamination following the Fukushima Daiichi Nuclear Power Plant (FDNPP) incident, with 137Cs concentrations in marine biota exceeding ecological screening values. However, these levels declined substantially over the subsequent decade, demonstrating the mitigating effects of radioactive decay and environmental redistribution. The ERICA assessment tool quantified absorbed dose rates, highlighting elevated exposure for sediment-associated organisms in the first five years. By the 10th year, dose rates and risk quotients fell below critical thresholds, suggesting reduced ecological risk. The findings underscore the spatial and temporal variability of 137Cs distribution, influenced by ocean currents and regional proximity to contamination sources. This review emphasizes the importance of integrating biota data with seawater measurements for comprehensive radiological risk assessments. The insights provided can inform environmental radiation protection strategies and enhance understanding of radionuclide dynamics in marine ecosystems. Continued long-term monitoring is vital to safeguarding marine biodiversity and food security from the persistent effects of radiological contamination.