Radioactivity of 14C, OBT, and TFWT in seafood from coastal areas of Zhejiang Province: Assessment of internal exposure to the public

Environmental radioactivity monitoring around nuclear facilities is crucial for providing baseline data that enables practical, effective radiological risk assessment to the local public and timely detection in case of radioactive releases in the region. As a coastal province with a significant number of nuclear power facilities, Zhejiang Province has a crucial need for a comprehensive assessment of radiation exposure to the residents from seafood consumption. This study investigated the radioactivity levels of ¹⁴C, organically bound tritium (OBT), and tissue-free water tritium (TFWT) in five types of seafood, including marine fish, prawn, shellfish, sea crab, and algae, sourced from the coastal areas of Zhejiang Province. This is the first comprehensive study to cover most coastal regions of Zhejiang Province, investigating ¹⁴C, OBT, and TFWT activity in seafood and related radiological risk assessment. Our results showed that the ranges of activity concentrations of ¹⁴C, OBT, and TFWT were 2.04–64.30 Bq/kg-fresh, 0.03–1.60 Bq/kg-fresh, and 0.37–10.24 Bq/kg-fresh, respectively. The total annual committed effective dose (ACED) along the Zhejiang coast ranged from 0.244 to 0.676 μSv/year, accounting for an average of 0.16% of the annual dose constraint. Furthermore, compared to other cities, ACED values based on ¹⁴C, OBT, and TFWT were significantly higher in Zhoushan City. Still, all ACED values obtained in this study remain below the ICRP's recommended thresholds.