Radioactivity in water and food from Hangzhou, China in the past decade: Levels, sources, exposure and human health risk assessment

There were few studies reported the temporal trend of radioactivity in water and food. Here, using Hangzhou (Zhejiang, China) as a case study, we determined the radioactivity (Sr-90,Cs-137, gross alpha, and gross beta) levels and temporal variations in water and food samples during 2012-2019, and in the meanwhile the Cs-137/Sr-90 activity ratios were calculated and a dose assessment was performed. Results showed that the 90Sr and 137Cs concentrations in water varied from (1.6-17.2) x 10(-3) and (0.66-15.1) x 10(-3) Bq/L, respectively. The temporal variations in gross alpha and gross beta radioactivity of water were small, except those for Qiantang River. Radioactivity levels of gross alpha (< 0.0160.059 Bq/L) and gross beta (< 0.028-0.69 Bq/L) in water were lower than World Health Organization recommendations. In food samples, Sr-90 concentrations varied from 0.0291.3 Bq/kg fresh weight while Cs-137 concentrations were mostly below the minimum detectable activity except for haritail (up to 0.13 Bq/kg); both were significantly below the limits recommended by Chinese national standard for radiation safety. Sr-90 and Cs-137 concentrations were relatively constant in water samples across the entire study period. Significant variations were observed in the 90Sr concentrations of foods among different years and different food types. The available activity ratios of Cs-137/Sr-90 in food and water samples demonstrate notable increase in the period of 2015-2017, which further enlightens the potential existence of local radioactive release in the study region, though without causing any radiation safety concerns. This study indicated that all annual effective doses estimated for water and food ingestion were below the permissible limits and recommendations. (C) 2022 The Author(s). Published by Elsevier B.V.