Radioactivity and elemental oxidation composition in soil from Yangjiang, a high background natural radiation area, China.

Soil is an important source and medium of radionuclides, and the content of radioactivity in soil is crucial for radiological impact evaluation. In this study, twenty soil samples in the high background natural radiation area of Yangjiang, China were collected and analyzed for 226Ra, 232Th, 40K and 137Cs concentrations in order to evaluate the radiological health risk in the area. Results showed that the average activity concentrations of 226Ra, 232Th and 40K are 66 Bq/kg, 109 Bq/kg and 211 Bq/kg, respectively. The calculated radiological parameters of radium equivalent activity (Raeq), absorbed dose rate (D), annual effective dose equivalent (AEDE), internal and external hazard indices (Hin and Hex) show a large variation at different sampling sites. Additionally, the elemental oxidation composition and 40K/K mass ratio in the soil were analyzed to further augment the background information of the high background radiation area in Yangjiang.

Dietary exposure of radionuclides and heavy metals in adult residents in a high background natural radiation area using duplicate diet method.

Intake of radionuclides and heavy metals through food consumption is one of the important pathways for long-term health considerations. In this paper, the dietary exposure to radionuclides (210Pb, 210Po, 226Ra, 228Ra, 40K, 137Cs and 129I) and heavy metals (As, Hg, Pb, Cd and U) of adult residents in the high background natural radiation area (HBNRA) in Yangjiang, China, was comprehensively assessed using duplicate diet method. The estimated effective dose received by the inhabitants in HBNRA from ingestion of radionuclides was 0.33 mSv/y, and the associated lifetime cancer risk was 1.1 × 10-3. Both the dose and cancer risk to humans were at the acceptable range, and showed no difference between the HBNRA and the control area. With respect to heavy metals, the estimated daily intake of heavy metals (DIM) values for As, Hg, Pb, Cd and U in HBNRA were 0.47, 0.03, 15.0, 0.26 and 0.04 µg/kg bw/d, respectively, and the corresponding target hazard quotient (THQ) were 1.58, 0.09, 3.7, 2.56, 0.18. The DIM and THQ of Cd and U in HBNRA were similar to the control area, but the DIM and THQ of Pb were much higher than the corresponding values of 0.39 and 0.03 in the control area. The hazard index (HI) value of heavy metals in HBNRA was almost twice that of the control area. This suggests that the inhabitants in the HBNRA may have a health risk associated with the heavy metals.

Determinations of 210Pb contents in food, diet, environmental samples and estimations of internal dose due to daily intakes.

210Pb in food, diet and environmental samples collected in China during the period of 2015-2017 was analyzed and discussed in this study. The activity concentrations of 210Pb were measured by gamma spectrometry, the average of which in sea food, cereal, mushroom, duplicate diet, soil, sediment, biomass ash and aerosol samples were 1.22 ±â€¯0.69 Bq kg-1 fresh weight, 2.77 ±â€¯0.33 Bq kg-1 fresh weight, 8.2 Bq kg-1 dry weight, 1.21 Bq kg-1 dry weight, 172 ±â€¯44 Bq kg-1 dry weight, 87.2 ±â€¯39.2 Bq kg-1 dry weight, 140 ±â€¯185 Bq kg-1 and 813 ±â€¯520 µBq m-3, respectively. The results were higher than those observed in various countries except for seafood. The annual effective dose due to mushroom, duplicate diet and aerosol were estimated. Furthermore, the transfer factor (TF) of 210Pb from soil to some species of mushroom were also considered. This study provided useful data for radiation protection of the public.