A radiological risk Assessment of 226Ra, 228Ra and 40K isotopes in tilapia fish and its granitic environment in Singida municipality, Tanzania
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Date
2023
Journal Title
Journal ISSN
Volume Title
Publisher
MDPI
Abstract
: Consumption of fish containing elevated levels of radionuclides can lead to undesirable
health effects for consumers. People in the Singida Municipality harvest fish from lakes and ponds
of granite rocks which are linked with hazardous radioisotopes that may be bio-concentrated by
fishes they consume. Currently, no study has ascertained the levels of radioisotopes in fish from
these environments. This study was carried out to analyse the radioactivity levels of 226Ra, 228Ra and
40K isotopes in order to assess the radiological risk associated with Tilapia fish consumption and its
environment in Singida Municipality. Some 51 samples, which included water (20), sediment (20), Nile
tilapia (8) and Manyara tilapia (3), were randomly sampled and composited; then, they were analysed
using a high-purity germanium (HPGe) detector, between May and June 2022. The results revealed
that (i) the activity levels of 228Ra were below the detection limit for fish and water samples, while
in sediment, the combined activity of 228Ra was within the acceptable international levels; (ii) the
mean activity concentrations of 226Ra and 40K in all other samples were within the recommended
levels; (iii) the activities of radionuclides in the samples analysed were high in sediments, followed
by fish, and lastly water; (iv) the bioaccumulation results show that only 40K was bio-accumulated
(with 1.26 in Nile tilapia), while other radionuclides (226Ra, 228Ra) were not bio-accumulated; (vi) the
radionuclide transfer from water to fish was higher compared to the radionuclide transfer from
sediment to fish; (vii) the human effective doses due to consumption of Nile tilapia and Manyara
tilapia were 0.00973 and 0.005 mSv/y, respectively, which is below the 1 mSv/y international limit.
These findings therefore show that the current levels of radioactivity in fish in the study area do not
pose a significant radiological risk to fish consumers. However, more studies on other types of fish
are recommended.
Description
Journal Article
Keywords
Sediment, Water, Radionuclides, Gamma spectrometry, Annual effective dose