Modeling Radionuclide Transfer from Pasture to Milk in Kisoro, South- Western Uganda
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Date
2023-06-30
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East African Journal of Science, Technology and Innovation,
Abstract
Determination of radionuclide transfer from animal feeds to animal products and ingestion transfer
rates is important in assessing internal radiation risk to humans who consume the animal products.
Seventy-nine (79) pasture samples and milk samples were collected from cattle farms in seven sub-
counties. Activity concentrations of radionuclides in the samples were determined using gamma
spectroscopy. Transfer ratios of radionuclides to from pasture to milk were calculated. Ingestion
transfer rates of radionuclide from pasture to cow were also determined. Radionuclide accumulation
to the body of the cow was modeled. Contributions to radiological effects due to accumulation of
radionuclides in the body were estimated. Transfer ratios of uranium and thorium from pasture to
milk varied from 0.07 to 0.17, and 0.05 to 0.17, respectively. The ingestion transfer rates of uranium
varied from 3.1 10-6 to 7.6 10-6 y l-1 while for thorium, the ingestion transfer rates varied from 2.2
10-6 to 7.5 10-6 y l-1. The contribution to radium equivalent (Bq l-1), annual effective dose equivalent
(mSv y l-1), and excess lifetime cancer Risk due to the radionuclide transfer were 0.074, 0.002, and
0.0061 10-3, respectively. Comparing with the safe values of annual effective dose equivalent in
foodstuffs of 0.14 mSv y l-1 which translates to excess cancer risk of 0.42 10-3, these contributions to
radiological effects only account for about 1.5% of the total safe value of excess lifetime cancer risk,
therefore, radionuclide transfer from pasture to milk causes a minimal radiation hazard to the milk
consumers in Kisoro District.