Abstract

The presence of radioactive elements in aquatic ecosystems poses environmental and public health risks, particularly in 
communities dependent on water bodies for drinking, agriculture, and fishing. This study analyzed the concentration of 
selected radionuclides (22⁶Ra, 232Th, and 4⁰K) in the fish samples and the gross alpha and gross beta radioactivity in the 
water samples of Lake Edward, Rukungiri District, Uganda, to assess potential radiological impacts on the local popula
tion. Fish samples were collected from the lake and analyzed using gamma spectroscopy. Water samples were collected 
from different zones of the lake and analyzed using liquid scintillation counting techniques. The study measured radio
nuclide activity concentrations, calculated absorbed dose rates and effective doses, evaluated hazard indices for fish, 
and assessed gross alpha and beta radioactivity in water samples. The activity concentrations in fish ranged from 12.76 
to 18.73 Bq/kg for 22⁶Ra, 2.28–4.83 Bq/kg for 232Th, and 165.33–209.06 Bq/kg for 4⁰K. The mean absorbed dose rate (41.00 
nGy/h) and effective dose (0.59 mSv/y) were below global safety limits. Hazard indices for external (0.27) and internal 
(0.31) exposure were well below the recommended threshold of 1. Water activity concentrations also met WHO safety 
standards, though the farming zone exhibited higher beta activity, likely due to agricultural runoff. The results indicate 
that the radionuclide levels in Lake Edward’s water and fish pose no significant radiological risk. However, agricultural 
practices, particularly fertilizer use, may contribute to elevated radionuclide concentrations. Regular monitoring is rec
ommended to ensure long-term environmental and public health safety, with further studies focusing on agricultural 
runoff and its potential impact.