Abstract:
There is extensive contamination of the aquatic environment when rivers and streams flow
through areas of high human activities such as industrial cities and major towns. These
contaminations may include enhanced background levels of naturally occurring
radioactive materials resulting from rapid urbanization and other human activities. The
natural radionuclides (40K, 238U and 232Th) contents in farm-raised and wild catfish
(Clarias gariepinus ) from five fish farms and three major rivers within Ibadan metropolis
have been studied using gamma-ray spectrometry technique. The results shows that the
average committed effective dose through the consumption of catfish were 4.68 ± 0.17
and 7.31± 0.21 μSv/y for farm-raised catfish and 11.97 ±0.12 and 21.26±1.7 μSv/y for
wild catfish in adult and children of ten (10) years, respectively. The excess lifetime
cancer risk due to the consumption of catfish in farm and river was calculated to be
1.5x10-6 and 2.46x10-6 in farm-raised catfish and 1.6x10-6 and 2.6x10-6 due to intake of
wild catfish for adult and children of ten (10) years, respectively in the study area which is
within the USEPA acceptable limit for excess lifetime cancer risk ranging between 1x10-6
and 1x10-4. It can be concluded that the consumption of catfish poses no significant
radiological hazards to the population of the study area.
