Radiological assessment of radionuclides in fishes and health risks on the consumer from Ijagun River in Ijebu area of Ogun State

Abstract

Authors: Olusegun Sowole*, Mary Abidemi Faleke, Adetokunbo Abayomi Okusanya and Temitope

Olasile Fowodu

Natural radionuclides have specific half lives and are capable of disintegrating with the release of ionizing radiations along with huge amount of energy which can be so harmful to living organisms. Activity concentrations and radiological indices of ⁴⁰K, ²²⁶Ra and ²²⁸Ra in fish species from Ijagun River in Southwest of Nigeria where mining activities are taking place,  had been determined by gamma spectrometry method  using NaI (TI) detector coupled with a pre-amplifier base to a multiple channel analyzer (MCA). Twenty (20) samples of fishes were collected from the River having four (4) species: Hemichromis fasciatus, Clarias gariepinus, Foerschichthys nigeriensis and Clarias anguillaris. The samples were collected at distance of 15m – 30m location from one another along the River with the use of fishing net. The highest dose rates of ⁴⁰K, ²²⁶Ra and ²²⁸Ra were obtained in Clarias gariepinus of values 0.407 x 10^-4mGyhr^-1, 0.951 x 10^-9mGyhr^-1 and 0.629 x 10^-15mGyhr^-1 respectively. The highest annual committed effective dose of ⁴⁰K to man the consumer was 0.0450mSvyr^-1 from Clarias gariepinus, that of ²²⁶Ra was 0.2286mSvyr^-1 from Foerschichthys nigeriensis and that of ²²⁸Ra was 0.5654mSvyr^-1 from Hemichromis fasciatus .The highest excess lifetime cancer risk of ⁴⁰K to the consumer was 0.1574 x 10^-3, that of ²²⁶Ra was 0.8002 x 10^-4 and ²²⁸Ra was 1.9788 x 10^-4. All the values obtained were within the limits recommended globally; indicating that there was no significant radiological health risk to the aquatic animals and man the consumer.