Determination of 40K, 226Ra and 228Ra concentrations with dose rates in crayfish from Ode Omi River and radiological implications to the consumers

Abstract

Natural radionuclides such as ⁴⁰K, ²²⁶Ra and ²²⁸Ra are found naturally in water and sediments of rivers, likewise in soils. They are transferred to aquatic animals through ingestion. Radioactivity concentrations and dose rates of ⁴⁰K, ²²⁶Ra and ²²⁸Ra in crayfish species from Ode Omi River in coastal region, Ogun State Southwest of Nigeria were determined by gamma spectrometry using NaI (TI) detector coupled with a pre-amplifier base to a multiple channel analyzer (MCA). 15 samples of crayfish were collected. Cherax tenuimanus had the highest mean concentration and dose rate of values 106.87 ± 9.11 Bq kg^–1 and 0.00960 mGy hr^–1 respectively for ⁴⁰K. Moreso, for ²²⁶Ra, Cherax quadricarinatus had the highest mean concentration and dose rate of values 2.57 ± 0.82 Bq kg–1 and 4.50 x 10–7 mGy hr^–1 respectively. Concerning228Ra, Astacopsis gouldi had the highest mean concentration and dose rate of values 5.23 ± 0.46 Bq kg–1 and 5.86 x 10–13 mGy hr^–1, respectively. The average dose rate of the radionuclides in all the crayfish was calculated to be 4.62 x 10 ̶ 3 mGy hr^–1 which was below the 0.4 mGy hr^–1 limit recommended. The average annual committed effective dose and average excess lifetime cancer risk of all the radionuclides to the consumers were 0.0807 mSv yr^–1 and 0.589 x 10^–4, respectively, which were below global limits of 1.0 mSv yr^–1 and 0.29 x 10^–3, respectively, therefore, the ingestion of these natural radionuclides could not pose any radiological health hazards to the aquatic animals, likewise man the consumers.

Keywords: Radionuclide concentration, Dose rate, Cancer Risk.