Assessment of natural radionuclides levels in drinking water from Ogun State, Nigeria

Abstract

Naturally occurring radionuclides levels of 238U, 232Th and 40K were investigated in the water samples collected at different boreholes in all the local government of Ogun State using high-purity germanium (HPGe) detector (Canberra Industries Inc.). The activity concentrations measured from the water samples ranged from 0.06 to 1.37 Bq l-1 for 238U, 0.15 to 0.52 Bq l-1 for 232Th and 1.35 to 12.74 Bq l-1 for 40K. The measured activities concentrations for 238U, 232Th and 40K along with their ingested dose conversion factors were used to estimate the annual effective doses in accordance with International Commission on Radiological Protection (ICRP) based on age groups 0 -1y, 1-2y, 2-7y, 7-12y, 12-17y and >17y for water consumption. The total annual effective doses calculated varied from 0.004 to 0.517, 0.002 to 0.092, 0.001 to 0.078, 0.001 to 0.076, 0.024 to 0.110 and 0.002 to 0.117 for the age groups accordingly. The physiochemical results showed that 85% of the water was acidic as they have pH less than 6.5 and 65 % of them exceeded the copper concentration recommended limit. It revealed that consumption of the water is safe from natural background radiation for all groups except 0-1 y as the annual effective dose obtained for this group exceeded the average world limit (0.12). The study therefore, suggests that Ogun State populace should use less of these water samples for babies between the age 0-1 year.