RADIATION HAZARD INDICES AND EXCESS LIFETIME CANCER RISK IN SOIL, SEDIMENT AND WATER AROUND MINI-OKORO/OGINIGBA CREEK, PORT HARCOURT, RIVERS STATE, NIGERIA.
University of Port Harcourt, Port Harcourt
Accepted 30, October 2014
The growth of human population and rapid industrialization has led to increased use of urban waters as sewers, compromising their other uses. The discharge of industrial effluents has led to inevitably alterations in the quality of the environment. The objective of this work therefore, was to estimate the radiation health hazard indices and excess lifetime cancer risk associated with exposure to river water, soil and sediments from Mini-Okoro/Oginigba Creek. The determined activity concentrations of 238U, 232Th and 40K in all the samples were within the world acceptable values but was higher than results of other works done in similar environment. There were poor correlations between 238U and 232Th, 238U and 40K and 232Th and 40K. The ratio of Th/U for water, sediment and soil samples ranged from 0 to 7.63, 0.54 to 4.72 and 0.17 to 3.64 respectively. Whereas, the ratio K/U and K/Th ranged from 0 to 0.33, 0 to 1.66 and 0.01 to 0.87 and 0.04 to 0.16, 0 to 0.35 and 0.01 to 0.77 for water, sediment and soil respectively. To assess the radiological hazard of river sediments, water and soil ,the radiological hazard indices such as absorbed dose rate, annual effective dose equivalent (AEDE), hazard indices (Hin and Hex),activity utilization index (I), annual gonads dose and excess lifetime cancer risk (ELCR) were calculated and found to be below the internationally recommended values. The contribution of 238U, 232Th and 40K to the effective dose were 56.9%, 27.2% and 15.9% respectively in water, 33.6%, 21.2% and 45.2% respectively in sediment and 71.8%, 14.2% and 14.0% respectively in soil. The results indicate that the radiation hazard from primordial radionuclide in all river water, river sediments and river bank surface soil samples from the area studied is not significant. Therefore there is no immediate radiation health hazard associated with the use of any of the samples studied.
KEY WORDS: Radionuclide, Mini-Okoro/Oginigba, Spectroscopy, lifetime cancer risk, Gonad