Determination of Radiological Health Risk Due to Gamma Exposure from River Water around Oil Bunking Centre in Rivers State, Nigeria

Abstract

Aim: The aim of this study is to assess radiation health risk due to gamma exposure from river water around oil bunkering centers in Rivers state, Nigeria. Study Design: This study was purely an experimental work. Place and Duration of Study: Sampling started from the meeting point of Otamiri tributary and Imo River at the Abia /Rivers boundary to over seven kilometers along the Imo River; between July 2016 and January, 2017. Methodology: 20 samples of river water were collected along coastal shore of Imo River with pre-washed 1.5 ml Polypropylene bottles. The bottles were rinsed with the water before collection and acidified immediately after collection with few drops of nitric acid. The bottles were sealed tightly with vinyl tapes and kept in the laboratory for 4 weeks for secular equilibrium of the radionuclides. The activity concentration of the radionuclides was measured using well calibrated Sodium Iodide detector. Results: The mean activity concentrations of 238U, 232Th and 40K were 2.02±0.02, 3.59±0.21 and 10.43±1.13 BqL-1. The mean annual effective dose estimated for infants, children and adult citizens that ingest river water sampled were 58.64, 0.19 and 0.24 mSvy-1 respectively. The values of annual effective dose for infants and adults exceeded the reference levels of 0.26, 0.2 and 0.10 mSvy-1 respectively while that for children is within the safe reference level. The estimated fatal cancer  risk to adult citizens and the lifetime hereditary effects show that 53 out of 10,000 citizens may suffer some form of cancer fatality and  596 out of 1000,000 citizens may suffer some form of hereditary effect since the values exceeded the USEPA recommended range. Conclusion: The result of this study show that the river water under study has been radiologically impacted by oil bunking activities and may cause significant health risk. Hence few recommendations were made in this work which will help to reduce radiation exposure and possible health impact.