Radionulide analyses of ingested water from some estuaries within the coastal area of Akwa Ibom State, Nigeria

Abstract

Radionuclide analyses of ingested water from three selected estuaries within the coastal areas of Akwa Ibom State, Nigeria have been carried out. Fifteen water samples collected at strategic points from the estuaries were pre-treated and each placed on the sodium iodide NaI (Tl) -model 802 detector for 3600 s to obtain the gamma radiation count rate. The activity concentrations and other radiological risk parameters were computed. The effective dose rate of radiation due to ingested water (E.D.I.W.) ranged between 0.25 and 1.86 mSv yr, the effective equivalent dose rate due to absorbed radiation in air (Deq) ranged between 0.0065 and 0.0369 mSv yr and the total equivalent dose rate of radiation ranged between 0.257 and 1.87 mSv yr. The E.D.I.W exceeded the International Commission on Radiological Protection (ICRP) permissible limit of 0.1 mSv yr set for ingested radionuclides from food. Most surveyed points had their total equivalent dose rate of radiation greater than the ICRP permissible dose limit of 1 mSv yr for radiation exposure from all internal and external sources. The annual gonadal dose equivalent ranged between 0.008 and 0.041 mSv yr and are below the world average value of 0.3 mSv yr. The excess lifetime cancer risk ranged between 0.7 × 10 and 5.07 × 10 and are above the world average value of 0.29 × 10. The elevation of most of the radiation risk parameters over the standard limits shows that oil production activities may have raised the background radiation levels of the area. This research also revealed that computing only the Deq and neglecting the E.D.I.W would mean under estimating the radiation doses received by an impacted person by 97.4%-98.3%. Water consumed from these sources could enhance the radionuclide content and the percentage probabilities of developing cancer by impacted persons.