Measurement of Outdoor Ambient Radiation and Evaluation of Radiological Risks of Coastal Communities in Ndokwa East, Delta State, Nigeria

Aim: The aim of this study is to measure the outdoor ambient radiation and evaluate its associated radiological risk parameters of the coastal communities of Ndokwa East.

Study Design: The design of this study is purely experimental work.

Place and Duration: This study was carried out in five coastal communities of Ndokwa East. Methodology: Measurement of outdoor ambient radiation of the five coastal communities was done using a Radalert-200 nuclear radiation monitor (S.E international, inc. Summer town, USA), containing a Geiger Muller tube capable of detecting α, β, γ and X-rays within the temperature range of -10° to 50°C, and a geographical positioning system (GPS) were used to measure the precise location of sampling. Measurements were repeated six times at each site on different days within the 1 months to take care of any fluctuation in the environmental temperature, and this was repeated for 6 months in which the monitoring was carried out.

Results: The values of radiation exposure obtained range from 7.00 ± 0.05 µRh-1 (3.12 ± 0.45 µSv/week) in Asemuku08 and Okpai01 communities to 29.00 ± 0.021 µRh-1 (8.46 ± 2.05 µSv/ week) in Okpai 07 near oil and gas drilling company site. The estimated mean outdoor absorbed dose rate for the five coastal communities ranges from 77.20 to 113.07 nGyh-1.The mean annual effective dose equivalent estimated for the five coastal communities ranges from 0.143 to 0.173 mSvy-1while the mean estimated excess lifetime cancer risk ranges from 0.495 × 10-3 to 0.607 × 10-3 which were higher than the world level of 0.29× 10-3.

Conclusion: The result of this studies clearly show that those coastal communities have been radio logically polluted by the oil and gas activities and farming practices in the area. Though these values obtained may not cause immediate health problems there is a probability of long term health risk on the residents of these communities.