Résumé
The γ radiation exposure due to radioactivity concentration of 40K, 238U and 232Th in soil samples from 250 different locations from 40 communities in the oil – producing region of Nigeria was carried out. The radioactivity concentrations of these radionuclides were used to determine the absorbed dose, annual effective dose equivalent, the health hazard indices and cancer risk using standard analytical methods. The range of values for the absorbed dose are 6.97 nGyh-1 to 33.29 nGyh-1, annual effective dose equivalent (outdoor) are 8.55 μSvy-1 to 40.83 μSvy-1 and (indoor) are 34.19 μSvy-1 to 163.36 μSvy-1. The external hazard index ranges from 0.038 to 0.174 while the internal health hazard index is from 0.045 to 0.191. The cancer risk obtained for the communities ranges from 0.030 x 10-3 to 0.143 x 10-3. All these values are below the standard limits when compared to the world permissible United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR) values for such environment. This shows that the exploration and exportation of crude oil in Nigeria did not pose a radioactive health hazard to the oil producing communities.
Résumé
Radioactivity measurements were carried out in and around Warri Refining and Petrochemical Company in the Niger Delta region of Nigeria for the naturally occurring radionuclides of 40K, 238U and 232Th. The values were used to determine the excess lifetime cancer risk (ELCR) and the radiation health hazard indices. Results show that the ELCR value within the company premises is 0.12×10-3 while the highest value was 0.17×10-3 from Ugborikoko Community. The internal health hazard index ranged from 0.02 – to 0.64 and the external health hazard index ranged from 0.02 – 0.33. All these values were less than the world permissible standards. It could be concluded that the potential carcinogenic risk from gamma radiation doses to the population in and around the refining and petrochemical company is low.