Uncontrolled disposal of oilfield produced water in the surrounding environment could lead to soil contamination by naturally occurring radioactive materials (NORM). Large volumes of soil become highly contaminated with radium isotopes (226Ra and 228Ra).
The concentration of the naturally occurring radionuclides 226Ra, 232Th and 40K in the contaminated soil were determined using gamma ray spectrometry in order to assess the radiological health hazards and excess lifetime cancer risks associated with the use of the soil. The mean activity concentrations of 226Ra, 232Th and 40K were found to be 1939.56, 737.86 and198.21 Bq kg_1, respectively. The results of the radiological indices and annual effective dose & cancer risk estimated by RESRAD obtained in this study were all higher than their worldwide mean values. This indicating the danger of discharging the produced water resulting from oil and gas production into evaporation ponds without taking preventive measures that limit soil contamination and thus limiting workers' exposure to natural radioactive materials.