Background: Long-term exposure to environmental radioactivity and the associated external exposure due to gamma emitting radionuclides have serious health effects particularly on cancer risk. Of course, the soil radioactivity depends on the underlying rocks and consequently, the soil type and geographic conditions.Objectives: Evaluation of excess life time cancer risk due to natural radioactivity of the soil of the surface layer of the Nichahoma lignite belt and the soil of villages surrounding the lignite belt.Methods: In this particular study, stirring radionuclides of the Ra226, Th232, and K40 present in the soil samples of the lignite belt and soil of the villages surrounding the lignite belt were measured by using a low-background Pb-shielded gamma spectroscopic counting assembly utilizing NaI(Tl) detector for the measurement and to evaluation the radiation hazard indices and excess lifetime cancer risk.Results: The excess lifetime cancer ranged from 0.65×10-3 to 0.71× 10-3 (average ~0.68×10-3) for the soil of the lignite belt and from 1.15×10-3 to 1.34×10-3(average ~1.25×10-3) for the soil of the villages surrounding the belt. The correlation analyses, performed between the radium equivalent activity and excess lifetime cancer risk for the two types of the sample, showed a very strong and linear dependence of excess lifetime cancer risk on radium equivalent activity and measured dose rate for the soil of the lignite belt compared to the soil of the villages surroundingthe lignite belt.Conclusion: Compared to the world average, the average value of computed excess lifetime cancer risk for both the categories of investigated samples in the study was found to be higher than 0.29. JMS 2018: 21 (2):101-108
Determination of the Radiation Hazard Indices and Excess Lifetime Cancer Risk in Iraqi Bentonite