An evaluation of the equivalent dose due to natural radioactivity in the soil around the consolidated Tin mine in Baukuru-Jos, plateau state of Nigeria

Background: The equivalent dose in the human body due to the natural gamma-emitting radionucides (238U, 232Th and 40K) in the surface soil surrounding the Consolidated Tin mine site in Bukuru-Jos, Nigeria has been determined in this study. Materials and Methods: Measurements of the soil natural radioactivity were made using a multi-channel pulseheight analyzer (Canberra Series 10 plus) coupled to a 76 mm×76 mm Nal (Tl) scintillation detector. Results: The mean concentrations obtained for each of the radionuclides is 35.4±17.6 Bq/kg for 40K 776.0± 158.0 Bq/kg for 238U and 2.72±0.58 kBq/kg for 232Th. The mean absorbed dose rate due to natural radioactivity calculated at a height of 1.0 m above the ground is 2.16 µGy/hr which converts to an equivalent dose of 3.0 mSv/y. Conclusion: The results obtained in this study are far above the world average equivalent dose of 0.41 mSv/y but lower than the annual limit of 20 mSv/y for radiation workers but still represents a health risk to workers on the site.