en Radiation Biology Radiation Biology تحقيق بديع Original Research <strong>Background:</strong> 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. <strong>Materials and Methods:</strong> 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. <strong>Results:</strong> 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. <strong>Conclusion:</strong> 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. Equivalent dose, natural radioactivity, gamma ray,scintillation detector, soil, absorbed dose. 203 206 http://ijrr.com/browse.php?a_code=A-10-1-258&slc_lang=en&sid=1 I.R. Ajayi isajayi@yahoo.com 79003194753284600913 79003194753284600913 Yes