Evaluation of Radiological Hazard Indices Due to Radioactivity in Quarry Sites in Itu, Akwa Ibom State, Nigeria

Abstract

The radiological hazard indices due to the radioactivity in soils at quarry sites in Ayadehe, Oku Iboku, Odiok Itam and Ntak Inyang villages in Itu Local Government Areas of Akwa Ibom State, Nigeria were evaluated. Soil samples were randomly collected at the depth of 30 cm in different locations from each of the quarry site. The radionuclide activity concentrations in the soil samples were measured using gamma spectroscopy method. The average values of 40 K, 238 U and 232 Th obtained is (143.54+7.56) BqKg -1 , (2.47+0.26) BqKg -1 and (3.70+ 0.22) BqKg -1 respectively for Ayadehe, (73.69+3.89) Bqkg -1 ,(2.04+0.24) BqKg -1 and (2.85+0.17) BqKg - 1 for Oku Iboku, (33.96.54+1.79) BqKg -1 , (8.84+0.92) BqKg -1 and (3.01+ 0.22) BqKg -1 for Odiok Itam and (63.77+3.34) Bqkg -1 , (7.81+0.84) BqKg -1 and (2.31+0.14) BqKg -1 for Ntak Inyang quarry sites. The average values obtained for radium equivalent, absorbed dose rate, annual effective dose equivalent, internal hazard index, external hazard index and excess lifetime cancer risk are 18.81 BqKg -1 , 9.80 nGyh -1 , 0.0614mSvy -1 , 0.1491, 0.0574, 0.0444 and 0.2163x10 -3 respectively for Ayadehe and 11.78 BqKg -1 , 5.93 nGyh -1 , 0.0365 mSvy -1 , 0.0912, 0.0373, 0.0315 and 0.1291x10 -3 respectively for Oku Iboku, 15.74 BqKg -1 , 7.22nGyh -1 , 0.0582 mSvy -1 , 0.1115, 0.0664, 0.0436 and 0.2046 x10 -3 respectively for Odiok Itam and 16.04 BqKg -1 , 7.61 nGyh -1 , 0.0933mSvy -1 , 0.1117, 0.0644, 0.0433 and 0.1850x10 -3 respectively for Ntak Inyang quarry sites. The values for the indices obtained when compared with their corresponding world permissible limits were found to be below the standard limits for such environments. Therefore the level of exposure at the study areas presently poses no significant health threat; hence, the quarry products of these areas can be used as building material.