Abstract
The study presents a radiometric survey of Background Ionizing Radiation (BIR) dose levels in ten quarry sites located in Ebonyi State, Nigeria. In-situ BIR dose rate measurements, by means of nuclear radiation survey meter, at 1 m above ground level were carried out at the excavation section (ES) and quarrying section (QS) of the investigated quarry sites. The obtained results indicated dose rates ranging from from 0.14 to 0.18 μSv/h with mean of 0.15±0.01 μSv/h at the ES and 0.16 to 0.19 μSv/h with mean value of 0.18±0.01 μSv/h at the QS. While the values obtained at the QS are respectively higher than those measured at the ES, they are all higher than the worldwide average value of 84 nSv/h signifying BIR elevated environments. The estimated mean annual effective dose (AED) and excess lifetime cancer risk (ELCR) are 0.27±0.03 mSv/y and 0.94×10–3 respectively at the ES and 0.31±0.02 mSv/y and 1.07×10–3 at the QS. The obtained AED values for all the sites are well above the outdoor worldwide average value of 0.07 mSv/y but lower than the International Commission on Radiological Protection recommended permissible limits of 1.0 mSv/y for the general public. Generally, the BIR levels of the quarry sites are within acceptable limits and no immediate radiological health threat may be derived from the current levels. However, long-term health effects due to continuous exposure to low-level radiation doses may manifested in future over a lifetime exposure of 70 years as indicated by the ELCR values.
 Keywords: Background ionizing radiation, Dose rate, Annual effective dose, Quarry site, Ebonyi State
Highlights
MATERIALS AND METHODSStudy locations: Generally, the study location, Ebonyi State, Nigeria lies between 6°15ꞌN and 8°05ꞌE with low-lying to gentle undulating terrain of about 85-100 m above sea level and punctuated by few isolated lowhills (Ezepue et al, 1984)
The study presents a radiometric survey of Background Ionizing Radiation (BIR) dose levels in ten quarry sites located in Ebonyi State, Nigeria
The present study was designed to measure the background ionizing radiation (BIR) dose levels of some quarry sites located in Ebonyi State, Nigeria
Summary
Study locations: Generally, the study location, Ebonyi State, Nigeria lies between 6°15ꞌN and 8°05ꞌE with low-lying to gentle undulating terrain of about 85-100 m above sea level and punctuated by few isolated lowhills (Ezepue et al, 1984). The state is situated on the plains of Southeastern Savanna belt and southern end of the lower Benue trough of Nigeria (Chiadikobi et al, 2011). The state is associated with the occurrence of igneous intrusion and volcanic with sedimentary rocks. The sites were carefully selected in such a way as to cover all the local government areas of the state where quarrying is actively functional (Figure 1) and to cover the different geological formations that exist in the state
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