An Original Investigation of the Radiobiological Basis of Low-Dose Diagnostic Radiation Risks in Nigerian Populations: Polymorphism, Repair Kinetics, and Epidemiological Implications

The risk of radiation-induced cancer from diagnostic imaging exposures is extrapolated from high-dose atomic bomb survivor data using the linear no-threshold model, yet emerging evidence on DNA repair polymorphisms, adaptive responses, and population-specific radiosensitivity suggests that risk estimates may require population-specific calibration that has never been investigated in Nigerian populations. This study conducts an original investigation of the radiobiological determinants of diagnostic radiation cancer risk in Nigerian populations, combining molecular genetic, cellular radiobiology, and epidemiological approaches. Phase one characterises DNA double-strand break repair kinetics and repair gene polymorphisms (XRCC3, BRCA2, ATM) associated with radiosensitivity in a biobank of 500 Nigerian blood donors from three geopolitical zones. Phase two uses gamma-H2AX foci assay to quantify DNA damage and repair in peripheral lymphocytes from 120 Nigerian participants exposed to CT-equivalent diagnostic radiation doses ex vivo, comparing repair kinetics across polymorphism genotypes. Phase three constructs a Nigerian-population-adjusted radiation risk projection model using organ dose measurements, population demographics, and repair kinetics data. The original contribution is a Nigerian Population Radiobiological Risk Model incorporating local genetic polymorphism data and repair kinetics, the first such model developed for a sub-Saharan African population. Available radiobiology literature identifies significant inter-population repair capacity differences that are insufficiently incorporated in current radiation risk models. The Linear No-Threshold Model, the Radiation Biology Framework, and the Hardy-Weinberg polymorphism analysis provide the theoretical reference. Keywords: radiobiology, DNA repair, radiation risk, Nigerian population, diagnostic radiation.