Assessment of Background Ionizing Radiation Level and Radiological Mapping of Funakaye and Nafada Local Government Areas of Gombe State, North-Eastern Nigeria

This study assessed background ionizing radiation (BIR) levels and produced a radiological map of Funakaye and Nafada Local Government Areas (LGAs) of Gombe State, North-Eastern Nigeria. In-situ measurements of absorbed dose rate (ADR) were carried out at 240 strategically selected sampling points (10 per LGA) corresponding to the official electoral wards of each LGA using a Radiacode 110 (RC110) survey meter. Geographic coordinates of each point were recorded with a GPS-enabled device. Radiological health risk indices, annual effective dose equivalent (AEDE) and excess lifetime cancer risk (ELCR) were computed from the measured ADR values. Spatial distribution of radiation levels was visualized using GIS-based Kriging interpolation in ArcGIS. Mean ADR values ranged from 67.11 to 144.13 nGy h⁻¹ in Nafada LGA (overall mean ≈ 102.4 nGy h⁻¹) and from 66.09 to 144.65 nGy h⁻¹ in Funakaye LGA (overall mean ≈ 103.0 nGy h⁻¹). Corresponding mean AEDE values were 0.33–0.71 mSv y⁻¹ (Nafada) and 0.32–0.71 mSv y⁻¹ (Funakaye), all below the ICRP recommended public dose limit of 1.0 mSv y⁻¹. ELCR values ranged from 1.2 × 10⁻³ to 2.7 × 10⁻³ across both LGAs. Elevated levels were recorded around Barwo/Nasarawo (Nafada) and Bage, Kupto and Ashaka (Funakaye), areas associated with mining/quarrying and intensive agriculture. The radiological map identifies these locations as relative hotspots. The study provides the first comprehensive ward-level baseline data and radiological map for Funakaye and Nafada LGAs, supporting future environmental monitoring and public-health decision-making in North-Eastern Nigeria.