Radiological health risk assessment of borehole water in Arua City, Northern Uganda

Access to safe drinking water is essential for public health. In Arua City, Northern Uganda, boreholes serve as a primary water source, but their safety may be compromised by radionuclide contamination. This study assessed the radiological quality of borehole water in Arua City, Northern Uganda, with a focus on activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K, the associated Annual Effective Dose (AED), and Excess Lifetime Cancer Risk (ELCR). Water samples were collected from six boreholes across three divisions: Ayivu East, Ayivu West, and Arua City Central. Gamma spectrometry was used to quantify radionuclide concentrations, and risk indices were calculated based on international dose conversion factors. The activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K, ranged from 0.191-0.971 Bq·L⁻¹, 0.025-0.244 Bq·L⁻¹, and below detection limit to 4.36 Bq·L⁻¹, respectively. ANOVA revealed significant differences in ²²⁶Ra concentrations between Ayivu East and the other divisions. The AED values varied between 47.3 and 234.9 μSv·y⁻¹, with all boreholes in Arua City Central exceeding the WHO guidance level of 100 μSv·y⁻¹. ELCR values ranged from 1.89 × 10⁻⁴ to 9.39 × 10⁻⁴, with the highest risks recorded in BH4-C and BH5-C. The results indicate that certain boreholes in Arua City may pose radiological health risks and require monitoring and mitigation to ensure water safety.