Evaluation of Radon concentration and age-dependent health risks from water samples within selected university environments of Katsina State, Nigeria

Abstract

Groundwater is the principal drinking-water source on Nigerian university campuses, yet its radiological quality, and the age-differentiated radon doses delivered to the students, staff and resident children who depend on it, remains largely uncharacterised, and no comparative campus-scale assessment exists for the semi-arid basement terrain of Katsina State. This study assessed radon gas concentration and associated radiological health risks in drinking water samples collected from three universities in Katsina State, Nigeria: Federal University Dutsin-Ma (FUDMA), Umaru Musa Yar'adua University, Katsina (UMYU), and Federal University of Transportation Daura (FUTD). A total of 30 water samples were analyzed for radon activity concentration, and the annual effective doses (AED) due to inhalation and ingestion were calculated for adults, children, and infants. Total annual effective doses (TAED) and excess lifetime cancer risks (ELCR) were also determined. Radon concentrations ranged from 10⁻⁴ to 1.14×10⁻¹ Bq L⁻¹ at FUDMA, 8×10⁻³ to 1.875 Bq L⁻¹ at UMYU, and 6.1×10⁻² to 12.964 Bq L⁻¹ at FUTD, with mean values of 1.58×10⁻², 6.81×10⁻¹, and 4.501 Bq L⁻¹, respectively. All mean concentrations were below the WHO/UNSCEAR safe limit of 11 Bq L⁻¹. However, the Admin Block at FUTD recorded 12.964 Bq L⁻¹, slightly exceeding this threshold. The mean TAED values remained well below the ICRP reference level of 0.1 mSv yr⁻¹ across all institutions, though FUTD's Admin Block slightly exceeded this limit (0.198 mSv yr⁻¹ for infants). ELCR values were generally within acceptable EPA ranges (10⁻⁶–10⁻⁴), except at FUTD's Admin Block where infant ingestion risk reached 6.61×10⁻⁴, nearing the upper bound of acceptability. Infants consistently exhibited the highest doses and cancer risks across all sites, followed by children and adults. The findings indicate that while most water sources are radiologically safe, localized hotspots, particularly at FUTD require continuous monitoring.