Radon-222 levels in ground water sources and associated health risks in Bauchi State, Nigeria

Abstract

Radon-222, a naturally occurring radioactive gas, poses significant health risks when present in drinking water, particularly through inhalation and ingestion. This study assessed Radon-222 concentrations and associated radiological health risks in borehole water across seven Local Government Areas in the Northern Agricultural Zone of Bauchi State, Nigeria—a region underlain by uranium-rich geological formations. Groundwater samples were analyzed using Liquid Scintillation Counting (LSC), and quality control measures ensured data accuracy. Health risk assessments followed WHO, USEPA, and ICRP guidelines. Results revealed radon concentrations ranging from 56.37 to 914.46 Bq/L, with a mean of 369.99 Bq/L—substantially exceeding both WHO (100 Bq/L) and USEPA (11.1 Bq/L) limits. While ingestion-related doses remained below the 0.1 mSv/year threshold, the average inhalation dose (16.28 mSv/year) far exceeded the ICRP's 1 mSv/year limit, with an average lung dose of 1.95 mSv/year. The Excess Lifetime Cancer Risk (ELCR) averaged 0.057 (5.7%) and reached up to 0.141 (14.1%) in some locations. These findings indicate a serious public health threat, primarily through inhalation of radon released during domestic water use. Immediate interventions, including effective water treatment methods and public awareness campaigns, are strongly recommended to mitigate cancer risk and safeguard the health of affected communities.