Radiological Risk Assessment of Naturally Occurring Radionuclides in Commonly Consumed Stimulants in Akwa Ibom State, Southern Nigeria

Abstract

This study aims at evaluating the presence and potential health risks of naturally occurring radioactive materials (NORM) such as Uranium-238 (²³⁸U), Thorium-232 (²³²Th), and Potassium-40(⁴⁰K) in selected stimulants commonly consumed in Akwa Ibom State, Southern Nigeria. Ten representative stimulant samples, including kola nut, bitter kola, ginger, turmeric, marijuana, ginseng, cloves, cocoa seed, snuff, and wonder kola, were procured from local markets and analysed using gamma spectrometry with a sodium iodide (NaI(Tl)) detector. The specific activity concentrations of ²³⁸U, ²³²Th, and ⁴⁰K ranged from 16.06–31.47 Bq/kg, 1.54–3.76 Bq/kg, and 1.56–2.53 Bq/kg, respectively. Radiological indices such as absorbed dose, committed effective dose (CED), annual gonadal equivalent dose (AGED), excess lifetime cancer risk (ELCR), radium equivalent activity (Ra eq.), gamma index, and both internal and external hazard indices were computed. All measured values were below the safety thresholds established by UNSCEAR, ICRP, and WHO, indicating negligible radiological health risk from the consumption of these stimulants. The highest activity and associated risk indices were observed in cloves (CZ) and bitter kola (BK), while ginseng (G5) and ginger (GN) recorded the lowest. Pearson correlation and heat-map analyses demonstrated strong relationships between radionuclide activity and derived radiological parameters. This study provides essential baseline data for radiological food safety in the region and underscores the importance of routine monitoring to safeguard public health.