Radiological and stochastic risk assessments of natural radionuclides in soils of selected hospital waste sites in Anambra State, southeastern Nigeria

Abstract

Abstract The study focused on measuring radionuclides in 52 soil samples collected around three hospital dumpsites in Anambra State using gamma-ray spectrometry and assessing the associated radiological risks. The average activity concentrations (Bq/kg) of the natural occurring radionuclides ( 226 Ra, 232 Th, and 40 K) in soils of ANA1 (39.02 ± 18.97, 44.71 ± 23.52, and 72.97 ± 54.18), ANA2 (45.42 ± 21.10, 54.52 ± 26.52, and 140.74 ± 67.51), and ANA3 (52.10 ± 26.16, 66.73 ± 30.03, and 157.55 ± 86.64) were above global recommended averages for 226 Ra and 232 Th, with more than 60% of the samples having their concentrations above global averages. The radiological effects (average) indicated that the absorbed dose rate for ANA2 and ANA3 was above the threshold; the Representative Level Index and Excess Lifetime Cancer Risks for the study areas were high, close to their permissible values; and the Annual Gonadal Equivalent Doses for the study areas were above the recommended value. Other estimated radiological indices were within their acceptable limits. The statistical analyses showed high variability and heterogeneous spatial patterns, with near-normal distributions, suggesting anthropogenicity influenced concentrations. Stochastic risk assessments using Monte Carlo simulation revealed high risks of cancer effects over long-term exposure. The study reinforced concerns about radiation exposure near hospital waste sites and the urgent need to develop effective mitigation strategies to reduce risks.