A review on radionuclide pollution in global soils with environmental and health hazards evaluation

Abstract

Human populations are being exposed to a wide spectrum of radiation from soils as a result of the availability of radiation sources. Assessing the ecological and health effects of radionuclides in soils is crucial to support the optimal soil management practices but large-scale studies are limited. This study compiled data on radionuclides (²²⁶Ra, ²³²Th, ⁴⁰K, ²³⁸U, and ¹³⁷Cs) in soils located across the world (44 countries and 159 places) between 2008 and 2022 and applied radiological hazards indices and several multivariate statistical approaches. The average activity concentration (Bq/kg) of ²²⁶Ra, ²³²Th, ⁴⁰K, ²³⁸U, and ¹³⁷Cs were 408.56, 144.80, 508.78, 532.78, and 83.12, respectively, whereas ²²⁶Ra, ²³²Th, ⁴⁰K, and ²³⁸U exceeded the standard limits. The principal component analysis explained more than 91% of variation in soils. Based on the geoaccumulation index, ⁴⁰K posed moderately to heavy contamination whereas ²³⁸U and ²²⁶Ra posed moderate contamination in soils. Moreover, the mean values of radiological hazards evaluation such as radium equivalent activity (487.17 Bq/kg), external radiation hazard indices (1.32), internal hazard indices (2.15), absorbed dose rate (247.86 nGyh^-1), annual effective dose rate (1.82 mSvy^-1), activity utilization index (4.54) and excess lifetime cancer risk (63.84 × 10^-4) were higher than recommended limit suggesting significant radiological risks in study region soils. The findings indicated that the study area soils were contaminated by radionuclides and unsafe for hazards in terms of the health risks linked with studied radioactive contents. The study is valuable for mapping radioactivity across the globe to determine the level of radioactivity hazards.

Keywords: Absorbed dose rate; ELCR; Geoaccumulation index; PCA; Radionuclide; Soils.