Radionuclide Contamination in Soil and Radiological Hazard Assessment from Industrial Areas: A Systematic Review

Abstract

Background: The production of radionuclides as industrial by-products such as radium (²²⁶Ra), thorium (²³²Th), potassium(⁴⁰K), and uranium (²³⁸U) might contaminate the soil and have long-term adverse health effects on the population living near the industrial area. Due to the limited evidence of the associated relation and lack of public awareness of the potential risk, people tend to ignore this concerning issue. Therefore, this study aims to assess the levels of the aforementioned radionuclides in the soil's nearest industrial vicinity and to review the radiological hazard assessments presented in the existing literature. Method: This systematic review was conducted using Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA 2009) on online databases such as PubMed, SpringerLink, Scopus, and ProQuest Health & Medical Complete. The following criteria were included: full-text English journal, studies from 2014 onwards with search keywords of “radionuclide*exposure” AND “radiological hazard” OR “health effect”. Results: A total of 1025 articles were screened and only 7 full-text articles were evaluated. Based on the review, the types of industries that produce ²²⁶Ra, ²³²Th, ⁴⁰K, and ²³⁸U were petrochemical, rare-earth element (REE), and gold mining industries in Saudi Arabia, Nigeria, Thailand, and Malaysia. It was recorded that the range of mean activity concentration of radionuclides; ²²⁶Ra, ²³²Th, ⁴⁰K, and ²³⁸U in soil samples were 37.94-6.56Bq/kg, 151.15-3.76Bq/kg, 380.34-41.02Bq/kg and 41.60-8.80Bq/kg respectively. The range of mean radium equivalent activity was 288.51-24.92Bq/kg, the absorbed dose was 127.00-11.16nGy/h, the annual effective dose was 0.016-0.10mSv/y and the external hazard index was 0.78-0.07. The range of representative gamma index (I?r) and excess lifetime cancer risk (ELCR) were 2.06-0.33 and 0.55x10^-3-0.39x10^-3, respectively. Conclusion: In conclusion, scientific data showed that the released of radionuclides by-products were below the global average according to the values recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) based on the evaluation of activity concentration and radiological hazard assessment. Therefore, more clinical studies are needed to investigate the real impact of certain radionuclides on human health.