Radiological assessment on Caesium-137 (137Cs) radionuclide contamination from metal recycling facility and its surrounding environment, South - South Nigeria

Background: Radioactive material through scrap metal dealers, is often sold to steel processing facilities, which contaminate products with associated waste ends up in the environment. This study was to conduct radiological assessment of 137Cs contaminated at metal processing facility and surrounding environment at Southern Nigeria as a function of time. Materials and Method: Samples were randomly collected within the facility and at surrounding environment, and analyzed using HpGe detector. Results: The 137Cs concentration ranged (1.61±0.25- 2619.35±133.80) Bq/g, with mean of 417.17±23 Bq/g. The 137Cs concentration at 500 meters from the facility ranged (0.21±0.02- 3.63±0.25) Bq/g with the mean of 1.30±0.16 Bq/g. The 137Cs concentration in the facility was above admissible limit of 100 Bq/g except that recorded at 500 meters away. The radiological hazards within the first year were estimations, which showed Dose through Inhalation Pathways was 6.89x10-3 mSv/yr. Dose through Soil Ingestion Pathways was 0.91 mSv/yr, and Sum External Dose from all the Pathways to be 1.44 x103 mSv/yr. The sum of evaluated radiological risk was found to be higher than the 0.25 mSv/yr or 1 mSv/yr admissible limits. An evaluated Excess Life Cancer Risk was found to be 2.5 quite above admissible limit of (029x10-3). Conclusion: It is inferred from the assessment that, there is a likelihood of radiological health risk due 137Cs contaminated to workers, public and other biota. Therefore, immediate remediation is recommended and as well as restrictions of the public using materials from the area for soil stabilization and farming purpose.