Artisanal mining of monazite and cassiterite in the Amazon: Potential risks of rare earth elements for the environment and human health

Artisanal mining is intensely carried out in developing countries, including Brazil and especially in the Amazon. This method of mineral exploration generally does not employ mitigation techniques for potential damages and can lead to various environmental problems and risks to human health. The objectives of this study were to quantify the concentrations of rare earth elements (REEs) and estimate the environmental and human health risks in cassiterite and monazite artisanal mining areas in the southeastern Amazon, as well as to understand the dynamics of this risk over time after exploitation. A total of 35 samples of wastes classified as overburden and tailings in active areas, as well as in areas deactivated for one and ten years were collected. Samples were also collected in a forest area considered as a reference site. The concentrations of REEs were quantified using alkaline fusion and ICP-MS. The results were used to calculate pollution indices and environmental and human health risks. REEs showed higher concentrations in anthropized areas. Pollution and environmental risk levels were higher in areas deactivated for one year, with considerable contamination factors for Gd and Sm and significant to extreme enrichment factors for Sc. Human health risks were low (< 1) in all studied areas. The results indicate that artisanal mining of cassiterite and monazite has the potential to promote contamination and enrichment by REEs.

Health risk assessment of radioactive footprints of the urban soils in the residents of Dera Ghazi Khan, Pakistan

The aim of the study was to evaluate the radiation levels, radiological doses and excess lifetime cancer risk possessed by the urban soils that were collected from the vicinity of the exclusive mining and excavation centers of Dera Ghazi Khan. The high purity germanium detector was utilized for assessment of naturally occurring radionuclides (NORMs) in soil and results showed that the average activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K (37 Bq/kg, 43.07 Bq/kg, 737 Bq/kg respectively) surpassed the world's average documented values (35 Bq/kg, 30 Bq/kg, and 400 Bq/kg respectively). Moreover, the average values of radiological hazards assessment like radium equivalent, internal and external hazard indices, absorbed dose rate, annual gonadal dose equivalent and excess lifetime cancer risk were 155.70 (Bq/kg), 0.4, 0.5, 73.96 (nGy/h) 90.73 (μSv/y), 476.24 (μSv/y) and 0.31(10^-3) respectively. The data acquired was analyzed using descriptive statistics, cluster analysis and principal component analysis. ArcGIS (10.5) software was utilized for developing maps of radionuclide's concentration for the study area. Results of the study may serve as an important baseline radiometric data for future epidemiological studies and monitoring initiatives in the study area.