Assessment of radioactivity in sand samples from eastern Nepal in perspective of radiological hazards.

This study investigates the activity concentrations of naturally occurring radionuclides ^226Ra, ^232Th, and ^40K in sand samples collected from 16 major rivers in eastern Nepal, assessing associated radiological health hazards using a NaI (Tl) gamma spectrometer. The average activity concentrations were 24.8 ± 10.1 Bq/kg for ^226Ra, 39.8 ± 16.4 Bq/kg for ^232Th, and 531.3 ± 52.8 Bq/kg for ^40K, with all radiological hazard indices—including radium equivalent activity, absorbed gamma dose, annual effective dose, hazard indices, gamma index, and excess lifetime cancer risk—falling below internationally recommended safety limits. The strong positive correlation between ^226Ra and ^232Th suggests a common geological origin, while ^40K likely originates differently, possibly influenced by agricultural activities. Overall, the findings indicate that river sands from this region pose no significant radiological risk when used as building materials, providing baseline data for future environmental radiation monitoring.