Evaluation of terrestrial radionuclide levels and concomitant radiological risks of bentonites used in many industries

Abstract

Bentonite is a soft, porous, easily shaped, and absorbent material rich in aluminum, sodium, and potassium. Bentonite is a mineral widely utilized as drilling mud, ore pelletizing, absorbent/adsorbent, bleaching agent, water impedance, coating, and raw material in various industries. In this study, radiometric measurements of 90 bentonite samples collected from 21 quarries in Turkey were performed using gamma-ray spectrometry. The radiological hazards caused by indoor exposure to adults due to the utilization of bentonites as raw materials in the construction industry and outdoor external exposures to quarry workers were evaluated by estimating the activity concentration index, annual effective doses, and lifetime cancer risk. The average activity concentrations of Ra-226, Th-232 and K-40 measured in bentonite samples were found as (50 +/- 5) Bq/kg, (76 +/- 4) Bq/kg and (373 +/- 19) Bq/kg, respectively. The evaluation results reveal that the bentonites examined could be safely utilized as raw materials.