ANNUAL EFFECTIVE DOSE ESTIMATION DUE TO THE NATURAL RADIOACTIVITY IN YAM TUBERS (Dioscorea rotundata) CULTIVATED IN NORTHCENTRAL NIGERIA

Yam tubers (Dioscorea rotundata) and soil from commercially cultivated farmland in northcentral Nigeria were collected and investigated for their natural radioactivity content using a 3” × 3” NaI(Tl) gamma detector. Average activities of 238U, 232Th and 40K in the investigated farm soil were 38.13±3.76 Bq kg-1, 15.06±0.99 Bq kg-1 and 381.80±15.50 Bq kg-1, respectively. The results agree with the world’s acceptable levels of safety. Activities measured in the yam tubers were in the range from BDL -76.68±9.73 Bq kg-1 for 238U, BDL - 19.77±1.30 Bq kg-1 for 232Th and 312.50±20.73 - 627.94±38.37 Bq kg-1 for 40K, with average values of 29.23±4.0, 13.10±0.72 and 445.10±27.20 Bq kg-1, respectively. The total effective dose from radionuclide intake from yam ingestion fluctuated between 272.12 μSv y-1 and 935.97 μSv y-1. Correlation analysis identified 238U and 232Th as the leading contributors to the total effective dose from ingesting yam tubers cultivated in northcentral Nigeria.