Natural radionuclide activity in food and dietary dose from 226Ra and 228Ra in southeastern coastal India

This study presents the first systematic assessment of dietary radiation exposure among the southeastern coastal population of India using Market Basket Survey (MBS), Canteen Meal Survey (CMS) methodologies. Locally consumed food items collected over a decade were analyzed using high-resolution gamma spectrometry to determine the activity concentrations of 226Ra, 228Ra, 40K, and 137Cs. As the ingestion dose from 40K remains relatively constant due to homeostatic regulation and 137Cs levels were negligible, the annual effective ingestion dose was evaluated based on 226Ra and 228Ra using measured concentrations and regional adult consumption rates. The estimated annual doses were 0.019 ± 0.01 mSv (MBS) and 0.007 mSv (CMS), with the higher MBS value reflecting its conservative nature. Comparison with similar studies from India and other regions indicates that the estimated doses lie within the global range reported for normal background radiation areas. These results provide a site-specific baseline for chronic ingestion exposure and support regional radiological risk assessment and long-term environmental monitoring.