Assessment of K-40 and Cs-137 radioactivity concentrations and annual effective dose due to ingestion of staple foods in South Korea.

Abstract

The Korea Institute of Nuclear Safety (KINS) has designated Rice and Napa cabbage, which account for a large proportion of the Korean diet, as staple foods for continuous radioactivity monitoring. Assessing internal exposure from food ingestion is essential for public health and radiation safety. This study evaluated the radioactivity concentrations of these foods and quantified annual effective doses from their ingestion. Samples of Rice and Napa cabbage collected from 15 regions nationwide from 2014 to 2023 by Regional Radioactivity Monitoring Stations (RRMSs) were analyzed for K-40 and Cs-137. Soil types were classified using the United States Department of Agriculture (USDA) soil texture triangle, and regional variations in food radioactivity concentrations were assessed relative to soil texture. Based on these data and intake statistics from the Korea National Health and Nutrition Examination Survey, the annual effective dose from K-40 ingestion was calculated using the International Commission on Radiological Protection (ICRP) dose conversion factor of 0.062 μSv/Bq. K-40 concentrations ranged from 1.65 to 75.6 Bq kg-1-fresh in Rice and 10.4-122 Bq kg-1-fresh in Napa cabbage, with cabbage averaging about three times higher. The estimated annual effective doses were 7.53 μSv for Rice and 10.1 μSv for cabbage, corresponding to ∼0.7 % of natural background exposure (2400 μSv y-1) and ∼5.8 % of the dose from total food ingestion (290 μSv y-1). These results demonstrate that the radiological impact of staple food consumption in South Korea is negligible and provide a scientific basis for food-based environmental radioactivity monitoring and radiological emergency preparedness.