ASSESSMENT OF DOSES FROM INGESTION OF NATURALLY OCCURRING RADIONUCLIDES K-40 AND RA-226 IN RICE CONSUMED IN TAIWAN

This study investigated natural gamma emitting radionuclides 40K and 226Ra in rice consumed in Taiwan. Thirty rice samples, collected from local markets, included 24 local rice and 6 imported rice samples. Radionuclide activities were 24.05 ± 10.21 and 0.62 ± 0.61 Bq/kg for 40Kand 226Ra for all rice samples. The activity of each radionuclide was insignificantly different for local and imported samples (p = 0.33 and 0.52 for 40K and 226Ra, respectively). The annual effective doses from rice consumption were estimated to be 6.80 ± 2.89 and 7.86 ± 7.81 μSv/y for 40K and 226Ra, respectively, and the sum ingestion dose of 226Ra and 40K was 14.66 ± 8.57 μSv/y. These values were one order of magnitude less than the 290 μSv/y world average of the ingestion exposure from natural sources. The results suggest that rice consumption in Taiwan is radiologically safe for the investigated radionuclides.