230,232Th in milk, meat, and grain in korea

The concentrations of natural radioisotopes 230Th and 232Th in Korean foods were measured by the method of calcium oxalate co-precipitation in addition to the conventional anion-exchange method and alpha spectroscopic measurement. The 230Th concentrations(mBq/kg-fresh) in Korean foods were found to be as follows: milk 0.14~2.45, pork 2.98~8.97, beef 1.94~9.80, chicken 1.22~13.0, rice 0.43~2.35, wheat 0.53~14.4, and soybeans, 8.44~91.6. The 232Th concentrations(mBq/kg-fresh) in Korean foods were found to be as follows: milk 0.01~2.46, pork 0.28~9.32, beef 1.02~5.34, chicken 0.56~4.98, rice 0.32~2.54, wheat 0.53~20.0, and soybeans, 2.30~42.2. The annual internal dose of Th was also estimated. The annual internal dose of 230Th and 232Th in milk was about 0.006 uSv/yr and much lower than that of other countries because of the low intake of milk in Korea compared to other countries. The annual internal dose of 230Th and 232Th in the rice was about 0.043 pSv/yr and highest because rice is the staple food of Kor...