Radionuclide Levels and Dose Estimates in Milk Samples in South Korea

Milk is an essential source of nutrition. This study quantitatively analyzed the concentrations of natural (40K, 226Ra, 232Th) and artificial (131I, 134Cs, 137Cs, 90Sr) radionuclides in 10 domestically produced Korean milk samples using high-purity germanium gamma spectrometry and radiochemical separation methods. The mean activities of 40K and 226Ra were 60.3 ± 4.5 and 0.12 ± 0.02 Bq/kg, respectively, while those of 232Th and artificial radionuclides were below the minimum detectable activities and international regulatory limits. 137Cs and 90Sr levels were <0.05 Bq/kg, considerably lower than the CODEX Alimentarius guideline limit of 100 Bq/kg. Annual effective dose assessments ranged from 0.001 mSv/y (adults) to ∼0.01 mSv/y (1-year-old infants). All values were >1 mSv/y public dose limit recommended by the International Commission on Radiological Protection. Age-specific analysis yielded doses ∼10 times higher in infants than in adults and slightly elevated doses in 15-year-olds owing to bioaccumulation and intake differences. Nonetheless, these increased doses remain extremely low and pose negligible health risks. These results confirm the radiological safety of Korean milk and highlight the importance of continuous monitoring and targeted risk assessment for sensitive populations.