CBRN event in Kimchaek, Korea, Democratic People's Republic of on Mon 23rd March 2026

A quarter of North Korean defectors from regions near the Punggye-ri nuclear test site in the northeastern part of the country have shown chromosome mutations possibly attributable to exposure to radioactivity, data showed Monday. Radioactive exposure tests conducted in 2024 by the Korea Institute of Radiological & Medical Sciences (Kirams) on 35 North Korean defectors from eight regions near the Punggye-ri nuclear test site found that 12 of them, or 34 percent, showed chromosome mutations possibly linked to radiation exposure, according to the Ministry of Unification. The regions include Kilju, Kimchaek and Paekam. Since 2006, the North has conducted all six of its nuclear tests at the Punggye-ri nuclear test site, located in Kilju County. In similar tests conducted last year, 15 of 59 defectors tested showed possible chromosome mutations, bringing the total number of North Korean defectors with such findings to 44 out of 174 individuals tested between 2023 and 2025, or 25 percent. The tests measure levels of chromosomal aberrations in individuals to assess their accumulated radiation exposure, with a minimum detectable range of 0.25 gray of absorbed radiation from radionuclides such as cesium and iodine. None of those tested has been diagnosed with a radiation exposure-related cancer, and it remains unproven that the mutations were a result of radiation exposure. The tests were conducted as part of the ministry's research on North Korean defectors launched in 2023. A total of 800 defectors from eight regions near the nuclear test site have arrived in South Korea so far. Under the previous Yoon Suk Yeol government, the project was scaled back, while the test results were withheld from public disclosure. A Kirams official called it a "reasonable suspicion" to attribute the high rate of chromosomal abnormalities to possible radiation exposure among defectors from the nuclear site region, emphasizing the need to continue the test project. Yonhap