Some defectors hailing from areas around North Korea’s nuclear test site have been found to have chromosomal abnormalities, according to a new report, though researchers say they cannot prove this is a result of the country’s nuclear tests.

Seoul’s Ministry of Unification and the Korea Institute of Radiological & Medical Sciences (KIRAMS) announced that 17 out of 80 defectors screened for radiation exposure showed cumulative exposure doses exceeding the minimum detectable limit in stable chromosomal abnormality tests.