Groundwater from an underground nuclear weapons test site in North Korea could be spreading dangerous radioactive material to people living in the country and overseas, according to a report. A study by the Seoul-based Transitional Justice Working Group published Tuesday said eight cities and counties near the Punggye-ri site—where Pyongyang is believed to have carried out six tests between 2006 and 2017—could be affected. Over one million people live in the potentially impacted region, where groundwater is used in daily life, including for drinking. The human rights organization also claimed that people in the neighboring countries of South Korea, China, and Japan could also be at risk due partly to agricultural and fisheries products smuggled out of North Korea.