As North Korea continued its barrage of missile tests, a new report has said that a large population in South Korea, China and Japan could be exposed to radiation risk.
According to a Seoul-based human rights group, people in North Korea, Japan, South Korea, and China may be exposed to radioactive materials spread through groundwater from an underground nuclear test site.
According to the US and South Korean governments, North Korea secretly conducted six tests of nuclear weapons at the Punggye-ri site in the mountainous North Hamgyong Province between 2006 and 2017.
The study by the Transitional Justice Working Group said that the radioactive materials could have spread across eight cities and counties near the site, where more than 1 million North Koreans live, and where groundwater is used in everyday lives, even for drinking.
The report said that South Korea, China, and Japan might be at risk due mostly due to the agricultural and fisheries products that get smuggled from the North.
The group worked with nuclear and medical experts and defectors and used open-source intelligence and publicly available government and UN reports for the study, which was backed by the National Endowment for Democracy, a non-profit corporation funded by the US Congress, reported Reuters.
"This report is significant in showing that North Korea's nuclear tests could threaten the right to life and health of not only the North Korean people, but also of those in South Korea and other neighbouring countries," said Hubert Young-hwan Lee, the group's chief, and a co-author.
North Korea has said there were no leaks of harmful materials following past nuclear tests, but it did not provide any evidence. North Korea in 2018 had invited foreign journalists to witness the destruction of some of these tunnels, but it confiscated their radiation detectors.
In 2015, South Korea's food safety agency detected nine times the standard level of radioactive cesium isotopes in imported hedgehog mushrooms that had been sold as Chinese produce. But the actual origin of these mushrooms was North Korea, and was later smuggled to China.
The isolated nation first began developing its nuclear capabilities in the 1980s, and has since conducted multiple nuclear tests and launched numerous ballistic missiles.
North Korea has conducted a total of six nuclear tests, the first of which took place in October 2006.
The North Korean government has stated that its nuclear program is intended for self-defence, and that it is necessary to deter potential aggression from the United States and its allies. However, the international community has expressed concerns that North Korea's nuclear program could be used to launch a preemptive strike, or that it could sell nuclear technology to other countries or terrorist organisations.
October 9, 2006: North Korea conducted its first nuclear test at the Punggye-ri Nuclear Test Site in the northeastern part of the country. The yield of the explosion was estimated to be less than one kiloton.
May 25, 2009: North Korea conducted its second nuclear test at the Punggye-ri site. This test had a yield of about two kilotons.
February 12, 2013: North Korea conducted its third nuclear test at the Punggye-ri site. The yield of this test was estimated to be between six and nine kilotons.
January 6, 2016: North Korea conducted its fourth nuclear test at the Punggye-ri site. The yield of this test was estimated to be between six and nine kilotons.
September 9, 2016: North Korea conducted its fifth nuclear test at the Punggye-ri site. This test had a yield of around 10 kilotons.
September 3, 2017: North Korea conducted its sixth and most powerful nuclear test to date at the Punggye-ri site. The yield of this test was estimated to be between 100 and 250 kilotons.
In addition to the Punggye-ri site, there are several other suspected nuclear sites in North Korea, including the Yongbyon Nuclear Scientific Research Center, which is believed to be the country's main nuclear facility.
Other suspected sites include the Kangson uranium enrichment plant and the Chongsu Research Center. However, information on North Korea's nuclear program and facilities is limited, and it is difficult to verify the existence or activities at these sites.
North Korea fired two short-range ballistic missiles into the sea east of the country on Monday in its second test launch in three days. Seoul and Washington have said Pyongyang could be preparing for a seventh nuclear test.
In the last one year, North Korea has launched more than 70 missiles, the most ever. The missile launches have increased since the South Korean and US militaries started conducting larger and more frequent drills, which North Korea sees as preparation for an invasion.
North Korea has claimed to have missiles capable of striking both the US mainland and South Korea with nuclear weapons.