Japan has yet to dispose of arsenic residue from chemical weapons its Imperial army abandoned in China at the end of World War II, a source close to bilateral relations said Wednesday, noting there are calls for the toxin to be sent to Japan.
The arsenic comes from arms that were destroyed in a chemical weapons disposal project in Nanjing, Jiangsu province, from October 2010 to June 2012, the source said, adding the chemical agent also has yet to be eradicated.
The arsenic residue is being temporarily stored in airtight plastic containers in an area in Nanjing controlled by the Chinese military, but it could leak into the soil and cause health risks if hit by floods, the source said.
One option for permanent disposal would be to bury the arsenic in a sealed underground site, but the two governments have yet to agree to this.
Japan started the disposal project in accordance with a bilateral accord in July 1999 whereby it would provide money, technology and facilities to dispose of the weapons.
The Abandoned Chemical Weapons Office of the Cabinet Office said roughly 35,000 chemical weapons had been blown up in Nanjing, and the chemical agents inside them had been detoxified. But the arsenic, as an element, remains and cannot disintegrate any further.
There are thus calls in China to send the residue to Japan, the source said.
But Tsukasa Hirota, deputy chief of the office, said it is "more important" to speed up efforts to dispose of the abandoned chemical weapons than the arsenic residue, indicating a final method of arsenic disposal is not in the offing.
Japan has retrieved some 50,000 chemical weapons in various parts of China, including Nanjing.
The biggest concentration of abandoned chemical weapons is in Haerbaling in Jilin province, where 300,000 to 400,000 arms remain buried.