For the first time in 30 years, the Environment Ministry decided in April to begin a nationwide inquiry into poison gas used by the Japanese military before and during World War II.
Last November, Chief Cabinet Secretary Yasuo Fukuda spoke negatively about resuming the search, saying safety measures have been taken against the gas everywhere in Japan.
But apparently this stance has changed. Whatever the reason for the change of heart, I welcome the government's decision to look into the situation again.
I believe arsenic poisoning of residents of Kamisu, Ibaraki Prefecture, in April prompted the government to change its stance.
Residents who drank water from wells developed symptoms such as dizziness and numbness in their limbs. Their sickness is believed to have been caused by a vomiting gas, a form of poison gas produced by the former Imperial Japanese Army.
It is believed the symptoms were caused not by the toxicity of the vomiting gas itself, but by a substance produced as a result of the gas' decomposition.
Lewisite, an arsenic-based fluid that causes sores and blisters, was found last autumn in old beer bottles in Samukawa, Kanagawa Prefecture.
In the search conducted 30 years ago, both Kamisu and Samukawa cases were undetected. The past six months has exposed the inadequacy of the previous investigation into the issue. I urge the Environment Ministry to conduct a more thorough search this time.
But there is another matter that must be dealt with without delay: The ministry should immediately dispose of vomiting gas buried in a resort facility under its jurisdiction on Okuno island off Hiroshima Prefecture. The island housed a chemical-weapons factory operated by the former Japanese army, and past searches revealed large quantities of vomiting gas are kept in an air-raid shelter on the island.
At the time of storage, the gas was treated with bleaching powder and seawater. But arsenic's toxicity is unaffected by such treatment.
In 1996, the island's small water supply system was contaminated by arsenic and had to be temporarily stopped. Although no certain link to the vomiting gas has been established, as was the case in Kamisu, serious contamination occurred right under the nose of the then-Environment Agency.
Before conducting a nationwide survey, the ministry should first dispose of the vomiting gas on the island.
I call for the disposal for two reasons. First, the ministry should meet public expectations for environmental administration, and second, this presents an opportunity for Japan to take the initiative in advancing the reduction of chemical weapons.
The Chemical Weapons Convention does not define vomiting gas as a chemical in its Schedule and leaves it to the discretion of individual countries to dispose of such gas buried within their territories before 1977.
But Tokyo has an agreement with Beijing to dispose of vomiting gas along with other chemical weapons it left behind in China. This agreement indicates that Japan and China both recognize vomiting gas as a chemical weapon covered by the convention. In this sense, it is significant in promoting disarmament.
To prove that the agreement is not just a diplomatic stunt but an expression of Tokyo's intention to advance arms reduction, the government should dispose of vomiting gas on Okuno island. This would be a good opportunity for Japan to show it is serious about cutting back on chemical weapons.