The Minamata Convention

Japan completed a procedure with the United Nations last month to ratify the Minamata Convention on Mercury. The convention is named after the city in Kumamoto Prefecture where industrial wastewater containing methyl mercury released by Chisso Corp.’s chemical factory into the sea caused birth defects and neurological diseases — known as Minamata disease — among thousands of people. Having experienced the dreadful results of mercury poisoning, Japan has a responsibility to help other countries in their efforts to prevent environmental pollution caused by mercury and mercury compounds. This is the aim of the convention.

Countries taking part in a U.N.-led conference held in the city of Kumamoto in 2013 adopted the convention, which describes mercury as a “chemical of global concern.” So far 128 countries have signed the convention and 24 of them have ratified it. Japan is the 23rd country to ratify the convention, which needs to be ratified by at least 50 countries to take effect.

The convention prohibits the export and import of mercury except for certain kinds of use. Signatory countries must stop the production, export and import of products containing mercury such as thermometers, batteries and fluorescent lights by 2020 in principle. They also have a duty to reduce the release of mercury into the environment and to properly store and dispose of it. Japan needs to faithfully carry out the promise it made at the Kumamoto conference — to provide funds to developing countries and assist their governments in human resources development in their endeavor to minimize damage caused by mercury pollution.

The first case of the disease was officially discovered in 1956 in Minamata. Three years later, Kumamoto University announced that organic mercury was the cause of the disease — an analysis confirmed by a study group at the then Health and Welfare Ministry. But it was only in 1968 that the government officially recognized that methyl mercury contained in industrial waste released by Chisso’s Minamata factory was responsible for the disease. In the meantime, the firm continued to release polluted water into the sea, contaminating fish that were then consumed by local people. This resulted in the expansion of areas where the disease occurred and a jump in the number of victims.

The disease is not limited to the city of Minamata and its adjacent areas. In 1965, the presence of people showing the same symptoms as Minamata disease was recognized in the basin of the Agano River in Niigata Prefecture. There the disease is called Second Minamata disease or Niigata Minamata disease. It was determined that the disease was caused by methyl mercury in wastewater released from Showa Denko K.K.’s plant in Kanose, Niigata Prefecture.

While Minamata disease in Japan was caused by wastewater from chemical factories handling mercury, in developing countries gold mining areas are being polluted by the same substance. Mercury used in the process of extracting gold from ore is not only damaging the health of miners but also finding its way into wastewater from mines and polluting the environment. As Japan’s experience of Minamata disease shows, prompt action to halt such pollution once it is found is indispensable. Japan needs to uphold the promise it made at the Kumamoto conference and contribute to efforts to eliminate mercury pollution and to the medical treatment of miners who have been poisoned by it.

The government also must not forget that Minamata disease remains a serious problem at home. Many Minamata disease victims remain shut out of the relief scheme due to the official criteria for recognizing people as sufferers of the disease, which is a requirement for receiving relief. In 1977, the government adopted strict criteria that mandated people must display sensation disorders in the limbs as well as other symptoms such as a narrowing of their field of vision and motor ataxia to be recognized as Minamata disease victims. This led to the rejection of many people who had applied for relief. In 2004, the Supreme Court ruled that the 1977 criteria should be interpreted in a restrictive way and that a person who displayed only a single symptom should also be recognized as a Minamata disease victim if certain conditions are met. In 2013, the top court ruled that people who exhibit only sensation disorders can be recognized as Minamata disease victims, reversing an administrative decision that rejected a woman’s application.

The government still refused to drop the 1977 criteria despite the Supreme Court rulings but in 2014 revised the guideline for its application. The revised guideline says that while a person only with sensation disorders can be recognized as a Minamata disease victim, objective materials linking the disorders with organic mercury pollution must be prepared. On the basis of the new guideline, the prefectural governments of Kumamoto, Kagoshima and Niigata are working to recognize additional Minamata disease victims. But more than 2,000 people in the three prefectures are still waiting for the process to be concluded. Thus the task of providing relief to all Minamata disease victims has yet to be completed 60 years since the official discovery of the first case.

Outside Japan, people will continue to suffer from mercury poisoning unless steady efforts are made by governments and other parties concerned to faithfully implement the Minamata Convention and stop methyl mercury from damaging the environment and people’s health. The mission will take considerable time and effort, and Japan should do its utmost to help ensure its success.