U.N. treaty on mercury owes name to disease in Minamata

The Asahi Shimbun 16 August 2017 | Masatoshi Toda and Masamitsu Oku

An international treaty that takes its name from the Japanese city that opened the eyes of the world to the devastating effects of mercury poisoning went into effect Aug. 16.

The U.N. Minamata Convention on Mercury is designed to control both the use and trade of mercury, especially in developing nations. As of Aug. 8, it had been ratified by 74 nations and regions.

The first meeting of signatories to the convention will be held in Geneva from Sept. 24 through 29 to discuss ways to help developing nations deal with mercury poisoning.

Minamata disease victim Shinobu Sakamoto, 61, is planning to attend the conference to talk about the toll the disease has taken on her health.

Sakamoto, who is from Minamata, Kumamoto Prefecture, was born with congenital Minamata disease, which causes numbness in the limbs, muscle weakness, and vision, hearing and speech impairment. In extreme cases, it leads to coma and death.

Minamata disease was caused by methyl mercury discharged into Minamata Bay by the chemical company Chisso Corp. in the 1950s. The mercury contaminated the marine life upon which city residents relied.

"I want to tell people that the Minamata disease has not ended and mercury problems should be dealt with properly in all nations," Sakamoto said at an Aug. 16 news conference in Minamata. "I felt at one time about how much longer I will be able to talk about my experience, so I now want to do what I can."

In 1972, at the age of 15, Sakamoto addressed the U.N. Conference on the Human Environment held in Stockholm. Her testimony and account of her suffering due to mercury poisoning shocked the world.

Sakamoto's health has deteriorated over the years, and she can now only get around using a wheelchair.

The Minamata Convention is designed to restrict the mining, trade and use of mercury in order to prevent environmental pollution and damage to human health.

Among other things, its provisions ban development of new mercury mines; prohibit the manufacture and trade of fluorescent lamps and thermometers that use more than a certain level of mercury; and call for proper management of mercury waste.

An international conference held in Minamata in 2013 adopted the convention. The number of ratifying nations exceeded 50 in May 2017, paving the way for the convention to take effect.

In the 1960s, Japan used as much as 2,500 tons of mercury a year. But levels have now fallen to under 10 tons annually.

However, mercury is still around the world, mainly in South America and Africa. In 2005, global demand for mercury reached 3,800 tons.

Mercury is still used by gold miners as a catalyst to separate gold from its ore, which has raised concerns about possible health problems for those miners as well as anybody who lives nearby.

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