Earlier this month, delegates from over 130 nations gathered in Kumamoto to launch the Minamata Convention on Mercury. The U.N.-brokered treaty aims to limit mercury use and emissions. It comes at a time when the U.N. Environmental Program warns half of all global anthropogenic mercury emissions come from Asia, with East and Southeast Asia accounting for about 40 percent of the total.
At the start of the conference, Prime Minister Shinzo Abe angered Minamata disease victims and environmental activists. In remarks that reminded some of his controversial assertion to the International Olympic Committee that the Fukushima No. 1 nuclear plant crisis was under control, Abe said that, while Japan had given rise to Minamata disease, which was caused by mercury poisoning, it also recovered.
Japan does have strict mercury standards, but concerns about contamination remain.
When was mercury recognized as a problem in Japan?
In 1959, Kumamoto University scientists identified mercury poisoning as the cause of Minamata disease, three years after the first victims were officially recognized.
This led to decades of confrontations between the victims and Chisso Corp., which was responsible for dumping mercury into Minamata Bay.
The central government also fought the victims and Kumamoto University scientists for years, denying any connection between Chisso and the poisoning.
How many Minamata poisoning victims were there?
The estimates are tricky because of the difference between those the central government recognizes and the number of claims.
The true figure is unknown, as the disease has been passed down through several generations.
As of December 2008, only 2,271 recognized victims had been compensated. Over 7,600 had applied for recognition, and more than 26,000 people are receiving free medical treatment.
How has Minamata disease affected mercury use in Japan?
Japan is using less than one half of 1 percent of the amount of mercury it used in the 1960s.
A 2002-2006 Environment Ministry survey showed Japan was using about 13 tons annually, most of it in the manufacturing of fluorescent lights and LED screens, medical equipment and silver oxide batteries.
Industrial discharges of mercury were estimated to be between 21 and 28 tons annually in 2009, down from nearly 35 tons annually in 1990.
What safety standards are in place for mercury discharges and how do they compare with rules abroad?
For seafood, excluding tuna, the standard is less than 0.4 mg of mercury per kilogram, and less than 0.3 mg/kg for methyl mercury, which is produced when waste containing inorganic mercury is incinerated. It also comes from burning fossil fuels, particularly coal.
In the U.S., the methyl mercury standard for fish is less than 1 mg/kg. In the European Union, it’s less than 0.5 mg/kg, although carnivorous fish — including sharks — are required to have less than 1 mg/kg.
The U.S. standard for methyl mercury intake, called the lowest observed adverse effect level, is 0.26 mg per day. Japan’s methyl mercury standard is 0.17 mg per week, or 0.024 mg per day.
So do these standards mean mercury levels in Japan are not a problem?
There are several problems that environmental activists and food safety experts have pointed to with Japan’s official policy toward mercury contamination.
First is the comparatively high mercury levels found in fish, especially the sushi favorite Pacific bluefin tuna, which contains 1 microgram per gram of mercury.
Zero Mercury Working Group, a European NGO, recently assessed the hair mercury levels of women of childbearing age in nine countries, including Japan. Of the 22 Japanese women, 71 percent had mercury levels above the 1 mg per gram level the U.S. considers safe. High mercury levels have also been recorded among residents of Taiji, Wakayama Prefecture, who eat dolphin meat.
Food safety experts also point out that the kind of public awareness programs about the risks mercury pose to pregnant women and the highly visible mercury labeling warnings found on food items in other countries are largely absent in Japan.
Besides food, what are some other sources of mercury in the environment?
Trace amounts of mercury can be found in consumer products like cosmetics, and in certain pesticides, but also in places you might not expect. Many old temples and shrines, for example, were built using mercury, some more than others. The Daibutsu (Great Buddha) at Nara’s Todaiji Temple was built with 2.5 tons of mercury.
It was also recently revealed that mercury levels higher than average were recorded on the top of Mount Fuji.
The mercury is believed to have come from Chinese smog, long a problem in western Japan, especially in Kyushu, but something that has only drawn nationwide attention in recent years. China’s economic expansion has led to the use of more fossil fuels, especially cheap coal containing mercury, and the resulting pollution has drifted to Japan, prompting the government to issue pollution alerts.
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