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Home > Outline of Japan's Industrial Pollution Abatement > Preventative Measures Against Water Pollution Jinzu River, Toyama Prefecture > 1) Result of countermeasures at the pollution-generating source

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Update:April 1, 2010

1) Result of countermeasures at the pollution-generating source


Some 20 years have past since. the court`s ruling on the itai-itai disease. Pollution prevention at the Kamioka Mines has made incredible progress owing to scientific and general research and the epoch-making pollution prevention agreement yet seen anywhere else in the world. A gist of the results are as follows.

  • (1)The amount of cadmium discharge at the waste water gate of the Kamioka Mines was reduced from the 35 kg per day of 1972 to an approximate 5 kg per day by 1992, or just one seventh, And, cadmium concentration in waste water was reduced from 8 ppb to the 1.4 ppb of natural water.
  • (2)The amount of cadmium found in gas exhausted from the mines was reduced from the 5 kg per day of 1972 to 1 kg per day by 1992, or one fifth.
  • (3)Measures were taken, based on survays, to prevent cadmium runoff into abandoned shafts and heaped waste.
  • (4)Investigations were made into water quality and the river bed in the Jinzu River water system, from which the cadmium polluting mechanism and the cadmium contamination load were identified. Pollution in the river bed and water was reduced to less than one tenth, with a 0.1 ppb concentration being achieved in the river's upper reaches.

There used to be some 600 or more mines operating in Japan during the 1950s and 1960s. But, because of the oil crisis and the rising yen, mines began to close down, bringing this number to 236 in the 1970s and just 25 by 1989. Now, there are less than 10 mines in operation, The fact that the Kamioka Mines have survived in the itai-itai disease story despites the ongoing situation, not only points out the mammoth scale of the operations, but also the cooperation that the local residents, Mitsui Mining and Smelting and the government showed in disclosing and sharing information. Arduous scientific and general investigative research formed the foundation of a technical and economical response unrivaled to date.