Transition in Pollution Level of Fished in Agano River Basin

In the Agano River basin, continuous methylmercury exposure at the level which could cause Minamata disease existed until no later than 1965, and that after that, there has not been such exposure that could lead to the onset of Minamata disease.

Source: Niigata prefecture 1979, Yukio Takizawa 1989

(Note) The provisional regulatory standard in fish of 0.4 ppm of total mercury and 0.3 ppm of methylmercury have been set.
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