Timeline Events / Identification of Minamata Disease
Minamata disease is one of the most severe diseases caused by environmental pollution in the world, which was first confirmed in 1956 in Minamata city, Japan, as caused by a heavy metal. However, The investigation was carried out energetically mainly by Kumamoto University, and in November 1956, the university reported that the disease is a certain type of heavy metal poisoning transmitted via fish and shellfish. However, due to limitations in knowledge and analytical technologies related to detecting environmental pollution at that time, the exact cause was confirmed only in 1967 as due to release of methylmercury in the industrial wastewater from the chemical firm, Chisso Corporation, contaminating nearby Minamata Bay.
Local citizens were poisoned by eating contaminated fish and shellfish from the bay (where the mercury bioaccumulated). The widespread mercury poisening caused neurological symptoms including muscle weakness and damage to the senses, and even death, as well as congenital effects to fetuses, affecting thousands of citizens.
As a result of this tragedy as well as other severe diseases discovered to result from industrial pollution, the Government of Japan established strong environmental pollution regulations based on the ‘Basic Law for Environment Pollution Control’ (legislated: 3rd August 1967), as well as compensation schemes for the victims.
Timeline entry contributed by Nobuyuki Konuma
Source: Ministry of the Environment, Government of Japan website