Timeline of Minamata disease

Main article: Minamata disease

The following is a timeline of key events related to Minamata disease:

Date	Event
1908	Nichitsu opens a chemical factory in Minamata
1932	Acetaldehyde production using a mercury catalyst begins
1945	Japan is defeated in World War II. The Allied occupying forces order the dismissal of Nichitsu
1950	Shin Nichitsu is founded as the successor to the old company
August 1951	The co-catalysed was changed from manganese dioxide to ferric sulfide resulting in side production of methylmercury
1956
1 May	Company hospital director Hajime Hosokawa reports the discovery of Minamata disease
24 August	Kumamoto University research group formed
4 November	Kumamoto University research group reports initial suspicion of a heavy metal poisoning, presumably through eating contaminated fish
1958
March	British neurologist Douglas McAlpine suggests that Minamata disease symptoms resemble those of organic mercury poisoning
September	Shin Nichitsu changes the acetaldehyde plant wastewater discharge route from Minamata Bay to Minamata River
1959
February	Investigations of Minamata Bay uncover shocking mercury contamination
29 August	Mediated compensation agreement between Chisso and the Minamata Fishing Cooperative for damage to fishing
21 October	Shin Nichitsu changes the acetaldehyde plant wastewater discharge route back from Minamata River to Minamata Bay
2 November	Members of the Kumamoto Prefectural Alliance of Fishing Cooperatives invade the Minamata factory and riot, causing damage amounting to JPY10 million
12 November	The Ministry of Health and Welfare reports that "Minamata disease is a poisoning disease... caused by the consumption of large quantities of fish and shellfish living in Minamata Bay and its surroundings, the major causative agent being some sort of organic mercury compound."
17 December	Mediated compensation agreement between Chisso and the Kumamoto Prefectural Alliance of Fishing Cooperatives for damage to fishing
29 December	Mediated compensation agreement between Chisso and the Minamata Disease Patients Families Mutual Aid Society
29 November 1962	18 children are certified as the first congenital Minamata disease victims
1965
1 January	Shin Nichitsu changes its name to the Chisso Corporation
12 June	The outbreak of a second Minamata disease in Niigata Prefecture is made public
1968
March	Niigata patients file a lawsuit against Showa Denko
26 September	The national government issues an official conclusion as to the cause of Minamata disease and Niigata Minamata disease
1969
14 June	Litigation Group of the Mutual Aid Society files a lawsuit against Chisso in the Kumamoto District Court
1970
4 July	Hajime Hosokawa testifies from his deathbed about his cat experiments in the Litigation Group trial
27 May	Arbitrated compensation agreement between Chisso and the Arbitration Group of the Mutual Aid Society
1971
29 September	Showa Denko found guilty of negligence; Niigata patients win compensation
1973
20 March	Chisso found guilty of negligence; Litigation Group patients win compensation
1977
1977	A net is installed around Minamata Bay to prevent toxic sludge and fish from contaminating other areas
1997
1 September 1997	The net surrounding Minamata Bay is removed and fish caught there are declared safe to eat
2004
15 October 2004	The Supreme Court of Japan rules that the national government was responsible for not preventing the spread of Minamata disease after 1960