Eating Fish breaks our nervous system by causing the disease Minamata. Minamata disease is a poisoning disease of the central nervous system caused by methyl mercury compound, which was produced of manufacturing acetaldehyde. This neurological disorder was caused by ingestion of large quantities of fish contaminated with methyl mercury by two industrial effluents in Minamata and Nilgata (Japan). After World War II (around 1952), the production of acetaldehyde boomed. So, too, did the local economy – and most residents welcomed their improved lifestyles. About the same time, fish began to float in Minamata Bay. Chisso, as it had since 1925, continued to pay indemnity to local fishermen for possible damage to their fishing waters. Also at that time, cats began to exhibit bizarre behavior that sometimes resisted in their falling into the sea and dying, in what residents referred to as “cat suicides.”

Symptoms of the Disease

· Constriction of visual field
· Superficial sensory disturbance
· Deep sensory distortances
· Ataxia (adiadochokinesis)
· Ataxia writing
· Ataxia in buttoning
· Ataxia in finger-finger in finger-nose tests
· Ataxia (Romberg's sign)
· Impairment of speech
· Impairment of hearing
· Impairment of gait
· Tremor
· Muscular rigidity
· Ballism
· Chorea
· Athetosis
· Contracture
· Exaggerated tendon reflex
· Weak tendon reflex
· Hemiplegia
· Salivation
· Sweating
· Slight mental disturbance

Diagnosis of the Disease

Because various symptoms of Minamata disease can be caused by other diseases as well, diagnosis of the disease in people who have been exposed to methyl mercury compound is carried out on the basis of diagnostic criteria, in order to raise the level of diagnostic probability. While diagnosis on this basis is fairly easy for typical patients who have all the major symptoms, in the case of incomplete type or moderate type of this disease, however, it may be difficult to distinguish it from the following disease.

Timeline of the Disease

1908: – Nichitsu opens a chemical factory in Minamata (Japan).

1932: – Acetaldehyde production using a mercury catalyst begins.

1956 (1st May): – Company hospital director Hajime Hosokawa reports the discovery of Minamata disease.

1956 (4th November): – Kumamoto University research group reports initial suspicion of a heavy metal poisoning, presumably through eating contaminated fish.

1958 (March): – British neurological Douglas Mc Alpine suggests that Minamata disease symptoms resemble those of organic mercury poisoning.

1958 (September): – Shin Nichitsu changes the acetaldehyde plant wastewater discharge route from Minamata bay to Minamata river.

1959 (February): – Investigations of Minamata Bay uncovers shocking mercury contamination.

1959 (29th August): – Mediated compensation agreement between Chisso and Minamata fishing cooperative for damage to fishing.

1959 (21st October): – Shin Nichitsu changes the acetaldehyde plant wastewater discharge route from Minamata River to Minamata Bay.

1959 (12th 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 agents being some sort of organic mercury compound ”

1959 (29th November): – 18 chindren are cerated as the first congenital Minamata disease victims.

1965 (1st January): – Shin Nichitsu changes its name to Chisso Corporation.

1965 (12th June): – The outbreak of a second Minamata disease in Nigata Perfect is made public.

1968 (March): – Nilgata patients file a lawsuit against Showa Denko.

1968 (26th September): – The national government issues an official conclusion as to the cause of Minamata disease and Nilgata Minamata disease.

1969 (14th June): – Litigtion group of the Mutual Aid Society files a lawsuit against Chisso in the Kumamoto District Court.

1970 (4th July): – Hajime Hosokawa testifies from his deathbed about this cat experiments in the Litigation group trial.

1971 (29th September): – Shawa Denko found guilty of negligence; Nigata patients win compensation.

1972-1973: – 20 March, Chisso found guilty of negligence; litigation group patents.