Part 1 Experiences and Lessons from Minamata Disease
Whatt iis Miinamatta Diisease?
Minamata Disease is a toxic nervous disease caused by eating seafood contaminated with methylmercury
compounds discharged from the Minamata plant (in Kumamoto Prefecture) of Shin-Nippon Chisso Hiryo
K.K. (subsequently renamed “Chisso Corporation” at a later date, hereinafter referred to as “Chisso”) or the
plant of Showa Denko K.K. (hereinafter referred to as “Showa Denko”) in Kanose Town (presently named
Aga Town), Niigata Prefecture (See Fig. 1 and Fig. 2).
Its major symptoms include sensory disturbance, ataxia, concentric constriction of the visual field, and
auditory disorders. If a mother is highly exposed to methylmercury during pregnancy, her baby might
suffer from fetal Minamata Disease, which sometimes shows different symptoms from the adult one.
Emergence and Expansiion off Miinamatta Diisease
All pollution requires scientific investigation to determine the cause. The history of Minamata Disease,
from its official acknowledgement in 1956 to the final identification of its cause in the form of a consensus
opinion of the government issued in 1968 is described next along with the background of these events.
Official Acknowledgement of Minamata Disease
In April 1956, a young girl living in the Tsukinoura District of Minamata City was hospitalised at the
Chisso Minamata Plant Hospital complaining of severe numbness of the limbs, inability to speak and
inability to eat. Director Hosokawa at the hospital took the matter seriously and notified this case in the
Tsukinoura District of a serious brain disorder due to an unknown cause to the Minamata Health Centre on
May 1 of the same year. This notification constituted the "official acknowledgement of Minamata Disease".
Initial Response
Following its official acknowledgement, the Health Centre, local medical association, municipal hospital,
Chisso Minamata Plant Hospital and Health Section of Minamata City jointly established the Committee
for Countermeasures Against Strange Disease in Minamata City. Other efforts to investigate the disease