The Minamata disease got its name from Minamata Bay in Southwestern Japan where it was first observed in nearby communities. It was officially discovered in 1956, and a few years later it was known to be caused by ingestion of fish that had been contaminated by mercury left off from a chemical manufacturing plant. Levels of methylmercury chloride were very high: upto $50 \mathrm{ppm}$ in fish and $85 \mathrm{ppm}$ in shellfish from the contaminated areas. 121 people were poisoned from eating the contaminated fish, 46 of which died. Dogs, cats, pigs, rats and birds that were living around the bay also showed the signs of mercury poisoning, and many died.
The initial symptoms were numbness of the limbs and the area around the mouth, sensory disturbance, and difficulty with everyday hand movements. Also there occurred a lack of coordination, weakness and tremor, slowed and slurred speech, and altered vision and hearing. These symptoms worsened and led to general paralysis, involuntary movements, difficulty in swallowing, convulsions, brain damage and death.