Q4: How was the cause of Minamata disease revealed?
A4: It was demonstrated by a lot of research including studies on the patients,
animal experiments, chemical analysis, etc.
At first, since the majority of the patients were fishermen who ate large
amounts of marine products, and the neighboring cats also showed abnormalities,
it was suspected that polluted fish might be a cause.
Later, the cause of Minamata disease was identified as methylmercury based
on the findings such as: 1) the characteristic symptoms shown by the patients,
2) the detection of mercury in urine from the patients, 3) the experimental
results of cats given methylmercury-contaminated food, and 4) detection
of methylmercury in the wastewater of Chisso's factory.