The four big pollution diseases of Japan (四大公害病, yondai kōgai-byō) were a group of man-made diseases all caused by environmental pollution due to improper handling of industrial wastes by Japanese corporations.[1] The first occurred in 1912, and the other three occurred in the 1950s and 1960s.
Despite the moniker of 'four' becoming the prominent way to refer to the events, Minamata disease and Niigata Minamata disease were the same pollution disease caused by the same poison, just in different locations and times.
| Name of disease | Japanese prefecture affected | Cause | Source | Year |
|---|---|---|---|---|
| Itai-itai disease | Toyama Prefecture | Cadmium salts | Mitsui Mining & Smelting Company | 1912 |
| Minamata disease | Kumamoto Prefecture | Organomercury compounds | Chisso Corporation | 1956 |
| Niigata Minamata disease | Niigata Prefecture | Organomercury compounds | Showa Denko | 1965 |
| Yokkaichi asthma | Mie Prefecture | Sulfur dioxide | Various sources | 1961 |
Due to lawsuits, publicity, and other actions against the corporations responsible for the pollution, as well as the creation of the Environmental Agency in 1971, increased public awareness, and changes in industrial practices, the incidence of these kinds of diseases declined after the 1970s. These cases also set precedents for private tort law and civil law in issues of compensation for technology-related mass damage which continue to have repercussions in legal cases in Japan today.[2]