Four Big Pollution Diseases of Japan

The four big pollution diseases of Japan (四大公害病, yondai kōgai-byō) were a group of man-made toxicopathological outbreaks during the 20th century in Japan. All instances were caused by environmental pollution that came from the chronic, improper handling of industrial waste by Japanese corporations. The first occurred in 1912, and the other three occurred in the 1950s and 1960s.

The term "four big pollution diseases" is a calque of the Japansese term used to describe these series. Taken literally, the term may be incorrectly taken to mean that each of the respective outbreaks manifested novel illnesses on their own. Contrarily, both outbreaks of Minamata disease were pathologically and etiologically the same, only differing in location and time.

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.