Itai-itai disease: Lessons from the investigations of environmental epidemiology conducted in the 1970's, with special reference to the studies of the Toyama Institute of Health.

The outbreak of itai-itai disease, which is the most severe stage of chronic cadmium poisoning, has occurred in the cadmium-polluted Jinzu River basin in Toyama. In this area, the river was contaminated by slags from a mine upstream; consequently, the soil in rice paddies became polluted with heavy metals including cadmium through irrigation water streams from around 1910 to the 1960s. The inhabitants of the Jinzu River basin used the river water for drinking and cooking until around 1960. In this paper, we review the geographical features of the Jinzu River basin and the endemic area of itai-itai disease, and reevaluated the studies conducted in 1970's by the Toyama Institute of Health, because these studies have revealed a clear relationship between renal dysfunction or occurrence of itai-itai disease and exposure to cadmium through irrigation water streams.