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, (literally: "ouch-ouch" disease) was the first documented case of mass cadmium poisoning in the world in Toyama Prefecture, Japan in 1950. The cadmium poisoning caused softening of the bones and kidney failures. The name of the disease comes from the painful screams (Japanese: 痛い itai) due to the severe pain in the joints and the spine. The cadmium was released in the rivers by mining companies in the mountains. The mining companies were successfully sued for the damage. Itai-itai disease is known as one of the Four Big Pollution Diseases of Japan.
Cause Itai-itai disease was caused by cadmium poisoning due to mining in Toyama Prefecture. The earliest records of mining for gold in the area date back to 710. Regular mining for silver started in 1589, and soon thereafter, mining for lead, copper, and zinc began. Increased demand for raw materials during the Russo-Japanese War and World War I, as well as new mining technologies from Europe, increased the output of the mines, putting the Kamioka Mines in Toyama among the world's top mines. Production increased even more before World War II. Starting in 1910 and continuing through 1945, cadmium was released in significant quantities by mining operations, and the disease first appeared around 1912. Prior to World War II the mining, controlled by the Mitsui Mining and Smelting Co., Ltd., increased to satisfy the wartime demand. This subsequently increased the pollution of the Jinzu River and its tributaries. The river was used mainly for irrigation of rice fields, but also for drinking water, washing, fishing, and other uses by downstream populations.
Effect Due to the cadmium poisoning, the fish in the river started to die, and the rice irrigated with river water did not grow well. The cadmium and other heavy metals accumulated at the bottom of the river and in the water of the river. This water was then used to irrigate the rice fields. The rice absorbed all heavy metals, especially the cadmium. The cadmium accumulated in the people eating contaminated rice.The population complained to the Mitsui Mining and Smelting about the pollution. The company subsequently built a basin to store the mining waste water before leading it into the river. It was too little too late, and many people were already very sick. The causes of the poisoning were not well understood and, up to 1946, it was thought to be simply a regional disease or possibly a type of bacteria.Medical tests started in the 1940s and 1950s, searching for the cause of the disease. Initially, it was expected to be lead poisoning due to the lead mining upstream. Only in 1955 did Dr. Ogino and his colleagues suspect cadmium as the cause of the disease. Ogino coined the term itai-itai disease. Toyama prefecture also started an investigation in 1961, determining that the Mitsui Mining and Smelting's Kamioka Mining Station caused the cadmium pollution and that the worst affected areas were 30 km downstream of the mine. In 1968 the Ministry of Health and Welfare issued a statement about the symptoms of itai-itai disease caused by the cadmium poisoning. The reduction of the levels of cadmium in the water supply reduced the number of new disease victims; no new victim has been recorded since 1946. While the victims with the worst symptoms came from Toyama prefecture, the government found victims in five other prefectures. One of the main effects of this painful cadmium poisoning are very weak and brittle bones: For details of the symptoms see Cadmium poisoning.The mines are still in operation.
Legal action 29 plaintiffs, consisting of nine victims and 20 family members of victims, sued the Mitsui Mining and Smelting Co. in 1968 in the Toyama Prefectural court. In June 1971, the court found the Mitsui Mining and Smelting Co. guilty. Subsequently, the company appealed to the Nagoya District Court in Kanazawa, but the appeal was rejected in August 1972. The Mitsui Mining and Smelting Co. agreed to pay for the medical care of the victims; finance the monitoring of the water quality performed by the residents; and pay reparations to the victims of the disease.People who consider themselves victims of itai-itai disease have to contact the Japanese Ministry of Health, Labor and Welfare to have their claims assessed. Many victims were not satisfied with government actions and demanded a change in the official procedures. This caused the government to review the criteria for recognizing a victim legally; the government also reassessed the treatment of the disease.A person is considered to have itai-itai disease if he or she lived in the contaminated areas, has kidney dysfunctions, softening of the bones, but no related heart problems. 184 victims have been legally recognized since 1967, of whom 54 were recognized in the period from 1980 to 2000. 15 victims were still alive as of 1993.
In 1992, the average annual health expense compensation was 743 million yen. Agricultural damage was compensated with 1.75 billion yen per year, or a total of annually 2.518 billion yen. Another 620 million yen were invested annually to reduce further pollution of the river.
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