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Itai-itai disease (イタイイタイ病, itai-itai byō, "it hurts-it hurts disease") was the name given to the mass cadmium poisoning of Toyama Prefecture, Japan, starting around 1912. The term "itai-itai disease" was coined by locals for the severe pains (Japanese: 痛い itai) people with the condition felt in the spine and joints. Cadmium (Cd) poisoning can also cause softening of the bones and kidney failure. Effective treatments involve the use of chelators to promote urinary excretion of Cd. The cadmium was released into rivers by mining companies in the mountains, which were successfully sued for the damage. Remediation efforts in the affected region have been ongoing since 1972 and mostly completed as of 2012. [11] Monetary costs of the cleanup have been paid for in part by Japan’s national government, Mitsui Mining, and the Gifu and Toyama prefectural. Itai-itai disease is known as one of the Four Big Pollution Diseases of Japan.

Symptoms

One of the main effects of cadmium poisoning is weak and brittle bones. Spinal and leg pain is common, and a waddling gait often develops due to bone deformities caused by the long-term cadmium exposure. The pain eventually becomes debilitating, with fractures becoming more common as the bone weakens. Permanent deformation in bones can occur. Other complications include coughing, anemia, and kidney failure, leading to death.[3]

A marked prevalence in older, postmenopausal women has been observed, however, the cause of the phenomenon is not fully understood, and is currently under investigation. Current research has pointed to general malnourishment, as well as poor calcium metabolism relating to the women's age. The cause of this phenomenon is not fully understood, and is currently under investigation. Current research has pointed to general malnourishment, as well as poor calcium metabolism relating to the women's age.

A marked prevalence in older, postmenopausal women has been observed. Cadmium poisoning in postmenopausal women may also result in an increased risk for osteoporosis. The cause of this phenomenon is not fully understood, and is currently under investigation. Current research has pointed to general malnourishment, as well as poor calcium metabolism relating to the women's age.[3]

Recent animal studies have shown that cadmium poisoning alone is not enough to elicit all of the symptoms of itai-itai disease.[3] These studies are pointing to damage of the mitochondria of kidney cells by cadmium as a key factor of the disease.

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 1710. 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.

In the 1920s, levels of contaminated tailing waste increased after the creation of new froth flotation processes that boosted zinc production. Fine powdered mineral particles formed in the frothing process escaped and were able to drift down river. These particles were subsequently oxidized into ions that were absorbed by surrounding vegetation and humans. Sphalerite, the main zinc containing ore in Komioka, is almost always coupled with Greenockite, the only major cadmium containing mineral in the world. Because of this, cadmium is a regular by-product of the zinc ore mining process. Up until 1948, cadmium was discarded as waste into the Jinzu River due to it being of no industrial value, further exasperating the levels of the element’s release into the waterbody.

Prior to World War II, the mining, controlled by the Mitsui Mining & Smelting Co., Ltd., increased to satisfy the wartime demand. This subsequently increased the pollution of the Jinzū 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.

Studies conducted to estimate the amount of cadmium exposure necessary to develop Itai-Itai Disease found permissible lifetime cadmium intake (LCD) levels for humans to be 1.7 to 2.1 g. When Itai-Itai Disease was first being recognized in just 5% of the afflicted population, LCD levels are estimated to have already been at 2.6 g.

Etymology

The term itai-itai disease (in Japanese イタイイタイ病 itai-itai byō, "it hurts-it hurts disease" or "ouch-ouch disease") was coined by the affected locals for the severe pains that people with itai-itai disease felt in the spine and joints. In Japanese 痛い itai is used as an adjective meaning "painful" or as an interjection equivalent to "ouch".

Society

Legal action

Twenty-nine plaintiffs, consisting of 9 people with itai-itai disease and 20 of their family members, 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 people who had been affected, finance the monitoring of the water quality performed by the residents, and pay reparations to the people with the disease. Out of the four major pollution events, it was only in the case of Itai-itai Disease that victims succeeded in instilling almost complete pollution control through legal action.

The cadmium pollution had contaminated many agricultural areas. Heavy metal pollution affected many areas in Japan, and as a result the Prevention of Soil Contamination in Agricultural Land Law of 1970 was enacted. It ordered planting to be stopped so that restoration of the soil could be enacted to areas with 1ppm of cadmium or more contamination in the soil. Surveying in Toyama Prefecture began in 1971, and by 1977, 1500 hectares along the Jinzū River were designated for soil restoration. These farmers were compensated for lost crops and for lost production in past years by the Mitsui Mining and Smelting, Toyama Prefecture, and the national government. As of 1992, only 400 hectares remained contaminated.

Continuous inspections following the lawsuit showcase the vast improvements in terms of greatly reduced pollution levels. Total amounts of cadmium discarded decreased from 35 kg mo−1 in 1972 to 3.8 kg mo−1 in 2010; the average concentration of cadmium in the mine’s discharge had been reduced to 1.2 ppb in 2010 from 9 ppb in 1972; and in response to improved dust collection methods, the total amount of cadmium discharged in smoke dropped from >5 kg mo−1 in 1972 to 0.17 kg mo−1 in 2010. In 1996, the mean concentration of cadmium in agricultural lands lowered to the background level of 0.1 ppb, signifying trivial cadmium outflow. This is a success in regards to the lawsuit.

On 17 March 2012, officials concluded the cleanup project of the cadmium-polluted areas in the Jinzū River basin. Eight-hundred and sixty-three hectares of topsoil had been replaced since the cleanup began in 1979 at a total cost of ¥40.7 billion. The project had been financed by the Japanese national government, Mitsui Mining, and the Gifu and Toyama prefectural governments.