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 were mostly complete as of 2012. Monetary costs of the cleanup have been paid for in part by Japan's national government, Mitsui Mining, and the Gifu and Toyama prefectural governments. Itai-itai disease is known as one of the Four Big Pollution Diseases of Japan.
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".
Causes
Itai-itai disease was caused by cadmium poisoning due to mining in Toyama Prefecture. Regular mining for silver started in 1589, and soon thereafter, mining for lead, copper, and zinc began. The earliest records of mining for gold in the area date back to 1710. Cadmium is a metal byproduct of mining that is toxic to most organisms.
Animal studies have shown that cadmium poisoning alone is not enough to elicit all of the symptoms of itai-itai disease. These studies point to damage of the mitochondria of kidney cells by cadmium as a key factor of the disease.
History
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.
The reduction of the levels of cadmium in the water supply reduced the number of new cases; no new case has been recorded since 1946. While the people with the worst symptoms came from Toyama prefecture, the government found patients with itai-itai disease in five other prefectures.
After the first reports of Itai-Itai in 1912, it took 55 years for the epidemiological investigation to discover that the disease was due to cadmium poisoning. Delayed bureaucratic response was a common thread in the Four Big Pollution Diseases of Japan. Cadmium adversely affected fish, causing endocrine disruption and inhibited reproduction, and sometimes mortality. The local residents' consumption of this rice and drinking water then resulted in elevated cadmium body burdens – leading directly to symptoms characteristic of itai-itai disease. Cadmium is now considered one of the most dangerous toxic metals due to its ability to threaten food safety through being easily absorbed into the rice paddies, then subsequently the rice.
Cadmium accumulates mainly in the liver and the kidneys, but has more of an effect on the kidneys. The severe symptoms seen in Itai-itai disease are a direct result of prolonged exposure to cadmium.
Cadmium enters the kidneys by binding to metallothionein in the blood and traveling to the glomerulus in the kidney. Once the cadmium makes it into the tubular cells in the kidneys, the cadmium is released and accumulates in the renal cortex until it reaches toxic levels. These specialty checks specifically monitor water originating from the mine, as it has high levels of cadmium, which requires it to be separated and diverted to the Kamioka Mine slag dump. The water and solids are separated and processed before leaving the mine to ensure no groundwater contamination to the surrounding area. The treatment facilities' exhaust is also monitored to ensure the absence of cadmium in the airborne byproduct of the zinc refining process.