Itai-itai disease - Itai-itai disease

Japanese: イタイイタイ病 - イタイイタイびょう（英語表記）Itai-itai disease

What is the disease?

Hagino Noboru and others first reported a rare disease of unknown cause in October 1955, which was commonly seen among women who had given birth after menopause and lived in the Kumano region of the Jinzu River basin in Toyama Prefecture, and which manifested as pain throughout the entire body. This disease became widely known when it was reported.

As a result of further research, in May 1968, the Ministry of Health and Welfare (at the time) announced that "Itai-itai disease is caused by chronic cadmium poisoning, which first causes kidney damage, then Osteomalacia ( Tips and tricks ) The report states that "the cause of chronic poisoning is pregnancy, lactation, endocrine disorders, aging and nutritional deficiencies such as calcium deficiency. Cadmium, the causative agent of chronic poisoning, has only been found in wastewater from the Kamioka Mine of Mitsui Mining & Smelting Co., Ltd."

Subsequently, in February 1971, the "Special Measures Law for Pollution-Related Health Damage Relief" came into force, providing medical relief, etc., and in September 1974, the "Pollution-Related Health Damage Compensation Law" came into force, providing medical relief, etc.

As of March 2009, 195 people have been certified as having Itai-itai disease under these laws.

What is the cause?

It is considered to be chronic cadmium poisoning. Cadmium is ingested through food and water, causing abnormalities in the metabolism of phosphorus and calcium. Renal tubules ( People's Bank ) Dysfunction (Fanconi syndrome) occurs, leading to osteomalacia and osteoporosis ( Tips and tricks ) It is believed that the disease occurs when a combination of precipitating factors such as pregnancy, childbirth, and malnutrition occurs.

It is believed that chronic cadmium poisoning is caused by ingesting drinking water or agricultural produce contaminated by cadmium contained in wastewater discharged from the Kamioka Mine of Mitsui Mining & Smelting Co., Ltd., upstream of the Jinzu River. Since 1955, there have been almost no severe cases of this disease, and no new cases have been reported in recent years.

Cadmium is most strongly suspected as the causative agent of this disease, but the theory that cadmium is the sole cause is unreasonable, and nutritional disorders such as low protein and low calcium are also thought to be contributing factors. However, the true cause has not been clarified due to the difficulty of reproducing the disease in animal experiments.

How symptoms manifest

The main lesions are renal tubular resorption disorder and osteomalacia and osteoporosis. The main symptom is pain, which starts with lower back pain and muscle pain in the legs, gradually spreading to other parts of the body, and when it gets worse, it is difficult to move the body even slightly. cough ( cough ) Even just doing this can cause severe pain.

The process is very slow, sprain ( Sprain ) A minor injury such as this can cause walking problems, and in the final stages the patient will be unable to walk, becoming bedridden, and may develop pathological fractures due to even a slight external force.

Renal tubular damage is characterized by increased excretion of low molecular weight proteins such as _β2 microglobulin, sugar, protein, and amino acids in the urine.

Treatment methods

For bone lesions, treatment with large doses of vitamin _D2 or activated vitamin _D3 is generally effective, and although there are cases where the condition worsens repeatedly, it tends to improve in the long term.

Toshio Matsui

Source: Houken “Sixth Edition Family Medicine Encyclopedia” Information about the Sixth Edition Family Medicine Encyclopedia

Japanese:

どんな病気か

　富山県神通川流域、熊野地域住民の更年期以降の出産経験のある女性に多くみられた全身の痛みを主訴とする原因不明の奇病について、萩野昇らが1955（昭和30）年10月に初めて報告し、その存在が広く知られるようになりました。

　その後の研究の結果、1968（昭和43）年5月に厚生省（当時）は、「イタイイタイ病はカドミウムの慢性中毒により、まず腎臓障害を生じ、次いで骨軟化症(こつなんかしょう)を来し、これに妊娠、授乳、内分泌の変調、老化および栄養としてのカルシウム等の不足などが誘因となって生じたもので、慢性中毒の原因物質としてのカドミウムは、三井金属鉱業株式会社神岡鉱業所の排水以外には見当たらない」とする見解を発表しています。

　その後1971（昭和46）年2月からは「公害に係る健康被害の救済に関する特別措置法」が施行され、医療等の救済が行われてきました。1974（昭和49）年9月からは「公害健康被害補償法」による医療救済等の措置が実施されています。

　これらの法によるイタイイタイ病の認定患者は2009年3月までに195名となっています。

原因は何か

　慢性カドミウム中毒とされています。食べ物や水を介して摂取されたカドミウムによりリンやカルシウムの代謝異常を伴う腎尿細管(じんにょうさいかん)機能異常（ファンコーニ症候群）が生じ、骨軟化症および骨粗鬆症(こつそしょうしょう)を引き起こして、そこに妊娠、出産、低栄養などの誘発因子が加わることで本症が発生すると考えられています。

　神通川上流の三井金属鉱業神岡鉱業所から排出された廃水に含まれていたカドミウムによって汚染された飲料水や農作物を摂取することで、慢性カドミウム中毒になることが原因と考えられています。1955年以後は重症者はほとんどみられなくなり、近年、本症の新たな発症は認められていません。

　本病の原因物質としてカドミウムが最も強く疑われていますが、カドミウムの単独原因説には無理があり、低蛋白、低カルシウムなどの栄養上の障害も原因のひとつと考えられています。なお、動物実験での再現が困難なことから真の原因は解明されていません。