四大公害病のうち
「イタイイタイ病」を取りあげたのにはちゃんとした理由(allowance の見解)があります。

それは、公害の民事裁判において、初めて原告側が勝訴した公害問題だったからです。
足尾鉱毒裁判以降も、日本各地で
公害の被害を訴える裁判は数多く
行われていましたが、そのことごとくが被害民(原告)の敗訴に終わりました。

私(allowance )は理由は三つあったと考えています。

１つ目の理由は、原告側が力のある弁護人を立てられなかった事です。
弁護人も生活がある以上、出来るだけ金払いがいい顧客に雇われたいのは
責められません。
そして、公害を発生させた側は
大企業がほとんどで、金払いも良かったので、
 有能な弁護士は彼らに囲いこまれていました。

２つ目の理由は被害民が分断されていた事です。
つまり、被告企業に作業員として雇われていた人間が少なからず存在していたと言うことです。
第二次世界大戦後、GHQによる農地改革で、大地主の農地は小作人たちに
捨て値で払い下げられました。
その政策自体は画期的なものではありました。
ただ、特に北陸以北の地域は冬は雪に覆われ、その間収入が得られなかった。そこで、特に男性の働き手は出稼ぎをする必要がありました。
そんな時働き場を提供したのが、
鉱山や炭鉱、あるいは工場だったのです(公害の発生元でもあります)。

３つ目の理由は
「高度経済成長」です。
日本は大東亜戦争(あえて太平洋戦争とは書きません)に破れた後、ハイパーインフレーションになり、また、給料の未払いが横行し、庶民の生活は破綻寸前でした。
しかし、君主豹変で、東西冷戦のさなか、西側諸国は日本を反共産主義の防波堤にすべく、経済力を上げさせる事と、日本自身を防衛するための再軍備(警察予備隊)を組織させました。
その結果、日本は戦前の工業生産力を回復させて、戦後に産まれた子供たちが生産年齢に達すると、金の卵として
どんどん工場や鉱山などの職場に入れるようになって行きました。
この行き過ぎた製造業偏重に警鐘を鳴らす学者たちも存在していましたが、ほとんどの人々は経済成長に浮かれ、ひたすら大量生産、大量消費に邁進しました。

「四大公害病」はこれらの要因が産み出した怪物でした。

話をイタイイタイ病に戻すと、当初は鉱山で働いていた人々や、また公害があると言う事で風評被害が起こる事を恐れた農家などから慎重な意見が上がりました。

しかし、被害で家族を失った遺族の
涙の訴えにより、ついに被害者たちは
裁判を起こす事を決断しました。

被告企業の弁護団は様々な公害争議を扱ってきた凄腕揃い。

他方原告側の弁護士は平均年齢37歳の若手で、しかも裁判費用は彼ら自身の工面。

裁判は長期化すると思われました。

しかし、昭和40年代に入り、経済成長の歪みが河川の汚濁、東京湾に代表されるヘドロ、さらに大気汚染による健康被害として現れるにつれ、世論は被害者救済と公害の原因企業に対して対策をするよう圧力をかけるようになって行きました。

この世論に裁判所もついに動き、
昭和46年6月30日午前10時。
富山地方裁判所は
「公害と原因物質の因果関係の立証には、必ずしも科学的な証明は必要なし。よって原告の訴えを全面的に認め、企業に対して補償と公害の改善を命じる。」
原告側の全面勝訴でした。
控訴審も同様の判決を言い渡し、
勝訴が確定しました。

There is a good reason why I chose "Itai-itai disease" among the four major pollution diseases.

This was because it was the first pollution issue in which the plaintiffs prevailed in a civil trial for pollution.
After the Ashio Mineral Poisoning Trial, there have been numerous lawsuits in various parts of Japan claiming damages from pollution, but in every case, the victims(plaintiffs) lost the case.

I believe there were three reasons for this.

The first reason was the plaintiffs' failure to have strong counsel.
Since defense attorneys have a living to make, one cannot blame them for wanting to be hired by clients who pay as well as possible.
And since most of the polluters were large corporations that paid well, they had access to competent lawyers.

The second reason was that the victim population had been divided.
This means that were a small number of victim people who were employed by the defendant company as workers.

After World War Ⅱ,the farmland of large landowners was sold off to small farmers at throwaway prices under agrarian reform by GHQ.
The policy itself was groundbreaking.
However, especially in areas north of the Hokuriku region, winters were covered with snow and income not earned during that time.
Therefore, especially male workers, had to migrate to get their income.
It was mines, coal mines, or factories that provided them with places to work at such time.(They were also a source of pollution.)

The third reason was 
"rapid economic growth"
(esp.that of Japan in the post-WWⅡ period).

After Japan was defeated in the Greater East Asia War(I dare not write "Pacific War", Japan was in a state of hyper-inflation and unpaid wages were rampant, and the lives of the common people were on the verge of bankruptcy.
However, in the midst of the Cold War, the Western powers had Japan increase its economic power and rearm Japan to defend itself(the National Police Reserve) in order to make Japan a bulwark against communism.
As a result, Japan recovered its prewar industrial production capacity, and as children born after the war reached working age, they were increasingly placed in factories, mines, and other workplaces as "promised generation".

Although there were some scholars who warned against this excessive emphasis on manufacturing, most people were buoyed by economic growth and pushed forward with mass production and mass consumption.

The "four major pollution diseases" were monsters spawned by these factors.

Returning to the Itai-itai disease,
initially,people who worked in the mines and farmers who feared the reputational damage that could be caused by the pollution raised cautious opinions.

However,after tearful appeals from families who had lost family members to the damage, the victims finally decided to take the case to court.

The defense lawyers for the defendant company were all highly skilled, having handled a variety of pollution disputes.

On the other hand,the plaintiffs' attorneys were young, with an average age of 37, and they were responsible for their own court costs.

The trial was expected to be protracted.

In the 1960s, however, as the distortions of economic groth began to appear in the form of river pollution, sludge as typified by Tokyo Bay, and health hazards caused by air pollution, public option began to pressure the companies responsible for the pollution to take action and provide relief to the victims.

The court finally moved on this public option, and at 10：00 a.m on June 30, 1971.
The Toyama District Court ruled that
"proof of a casual relationship between pollution and the causative agent does not necessarily require scientific proof.Therefore, we fully admit the plaintiff's suit and order the company to compensate and remedy the pollution."

The plaintiffs won the case in its entirety.
The Court of Appeals rendered a similar decision,confirming the victory of the plaintiffs.