Four Big Pollution Diseases of Japan

The Four Big Pollution Diseases of Japan were all human-induced diseases and adversely affected the health of the Japanese people.


Four human-induced diseases affected the people of Japan between 1912 and the 1960’s. These diseases, the itai-itai disease, the Minamata disease, the Niigata Minamata disease, and the Yokkaichi asthma opened the eyes of the world to the detrimental effects of environmental pollutants on human health. These diseases helped increase public awareness about the need to check the contamination of the environment by industrial effluents. It also triggered the Japanese government and other authorities across the world to implement more stringent laws regarding the release of industrial waste into the environment.

Itai-itai Disease

Itai-itai meaning "it-hurts it-hurts” is one of the Four Big Pollution Diseases of Japan that was first detected in 1912 in Japan’s Toyama Prefecture. The cause of the disease was traced to the Mitsui Mining and Smelting Company that was releasing cadmium containing effluents into the Jinzū River basin. The cadmium then entered the human body through drinking water or via the consumption of food that was grown in the contaminated water. Bone fractures, skeletal malformations, renal dysfunction, extreme pain, and anemia, etc., were some of the clinical manifestations of the Itai-itai disease. After realizing the cause of the disease, the affected residents filed a lawsuit against the company responsible for the cadmium contamination of the water bodies. The lawsuit, filed in 1968, was won by the people and Mitsui Mining had to finally confess to the charges and pay a hefty price to return the land to a safe state.

Minamata Disease

Another infamous disease, the Minamata disease that was caused due to mercury poisoning, also originated in Japan. It affected the Kumamoto Prefecture in the country. The disease was first detected in 1956 and had a deadly impact on the victims of the poisoning. Many patients lost their normal mental state and died within months of contracting the disease. Investigations revealed that it was caused due to methylmercury poisoning. Consumption of contaminated fish caught from the Minamata Bay led to the poison entering the bodies of the victims. The poison then affected the central nervous system, resulting in the disease. Further inquiries revealed that the Chisso Corporation was dumping methylmercury into the bay. The company was found guilty and thus forced to pay compensation to the patients of the Minamata disease as well as fund the reclamation of the bay. The Minamata disease shook the world with its horrific consequences and led to Japan passing a historic regulation, the Japanese Water Pollution Control Act of 1970.

Niigata Minamata Disease

Another one of the Four Big Pollution Diseases of Japan, the Niigata Minamata disease that affected the people of the country’s Niigata Prefecture, was also caused by methylmercury poisoning. The disease was first detected in 1965 when patients in the area presented symptoms of the Minamata disease. Due to prior experience and knowledge, the outbreak was controlled at an early stage. This time, the source of methylmercury was water from the Agano River basin. The medical department of the Niigata University was tasked with detecting the main source of the pollutant. Although initially no single source could be singled out, later the Showa Denko Corporation factory was found responsible for dumping methylmercury into the Agano River. Although the company denied the charges, it was found to be guilty of negligence and had to pay heavy compensation to the victims of the Niigata Minamata disease. Five lives were lost due to the disease.

Yokkaichi Asthma

A city in Japan’s Mie Prefecture, Yokkaichi witnessed an outbreak of asthma following the construction of an oil refinery in the city in 1955. The refinery did not possess the technology to reduce the toxic components like sulfur dioxide present in its emissions. As a result, the air in the city became heavily polluted. Soon, a significant population of the city started suffering from respiratory illnesses. Investigations traced the source of such illness to air polluted with sulfur dioxide and the disease resulting from such pollution was named the Yokkaichi Asthma. With complaints pouring in, the government introduced a compensation scheme whereby all afflicted with Yokkaichi Asthma were paid money given certain criteria were fulfilled. Today, such disasters are kept at by bay by laws that regulate the volume of sulfur-dioxide that can be released into the air by factories.


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