An Overview of Minamata Disease

Minamata disease is methylmercury poisoning that leads to neurological symptoms. The condition develops after a person has been eating heavily contaminated seafood daily.

The first record of Minamata disease was in Japan in the 1950s. At the time, people ate fish that had been contaminated by large quantities of mercury compounds that were discharged into Minamata Bay by a chemical factory.

This article will go over what Minamata disease is, the history of how it developed, and what the effects are today.

The Minamata Disaster

The story of the poisonings starts in several small fishing villages on the edge of Minamata, Japan, on the coast of the Shiranui Sea. Given the location, the people living here ate a lot of seafood.

In the mid-1950s, the villagers started to notice their cats were behaving strangely—specifically, falling into the sea. Some people even believed the cats' behavior was an act of suicide.

Soon after, villagers started to report unusual symptoms like:

• Numbness in their limbs and lips
• Difficulty hearing or seeing
• Tremors in their arms and legs
• Trouble walking 
• Brain damage

Like the cats, some people began acting strangely and shouting uncontrollably. Something was affecting their nervous system—but what could it be? The fish-based diets of the villagers and cats seemed to be the common thread, leading scientists to suspect that the fish in Minamata Bay were being poisoned.

In July 1959, researchers from Kumamoto University discovered the source of the illness—high levels of mercury poisoning. They named the condition Minamata disease. Right away, a large petrochemical plant in Minamata, run by Chisso Corporation, was suspected as the source of the mercury.

Chisso denied the allegations and continued manufacturing without changing production practices. Chisso continued to deny that its mercury waste was causing any illnesses. It was later estimated that Chisso Corporation had dumped 82 tons of mercury compounds into Minamata Bay.

As the mercury dumping continued over time, poisoned people gave birth to babies who were also poisoned. The children were born with severe deformities including gnarled limbs, mental deficits, deafness, and blindness.

The fishermen of Minamata began protesting Chisso Corporation in 1959, demanding that the company stop dumping toxic waste and compensate the villagers for the illnesses linked to it. 

Chisso tried to make deals with people affected by mercury poisoning. The company provided them with legal documents that stated it would compensate them for their illnesses but would not accept present or future liability for the disaster. Many people felt this deal was their only chance of receiving any compensation, so they signed the papers.

Recovering From Minamata Disease

Chisso finally stopped poisoning Minamata’s waters in 1968. In October 1982, 40 plaintiffs filed suit against the Japanese government, saying that it had failed to stop Chisso from polluting the environment and had "looked the other way” while Chisso violated pollution laws.

In April 2001, the Osaka High Court determined that the government’s Health and Welfare Ministry should have started taking regulatory action to stop the poisoning at the end of 1959 when the researchers had concluded that Minamata disease was caused by mercury poisoning. The court also ordered Chisso to pay $2.18 million in damages to the plaintiffs.

On October 16, 2004, the Supreme Court of Japan ordered the government to pay 71.5 million yen ($703,000) in damages to the Minamata disease victims. The Environment Minister bowed in apology to the plaintiffs. After 22 years, the plaintiffs achieved their goal of making the people responsible for Japan’s worst case of industrial pollution pay for their negligence.

In 2010, Chisso was ordered to pay 2.1 million yen and monthly medical allowances to people who were not originally certified by the government as having the condition. 

More than 65,000 people applied for this compensation, showing that over five decades later, the effects of the disaster are still being felt.

Summary

Minamata disease was linked to poisoned water in a fishing village in Japan in the 1950s. A nearby company was dumping waste, leading to high levels of mercury in the water. When people (and cats) in the village ate the fish from the water, they also consumed high levels of mercury, which led to serious illnesses.

After decades of legal battles, the victims of the Minamata disaster were compensated. However, the effects of the disaster are still felt today as generations of villagers were affected by the mercury poisoning.