Essay: Environmental and social impacts of Minamata incident

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  • Environmental and social impacts of Minamata incident
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Introduction of Minamata City, Kumamoto Prefecture, Japan:

Image 1: Minamata City – extracted from Minamata Disease: Its History and Lessons
Minamata City is located in Kumamoto Prefecture, Japan in Kyushu. The city was established in 1889 as a village, then re-designated as town in 1912, and then as a city in 1949. During the war-era, Minamata City became famous for railroad infrastructure and began modernizing around that time. It has a land area of 162.9 km2 and is surrounded by the sea, so prosperity came from aquaculture and most importantly, by the Chisso Corporation, a chemical industry.

However, one day aquatic creatures began to die mysteriously and myriads fish were discovered floating on the surface of the water. Domesticated animals like cats began dancing around and going mad. This was the beginning of the perplexing disaster in the city. On April 26, 1956, a local child was admitted to the Chisso Hospital (run by Chisso Corporation) with symptoms of slurred speech, body convulsions, and paralysis, then eventual death. Not long after that, several more people were admitted to the hospital with alike symptoms.
May of the same year, official recognition of Minamata Disease had come after Dr. Hajime Hosokawa, Director General of Chisso Hospital reported the symptoms of the patients to the Minamata Public Health Center. At that time, the symptoms caused by a mysterious disease was known as the “strange disease”. The cause of the illness was left unknown for years, until it was discovered that the by-product of Chisso’s manufacture of a particular chemical compound acetaldehyde acetic acid, was methyl-mercury, which was discarded into the sea.

In this essay, environmental and social impacts of this incident will be discussed. The research question related to the impacts is “In what ways did the Minamata incident due to the release of methyl-mercury, impair the waters of Minamata Bay in Kumamoto Prefecture, Japan and how did that affect the people socially in Minamata City?”

Investigation methodology:

To get first-hand information, I contacted the Minamata Disease Municipal Museum through email for permission to interview the head museum curator and was granted to do so. Also, I was given a seat to attend a talk session of an actual Minamata disease sufferer (normally to attend the talk session, prior registration is required). I was able to obtain information directly from the talk session itself, and though I wanted to ask direct questions, I was refrained from doing so due to the sufferer being very old and having psychological instability from the distressing experience. Instead, I was able to take a picture with the disease sufferer.

After the talk session, I had a long interview with the head curator about the Minamata incident and its social and environmental impacts (see appendix). Some of the questions asked during the interview was refrained from answering due to the confidentiality of certain information about the incident. At the end of the interview, I had a picture taken with two museum curators.
Initially, my plan was to give out questionnaires about the incident to the citizens of Minamata City, but had to be turned down because of difficulty of getting consent of doing so and my position of being unauthorized to carry out such task to obtain information. At the end, I was able to gather adequate details of the Minamata incident through informative displays, talk session, and the interview with the curator. As most of the information was in Japanese, it was require to do translation.

Image 2: chemical structure of methyl-mercury – extracted from Mercury and Health

Mercury exists naturally on Earth and it comes out by volcanic explosions. It circulates throughout the environment from vaporization from land or sea and precipitation from the atmosphere. The common chemical forms of mercury are inorganic and metallic mercury, which both exists on Earth. In the modern days, mercury emission has increased greatly due to human activities such as coal combustion and gold mining.

Methyl-mercury is an organic form of mercury, which is generated naturally from inorganic mercury and is highly toxic to the environment and to organisms. It gets bio-accumulated in marine creatures, which is diffused through complex aquatic food webs, then leads to death of marine animals and mutated creatures. The larger the predatory level, greater amount of concentrations of methyl-mercury would be found because larger predators intake relatively great amounts of their affected prey, so methyl-mercury bio-magnifies in those predators.
As methyl-mercury enters the body, it is dispersed in gastrointestinal tract, kidney, liver, and brain. When a pregnant woman intakes the contaminant, the fetus is affected by methyl-mercury. The placenta has the function of filtering out toxins, but methyl-mercury easily passes through the placenta, then into the fetus’ system. Therefore, DNA mutations occur and the infant is born with disabilities.
The Minamata Incident:
The beginning:

Image 3: patients outbreak – extracted from Minamata Disease: Its History and Lessons

Minamata City prospered from the manufacture of chemicals by Chisso Corporation, alongside with agriculture and aquaculture. The sea was magnificent and fertile, blessed with natural fish reef. However, one day in the 1950s, myriads of sea creatures such as fish were found dead and were floating on the surface of the water. Shellfish died and seaweeds did not grow at all.

Around the time when sea creatures dies mysteriously, a child was admitted into Chisso Hospital (hospital run by Chisso Corporation) with symptoms of paralysis. Not long after that, three more patients were admitted with alike symptoms as the child. On May 1, 1956, a month after the admission of patients, Dr, Hajime Hosokawa, Director General of Chisso Hospital reported the patients with the symptoms of unidentified neurological disease to the Minamata Public Health Center.

Soon after that, the unidentified neurological disease became recognized as Minamata Disease. Patients with the symptoms of the “strange disease”, who were in other hospitals were apprehended as sufferers of Minamata Disease after the investigations were done. By the end of 1956, 54 cases including 17 deaths were substantiated.

Although the recognition of the disease took place, the source of this illness was still unknown. Due to that, it was believed that this so-called strange disease is contagious and epidemic, so people stayed away from the patients. While then, many fishermen and researchers began assuming that the waste water from the Chisso corporation. However, Chisso corporation refused to take the speculation into account and continued to release waste water into the bay. As a result, the investigation of the root cause prolonged and the effort it took was strenuous.

The official discovery of the root cause:

More than a decade later on May 31, 1965, Niigata University reported cases of mercury poisoning in Niigata Prefecture from an unknown starting point, and that was while Minamata Disease investigations were still ongoing. With this outbreak, it was found that the patients in Niigata Prefecture had identical symptoms as Minamata disease patients, and therefore, Niigata-Minamata disease was officially recognized on June 12, 1967. Right after that, Niigata’s fertilizer factory, Showa Denko was sued for dumping toxic by-products into the Agono River. Finally, Japan’s profound and extensive pollution trial began.

After the disclosure of the Niigata- Minamata disease, the national government declared its official opinion on Minamata disease on September 26, 1968. It was stated that Minamata disease is the illness of the central nervous system caused by a methyl-mercury compound released into the aquatic environment as a by-product of acetaldehyde acetic acid. Therefore, sea creatures were greatly affected by the substance, and as a result, Minamata disease is caused by the intake of the defiled seafood.

With this opinion being announced, it was eventually discovered that Minamata disease was pollution-based disease, and is not infectious. It took 12 years to officially regard Minamata and Niigata-Minamata disease as pollution-based illnesses. At this point, the making of acetaldehyde acetic acid was terminated permanently.

Theories of the cause of Minamata Disease before discovery of the root cause:

“Strange Disease” and contagious illness theories

From the day of the disease recognition, more patients got admitted in the hospital after showing symptoms of the “strange disease”. At that time, the disease was thought to be contagious, so houses were disinfected. Kumamoto University conducted autopsies on dead patients and directed medical examinations on patients under conscientious medical scrutiny, but were unsure of the true nature of the disease.

Heavy metal poisoning theories

Kumamoto University conducted a field survey in the extensive area. Samples pf drinking water, soil, seawater, and sea animals were taken. They reported that Minamata disease is not infectious, like suspected earlier, and is caused by some form heavy metal poisoning. It was assumed that the intoxication was caused by a large consumption of seafood polluted with heavy metal. Manganese, Solenium, Thalium, or the integrated effects were hypothesized as the cause of Minamata disease. Though Minamata disease was confirmed to be the cause of eating contaminated seafood, the pollutant was left unspecified for years.

Identification of methyl-mercury compound by the Kumamoto University Study Group

In 1960, Professor Makio Uchida and his study group extracted organic mercury crystals from shellfish of Minamata Bay. Then, in 1962 Professor Katsuro Irukayama asserted that methyl-mercury chloride has been isolated from the acetaldehyde acetic acid factory’s mercury deposit. Finally, in 1963 the study group made a formal announcement stating that the cause of inebriation was of methyl-mercury compound found in marine animals and in the sediments from Chisso Corporation factory. However, at that stage, the compounds found in the marine animals and in the sludge seemed to not have identical molecular structures.

Measures taken upon discovery of the root cause:

Regulations imposed on Chisso Corporation factory:

Since 1932, the methyl-mercury sludge had been deposited in Minamata Bay and briefly in the Minamata River. In 1960, though a bit flawed, a refined drain recycling system was brought into operation in order to filter mercury compounds. However, in 1966, this refined drain recycling system was put to a stop because an advanced pollutant processing system came into practice. By 1968, the release of the by-product was no longer apparent because the production of acetaldehyde acetic acid was permanently halted due to further discoveries of potential health and environmental hazards.

Regulations imposed in the city as a whole:

During the ongoing investigation of Minamata disease in 1956, it was confirmed that the disease was caused by intake of large quantities of contaminated seafood from the sea in Minamata Bay. With this confirmation, Kumamoto Prefecture reinforced policies of voluntary constraint on fishing and seafood consumption. Right after that, Committee of Measure Against Minamata Unknown Disease proceeded with enactment of Food Sanitation Act to the Ministry of Health and Welfare, but only to get the possible implementations rejected due to claims of evidence lacking to prove that seafood from the bay is contaminated. Consequently, Kumamoto Prefecture was unable to proceed with the enactments, leaving it to impose only voluntary fishing and seafood consumption restrictions. Seafood prices increased greatly when voluntary restrictions on fishing and seafood consumption were regulated.

In January 1974, Kumamoto Prefecture began constructing dividing nets at the mouth of Minamata Bay to ease social anxiety due to intoxication and plummeting seafood price, and also to avoid escalation of polluted marine animals. Then, the marine animals that are contaminated were collected and stuffed in barrels, then were buried and confined deep underground to avoid the spread of methyl-mercury on soil as well. The number of barrels used to store the contaminated marine animals were counted as 3500. By June 1978, Minamata City employed full time patrolmen to scrutinize people who are fishing due to the reinforcement of restraint on fishing in certain areas due to exceeding the tolerable amounts of mercury compounds in the waters of the bay. Not long after that, the city initiated active duty ocean patrol to inspect safety of fishing in certain areas.

Towards the end of the environmental restoration efforts

After 23 years of facilitation of dividing nets and constant scrutiny in the waters, Minamata Bay was declared safe in 1997. Under the condition where levels of methyl-mercury in the water and marine animals such as shellfish were much below tolerable, dividing nets were removed and scrutiny became less frequent. Once declared safe, Minamata Bay was reopened as the main aquaculture zone after a halt of more than two decades. Though the bay was declared safe, monitoring for caution lasted until 2000.

Image 4: methyl-mercury levels in water – extracted from Minamata Disease: Its History and Lessons

The diagram above shows the progression of the mercury concentration in marine animals from the time of Minamata disease outbreak until 2005. The mercury concentration level was at peak, until there were speculations and theories of the origin of the “strange disease”, where the concentration level drastically dropped as Chisso corporation initiated the use of sludge filtering machines. However, the filtering machine was not very efficient and facilitation of the machine was put to stop , so there was an increase of mercury concentration between 1962 and 1963. Right after that, there was a gradual decrease of acetyldehyde acetic acid production, which led to a gradual decrease in mercury concentration in waters of Minamata Bay. From 1970 to 2005, the mercury concentration levels were very low and stable, but the dividing nets were removed only in 1997 for constant monitoring around the bay.
Compensation for aquaculture by Chisso throughout the years
As the issue of Minamata disease became widespread, many seafood retail shops closed down due to inadequate sales. In 1959, when Minamata City Fresh Seafood Retailers Union experienced massive decline in sales, and demanded Chisso corporations for financial compensation, complete removal of contaminated deposits, and installation of pollutant-processing equipment. Chisso corporations counter-claimed that there is no clear proof of the cause of Minamata disease, but agreed to only pay urgent reparations to the fishery union, but the amount did not suffice. Soon after that, angry fishermen stormed into the meeting hall of the company and caused riots during demonstration against Chisso corporation. This incident had to have police involve due to the physical violence, which eventually lead to injuries among fishermen, company workers, and policemen. Few months after that, it was determined that there should be another formal meeting with Chisso to permanently terminate the creation of hazardous chemicals, but the company turned down the request, leading to another brawl between outraged fishermen and the company.
Then in 1989, though Pollution Prevention Project was completed, there were over-the-limit levels of mercury compounds discovered in marine animals in Minamata Bay. Due to this discovery, Chisso corporation eventually paid ¥900 million to the aquaculture industry head. Kumamoto Prefecture also aided fishermen who were in constant financial crisis throughout the years with loan and also provided employment assistance into other occupations for financial incomes.
Social impacts on Minamata incident:

Image 5: patients number – extracted from Minamata Disease: Its History and Lessons
The diagram above shows the number of recorded sufferers in several places in Kumamoto Prefecture and Kagoshima Prefecture. Though Minamata City has the greatest number of recorded Minamata disease sufferers, other towns and cities that are facing the bay had sufferers with Minamata disease. Aside from compensation to the fishermen, there had to be reparations paid to those recognized Minamata disease sufferers by Chisso corporation.
The Minamata incident was the prolonged discharge of methyl-mercury contaminated- sludge into the bay, and the reason of mercury compound intoxication was left unknown until several years later. When Minamata disease was officially acknowledged by the Ministry of Health and Welfare, the cause of symptoms such as paralysis, hysteria, and quivers were unknown and the disease was thought to be contagious. Consequently, those who displayed such symptoms were ostracized, alongside with their families by the society. Years after the discovery of the root cause and the proof of Mimamata disease being non-infectious, people started to be more understanding and aware of the nature of the sickness, but some were still being ignorant about it, thinking that Minamata disease is an epidemic illness. Therefore, discrimination against the sufferers were still apparent and many others refused to mingle with them.
Not only the sufferers and their families were prejudiced against, but those who are unaffected and are from Minamata City were discriminated. When people from Minamata City go to other regions and assert where they are from, they get stereotyped as Minamata disease sufferers. As a result, those who are unaffected by the disease and are from Minamata City blame and hold grudges against the actual sufferers of the illness because of being stereotyped in that way by outsiders.
Though the sludge from Chisso was investigated and showed traces of heavy metal compounds, the company still released waste water into the bay and also diverted the release of the sludge at the mouth Minamata river, causing spread of intoxication. During that time, Minamata disease was officially recognized, but the root cause was still left unknown although there were surmises that the source was from Chisso. This brought immense distress towards the sufferers of the disease and their families, as well as the society as a whole.
Compensation to the sufferers of Minamata disease:
The Minamata disease trial started in March 1973 and an agreement made between the court and Chisso corporation was to compensate 16-18 million JPY to the disease sufferers. In addition, the provisions included medical expenses, nursing costs, and funeral fees (Minamata Disease Municipal Museum ). Before the disease sufferers can receive compensation from the government and Chisso Corporation, they have to be officially recognized as Minamata disease suffers by Kumamoto Prefecture.

Image 6: certification process – extracted from Minamata Disease: Its History and Lessons
A person who thinks he/she has the disease applies for official certification, where medical examinations will take place. A medical report will be written by a physician regarding the symptoms. It will go through board with medical experts and final decision will be made whether or not the applicant can be certified as disease sufferers. Once certification is approved by the Prefecture, compensation will be given to the disease sufferers.
However, a lot of time is taken to certify many people who claim to suffer from the disease. When a certain number of people apply for certification, the board normally prioritize those who exhibit very severe symptoms. Those with mild symptoms are normally rejected or put to last for the proceedings. Also, there were cases of people applying for official certification without even contracting the disease because of aiming to get money from the compensation.
Aside from the Bhopal disaster and Chernobyl nuclear accident, this Minamata incident is one of the worst environmental calamity in the world because of its long-term pollution that was left undetected for several years. The environmental restoration took years with maximum efforts. Although it has been 6 decades since the tragedy, there is no end to this incident because to this day, there are sufferers who are still alive to tell their stories. In addition to that, some of the filed lawsuits from decades ago have not been settled at all, meaning the court trial is ongoing. Many fishermen lost their jobs and suffered from financial crisis, but many decided to become farmers to support themselves. As the number of farmers increases throughout the years, Minamata City became famous for producing citrus fruits like oranges. Though the sea in the Minamata Bay is declared safe and clean, the history still remains.
However, medical technologies improved and conventions on mercury compounds were initiated in order to prevent such similar cases from occurring. Thanks to the mercury convention, industries from all over Japan abide the policies regarding handling mercury compounds. The Minamata disease sufferers continue to live on by speaking about their life experiences. The purpose of their voices is not to blame and promote hatred, but to spread their message for future prosperity.

Appendix A:

1. What necessary measures we taken when methyl-mercury was discarded into the sea as a by-product of manufacture of fertilizers?

Extracts of the interview with head museum curator

A certain area of the sea was isolated by aquaculture nets in order to not let the methyl-mercury-contaminated aquatic organisms to spread over larger boundaries. Once isolated, those aquatic organisms were collected, stuffed in barrels, and the barrels were buried deep into the ground so that there would be minimal spread of the pollutant. The total number of barrel used was counted as 3,500.The clean-up itself took almost 14 years to complete. However, the concern is that when natural disasters such as earthquakes happen, there is no guarantee that the stuffed barrels would stay secured underground, so it is important to stay cautious of the hazards of methyl-mercury release.

2. In what ways did the agriculture/aquaculture get affected by this incident?

Agriculture did not get affected so much, but aquaculture in Minamata faced its worst destruction. Because Minamata is facing the sea, people and local fishermen relied on seafood as sources of protein. After the Minamata incident, aquaculture had to stop its operation. Fishermen relied mostly on fishing to make their living, but ended being financially unstable. However, fishermen shifted to agriculture and started earning money. Therefore, the advancement of agriculture was apparent as the number of farmers increased over time, which helped the city recover from financial and economic crisis. Thanks to the increase of number of farmers, Minamata became famous for growing citrus fruits.

3. In what ways did the Minamata disease suffers face prejudice and discrimination?

In the past, Minamata disease was not known until several years passed by. Numerous of people had the impression that Minamata disease was contagious and would spread through air. Due to that, they did not want to mingle with any of those who had the disease. Now that there are proofs that Minamata disease is not contagious, people are more aware, but still there are prejudice against the people. For instance, a child from Minamata moves to a place far from where he/she is from, and then tells those outsiders where he/she is from. After that, the people there think everyone in Minamata has the disease and the child feels insulted. As a result, the child would hate Minamata disease itself, then would blame the suffers for what he/she experienced just because he/she is from Minamata. Ignorant people still exist all over Japan, and maybe even in foreign land. Therefore, this museum is not here to only explain facts about the disease and the environmental impacts, but to educate all about the psychological attributes.

4. How has Japan changed overall since the Minamata incident?

Japan has changed overtime in terms of handling mercury. Thermometer in the past used mercury, but nowadays, due to safety, manufacturers use safe alternatives. Moreover, medical technologies improved thanks to the discovery of Minamata disease, so medical staffs are acquainted to attributes of mercury poisoning. Environmental monitoring is much more frequent not only in Minamata bay, but all over Japan. The mercury convention was created after the discovery of Minamata disease, so it is used when mercury is handled in certain industries. Any violation by any industry, impunity will be intolerable.

Works cited:

Hachiya, Noriyuki. “The History and the Present of Minamata Disease: Entering the second half a century”. 2006.
“Implementation of the Minamata Convention in the health sector: challenges and opportunities. World Health Organization. 2017.
“Mercury and Health”. Minamata Disease Archives. National Institute for Minamata Disease. Volume 4.1. 2013. Print.
“Minamata Disease: Its History and Lessons”. Minamata Disease Municipal Museum. March 2016. Print.
Takamura , Yukari. “The Minamata Convention on Mercury: Its Significance and Challenges”. Apr. 2014.

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