The outbreak of Minamata disease

The Chisso Corporation (hereinafter, Chisso) was established in Minamata in 1908 and contributed to Japanese economic growth through the chemical industry. However, Chisso had already caused damage to the fishing industry by dumping factory effluent into the environment in 1925-6 and had to compensate the fisheries cooperative. Chisso started the production of acetaldehyde, using mercury as a catalyst, in 1932 and once again began discharging untreated wastewater into the sea.

Chisso expanded its production of acetaldehyde after the 2nd World War and changed its production methods around 1950. At that time large quantities of methylmercury were present in the wastewater. Since then, abnormity and abnormal changes occurred in fish, shellfish, birds, cats, and pigs. The fish in Minamata Bay began to appear on the surface of the sea, crows fell from the sky, and cats began to dance madly.

Fishing catches suddenly decreased from the late 1940s. In 1956, two sisters, 2 and 5 years old, were admitted to a hospital attached to Chisso Hospital. The 5 year-old was admitted on April 21 and the 2 year-old on April 23. They both had neurological disturbances of unknown cause. The hospital director, Dr. Hosokawa, reported this to Minamata Public Health Center (managed by Hasuo Ito) on May 1. This is considered the first official recognition of Minamata disease. However, director Hosokawa tracked the outbreak in patients with similar symptoms of the nervous system back to December, 1953. In addition, Kumamoto University’s Second Minamata Disease Study Group reported a probable outbreak of Minamata disease in 1942.

Investigation into the cause of Minamata disease

During the initial investigation, the cause of Minamata disease wasn’t clear and it was called the, “strange disease”. Anyone suspected of being infected with the disease was quarantined and they and their families were subjected to discrimination.

During the Kumamoto Medical Convention in October 1956 the existence of an infectious disease in the area was denied. In December of the same year, Professor Kitamura of Kumamoto University proved the danger in seafood from Minamata Bay, but these studies were ignored by the Government and administration.

In September 1958, the outlet of the drainage ditch was changed from Minamata Bay to Minamata River, resulting in the pollution being spread by currents that flowed north and south in the Shiranui Sea (known locally as the Yatsushiro Sea).

In July 1959, Kumamoto University’s Study Group determined the cause to be organic mercury. Chisso and the Government did nothing to clarify the situation as to the cause of the disease.

On November 12th of the same year, the Minamata Food Poisoning Section of the Ministry of Health and Welfare - Food Sanitation Investigation Council announced that the cause of the “strange disease” was some sort of organic mercury and acknowledged the necessity of further investigation, but the Ministry of Health and Welfare dismissed the section’s acknowledgement and request the following day.

After that, no further research into the matter was done and neither were the Government’s Food Sanitation Law nor the town’s Water Quality Control Law, which could have been used to prevent further fishing, enforced. Chisso continued the production of acetaldehyde and the draining of the contaminated wastewater into the sea via the river.

The Supreme Court’s judgment pointed out that the policy of this country was wrong. In December, 1959, Chisso completed a wastewater treatment facility with a cyclator which was said to be effective in separating the mercury from the wastewater. However, it became clear that the facility was completely ineffective and methylmercury continued to be released in the wastewater.

On the 15 October 2004, this Supreme Court of Japan ruled that the national Government was responsible for not preventing the spread of Minamata disease after 1960.

The end of acetaldehyde production and the recognition of Minamata disease as disease related to environmental pollution

In May, 1968, Chisso finally stopped the production of acetaldehyde, using mercury as a catalyst, in Japan.

In September of the same year the Japanese Government officially recognized that the cause of Minamata disease was the methylmercury contained in the wastewater from the Chisso factory and recognized Minamata disease as a disease caused by environmental pollution. Twelve years had passed since the official discovery of Minamata disease and in those 12 years the numbers of Minamata disease victims and patients had continued to grow.

In 1969, the patients demanded compensation for damages from Chisso and filed a lawsuit. The Minamata disease patients were not able to get any proper compensation until the case was settled in 1973.

The patients and victims suffered not only physical and mental pain, they and their families were also victims of discrimination in the Minamata area. Before the cause of Minamata disease had been discovered it was said to be contagious. After the real reasons for the disease had been discovered, the discrimination continued and sufferers were accused of faking symptoms in order to get compensation money.

Victims and their families, in order to avoid discrimination, kept quiet about their suffering. It was more difficult for them to get jobs or even to find a partner and get married. In such an environment of discrimination it became very difficult to consult a doctor about the disease and to apply for compensation.

After the Government received a petition drawn up by Teruo Kawamoto and others, which expressed their dissatisfaction with the handling of the whole affair, the Environmental Agency was set up in July 1971. The agency was given the task of documenting the criteria to be used in the certification of Minamata disease victims.

The criteria stated that for a person to be certified as a victim of Minamata disease they had to have a history of consuming seafood that had been polluted by methylmercury and also at least one of a number of symptoms including sensory disturbance, visual construction, and ataxia of the limbs and so on.

However, at the time when those criteria were drawn up, there had been no comprehensive research into the effects of the pollution on the human body nor was it yet clear exactly what signs and symptoms were connected with the disease.

The establishment of the Minamata Clinic and the Katsurajima Study

As mentioned in “Introduction of the Clinic,” a group of doctors volunteered to examine patients in the Minamata area in June, 1970.

Dr. Tadashi Fujino, a member of Kumamoto University’s Second Minamata Disease Study Group, was among the doctors who came to examine Minamata disease patients. He saw many victims in the area who were struggling hard to make a living and who are not receiving any treatment or compensation. His observations led to the establishment of the Minamata Clinic in January, 1974.

The initiative taken by the group of doctors to help victims and patients was continued by the Kumamoto Association of Doctors against Environmental Pollution. As a result, many patients with neurological disorders, including sensory disturbance and ataxia, were discovered. Certification applications increased rapidly and Chisso began to have financial problems and the sale of prefectural bonds began. The Government stepped in and tried to rectify both problems by tightening up the requirements for certification in 1977, when the Minamata Disease Assessment Criteria were introduced.

As shown in Dr. Masazumi Harada’s pyramid model, Minamata disease has a wide range of clinical conditions, from mild cases to serious ones. In cooperation with the Kumamoto Association of Doctors against Environmental Pollution, Dr. Fujino conducted a study on Katsurajima Island to substantiate Dr. Harada’s findings.

Katsurajima is a remote island which lies 12 km south-west of Kumamoto City. At that time it was assumed that there was comparatively little pollution there and a study group from Kagoshima University had concluded, in 1973, that there were no cases of Minamata disease on the island. Dr. Fujino and the staff of Minamata clinic started an epidemiological investigation to compare the frequency of Minamata disease on the island with that of fishing village on the Amami islands in Kagoshima Prefecture.

The results of this study showed that the inhabitants of Katsurajima had sensory disturbances, visual constriction and other more significant symptoms. The study showed that there was a wide spectrum of symptoms, from mild sensory disorders to extremely severe cases with all the symptoms of the Hunter-Russell Syndrome. The study also discovered cases of Minamata disease exhibiting only sensory disturbances. After the study had been completed many of the inhabitants of Katsurajima were officially certified as Minamata disease patients.

The examination of Minamata disease

Using the results of the Katsurajima study, Minamata Kyoritsu Hospital and the Kumamoto Association of Doctors against Environmental Pollution established criteria that a patient who had eaten polluted seafood and had four-limb sensory disturbances could be diagnosed as having Minamata disease. After the new criteria were established, as mentioned in “Introduction to the Clinic”, as many as 10,000 patients were examined.

Up until 1977, although there was big increase in the number of patients applying for certification of Minamata disease, the number of deferred and postponed decisions began to increase and the number of certified patients began to decrease. In August 1985, in the Second Minamata Disease Lawsuit, the Fukuoka High Court recognized plaintiff patients who had previously been denied certification by the Government, as being victims of Minamata disease.

Chisso did not appeal against this decision and the case was settled. In the judgment, the certification criteria of the Government were criticized and the criteria of the Kumamoto Association of Doctors against Environmental Pollution were adopted. The Government did not change the criteria, but as they could not ignore the decision of the court they, together with the prefectural Government, introduced the Special Medical Project in 1986. The project did not certify patients as having Minamata disease, but instead, paid the obligatory national health insurance contributions for patients who had eaten polluted seafood and who suffered from sensory disturbances in their arms or legs.

This Special Medical Project later became the Comprehensive Measures of Minamata disease, and in 1995 was adopted in the Final Solution Scheme that was agreed on in the reconciliation between Chisso and the patient groups. On September 11 and 12th, 1985, a Medical Expert Meeting held by the Environmental Agency on Minamata disease, chaired by Itsuro Sobue, concluded that the 1977 Judgment Criteria were valid. Later, The Japanese Society of Psychiatry and Neurology conducted an investigation into that meeting and found that there were no scientific or medical grounds for the opinions expressed at that meeting.

From Minamata disease solution of 1995 to the present-day

In the Second Minamata Disease lawsuit, which sought to clarify the definition of Minamata disease (clinical picture), and in the Third Minamata Disease lawsuit, that fought to determine the responsibility of both the local Government and the national Government in the spread of the disease, clinical pictures and medical certificates were required as evidence.

After carrying out careful medical examinations, doctors from the Kumamoto Association of Doctors against Environmental Pollution and the Minamata Kyoritsu Hospital issued medical certificates to nearly 1,400 plaintiffs. The medical certificates presented by the many doctors who testified in court were accepted as evidence.

By the year 2000, a total of 2,263 patients in Kumamoto and Kagoshima Prefecture were recognized as Minamata disease victims, and a further 10,350 had received relief under the Comprehensive Measures of Minamata disease.

In the Minamata disease Kansai lawsuit, 58 plaintiffs continued their legal action, and in April 2001 the Osaka High Court recognized the responsibility of the Japanese Government and Kumamoto prefectural Government for the spread of Minamata disease. Most of the plaintiffs in the case were recognized as having Minamata disease. The Supreme Court supported the judgment of the Osaka High Court, and on October 15, 2004 the affirmed the responsibility of both the national and prefectural Government.

After the Supreme Court’s judgment thousands of residents began to apply for Minamata disease certification, the governor of Kumamoto Prefecture, Yoshiko Shiotani, proposed that health and environmental research should be carried out in the polluted area. But the Environmental Protection Agency refused to allow the research. The agency did not change the criteria for Minamata disease certification nor did it offer any relief measures to victims. In October 2005, the “No more Minamata lawsuit” was brought to court. In this lawsuit much of the research documented by Kumamoto Association of Doctors against Environmental Pollution was presented in court.

Of more than 1,000 inhabitants who were examined during the Shiranui Sea Coastal Area Health Investigation, carried out on the 21st and 22nd of September 2009, more than 90% of them were found to have neurological abnormalities which were particular to Minamata disease. Many patients and victims who had received no help or compensation were discovered. In March 2011 the No More Minamata lawsuit reached a settlement in which the Government recognized the plaintiffs as Minamata disease victims.

At present, patients who did not take part in this lawsuit are entitled to compensation through the law concerning Special Measures for Minamata disease victims. Although no official figures have been released of the number of patients who have received compensation, it is believed that up until now (September 2011) more than 60,000 residents have been compensated. Patients who have not lived in the designated area or who were born after December 1969 have received no compensation. As the law will only operate for a limited period of about three years, many patients are worried that they will be left out. There are still some groups involved in ongoing lawsuits.

1. Since the discovery of Minamata disease, not enough investigation has been carried out into the spread of methylmercury pollution, the health damage it causes and the disease mechanism itself. This lack of scientific and medical investigation is the result of Government policies and restrictions.

The speed of modern medical development is amazing. In any field of medicine, large amounts of data about new diseases, pathophysiology, and treatments are being continually collected by doctors and the best diagnostic and treatment methods are being searched for and then published in current medical magazines and textbooks.

However, even now, 60 years after its official recognition, correct information about Minamata disease is not generally known. Although, there was a study by Hunter and Russell in 1941 on methylmercury poisoning, such a huge outbreak of the sickness as in Minamata has never been seen anywhere in the world.

After Minamata disease was officially recognized, a procedure for dealing with the new sickness and the outbreak of clinical conditions should have been devised. The procedure should have included such things as prevention measures based on the provisional knowledge → research of the actual situation in the whole of the contaminated area → the elucidation of pathophysiology → provisional diagnostic criteria → and more research based on the medical investigation. However, such procedures have never been undertaken. Originally, research of the whole devastated area should have been done and a continual health survey of the residents should have been conducted.

In the early days of the disease the medical scientists who were involved with the diagnosis of the victims were only able to confirm a small number of cases before the Government stepped in, officially recognized the disease and then restrained them by setting up “proper procedures” for diagnosing the disease in victims.

In addition the active research into the disease being carried out by doctors of Kumamoto University’s Second Minamata disease Study was being suppressed and as a result the study of Minamata disease was considered to be taboo, especially if done by universities. Though there were hundreds of thousands of people who had been and were being exposed to methylmercury, the numbers of doctors who studied the disease was very small.

Not only that, but some “experts” formulated the so-called “1977 Judgment Criteria” (the Minamata Disease Assessment Criteria, 1977), which was adopted as the national standard for the diagnosis of Minamata disease, although it was not based on results gathered from medical examinations. Therefore, only some 2,000 people were certified and all the other applicants were refused on the grounds that their health problems were not related to methylmercury.

Medical Journals and books dealing with the disease have also followed this line of thought, so doctors, medical professionals and local clinicians all over Japan have been conditioned to say, “I don’t really understand about Minamata disease.”

As the main damage caused by Minamata disease is to the brain, it was considered a neurological disease. So many of the doctors who were engaged to draw up of the “1977 Judgment Criteria” were neurologists, many of them were also academics. Very few, if any, had any experience at all in actually treating Minamata disease and therefore had had no opportunity to learn about the real influence of methylmercury on human bodies. Ironically it was these “experts” who drew up the assessment criteria for the diagnosis of Minamata disease.

As neurologists, they could see that the brains of patients suffering from fulminant Minamata disease had a foam-like texture that was visible to the naked eye. But, that form of the disease was present in relatively few cases. The majority of victims of Minamata disease never developed the most severe symptoms and survived. Due to the ability of the nerve cells to regenerate new networks, while many patients had disabilities, those disabilities were only partial, e.g. the ability to learn and remember was not completely lost. Very little is known about the effect of exposure to methylmercury on the brain’s 14 billion neurons and to what degree various abilities are lost or diminished. The same is true for knowledge about the effects of varying levels of exposure to methylmercury in different age groups.

There are few neurological diseases which cause such a wide range of disabilities equivalent to methylmercury poisoning and which have had so little research done into the effects on victims.

In addition, in the case of the study of poisoning, such as methylmercury poisoning, you must observe the habitations of patients on-site and you must conduct research not only on severe cases but also on the full range of cases all the way down to the mildest ones. The differences between normal cases and mild cases are very important. Milder cases are one of the most important problems, but they are not clearly understood by neurological experts. However, the patient relief provided by the Law concerning Special Measures for Minamata disease, which began in 2010, is not for borderline sufferers, but for people with clear health disorders.

Neurological experts should have a clear understanding of the basic aspects of Minamata disease. Unfortunately there are not many such knowledgeable experts.

It is believed that the reason for this is because of the Government’s influence and pressure on the academic sector to desist from making any reference to Minamata disease. In the Asahi Shimbun newspaper, on July 17, 2009, the director of the (at that time) Environmental Health Department of the Ministry of the Environment said the following about the health check in the Minamata area, “although an investigation has been carried out it has been impossible to get a clear unbiased picture, as thoughts of compensation are always present when those investigated and questioned describe their symptoms. ” We understand that as meaning that any person claiming to be suffering from sickness or pain caused by environmental pollution should be ignored and that there is no need to carry out medical investigations to find links between the sickness and the pollution because the claimants are probably looking for compensation.

Although it has since been shown that the director’s remarks were inaccurate, the Ministry of the Environment has done nothing to refute them yet. We will now try and give a correct an accurate description of the real facts behind Minamata disease.

2. The inhabitants did not choose to be exposed to the dangers of methylmercury and they are not at responsible for becoming Minamata disease patients On the other hand, neither the victimizing company nor the Government have accepted responsibility and clarified the situation and how it was allowed to come about.

Even to this day patients are the victims of Minamata disease continued to be discriminated against in many different ways. Because of this many people have not informed their doctors or neighbors about any symptoms they may have and have kept quiet about their illness.

In the past you could hear remarks concerning Minamata disease such as, “Minamata disease is contagious” or “Minamata disease patients are only looking for compensation” voiced by people who are ignorant of the real causes of the disease or who refuse to accept the reasons for the disease. Whenever there is an outbreak of the disease that has been caused by pollution of the environment or food poisoning etc., the Government has a duty to investigate it thoroughly, inform the inhabitants about it and take measures to prevent it continuing and happening again.

In the case of Minamata disease the Government failed to do this. The responsibility to take action lies with the Government and not with the inhabitants of the area, victims of the disease or patients being treated for the disease.

Nowadays, if a company is responsible for polluting the environment, selling faulty products (e.g. electrical goods) or causing sickness among the consumers of its products (e.g. food products), it has legal obligations to rectify the problems and take precautions that they do not happen again.

Despite these obligations, in the case of Minamata disease the company involved and the Government should be taking action on behalf of the victims. However, even today, it is being left up to the patients to take the initiative and apply personally for certification of Minamata disease.

As recently as 2011, the Japanese Government and the Tokyo Electric Power Company failed to act quickly and correctly in face of the radiation contamination crisis at the Fukushima Nuclear Plant, that developed in the aftermath of the earthquake and tsunami of March 11th . This is the second time that such a serious situation has developed in Japan due to the Government’s secretive attitude. Sadly the Fukushima case is much worse than that of Minamata.

Chisso and the Government have done almost nothing to investigate and study the true extent and actual damage caused by methylmercury poisoning. Through their “non-action” they have, in fact, been responsible for an increased spread of the disease.

Almost all study into the health hazards caused by methylmercury poisoning done after World War II has been done without Government backing by organizations such as us.

Although severe cases of methylmercury poisoning have been studied there still remain an extremely large number of undiscovered cases involving victims exhibiting minor signs and symptoms. In addition, very little has been done to study the long-term effects of methylmercury pollution. So far, only small amounts of compensation have been paid to a limited number of victims.

3. Minamata disease encompasses a wide range of disorders from very mild ones to extremely serious ones. These depend on factors like the amount of methylmercury the victims have been exposed to and also to the length of time they have been exposed. It is impossible to make a correct diagnosis or to judge the grade of severity without 1.Taking into account the visible signs and 2.Carrying out a full investigation into the victims’ subjective description of their symptoms.

Perhaps, when you hear the words, “Minamata disease”, your imagination conjures up pictures of patients having violent convulsions accompanied by uncontrollable shaking that makes them look like crazed dancers. Or of patients with emaciated bodies and twisted joints.

Such signs and symptoms are only present in the most fulminant cases of Minamata disease. The majority of patients exhibiting these signs and symptoms have already died. Dr. Harada’s pyramid, shown below, illustrates the range of symptoms present from mild cases all the way up to the most severe and the relationship between them and the amount of exposure to methylmercury as well as individual susceptibility.

Moreover, especially in cases where adults have been exposed to methylmercury, more damage is caused to the sensory nervous system than to the somatic nervous system. This means, at first glance, they may not appear to have any disorders. When detailed studies are carried out mild cases can exhibit a broad range of slight damage whereas severe cases can exhibit a broad range of severe damage. Because the central nervous system is damaged symptoms can change and even improve in milder or moderate cases.

In mild cases disorders can sometimes only be detected after examining the patients very carefully and closely. In cases of congenital Minamata disease, where the fetus in pregnant victims was infected, some victims had obvious mobility disorders but no sensory disturbance. Minamata disease can show itself in many different ways and has many different “illness patterns”. Even doctors who have examined several thousand Minamata disease patients can have difficulty in diagnosing Minamata disease without listening carefully to the patient’s subjective description of their symptoms and performing a detailed neurological examination.

There is no short cut where a doctor can decide if someone has Minamata disease or not by just taking a quick look at them.

Some people, who misunderstand or are ignorant of the real facts connected with Minamata disease, sometimes, make inaccurate comments about the patient’s will, feelings, character and so on. Making comments based on ignorance and misunderstanding leads to discrimination.

The fact is that all of the local inhabitants regardless of their social position, personality or character are victims in one way or another and it is impossible to group them together and place them in a common psychological group. The inhabitants are continually under pressure and live in fear of being connected with Minamata disease and the possible discrimination that would follow.

4. Some of the facts about methylmercury had already understood and others are not yet understood. What is clear is that preparation for dealing with the hazards of low-level mercury pollution is becoming a global concern.

The “1977 Judgment Criteria” for diagnosing Minamata disease were solely based on the spectacular signs and symptoms of the first known cases of Minamata disease and therefore made no allowance for a positive diagnosis of milder cases. Until now, by adhering strictly to the “1977 Judgment Criteria”, the Pollution-related Health Damage Certification Council of Kumamoto and Kagoshima Prefectures has dismissed most of the applications for certification. Except for a short period of time, they have strictly applied the criteria.

Only a very few of the doctors that helped the Government had studied the sensory disorders found in mild cases.

Despite the severe conditions laid down by the Government, doctors like Dr. Masazumi Harada and Dr. Tadashi Fujino, members of Kumamoto University’s Second Minamata Disease Study Group have gathered data from a wide range of patients and made efforts to clarify and elucidate Minamata disease and its clinical conditions. Kumamoto Prefecture’s Association of Doctors against Environmental Pollution has uncovered many facts, especially about sensory disorders, from the study of Minamata disease symptoms. Especially in studies done in recent years, it has been found that both generalized sensory disturbance and peripheral dominant sensory disturbance can occur, and even though this is a central nervous disorder, it can cause the “glove and socks” type of superficial sensory disturbance like polyneuropathies from peripheral nerves disorders.

A lot of things, however, remain unclear. There have been few sicknesses in the past which, like methylmercury poisoning, cause such broad and varying degrees of damage to the central nervous system, especially to the cerebral cortical cells. Because disorders of the cerebral cortex can exhibit unstable symptoms, the predominant disturbance can show temporary, middle or long-term improvements. On the other hand, quite a lot of cases show that new symptoms may appear or existing symptoms may get worse where continuous exposure to low-level contamination occurs or in connection with failure of plasticity with ageing.

There are some Minamata disease patients who look normal, but can’t do their job well or show reduced understanding or judgment while engaged in simple occupational tasks. We are accumulating data about the influence of methylmercury on higher brain functions including intellectual faculties, judgment and concentration, but have not yet been able to elucidate the exact connection.

The influence of low-level mercury poisoning on the brain of adults and embryos has become a worldwide issue. Intelligence disorders and motor dysfunction in adults and children have been reported, in those cases the subject’s or mother’s hair mercury level is around 10ppm or less. Many countries have recommended that pregnant women and infants should refrain from consuming large fish such as whale and tuna which tend to have high methylmercury concentration.