Bahia de Minamata Índice Lugar Historia Consecuencias Enfermedad de Minamata Bioacumulación del mercurio. Medidas del gobierno. Minamata disease is a neurological syndrome caused by severe mercury poisoning. . Enseñanzas de la Enfermedad de Minamata y el Manejo del http :// Enfermedad cardiovascular. Exposición contaminado en la bahía de Minamata (Japón). Una em- presa química vertía directamente en el agua de la bahía.

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Signs and symptoms include ataxianumbness in the hands and feet, general muscle weaknessloss of peripheral visionand damage to hearing and speech.

In extreme cases, insanityparalysiscomaand death follow within weeks of the onset of symptoms. A congenital form of the disease can also affect fetuses in the womb.

Minamata disease was first discovered in Minamata city in Kumamoto prefectureJapanin It was caused by the release of methylmercury in the industrial wastewater from the Chisso Corporation ‘s chemical factory, which continued from to This highly toxic chemical bioaccumulated in shellfish and fish in Minamata Bay and the Shiranui Seawhich, when eaten by the local populationresulted in mercury poisoning. While cat, dog, pig, and human deaths continued for 36 years, the government and company did enermedad to prevent the pollution.

The animal effects were severe enough in cats that they came to be named as having “dancing cat fever”. As of March2, victims had been officially recognised as having Minamata mimamata 1, of whom had died [2] and over 10, had received financial compensation from Chisso. A second outbreak of Minamata disease occurred in Niigata Prefecture in The original Minamata disease and Niigata Minamata disease are considered two of the four big pollution diseases of Japan.

The Chisso Corporation first opened a chemical factory in Minamata in Initially producing fertilisers, the factory followed the nationwide expansion eenfermedad Japan’s chemical industry, branching out into production of acetyleneacetaldehydeacetic acidvinyl chlorideand octanolamong others. These pollutants had an environmental impact. Fisheries were damaged in terms of reduced catches, and in response, Chisso reached two separate compensation agreements with the fishery cooperative in and The rapid expansion of the Minamata factory spurred on the local economy and as Chisso prospered, so did Minamata.

This fact, combined with the lack of other industry, meant that Chisso had great influence in Minamata.

At one point, over half of the tax revenue of Minamata City authority came from Chisso and its employees, and the company and its subsidiaries were responsible for creating a quarter of all jobs in Minamata. The chemical reaction used to produce the acetaldehyde used mercury sulfate as a catalyst.

Starting Augustthe co-catalyst was changed from manganese dioxide to ferric sulfide. The physicians were puzzled by her symptoms: Two days later, her younger sister also began to exhibit the same symptoms and she, too, was hospitalised.

The girls’ mother informed doctors that her neighbour’s daughter was also experiencing similar problems. After a house-to-house fnfermedad, eight further patients were discovered and hospitalised. On May 1, the hospital director reported to the local public health office the discovery of an ” epidemic of an unknown disease of the central nervous system “, enfermead the official discovery of Minamata disease.

Owing to the localised nature of the disease, it was suspected to be contagious and as a precaution endermedad were isolated and their homes disinfected. Although contagion was later disproved, this initial response contributed to the stigmatisation and discrimination experienced by Minamata victims from the local community. During se investigations, the committee uncovered surprising anecdotal evidence of ds strange behaviour of cats and other wildlife in the areas surrounding patients’ homes.

From around onward, cats had been seen to have convulsions, go mad, and die. As the extent of the outbreak was understood, the committee invited researchers from Kumamoto University to help in the research effort.

Researchers from the School of Medicine began visiting Minamata regularly and admitted patients to the university hospital for detailed examinations. A more complete picture of the symptoms exhibited by patients was gradually uncovered. The disease developed without any prior warning, with patients complaining of a loss of sensation and numbness in their hands and feet.

They became unable enfermddad grasp small objects or fasten buttons. They could not run or walk without stumbling, their voices enfremedad in pitch, and many patients complained of difficulties seeing, hearing, and swallowing. In general, these symptoms deteriorated and were followed by severe convulsions, coma minmata, and dee death. Researchers from Kumamoto University also began to focus on the cause of the strange disease. They found that the victims, often members of the same family, were clustered in fishing hamlets along d shore of Minamata Bay.


The staple food of victims was invariably fish and shellfish from Minamata Bay. The cats in the local area, which tended to eat scraps from the family table, had died with symptoms similar to those now discovered in humans.

This minaamta the researchers to believe that the outbreak dw caused minnamata some kind of food poisoningwith contaminated fish and shellfish being the prime suspects. On November 4, the research group announced its initial findings: As soon as the investigation identified a heavy metal as the causal substance, the wastewater from the Nefermedad plant was immediately suspected as the origin.

The company’s own tests revealed that its wastewater contained many heavy metals in concentrations sufficiently high to bring about serious environmental degradation, including leadmercurymanganesearsenicthalliumand copperplus the chalcogen selenium. Identifying which enfermeddad poison was responsible for the disease proved to be extremely difficult and time-consuming. During andmany different theories were proposed by different researchers. At first, manganese was thought to be the causal substance due to the high concentrations found in fish and the organs of the deceased.

Thallium, selenium, and a multiple contaminant bahla were also proposed, but in Marchvisiting British neurologist Douglas McAlpine suggested that Minamata symptoms resembled those of organic mercury poisoningso the focus of the investigation centered on mercury.

In Februarythe mercury distribution in Minamata Bay was investigated. The results shocked the researchers involved. Bahiia quantities of mercury were detected in fish, shellfish, and sludge from the bay. The highest concentrations centred around the Chisso factory wastewater canal in Hyakken Harbour and decreased going out to sea, clearly identifying the plant as the source of contamination.

Indeed, Chisso did later set up a subsidiary to reclaim and sell the mercury recovered from the sludge. Hair samples were taken from the victims of the disease and also from the Minamata population in general. Minamata disease is a poisoning disease that affects mainly the central nervous system and is caused by the consumption of large quantities of fish and shellfish living in Minamata Bay and enfermeda surroundings, the major causative agent being some sort of organic mercury compound.

During the investigation by researchers at Kumamoto Universitythe causal substance had been identified as a heavy metal and it was widely presumed that the Chisso plant was the source of the contamination. Chisso was coming under closer scrutiny and to deflect criticism, the wastewater output route was changed. Chisso knew of the environmental damage caused by its wastewater and was well aware that it was the prime suspect in the Minamata disease investigation.

Despite this, from Septemberinstead of discharging its waste into Hyakken Harbour the focus of investigation and source of original contaminationit discharged wastewater directly into Minamata River. The immediate effect was the death of fish at the mouth of the river, and from that point on, new Minamata disease victims began to appear in other fishing villages up and down the coast of the Shiranui Seaas the pollution spread over an even greater area.

Chisso failed to co-operate with the investigation team from Kumamoto University. It withheld information on its industrial processes, leaving researchers to speculate what products the factory was producing and by what methods.

Food to which factory wastewater had enfermedas added was fed to healthy cats.

Seventy-eight days into the experiment, cat exhibited symptoms of Minamata disease and pathological examinations confirmed a diagnosis of organic mercury poisoning.

The company did not reveal these significant results to the investigators and ordered Hosokawa to stop his research. In an attempt to undermine Kumamoto University researchers’ organic mercury theory, Chisso and other parties with a vested interest that the factory remain open including the Ministry of International Trade and Industry and the Japan Chemical Industry Association funded research into alternative causes of the disease, other than its own waste.

Polluting wastewater had damaged the fisheries around Minamata ever since the opening of the Chisso factory in The Kumamoto prefectural government issued a partial ban on the sale of fish caught in the heavily polluted Minamata Bay, but not an all-out ban, which would have legally obliged it to compensate the fishermen. The fishing cooperative protested against Chisso and angrily forced their way into the factory on 6 August and 12 August, demanding compensation.


A committee was set up by Minamata Mayor Todomu Nakamura to mediate between the two sides, but this committee was stacked heavily in the company’s favour. On 29 August, the fishing cooperative agreed to the mediation committee’s proposal, stating: Since the change of route of wastewater output inpollution had spread up and down the Shiranui Sea, damaging fisheries there, too.

Emboldened by the success of the small Minamata cooperative, the Kumamoto Prefectural Alliance of Fishing Cooperatives also decided to seek compensation from Chisso.

On 17 October, 1, fishermen from the alliance descended on the factory to demand negotiations.

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When this produced no results, the alliance members took their campaign to Tokyosecuring an official visit to Minamata by members of the Japanese Diet. The violence was covered widely in the media, bringing the nation’s attention to the Minamata issue for the first time since the outbreak began. Another mediation committee was set up, and an agreement was hammered out and signed on 17 December.

Inthe victims of Minamata disease were in a much weaker position than the fishermen. Patients’ families were the minamaata of discrimination and ostracism from the local community. Local people felt that the company and their city that depended upon it was facing economic ruin. Mminamata some patients, this ostracism by the community represented a greater fear than the disease itself. After beginning a sit-in at the factory gates in Novemberthe patients asked Kumamoto Prefecture Governor Hirosaku Teramoto to include the patients’ request for compensation with the mediation that was ongoing with the prefectural fishing alliance.

Chisso agreed and after a few weeks’ further negotiation, another “sympathy money” agreement was signed. Patients who were certified by a Ministry of Health and Welfare committee would be compensated: On October 21,Chisso was ordered by the Ministry of International Trade and Industry to switch back its wastewater drainage from the Minamata River to Hyakken Harbour and to speed up the installation of wastewater treatment systems at the factory.

Chisso installed a Cyclator purification system on December 19,and opened it with a special ceremony. Chisso’s president Kiichi Yoshioka drank a glass of water supposedly treated through the Cyclator to demonstrate that it was safe.

In fact, the wastewater from the acetaldehyde plant, which the company knew still contained mercury and led to Minamata disease when fed to cats, was not treated through the Cyclator at the time. Testimony at a later Niigata Minamata disease trial proved that Chisso knew the Cyclator to be completely ineffective: The deception was successful and almost all parties involved in Minamata disease were duped into believing that the factory’s wastewater had been made safe from December onward.

This widespread assumption meant that doctors were not expecting new patients to appear, resulting in numerous problems in the years to follow, as the pollution continued.

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In most people’s minds, the issue of Minamata disease had been resolved. The years between the first set of “sympathy money” agreements in and the start of the first legal action to be taken against Chisso bahhia are often called the “ten years of silence”. In fact, much activity on the part of the patients and fishermen took place during this period, but nothing had a significant impact on the actions of the company or the coverage of Minamata in the national media.

Despite the almost universal assumption to the contrary, the wastewater treatment facilities installed in December had no effect on the level of organic mercury being released into the Shiranui Sea.

The pollution and the disease it caused continued to spread. The Kumamoto and Enfermedar prefectural governments conducted a joint survey in late and early into the level of mercury in the hair of people living around the Shiranui Sea. The results confirmed that mianmata mercury had spread all around the inland sea and that people were still being poisoned by contaminated fish. Hundreds of people were discovered to have levels greater than 50 ppm of mercury in their hair, the level at which people are likely to experience nerve damage.