Remembering Minamata (Part 1)

It was a tragedy that never should have happened in the peaceful city of Minamata in Japan's Kumamoto prefecture.  

Beginning in 1950, seabirds and household pets were struck with a strange epidemic in which the animal seemingly went "mad" with convulsions followed by a rapid death.  The first case involving a human victim was identified on April 21, 1956.  The victim, a five-year old girl, was presenting a range of symptoms including convulsions as well as difficulty walking and talking.  When her younger sister developed similar symptoms, she was also hospitalized and authorities became alarmed to discover that eight additional cases were found nearby.  By May 1,  local public health officials announced an "epidemic of an unknown disease of the central nervous system" which would be later termed Minamata disease.   

When the city doctors and local authorities formed the Strange Disease Countermeasures Commitee, they were baffled over what was causing the new mystery illness.   Out of fear that it was contagious, Minamata cases were isolated from the local community and their homes thoroughly sterilized.  Although these measures eventually proved to be unnecessary, they contributed to the stigma that victims were forced to endure.   As university researchers began investigating the disease more thoroughly, the first Minamata cases began dying.  By October 1956, forty patients had been discovered and fourteen had died (a fatality rate of 36.7%).   Researchers eventually traced the disease outbreak in humans and animals to the high concentrations of mercury found in the shellfish that represented one of the main food staples in the coastal city. 

Once mercury poisoning was identified, suspicion immediately fell on a nearby chemical factory run by the Chisso Corporation.  First opened in 1908, the factory produced a variety of chemical products (including fertiliser, acetic acid, vinyl chloride, and octanol) and waste products were directly released into Minamata bay.  Despite previous compensation paid to local fisheries over reduced catches, no cases of human exposure to the pollution had been identified.    That all began to change as researchers found high concentrations of heavy metals such as manganese and thallium in the organs of the deceased.    In 1948,  visiting neurologist, Donald McAlpine, suggested that organic mercury exposure was the likely culprit in Minamata disease given the nature of the symptoms which had also been observed in other cases of mercury poisoning.    Testing for mercury, researchers were shocked at the high concentrations  they found in the local sea life and even in samplings taken from the bay's sludge.    The highest concentrations were found immediately adjacent to the factory's wastewater canal (Chisso would later set up an operation reclaiming the mercury from the sludge to sell for a profit).

In subsequent research, it was determined that Chisso had been using metallic mercury as an industrial catalyst which was then discharged into the wastewater.  The process did not end there though.   Once the mercury entered the environment, it came into contact with the methylating bacteria that lurk at the bottom of ponds, rivers, and oceans.  Ordinarily converting sulfate into sulfide, the Tomokos_hand[1] bacteria combined the released mercury with carbon to produce methylmercury, a fetal toxicant.   Since persistent poisons become concentrated as they move up the food chain (through a process known as biomagnification),  the concentration of methylmercury in the sea life hauled into the fishing boats was as much as a million times greater than in the surrounding water.

By 1959, the Ministry of Health and Welfare was able to make a public announcement linking Minamata Disease to mercury exposure.   The Chisso Corporation, already knowing that they were under suspicion in the Minimata deaths, changed the course of the wastewater discharged from the plant directly into Minamata River.  This reduced the amount of discharge into the harbour (which was being investigated by researchers) but spread the contamination over a much wider area.  Further Minamata Disease cases occurred in fishing villages up and down the coast of the Shiranui Sea.   As well, the corporation continued to stonewall investigators seeking information about the plant and its industrial operations.   When Chisso's hospital director, Hajme Hokosawa, launched research which confirmed that the factory waste was causing the disease, he was ordered to stop and all information about the research was suppressed.  Chisso and other industrial interests also funded research looking into alternative causes of the disease.

Following a partial ban on fishing by the Kumamato prefecture (as opposed to the total ban which would have forced higher compensation), fishing cooperatives were able to win some grudging settlements but the human victims were not so fortunate.   The stigma surrounding Minamata Disease ensured that sufferers faced continuing ostracism and discrimination from the community at large.  Even the formation of the Minamata Mutual Aid Society did little to improve matters.  Only a sit-in at factory gates in November 1959 forced local governments to include victim compensation as one of the conditions of the compensation package being negotiated for the fisheries.  Chisso eventually agreed to pay "sympathy money"  for those victims duly certified as suffering from Minamata Disease.  The compensation package was not large with adults receiving 100,000 yen per year (equivalent to U.S. $ 278.oo) while children received substantially less (families of deceased Minamata Disease victims received a lump sum equivant to 889 U.S. dollars).  

Despite assurances by Chisso that factory wastewater would be chemically treated to prevent further mercury poisoning, nothing was really done and "ten years of silence" followed from 1959 to 1969 during which mercury pollution spread across the Shiranui Sea.   Despite surveys by the Kumamato and Kugashima prefecturates showing that mercury levels were still dangerously unsafe, the results were never made public and deaths were listed as being due to "unknown causes".    During the early 1960s, medical professionals found that children in the Minamata were developing cerebral palsy at an abnormally high rate.   The disease was eventually proven to be congenital with mothers being symptom-free while their children developed many of the same symptoms found in adult Minamata Disease sufferers.   

Not only were many of the children blind and deaf, but some had unusually small heads and deformed teeth.   Following autopsies on two children and identification of a congenital form of the disease, doctors pressured Chisso into paying "sympathy money" to the families of the children under the 1959 agreement.  Since not all affected children demonstrated the full range of symptoms that characterized Minamata Disease, the full extent to which the children in the contaminated areas were affected may never be known.   At least one study suggested that as many as 29 per cent of all exposed children born  between 1955 and 1959 showed signs of mental deficiencies.

Continue to Part 2.

           

Related Stories

  • Why Not all Concussions are the Same
  • The Rainmaker (Part One)
  • The Great Coca Cola Trial (Part 1)
 

 
disclaimer

The information provided on the PsyWeb.com is designed to support, not replace, the relationship that exists between a patient/site visitor and his/her health professional. This information is solely for informational and educational purposes. The publication of this information does not constitute the practice of medicine, and this information does not replace the advice of your physician or other health care provider. Neither the owners or employees of PsyWeb.com nor the author(s) of site content take responsibility for any possible consequences from any treatment, procedure, exercise, dietary modification, action or application of medication which results from reading this site. Always speak with your primary health care provider before engaging in any form of self treatment. Please see our Legal Statement for further information.

PsyWeb Poll

Are you currently taking or have you ever been prescribed anti-depressants?
Yes
50%
No
50%
Total votes: 3979