Case study on Minamata Incident
The Minamata Incident marked one of the worst cases of water pollution
In 1932, a factory in Minamata City, Japan began dumping its industrial effluent – Methylmercury, into the surrounding bay and the sea. Methylmercury is incredibly toxic to humans and animals alike, causing a wide range of neurological disorders.
Its ill-effects were not immediately noticeable. However, this all changed as methylmercury had started to bioaccumulate inside shellfishes and fish in the Minamata Bay. These affected organisms were then caught and consumed by the local population. Soon, the ill-effects of methylmercury was becoming apparent.
Initially, animals such as cats and dogs were affected by this. The city’s cats would often convulse and make strange noises before dying – hence, the term “dancing cat disease” was coined. Soon, the same symptoms were observed in people, though the cause was not apparent at the time.
Other affected people showed symptoms of acute mercury poisoning such as ataxia, muscle weakness, loss of motor coordination, damage to speech and hearing etc. In severe cases, paralysis occurred, which was followed by coma and death. These diseases and deaths continued for almost 36 years before it could be officially acknowledged by the government and the organisation.
Since then, various control measures of water pollution have been adopted by the government of Japan to curb such environmental disasters in the future.
Questions for discussion:
1. What was the main cause of Minamata incidence?
2. Explain impact of Minamata incidence with suitable example.
3. Suggest suitable measure to prevent occurring of such incidence in future.
Answers
Answer:
Minamata disease sometimes referred to as Chisso-Minamata disease is a neurological syndrome caused by severe mercury poisoning. Symptoms include ataxia, numbness in the hands and feet, general muscle weakness, loss of peripheral vision, and damage to hearing and speech. In extreme cases, insanity, paralysis, coma, and 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 prefecture, Japan, in 1956. It was caused by the release of methylmercury in the industrial wastewater from the Chisso Corporation's chemical factory, which continued from 1932 to 1968. This highly toxic chemical bioaccumulated in shellfish and fish in Minamata Bay and the Shiranui Sea, which, when eaten by the local populace, resulted in mercury poisoning. While cat, dog, pig, and human deaths continued for 36 years, the government and company did little 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 March 2001, 2,265 victims had been officially recognized as having Minamata disease (1,784 of whom had died) and over 10,000 had received financial compensation from Chisso. By 2004, Chisso Corporation had paid $86 million in compensation, and in the same year was ordered to clean up its contamination.On March 29, 2010, a settlement was reached to compensate as-yet uncertified victims.