Minamata Bay

Years of investigation traced the disease to the Chisso chemical company that, for decades, had dumped its mercury-tainted wastewater directly into Minamata Bay, poisoning the fishing community's steady diet of fish and shellfish that in turn affected the residents' central nervous system.

The tragic consequences of industrial release of methylmercury into Minamata Bay off Japan between 1932 and 1968 and the illegal dumping of inorganic mercury into the waters at Grassy Narrows, Ontario, Canada in 1970 demonstrated in horrific terms the effects of methylmercury on human health: defects in fetuses and neurological disruption in children and adults that, in severe cases, led to madness, paralysis and death.

Health effects associated with high levels of MeHg prenatal exposure (about 700 ppm), such as those that occurred in Minamata Bay, Japan, caused by the release of mercury in industrial wastewater between 1932 and 1968 (20), have included cerebral palsy, severe intellectual disability, movement and coordination disorders, dysarthria, and sensory impairments (1).

On Wednesday, delegates held a ceremonial opening of the diplomatic conference in Minamata, the city where many local people were poisoned after eating mercury-contaminated seafood from Minamata Bay.

A few years before her birth, dead fish and other sea creatures had begun appearing in Minamata Bay. (1) Seabirds were losing their ability to fly.

Minamata disease is known as one of Japan's worst pollution diseases caused by mercury-laced waste water released into Minamata Bay by Shin-Nippon Chisso Hiryo K.K., which was later renamed to Chisso Corp.

Case in point: Research on mercury toxicity was first published in 1968 (1) in Minamata Bay, Japan.

By the 1950s, it had become a major petrochemical company, which had been dumping its waste into Minamata Bay since the 1920s.

In the early 1960s, high levels of methylmercury in industrial wastewater accumulated in shellfish and fish in Minamata Bay, Japan, and were eaten by local people.