Mercury is considered to be highly toxic, and can be easily absorbed by ingestion, inhalation and contact with skin and mucous membranes. Repeated and prolonged exposure results in a condition called mercurialism, also known as mercury poisoning. The disease carries with it a wide range of nasty symptoms, including brain damage, corneal damage, hyper-tension, skin discolouration and developmental problems. It would appear that those most at risk of developing mercurialism, are unborn foetuses. As such, there are numerous guidelines in place for pregnant women to follow in regards to their diet and intake of mercury.
A particularly devastating example of mass-mercurialism occurred in the seaside town of Minamata, Japan, discovered in 1956.
Child with Mercury poisoning
A chemical manufacturing plant owned by the Chisso Corporation, opened its Minamata plant in 1908. Although it provided economic wealth for the residents of the town, it was dumping large amounts of mercury-laden waste water into the bay, which was the primary source of food for the Minamata residents. Years later, cats in the town began to exhibit bizarre neurological symptoms, followed by an inevitable death (see below video). Shortly after, large numbers of local children began to display similar symptoms to the cats, and conversely many died. The disease was dubbed "dancing cat disease", and later refined into Minamata disease.
In 1956, extensive research was conducted into the disease and it's apparent cause. It was soon discovered that the ocean in and around Minamata bay was heavily contaminated with mercury from the industrial waste. This led to high levels of mercury in the fish, which was a staple of the diet for the residents of Minamata.