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Abstract In the Japanese seaside city of Minamata, in the mid-1950s, residents began to notice cats
exhibiting bizarre behaviour – moving in a jerky fashion, stumbling, sometimes falling into the
nearby bay and drowning. In 1956 (although in retrospect it was clear that some cases had surfaced
earlier) similar difficulties began to appear in people: loss of motor control, dizziness, slurred speech,
confused thinking, convulsions, and even death. By the end of that year nearly 100 victims of this
syndrome had been identified and over 20 had died.
Investigations showed that the cause was the heavy metal mercury, which permeated the
sediments of the bay from which many residents (and cats) consumed seafood. The mercury came
from a local factory that manufactured acetaldehyde, used to produce plastics. It had entered the bay
for decades in the plant's wastewater and, in the organic form of methyl mercury, it had entered the
food chain.
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© UNEP - FAO 2008