Search

This article presents a follow-up study of the effects of mercury contamination in the indigenous tribe reservations in the province of Ontario, Canada. A previous study was conducted in 1975 when Minamata disease was already evident, although the symptoms were slight. In the current study, the characteristic symptoms of Minamata disease are now apparent. There was a high rate of occurrence of multiple-limb sensory disturbance and symptoms such as ataxia and tunnel vision. It was also observed that chronic Minamata disease can occur even when the level of mercury in the hair is below the provisional 50 ppm recommended as the safe level over a long period of time.