Manganese toxicity in humans is a well-recognised occupational hazard for people who inhale manganese dust. High concentrations of circulating manganese as a result of total parenteral nutrition have also been associated with manganese toxicity. People with chronic liver disease have neurological pathology and behavioural signs of manganese neurotoxicity, probably because elimination of manganese in bile is impaired. The most prominent effect is central nervous system pathology, especially in the extra-pyramidal motor system. The lesions and symptoms are similar to those of Parkinson’s disease.