It has been suggested that manganese cations are more toxic than the anion forms.
In 1901 research showed that manganese toxicity could result in neurological damage in humans.
However, it was not until a series of reports in the 1930s and 1940s describing a high incidence of manganese toxicity in manganese mine workers that manganese toxicity was recognized as a significant health workers. Chronic inhalation exposure of humans to high levels may result in a syndrome called manganism and typically begins with feelings of weakness and lethargy and progresses to other symptoms such as gait disturbances, clumsiness, tremors, speech disturbances, a mask-like expression, and psychological disturbances.
Additionally, individuals with liver failure are at greater risk for toxicity because manganese homeostasis is maintained largely by the liver through excretion in the bile.
Manganese toxicity secondary to liver failure is characterized by manganese accumulation within the liver and other organs such as the brain; accumulation in the brain results in neurologic abnormalities.
Psychological changes including mental irritability, headaches, nervousness, compulsive actions, and hallucinations can occur.
Toxicity of manganese
