Ingestion of greater than 15 grams may cause production of hydrogen sulfide from bacterial action in colon. Hydrogen sulfide thus produced can cause effects on central nervous system, including convulsions, changes in blood pressure and respiration, respiratory arrest, and possibly death. Chronic inhalation may cause bronchopulmonary disease which may be complicated by emphysema and bronchiectasis. Repeated and prolonged contact with manganese oxide fume can cause effects on central nervous system. Symptoms include fatigue, weakness, and loss of appetite.
Further exposure can lead to changes in speech, gait, muscle cramps, and tremors.
Symptoms of chronic manganese oxide toxicity are identical to those associated with Parkinson's desease. There is also some evidence that chronic manganese oxide exposure causes decreased fertility in males. None of note. Manganese is an essential element for humans. Immediately flush eyes with large amounts of water for at least 15 minutes.