Neurologic effects of manganese in humans: a review.

Manganese, which enters the body primarily via inhalation, can damage the nervous system and respiratory tract, as well as have other adverse effects. Occupational exposures occur mainly in mining, alloy production, processing, ferro-manganese operations, welding, and work with agrochemicals. Among the neurologic effects is an irreversible parkinsonian-like syndrome. An estimated 500,000 to 1.5 million people in the United States have Parkinson's disease, and physicians need to consider manganese exposure in its differential diagnosis. Since 1837, there have been many reports of cases and case series describing manganese toxicity. More recently, there have been epidemiologic studies of its adverse effects on health. Occupational medicine physicians can play critical roles in preventing the adverse health effects of manganese.