Health Assessment Document for Manganese. Final Report
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The document evaluates data on occurrence, sources, and transport of manganese in the environment and data on metabolism, pharmacokinetics, laboratory toxicological and epidemiologic studies to determine the nature and dose response relationship of potential health effects on humans. Nationwide air sampling data indicate that mean manganese concentrations have declined from 0.11 micrograms per cu. m. in 1953-1957 to 0.033 micrograms per cu. m. in 1982. The effects of major concern to humans exposed to manganese are on neurological and on pulmonary function. The CNS effects have been observed in humans at exposure levels above 5 mg/cu. m. and are incapacitating and generally irreversible. Data are equivocal between 1 and 5 mg/cu. m. but suggest decreased prevalence. There are no reports of these effects below 0.3 mg/cu. m. exposure. Pneumonia and chronic bronchitis occur at levels which are associated with neurological effects. Reduced lung function has been reported in children exposed to an estimated 3-11 micrograms per cu. m. from emission of a ferromanganese plant. However, studies of workers exposed to 40 micrograms per cu. m. did not show respiratory symptoms. Animal studies qualitatively support pulmonary effects of manganese exposure. Respiratory symptoms occur at lower levels than neurological symptoms and are therefore considered to be the critical effect based on available data.