Evaluation of the chronic inhalation toxocity of a manganese oxide aerosol. II. Clinical observations, hematology, clinical chemistry and histopathology.

Monkeys and rats were exposed to 11.6, 112.5, or 1152 microgram Mn/m3 as an Mn3O4 aerosol twenty-four hours per day for nine months. Various serum biochemical, and hematologic evaluations were conducted on both specie. Body weight gain was accelerated in rats exposed to 1152 microgram Mn/m3. Hemoglobin concentrations were slightly elevated for both sexes and both specie exposed to 1152 microgram Mn/m3; however, the effect may not be directly related to Mn. Some evidence of hypophosphatemia was observed. No exposure related effects were demonstrated by organ weight or histopathologic observations.