Abstract
Forty-two subjects working maximally for 15 years in a ferrite core manufactory were examined of their health. Nineteen of them were mainly exposed to about 9 mg/m3 (geometric mean) of the mixed dust of Fe2O3 (70%), ZnO, MgO and MnCO3. Sixteen of them were exposed to about 3 mg/m3 of spineled ferrite dust of Fe2O3 and so on. The others were exposed to less than 0.7 mg/m3 of the spineled ferrite dust. A significant change of chest X-ray film characterized by small round opacity was found in 4 subjects out of 33, who were exposed for 5 years or more. The two out of the four were exposed to the ferrite dust. When compared to the control group, workers of ferrite manufactory had significantly higher rate of constant coughing (almost 50%), about two times higher incidence rate of respiratory disease, and about two times more frequent hospital visit. While the neurological examination, pulmonary function, and zinc content in urine and blood revealed no abnormalities.
