- 日本衛生学雑誌 (ISSN:00215082)
- vol.37, no.2, pp.566-579, 1982-06-30 (Released:2009-02-17)
An epidemiological survey and clinical investigations were carried out on 162 retired workers from manganese mines and ore grinders, who were the residents of the Tamba district of Kyoto Prefecture. Most of the workers had been employed in small industrial factories with less than five employees under very poor working conditions. Fifty-five percent of them had worked in the mines and factories for longer than 11 years. Forty-six percent had been retired for 11-20 years, whereas 27% for longer than 21 years. A group of 124 people living in the same region but who had not been exposed to manganese served as the control group.The incidence of subjective symptoms associated with chronic manganese poisoning such as emotional instability, psychomotor irritability and neurologic abnormalities was apparently high in the experimental group and it increased with the period of exposure to manganese dust. Twenty-eight percent of the workers reported the subjective symptoms while they were employed, but 45% of them reported as late as six years after they retired.Of the retired workers, five (3.1%) had parkinsonism, three (1.9%) showed symptoms of hemiparkinsonism, and fifteen (9.3%) showed neurological symptoms including maskedlike, gait unbalance, slurred speech and imparied fine movements. Forty-five percent of these patients recognized these abnormalities for more than five years after they had left the contaminated workings. It is noteworthy that 39% of the retired workers were diagnosed as having pneumoconiosis.Some of the problems encountered in diagnosing manganese poisoning after exposure has been terminated is also discussed here.