OBJECTIVETo understand the toxic effects of manganese exposure on health by measurement of manganese concentration and occupational health inspection among workers in an enterprise exposed to manganese, and to provide a basis for occupational disease control.

METHODSThe air concentrations of manganese in 12 workplaces where workers often stayed were measured by typical sampling; occupational health inspection was performed among a total of 538 workers in the enterprise by cluster sampling.

RESULTSThe average concentrations of manganese in the workplace from 2011 to 2013 were 0.179 mg/m(3), 0.122 mg/m(3), and 0.082 5 mg/m(3), respectively, indicating a significant decrease in manganese level within the three years by rank-sum test (P < 0.05). The results of health inspection showed that 165 (30.7%) out of 538 workers had abnormal indices, and the incidence of autonomic nervous system abnormalities reached 32.7% (176/538). There was no correlation between manganese concentration in the workplace and the incidence of abnormal indices in health inspection, while the manganese concentration in the workplace was positively correlated with the incidence of autonomic nervous system symptoms (r = 0.718, P < 0.05).

CONCLUSIONThe manganese concentration in the workplace is positively correlated with the incidence of autonomic nervous system symptoms. Early exposure to a low level of manganese can induce functional changes and potential damages in the nervous system.