Neurological effects in workers exposed to manganese.

The purpose of this study was to examine the effects on the nervous system in enamels-production workers who have low levels of and long exposure to manganese (Mn). The study included 138 Mn-exposed workers and 137 controls who received questionnaires on symptoms, a battery of psychological tests, and assessments of blood concentrations of metal. The exposure levels to airborne Mn concentrations were determined by personal and stationary samplings. The mean duration exposure to Mn was 19.87 years (SD +/- 9). The workers exposed to Mn reported more nonspecific subjective complaints than the control group. No effect of Mn exposure was indicated by the results of any of the neuropsychological tests. The Mn workers did not have higher concentrations of Mn in blood than the controls. Exposures of workers currently working with Mn averaged 57 micrograms/m3 respirable (personal samplings) and 12 g/m3 (stationary samplings). In conclusion, long exposure to low levels of Mn (approximately 200 micrograms/m3), as induced in our study, showed no significant disturbance of neurological performance.