Investigation of occupational hearing loss in manganese-containing welding workers

  Objective  To investigate the combined effect of manganese exposure and noise on welding workers' hearing loss due to the use of electrodes containing manganese.

  Methods  A total of 198 noise-exposed workers from an automobile manufacturing company were selected and divided into two groups, namely the pure noise exposure group (n= 66) and the welding operation group (n= 132). Pure tone audiometry and urine manganese measurement were performed on all workers; the manganese concentration and noise level at the workplaces were measured, and the results of pure tone audiometry and noise-induced hearing loss detection between these two groups were compared.

  Results  There was no statistical difference in age and noise exposure time between these two groups (P> 0.05); the pure tone thresholds at 2, 3, and 4 kHz in the welding operation group were higher than those in the pure noise exposure group (P < 0.01); 35 cases of noise-induced hearing loss were detected in the welding operation group, with a detection rate of 26.5%; eight cases of noise-induced hearing loss were detected in the pure noise exposure group, with a detection rate of 12.1%, and the difference was statistically significant (P < 0.01).

  Conclusions  Manganese exposure due to manganese-containing welding operations may have a combined effect with noise to cause noise-induced hearing loss.