Effects of occupational exposure to low chromium on the noise-induced hearing loss

Objective To observe the combined adverse effect of simultaneous exposure to both chromium and noises on hearing loss. Methods A total of 419 male workers in an automobile manufacturing enterprise,exposed to both low concentration of chromate and noises at workplaces were studied, compared with 766 male workers exposed to only noises(the reference group). The occupational hazards at workplaces were analyzed, referring to the results of occupational health examination. Results The incidence of hearing loss was 10.73% in the combined exposed workers,significantly higher than that in reference group (χ²=18.221,P<0.05).The RR of hearing loss occurrence for combined group was 2.49(P<0.05). Conclusion Simultaneous exposure to both low concentration of chromium and noises may increase the risk of the hearing loss.