Audiometry in brass workers

Abstract

OBJECTIVES : To compare hearing impairment among brass workers with that of the general population. Study DESIGN - A cross sectional analytical design METHODOLOGY : One hundred and seventy male brass workers and 170 controls from the general population were selected as subjects. The control group was matched for the age of the brass workers. A questionnaire was used to extract socio demographic and relevant data related to hearing impairment. Pure tone audiometry was carried out in the order of 1000, 1500, 2000, 3000, 4000, 6000, 8000, 250, 500 and 1000 Hz for both ears. Noise levels were measured in 10 randomly selected brass workshops. RESULTS : The number of pairs included in the analysis was 154. Tinnitus and subjective hearing impairment were present in 1 (0.6%) and 18 (1 1.7%) respectively among brass workers while the respective figures in the control group were 3 (1.9%) and 13 (8.4%) the differences of which were not significant. Brass workers had ORR of 3 (95%CI of 1.6 -5.8) and 4.9 (95% CI = 2.3-10.4) for overall hearing impairment in the left and right ears respectively. On multiple logistic regression, being a brass worker in all frequencies except 1000 Hz. and advancing age in the frequencies of 3000 to 6000 Hz. were found to be risk factors . The duration of service was found be a risk factor in the frequencies of 3000 and 4000 Hz when data pertaining to brass workers alone were analysed. The noise levels in the workshops ranged between 84 dB to 103 dB. CONCLUSIONs : Brass workers were at a higher risk of hearing impairment due to the prevalent high noise levels. Cheap and effective preventive measures are recommended.