A description of the hearing profile in gold miners with tuberculosis

Abstract

Two of the primary occupational health threats to employees in the mining industry are noise-induced hearing loss (NIHL) and occupational lung diseases (OLD) with Tuberculosis (TB) included in the latter. The objective of this study was to investigate the hearing profile of a group of gold miners with and without TB to determine the effect of TB and its associated risk profile on hearing. Workers in AngloGold Ashanti mine in South Africa were recruited due to the fact that they present with these two health threats namely NIHL and TB. The audiological and medical surveillance data of 2698 subjects (between the years 2001 and 2009) were used in analyses. Hearing thresholds for the air conduction frequencies (0.5, 1, 2, 3, 4, 6, 8 KHz) in both ears were analysed in conjunction with biographic and occupational data. Subjects were divided into three groups, two experimental groups (Single TB treatment, n= 911 and Multiple TB treatment, n= 376) and one control group (n= 1411). A highly significant difference (p<0.01) was noted between the control group and both TB treatment groups across most frequencies and hearing parameters analysed, although the higher frequencies were more affected. Pair wise comparisons revealed the largest differences in hearing thresholds throughout between the control group and the multiple TB treatment groups. The smallest differences in hearing thresholds were evident between the two TB groups with the multiple TB treatment group presenting with the poorest thresholds. TB and its related risk profile had a pronounced influence on the decline of hearing thresholds. Thresholds for the multiple TB treatment group indicated more deterioration than the hearing thresholds of the single TB treatment group. This may point to the possibility that the influence of repeated TB on the subjects’ hearing thresholds over time was more pronounced than a single incidence of TB. It is still necessary however to separate the effects of the disease from the effects of the treatment on hearing.