The prevalence of noise-induced hearing loss among Tanzanian miners

Background Tanzania has a young mining history with several operating open pit and underground mines. No prevalence studies of noise-induced hearing loss (NIHL) have been conducted among mine workers to provide an impetus for the development of comprehensive hearing protection programmes. Aims To determine the prevalence of NIHL and associated factors among miners in a major gold mining company operating in Tanzania. Associated risk factors such as age, sex and duration of exposure were examined. Methods Audiograms obtained from periodic medical examinations were categorized using the UK Health & Safety Executive system. Results A total of 246 audiograms were studied. The prevalence of NIHL was 47%, with 12% with poor hearing and 35% with mild hearing impairment. The proportion of NIHL increased with total years of exposure to noise. Underground miners were more affected (71%) than open pit miners (28%). These findings were statistically significant. The highest proportion of miners with NIHL (60%) was among the youngest age group (20-29 years). Conclusions There was a high prevalence of NIHL in the company under study. There was a strong correlation with type of mining, age and years of exposure. The findings have been used to develop comprehensive hearing conservation programmes.