The prevalence of noise-induced hearing loss among Tanzanian miners

Abstract

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.