Prevalence of Noise-induced Hearing Loss in Cotton Ginning Factories in Parakou, North Benin

This research work aimed to determine the prevalence of noise induced hearing loss by in an industrial area. It is was descriptive cross-sectional study which was carried out from March to May 2014 in three (03) cotton ginning factories located in the city of Parakou. It involved the workers exposed to noise, who had accepted to participate to the survey and in whom an audiometry was performed. One hundred and thirteen workers were selected, including 104 (92%) male and 9 female (8%). Their mean age was 39.3 +/-9.6 years with extremes of 18 and 54 years. During 8 hours a day, 38% of the respondents were exposed to noise levels lower than 80 dB (A), 31% to levels higher or equal to 90 dB (A) and 31% to levels between 80 and 90 dB (A). The average seniority of the workers surveyed was 7 cotton seasons with extremes of one and 31 seasons. No employee had benefitted from medical consultation or audiometry on recruitment or thereafter. And all the employees reported not using any personal protective equipment. The overall prevalence of noise induced hearing loss in the cotton ginning factories in Parakou in 2014 was estimated at 88.5% (100 out of 113 respondents). The average hearing loss (AHL) was 40.8 dB +/- 8.8 dB in the right ear and 28.9 dB +/- 11.8 dB in the left ear. Taking into account only the deafest ear, AHL was light in 44% of cases, moderate in 54% of cases and severe in 2% of cases. There was a statistically significant relationship between the degree of NIHL and seniority in the firm (p=0.012).