Noise-induced hearing loss and hearing conservation in the iron and steel industry in South Africa

Abstract

BACKGROUND AND PURPOSE: The iron and steel industry in South Africa has been identified as one of the highest risk industries in terms of noise induced hearing loss (NIHL). The National Institute for Occupational Health was commissioned by the Department of Labour to audit the current noise exposure levels and hearing conservation practices in eight major producers of iron and steel, and to make recommendations regarding prevention strategies. METHODS: The audit was conducted in two parts: the noise exposure levels and hearing conservation practices were assessed by the occupational hygiene department. The occupational medicine department assessed the hearing conservation policies and procedures, reviewed employees’ medical records to ascertain the number of NIHL cases, and conducted verification of audiograms on a sample of employees working in noise zones. RESULTS: Area noise levels exceeding 105 dB(A) were measured in four of the eight workplaces. The estimated average annual incidence of NIHL varied from 0.7 - 8.3/1000/year. All companies did baseline, periodic and exit audiometric testing, but there were notable discrepancies between companies and verification audiograms and differences of more than 20 dB(A) were found. Although information and training on noise was reportedly done in all worksites, a high proportion of workers could not demonstrate correct fitting of hearing protection devices or recall when last they were trained. CONCLUSION: A detailed standard operating procedure should be implemented for medical surveillance for NIHL with action timelines that initiate remedial processes prior to employee developing compensable disease. Aggregated audiometric testing results should be communicated to managers and health and safety teams to provide guidance to prioritise areas for control measures. A quality assurance programme for audiometric testing must be implemented. An evaluation tool to measure the effectiveness of the noise and hearing conservation training provided to employees, including contracted employees, should be adopted.