13 JANUARY 2009 Occupational Risk Management OCCUPATIONAL HEALTH T he increase of mechanical equipment capable of producing hazardously loud noise levels, and the widespread availability of gunpowder, are among the causes for the significant increase in NIHL. It was NIHL, which gave birth to the profession of audiology in the 1940s, when soldiers returned from World War II with acquired hearing loss caused by gunfire and explosions. Today it is estimated that over a third of the 28 million Americans who have some degree of hearing loss, have been affected, at least partly, by noise (ASHA, 2007). The World Health by Susan Strauss and Dr De Wet Swanepoel Noise-induced hearing loss (NIHL) is no new phenomenon, but the last two centuries has seen a significant increase in its occurrence, due to the industrial revolution. Organisation estimates that 18% of adult onset hearing loss in the 20 southernmost countries in Africa (AFR-E region), includ- ing South Africa, might be due to NIHL in the workplace (WHO, 2002). Excessive noise can irreversibly damage the sensory hair cells of the inner ear. This results in a progressive, sensori-neural hearing loss that is predominantly noted in the high frequency region with a typical notch at 4 kHz. Significant individual variation in susceptibility to NIHL is evident and may be due to many factors, including a history of exposure to noise, certain medications, and organic solvents known to affect hearing, long-term smoking, gender, pigmentation, age and genetic make-up. Despite differences in susceptibility to NIHL, no one is immune to the devastating effect of loud noise over a prolonged period. Disabling NIHL results in a disabling condition, which affects a person’s ability to communicate negatively and interact socially also has a detrimental impact on work performance. Since occupational noise can result in disabling NIHL, which is a preventable condition, industries are obligated to protect their workers. Nowhere is this more important than in the South African mining industry. Mining employs 5.1% of workers in the non-agricultural, formal sectors of the economy, a reported total of 458 600 employees in 2006 (Mwape et al., 2007). The processes associated with mining generate tremendous noise because of activities including percussion drilling, blasting, and crushing of ore, often exacerbated by confined and reflective spaces. Despite the fact that NIHL is preventable and that the South African mining industry introduced hearing conservation programmes (HCPs) in 1988, a high prevalence of NIHL is still reported in South African mines. It contributed to some 15% of occupational disease claims submitted in 2005 to the Rand Mutual Assurance Company (RMA) who underwrites workers’ compensation benefits for the mining industry in South Africa. Furthermore, NIHL accounted for almost half of the compensation benefits paid to claimants in 2005 (RMA, 2005). Reports from the South African Chamber of Mines and the MHSC describe a particularly high incidence of NIHL in gold miners (Chamber of Mines, 2007, and MHSC, 2005) as indicated in the figure. Targets for 2009 and 2013 In view of the high prevalence of NIHL and the increasing financial impact of NIHL on the mining industry, the South African Mine Health and Safety Council (MHSC), comprising representatives of state, labour and employers, signed an agreement with the mining industry in 2005 to achieve two important milestones. Firstly, it was agreed that after December 2008, the hearing conservation programme Prioritising Noise-Induced Hearing Loss Noise-induced hearing loss number and rate per commodity 0 400 800 1200 1600 2000 Number 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 Rate per 1000 Total NIHL cases 68 52 48 17 1723 678 2 4 710 1352 NIHL Rate 2.41 2.07 6.53 2.67 11.04 4.32 0.38 0.83 4.40 12.25 2005 2006 2005 2006 2005 2006 2005 2006 2005 2006 Coal Diamond Gold Other Platinum NIHL number and rate per commodity (after Randera, 2007) Susan Strauss