2009-07-01 12:00 - Messages

Interventions to prevent occupational noise induced hearing loss

Millions of workers are exposed to noise levels that increase the risk of hearing loss and hearing impairment. In many countries there are mandatory hearing loss prevention programmes (HLPPs), which are considered an effective means to prevent noise induced hearing loss. However, the evidence for this assumption is unclear.

We found one study that showed that noise levels decreased after a change in legislation in the mining industry. In six studies with 169 workers, hearing protection reduced noise exposure of workers. However, one high quality study showed that if workers lack proper instructions in the use of earplugs, hearing protection is insufficient. We found 15 studies with 75,672 participants that evaluated the long-term effects of protection against noise exposure. Six studies compared the effects of prevention programmes on workers' hearing loss to hearing levels in non-exposed workers. One of these studies showed that army recruits are at a three-fold increased risk of hearing loss compared to non-exposed controls. Another study found a four-fold increase in hearing loss among workers that were exposed but protected compared to non-exposed workers. In the remaining four studies, there was no difference in hearing loss between protected and non-exposed workers but there is still considerable uncertainty about the validity of this result. In four studies the risk reduction depended on the quality of hearing loss prevention programmes. There is contradictory evidence on the effectiveness of hearing protection and hearing loss prevention programmes. Higher quality prevention programmes and better implementation of legislation are needed.



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