Noise-induced deafness

Scale of noise-induced deafness

The number of people in Great Britain suffering from hearing difficulties as a result of exposure to noise at work was estimated at 509  000 by a Medical Research Council (MRC) survey in 1997-98. This prevalence estimate was derived using an attributable fraction approach i.e. by comparing the prevalence of symptoms in noise-exposed and non-exposed groups (regardless of whether individuals attributed their symptoms to noise at work).

Results from the Self-reported Work-related Illness (SWI) questionnaire module included annually in the national Labour Force Survey (LFS), generates a much smaller estimate. The prevalence estimate for self-reported hearing loss when restricting the estimate to people who worked in the last 12 months in 2008/09 was an estimated 17 000 (95% CI: 11 000 and 24 000) individuals, according to the LFS. (Table SWIT3W12)

The difference may be explained by the fact that in the MRC survey all interviewees were specifically asked about hearing difficulties and the overall prevalence of work-related hearing loss was estimated by using an attributable fraction approach, whereas the SWI estimate was based on people who spontaneously reported work-related hearing problems when interviewed.

Benefit claims for noise induced deafness

The wide range of hearing ability which exists in the population inevitably means that different prevalence estimates can be obtained depending on the precise methodology used to identify those with a problem. The Department for Work and Pensions (DWP) estimate from a 10% sample of their records that a total of 14 000 people were receiving disablement benefit for occupational deafness in March 2001. Both the MRC and the SWI surveys will have included many sufferers who would not meet the DWP criteria for benefit.

To qualify for benefit under IIDB an individual must have at least 50 decibels of hearing loss in both ears this equates to 20% disability. Also under current rules, a worker must have been employed for a minimum of ten years in specified noisy occupations. (Table IIDB02) show the number of new awards of IIDB for occupational deafness over the last decade. The overall trend in the number of newly qualified cases of occupational deafness is downwards and while there has been an increase this year, the figures are still around their lowest levels for the past 10 years.

The requirement of 50 decibels or more of hearing loss represents quite a substantial impairment. For deafness, unlike other prescribed diseases, the information available from DWP does not give, on a comparable basis, the number of cases with insufficient disability to qualify for an award. However, estimates based on DWP audiological examinations in 1998 show that of almost 2 000 claims disallowed because the claimants had less than 50 decibels hearing loss, over 800 had between 35 and 49 decibels of hearing loss.

SWI01/02 Table 8.5 shows the comparison of the SWI surveys for 1990, 1995, 1998/99 and 2001/02 and allows some estimate to be made of trends in prevalence, although restrictive definitions have to be used, in particular estimates are restricted to people who worked in the previous 12 months, to make results for the four surveys comparable and each is subject to uncertainty due to sampling variation. For self-reported work-related hearing problems there was a generally downward trend in the prevalence estimates up to 1998/99 and then little change to 2001/02, which is consistent with the trend for new IIDB cases. More recently, between 2001/02 and 2008/09 the prevalence of self-reported work-related hearing problems in people who worked in the last 12 months has remained broadly level. (Table SWIT3W12).

Industry and Occupational Breakdowns

Based on average rates of new assessments for IIDB between 2006-2008 shows that the following industries had high rates of occupational deafness per 100 000 employees: Extraction, energy and water supply, manufacturing and construction as shown in Table IIDB10.