Occupational hearing loss

Hearing Difficulties Among Farmworkers in the México-US Southwest Border Region

Migrant and seasonal farmworkers are a vulnerable population with a potentially high risk for hearing loss due to farm-related noise exposures. Occupational noise-induced hearing loss (NIHL) is permanent, and it is associated with an increased risk for injuries on the job, as well as communication difficulties, isolation, and depression. The México/US border region is one of the most productive agricultural regions in the country, however, no known studies have explored hearing loss among farmworkers in this area. This pilot study was a first step toward measuring and addressing hearing loss and noise exposure among this region's farmworkers. We conducted a cross-sectional survey to estimate the prevalence of subjective hearing difficulties among Yuma County, Arizona farmworkers. Survey interviews took place during a late-night farmworker health fair from 2 am to 6 am to accommodate local farms' labor schedules. Multivariable regression adjusted for demographic and work covariates estimated subjective hearing loss prevalence ratios. Among 132 farmworker participants, 36% reported they have or might have hearing loss, and 62% reported no hearing loss. Subjective hearing loss prevalence was lower in farmworkers who report not working in noise compared to prevalence in farmworkers who work in noise [prevalence ratio, 0.44 (95% CI 0.23-0.82)]. This report contributes to understanding the perception of hearing-related health and occupational exposures among farmworkers in the México-US Southwest border region. The information from this line of research will inform appropriate safety measures known to lower the risk of experiencing occupational NIHL.

The effect of occupational exposure to noise and chemical agents on hearing abilities

Exposure to loud noise or chemical agents may cause hearing disorders such as tinnitus and recruitment, known as an increase in the perception of loudness in addition to hearing loss. Our study aims to evaluate the hearing abilities of hairdressers exposed to noise and chemical agents in the working environment. The study included one hundred hairdressers and one hundred participants who do not work as hairdressers or are nonworkers. The participants' demographic characteristics, working conditions, and auditory complaints were questioned, and each participant completed the Speech, Spatial, and Qualities of Hearing Scale (SSQ). A statistically significant difference was found between the two groups in speech perception, spatial perception, hearing quality, and general SSQ scores. Hairdressers' SSQ scores were significantly lower in all sub-dimensions and general scale scores (p < 0.001). The auditory complaints of the hairdressers and the low SSQ scores indicate that exposure to noise and chemical agents affects the hairdressers' hearing system.

Risk perception or hazard perception? Examining misperceptions of miners' personal exposures to noise

While perceptions of risk have been examined in the workplace to understand safety behavior, hazard perception has been overlooked, particularly for chemical, physical, and biological agents. This study sought to establish the prevalence of one type of mismatch in hazard perception, - noise misperception - among miners, to examine whether different types of noisy environments (e.g., continuous, highly variable, etc.) alter workers' misperception of their noise exposures, and to evaluate whether noise misperception is associated with hearing protection device (HPD) use behavior. In this cross-sectional study across 10 surface mines in the USA, 135 normal-hearing participants were surveyed on their perceptions of exposure to noise at work and were monitored for three shifts, each with personal noise dosimetry, to examine which workers had a mismatch in perceived versus true noise exposure by 8-hr, time-weighted average, NIOSH exposure limits (TWANIOSH). Mixed effects logistic regression and probit Bayesian Kernel Machine Regression (BKMR) models examining on the odds of noise misperception associated with four different noise metrics (kurtosis, crest factor, variability, and number of peaks >135 dB) were used to determine which types of noisy environments may influence noise misperception. The relationship between noise misperception and odds of not wearing HPDs during a work shift was further examined. Our findings showed that nearly 1 in 3 workers underestimated their exposure to noise when their true exposure was in fact hazardous (TWANIOSH≥85 dBA) for at least one shift, and 6% misperceived hazardous exposures for all shifts. Work shifts with highly kurtotic noise distributions (>3) had 3.1 (95% CI: 1.1 to 8.4) times significantly higher odds of resulting in misperceived noise; no other noise metric was significantly associated with noise misperception. BKMR modeling provided further evidence that kurtosis dominates this relationship, with an IQR increase in kurtosis significantly associated with 1.68 (95% CI: 1.13 to 2.50) higher odds of noise misperception. Although not statistically significant, misperception of hazardous noise exposure was associated with 3.2 (95% CI: 0.8 to 12.5) times higher odds of not using earplugs during a work shift. Misperception of noise occurs in the workplace, and likely occurs for other physical, chemical, and biological exposures. This hazard misperception may influence risk perceptions and worker behavior and reduce the effectiveness of behavior-related training. Elimination, substitution, or engineering controls of exposures is the best way to prevent hazard misperceptions and exposure-related diseases.

The relationship between hearing status, listening effort, and the need for recovery in employees of a manufacturing company

OBJECTIVE

Hearing screening can be used to detect hearing loss, but its value for identifying employees with work functioning difficulties is unclear. The objective of this study was to assess the association between the hearing status measured with an occupational hearing-in-noise screening test, Listening Effort (LE), and Need For Recovery (NFR) in employees of a manufacturing company, and to examine whether these associations depend on the perceived noise level at the workplace.

METHODS

Employees of coatings and paints manufacturing company were included. Their hearing status was assessed with an occupational hearing-in-noise screening test. An online survey was used to assess their LE, NFR, and the perceived noise level at the workplace. Responses from 143 employees were analyzed (mean age = 53 years) using hierarchical multiple regression analysis with the outcomes LE and NFR.

RESULTS

Regression analysis-with adjustments for gender, age, educational level, health status, pace/amount of work, job variety, and work pleasure-revealed that hearing status was significantly associated with LE, but the interaction between hearing status and the perceived noise level was not. Hearing status nor the interaction between hearing status and the perceived noise level was significantly associated with NFR.

CONCLUSION

The results confirm that poorer hearing is associated with higher LE, but not with higher NFR. These associations were unrelated to the perceived noise level at the workplace. Therefore, the value of occupational hearing screening appears to be early identification of hearing loss in employees, but not identification of work functioning difficulties.

Audiometric data analysis for prevention of noise-induced hearing loss: A new approach

Compliance with noise regulations in the past three decades has significantly reduced workplace noise exposures, particularly in the loudest industries and occupations. However, the overall effectiveness of hearing conservation programs in preventing occupational noise-induced hearing loss remains uncertain and unquantified, while the incidence and cost of occupational hearing loss remain inexplicably high. This review/commentary critically explores this paradox by examining why the billions of annual audiograms conducted worldwide have not been aggregately utilized or applied to predict early NIHL in groups of workers or to measure the efficacy of exposure controls. Principal contributory reasons include regulation of noise as a safety standard rather than as a health standard, the inherent complexity of audiometric data, and the lack of a standardized method of interpretation for audiograms. The unsuccessful history of efforts to develop and adopt methods and tools to analyze aggregate audiometric data is described. Consequently, the Standard Threshold Shift-a regulatorily defined, lagging indicator of individual, irreversible hearing loss that is not an effective preventive metric-remains the de facto standard of care. A population-based Best Practices approach is proposed to leverage the raw audiometric data already available and turn it into actionable data for effective secondary prevention to strategically manage and reduce occupational hearing loss risk. This approach entails statistical methods and information management tools necessary to transform audiometry from a compliance-driven, individual screening test with limited preventive capability into a medical surveillance process directly linked to aggregate corrective and prevention actions.

Retrospective assessment of the association between noise exposure and nonfatal and fatal injury rates among miners in the United States from 1983 to 2014

BACKGROUND

Mining is a significant economic force in the United States but has historically had among the highest nonfatal injury rates across all industries. Several factors, including workplace hazards and psychosocial stressors, may increase injury and fatality risk. Mining is one of the noisiest industries; however, the association between injury risk and noise exposure has not been evaluated in this industry. In this ecological study, we assessed the association between noise exposure and nonfatal and fatal occupational injury rates among miners.

METHODS

Federal US mining accident, injury, and illness data sets from 1983 to 2014 were combined with federal quarterly mining employment and production reports to quantify annual industry rates of nonfatal injuries and fatalities. An existing job-exposure matrix for occupational noise was used to estimate annual industry time-weighted average (TWA, dBA) exposures. Negative binomial models were used to assess relationships between noise, hearing conservation program (HCP) regulation changes in 2000, year, and mine type with incidence rates of injuries and fatalities.

RESULTS

Noise, HCP regulation changes, and mine type were each independently associated with nonfatal injuries and fatalities. In multivariate analysis, each doubling (5 dB increase) of TWA was associated with 1.08 (95% confidence interval: 1.05, 1.11) and 1.48 (1.23, 1.78) times higher rate of nonfatal injuries and fatalities, respectively. HCP regulation changes were associated with 0.61 (0.54, 0.70) and 0.49 (0.34, 0.71) times lower nonfatal injury and fatality rates, respectively.

CONCLUSION

Noise may be a significant independent risk factor for injuries and fatalities in mining.

Socio-economic disparity in the global burden of occupational noise-induced hearing loss: an analysis for 2017 and the trend since 1990

OBJECTIVES

To evaluate socio-economic disparity in the global burden of occupational noise-induced hearing loss (ONIHL) using disability-adjusted life-years (DALYs).

METHODS

The numbers of DALYs due to ONIHL, age-standardised DALY rates and national human development index (HDI) data from 1990 to 2017 were collected. The relationship between the age-standardised DALY rates and the 2017 HDI was analysed. A concentration index (CI) and a relative index of inequality (RII) were calculated to evaluate the trend in socio-economic disparity in the burden of ONIHL for the period 1990-2017.

RESULTS

From 1990 to 2017, the global DALYs due to ONIHL increased from 3.3 to 6.0 million, with the highest growth occurring in low-income countries (110.7%). Age-standardised DALY rates due to ONIHL were negatively associated with the HDI (β = -0.733, p<0.001), and these rates were significantly higher in countries with a lower HDI. From 1990 to 2017, the trend in between-country inequality was flat with little fluctuation, the CIs stayed near -0.17, and the RIIs remained near 0.35.

CONCLUSIONS

Over the past few decades, low-income countries have experienced the most rapid growth in DALYs worldwide. A widening socio-economic disparity has persisted in the global burden of ONIHL, with a higher burden in lower socio-economic countries. These data suggest that more prevention programmes and healthcare services should be provided for developing countries.

A National Survey of Health and Safety Knowledge and Beliefs Among Technical Vocational Faculty in Autobody Collision Repair Technology

OBJECTIVES

Career technical education (CTE) programs prepare new generations of technicians in a variety of trades. Even though occupational safety and health (OSH) ought to be included as an essential part of CTE curricula it is frequently absent or inadequately taught.

METHODS

OSH knowledge and beliefs were assessed in a national sample of 125 secondary and post-secondary faculty in autobody collision repair technology.

RESULTS

Over 50% of faculty thought at least 75% of OSH knowledge was learned at school, and 9% felt that safety was primarily learned on the job. Knowledge scores ranged from 22% to 78%. Overall knowledge scores were significantly lower high school than post-secondary instructors (42% vs 50%, P ≤ 0.001) and in two categories: hazard recognition (44% vs 54%, P ≤ 0.05) and hazard control and shop equipment (30% vs 37%, P ≤ 0.05).

CONCLUSIONS

There are substantial gaps in OSH knowledge among secondary and post-secondary CTE instructors. CTE programs should address these gaps by providing trade-specific safety and health education to their instructors upon hiring.

Factors influencing the need for recovery in employees with hearing loss: a cross-sectional study of health administrative data

Objective

Need for recovery is a predictor of work stress and health problems, but its underlying factors are not yet well understood. We aimed to identify hearing-related, work-related, and personal factors influencing need for recovery in hearing-impaired employees.

Methods

We retrospectively identified hearing-impaired employees (N = 294) that were referred to the Amsterdam University Medical Center between 2004 and 2019. Routinely obtained healthcare data were used, including a survey and hearing assessments. A directed acyclic graph was constructed, revealing the hypothesized structure of factors influencing need for recovery as well as the minimal set of factors needed for multiple regression analysis.

Results

Four variables were included in the regression analysis. In total, 46.1% of the variance in need for recovery was explained by the factors feeling that something should change at work (B = 19.01, p < 0.001), self-perceived listening effort (B = 1.84, p < 0.001), personal adaptations scale score (B = − 0.34, p < .001), and having a moderate/poor general health condition (B = 20.06, p < 0.001). Although degree of hearing loss was associated with self-perceived listening effort, the direct association between degree of hearing loss and need for recovery was not significant.

Conclusions

The results suggest that the way employees perceive their hearing loss and how they cope with it directly influence need for recovery, rather than their measured degree of hearing loss. Additionally, general health condition was found to be an independent factor for need for recovery. The results should be confirmed by future, longitudinal research.

Early diagnosis and treatment of unilateral or asymmetrical hearing loss in children: CODEPEH recommendations

The aim of this document is to improve the management and the treatment of unilateral or asymmetrical hearing loss in children. One in one thousand newborn infants has unilateral hearing loss and this prevalence increases with age, due to cases of acquired and delayed-onset hearing loss. Although the impact on the development and learning processes of children of these kinds of hearing loss have usually been minimized, if they are not treated they will impact on language and speech development, as well as overall development, affecting the quality of life of the child and his/her family. The outcomes of the review are expressed as recommendations aimed at clinical diagnosis and therapeutic improvement for unilateral or asymmetrical hearing loss.

Advanced noise-induced deafness among workers in singapore - what has changed?

Context:

Noise-induced deafness (NID) contributes a significant disease burden internationally, and is a leading occupational disease in Singapore.

Aims:

This study profiles the epidemiological characteristics of advanced noise-induced deafness (NID(A)) cases and explores whether these have evolved with time.

Settings and Design:

A quantitative retrospective analysis of prior NID(A) cases was performed. National records of NID(A) cases from 2001 to 2010 were obtained, with permission from the Ministry of Manpower, consisting of worker audiograms, case records, and noise monitoring reports.

Methods and Material:

Comparison was made with data from a prior study (127 cases, 1985–1994) to identify shifts in NID(A) epidemiology; 71 out of 73 NID(A) case records (2001–2010) from the national data were reviewed.

Statistical Analysis Used:

Statistical Package for Social Sciences (IBM) was used for statistical analysis.

Results:

Mean noise exposure (24–29.6 years) and age at diagnosis (48–54.6 years) have risen. Total case numbers (127 to 73 cases), average hearing loss levels (61.5 to 56.0 A-weighted decibels), and delayed reporting of NID(A) cases (82.7% to 47.9%) have decreased. Metal manufacturing and marine industries remain top contributors (69.1%, from 68.5%); 31% were noncompliant with hearing protector (personal protective equipment, PPE) use and 38% did not use PPE properly.

Conclusions:

NID(A) case profiles have shifted over time, with reduced case numbers, lower hearing loss levels at diagnosis, and earlier case notification, possibly linked to improvements in legislative coverage and NID prevention programs. Changes in age and average duration of noise exposure may be related to these improvements. Early case notification, PPE compliance, and proper usage should be focus areas for NID prevention and hearing conservation programs.

The effect of noise exposure on the vestibular systems of dental technicians

BACKGROUND

Noise exposure is the primary cause of acquired hearing loss in several occupational settings, including dental laboratories and clinics. However, the impact of noise exposure on the vestibular system is not as well researched.

PURPOSE

To investigate the nature of vestibular damage caused by working in dental laboratories and clinics with high levels of noise exposure due to loud dental equipment.

RESEARCH DESIGN

A descriptive, case study design was used to evaluate the vestibular function of dental technicians.

STUDY SAMPLE

Out of 30 dental technicians, 5 males who had been working for several years in dental settings were selected based on their reports of severe symptoms of imbalance.

DATA COLLECTION

Audiologic evaluations were conducted in the vestibular unit of the Doctor Tarek Khrais Center in Amman, Jordan, for one year. Each subject underwent several hearing tests, which included otoscopic examination, pure tone audiometry (PTA), impedance measurements, and speech testing. Assessment of vestibular function was then conducted using a diagnostic test battery which included electrocochleography, ocular vestibular evoked myogenic potentials (oVEMP), cervical vestibular evoked myogenic potentials (cVEMP), positional testing using the Thomas Richard-Vitton (TRV) chair, and standing stability testing.

RESULTS

All test subjects experienced some form of vestibular impairment, including benign paroxysmal positional vertigo (BPPV), endolymphatic hydrops (Meniere disease), or a combination of both. Three out of five cases displayed little or no hearing loss, indicating that vestibular function is more at risk than hearing acuity to continuous noise exposure in dental settings.

CONCLUSIONS

Exposure to loud noise in dental laboratories severely impacts the functioning of the vestibular system of the inner ear more than the cochlea. The main clinical implication of this study is that regular vestibular assessments are a necessity for dental technicians.

Noise Induced Hearing Loss among an Occupational Group of Textile Workers in Karachi, Pakistan

A cross sectional survey was conducted among textile workers of six textile factories of different industrial areas of Karachi to determine the frequency of hearing loss. A total of 264 workers were assessed for frequency of hearing loss with audiometric and otoscopic examination conducted by audiologist. About 79% workers had hearing impairment on audiometric assessment having hearing loss ≥25 dB. Of these, 19% of the workers had conductive deafness while 71% had mixed hearing loss. Otoscopic examination revealed that 38% had wax, 41.8 % had ear discharge and 1.6 % had perforation. The multiple logistic regression model shows sound level more than 25 dB aOR: 1.15; 95%CI: 1.10, 1.30 and ear discharge aOR: 2.23; 95%CI: 1.27, 3.92, was found as a strong risk factor of hearing loss (p<0.05). Hearing impairment affects a large proportion of the workers in Pakistan. There is a need for screening of workers exposed to occupational noise. Efforts should be made by the health care system to prevent the problem from an early stage and require effective management of ear-related diseases.

Accuracy of an internet-based speech-in-noise hearing screening test for high-frequency hearing loss: incorporating automatic conditional rescreening

Purpose

To validate the accuracy of an internet-based speech-in-noise hearing screening test for high-frequency hearing loss (HFHL) ‘Occupational Earcheck (OEC)’ incorporating an automatic conditional rescreening, in an occupationally noise-exposed population. Secondary objectives were to assess the effects of age on test accuracy measures, and to assess the test accuracy for different degrees of HFHL.

Methods

A study was conducted on cross-sectional data of occupational audiometric examinations, including the index test OEC and reference standard pure-tone air conduction audiometry, of 80 noise-exposed workers. Sensitivity, specificity, and likelihood ratios were calculated for the OEC, after automatic conditional rescreening, for a younger and an older age group, and for two degrees of HFHL (HFHL₂₅: PTA3,4,6 ≥ 25 dB HL, and HFHL₃₅: PTA3,4,6 ≥ 35 dB HL, both for at least one ear).

Results

Test specificity for HFHL₂₅ after a single test was 63%, and improved to 93% after the automatic conditional rescreen. Test sensitivity for HFHL₂₅ decreased from 65% to 59%. Test sensitivity and specificity including automatic conditional rescreening for HFHL₃₅ was 94% and 90%, respectively. The positive likelihood ratio for HFHL₂₅ was 8.4, and for HFHL₃₅ 9.4. The negative likelihood ratio for HFHL₃₅ was below 0.1.

Conclusions

The OEC is an appropriate screening test, especially for HFHL₃₅. Normal-hearing workers who obtained a positive test result for the first test for one or two ears, benefit from having an automatic rescreen, resulting in an improvement of the test specificity, and hence prevent unnecessary referral.

Prevalence of hearing loss among noise-exposed workers within the agriculture, forestry, fishing, and hunting sector, 2003-2012

BACKGROUND

The purpose of this study was to estimate the prevalence of hearing loss among noise-exposed US workers within the Agriculture, Forestry, Fishing, and Hunting (AFFH) sector.

METHODS

Audiograms for 1.4 million workers (17 299 within AFFH) from 2003 to 2012 were examined. Prevalence, and the adjusted risk for hearing loss as compared with the reference industry (Couriers and Messengers), were estimated.

RESULTS

The overall AFFH sector prevalence was 15% compared to 19% for all industries combined, but many of the AFFH sub-sectors exceeded the overall prevalence. Forestry sub-sector prevalences were highest with Forest Nurseries and Gathering of Forest Products at 36% and Timber Tract Operations at 22%. The Aquaculture sub-sector had the highest adjusted risk of all AFFH sub-sectors (PR = 1.70; CI = 1.42-2.04).

CONCLUSIONS

High risk industries within the AFFH sector need continued hearing conservation efforts. Barriers to hearing loss prevention and early detection of hearing loss need to be recognized and addressed.

Interventions to prevent occupational noise-induced hearing loss

BACKGROUND

This is the second update of a Cochrane Review originally published in 2009. Millions of workers worldwide are exposed to noise levels that increase their risk of hearing disorders. There is uncertainty about the effectiveness of hearing loss prevention interventions.

OBJECTIVES

To assess the effectiveness of non-pharmaceutical interventions for preventing occupational noise exposure or occupational hearing loss compared to no intervention or alternative interventions.

SEARCH METHODS

We searched the CENTRAL; PubMed; Embase; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; and OSH UPDATE to 3 October 2016.

SELECTION CRITERIA

We included randomised controlled trials (RCT), controlled before-after studies (CBA) and interrupted time-series (ITS) of non-clinical interventions under field conditions among workers to prevent or reduce noise exposure and hearing loss. We also collected uncontrolled case studies of engineering controls about the effect on noise exposure.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study eligibility and risk of bias and extracted data. We categorised interventions as engineering controls, administrative controls, personal hearing protection devices, and hearing surveillance.

MAIN RESULTS

We included 29 studies. One study evaluated legislation to reduce noise exposure in a 12-year time-series analysis but there were no controlled studies on engineering controls for noise exposure. Eleven studies with 3725 participants evaluated effects of personal hearing protection devices and 17 studies with 84,028 participants evaluated effects of hearing loss prevention programmes (HLPPs). Effects on noise exposure Engineering interventions following legislationOne ITS study found that new legislation in the mining industry reduced the median personal noise exposure dose in underground coal mining by 27.7 percentage points (95% confidence interval (CI) -36.1 to -19.3 percentage points) immediately after the implementation of stricter legislation. This roughly translates to a 4.5 dB(A) decrease in noise level. The intervention was associated with a favourable but statistically non-significant downward trend in time of the noise dose of -2.1 percentage points per year (95% CI -4.9 to 0.7, 4 year follow-up, very low-quality evidence). Engineering intervention case studiesWe found 12 studies that described 107 uncontrolled case studies of immediate reductions in noise levels of machinery ranging from 11.1 to 19.7 dB(A) as a result of purchasing new equipment, segregating noise sources or installing panels or curtains around sources. However, the studies lacked long-term follow-up and dose measurements of workers, and we did not use these studies for our conclusions. Hearing protection devicesIn general hearing protection devices reduced noise exposure on average by about 20 dB(A) in one RCT and three CBAs (57 participants, low-quality evidence). Two RCTs showed that, with instructions for insertion, the attenuation of noise by earplugs was 8.59 dB better (95% CI 6.92 dB to 10.25 dB) compared to no instruction (2 RCTs, 140 participants, moderate-quality evidence). Administrative controls: information and noise exposure feedbackOn-site training sessions did not have an effect on personal noise-exposure levels compared to information only in one cluster-RCT after four months' follow-up (mean difference (MD) 0.14 dB; 95% CI -2.66 to 2.38). Another arm of the same study found that personal noise exposure information had no effect on noise levels (MD 0.30 dB(A), 95% CI -2.31 to 2.91) compared to no such information (176 participants, low-quality evidence). Effects on hearing loss Hearing protection devicesIn two studies the authors compared the effect of different devices on temporary threshold shifts at short-term follow-up but reported insufficient data for analysis. In two CBA studies the authors found no difference in hearing loss from noise exposure above 89 dB(A) between muffs and earplugs at long-term follow-up (OR 0.8, 95% CI 0.63 to 1.03 ), very low-quality evidence). Authors of another CBA study found that wearing hearing protection more often resulted in less hearing loss at very long-term follow-up (very low-quality evidence). Combination of interventions: hearing loss prevention programmesOne cluster-RCT found no difference in hearing loss at three- or 16-year follow-up between an intensive HLPP for agricultural students and audiometry only. One CBA study found no reduction of the rate of hearing loss (MD -0.82 dB per year (95% CI -1.86 to 0.22) for a HLPP that provided regular personal noise exposure information compared to a programme without this information.There was very-low-quality evidence in four very long-term studies, that better use of hearing protection devices as part of a HLPP decreased the risk of hearing loss compared to less well used hearing protection in HLPPs (OR 0.40, 95% CI 0.23 to 0.69). Other aspects of the HLPP such as training and education of workers or engineering controls did not show a similar effect.In three long-term CBA studies, workers in a HLPP had a statistically non-significant 1.8 dB (95% CI -0.6 to 4.2) greater hearing loss at 4 kHz than non-exposed workers and the confidence interval includes the 4.2 dB which is the level of hearing loss resulting from 5 years of exposure to 85 dB(A). In addition, of three other CBA studies that could not be included in the meta-analysis, two showed an increased risk of hearing loss in spite of the protection of a HLPP compared to non-exposed workers and one CBA did not.

AUTHORS' CONCLUSIONS

There is very low-quality evidence that implementation of stricter legislation can reduce noise levels in workplaces. Controlled studies of other engineering control interventions in the field have not been conducted. There is moderate-quality evidence that training of proper insertion of earplugs significantly reduces noise exposure at short-term follow-up but long-term follow-up is still needed.There is very low-quality evidence that the better use of hearing protection devices as part of HLPPs reduces the risk of hearing loss, whereas for other programme components of HLPPs we did not find such an effect. The absence of conclusive evidence should not be interpreted as evidence of lack of effectiveness. Rather, it means that further research is very likely to have an important impact.

Association between metabolic syndrome and sensorineural hearing loss: a cross-sectional study of 11,114 participants

BACKGROUND/OBJECTIVES

Hearing loss (HL) is associated with certain diseases and affects health, resulting in a low quality of life. Some components of the metabolic syndrome (MetS) coincide with the risk factors for sensorineural hearing loss (SNHL). To date, very few studies have examined the link between MetS and HL. The aim of the current study was to try to understand the potential association between MetS and HL.

METHODS

Using Iranian health surveys of professional drivers, we enrolled 11,114 individuals aged 20-60 years, whose main job is to operate a motor vehicle. We examined participants for the presence and absence of SNHL and the components of the MetS. Additionally, we investigated the relationship between MetS and the pure tone air conduction hearing thresholds of participants with SNHL, including low-frequency and high-frequency thresholds.

RESULTS

This cross-sectional study consisted of 11,114 participants: 3202 (28.81%) diagnosed with MetS and 7911 (71.18%) without and 2772 (24.94%) with SNHL and 8432 (75.86%) without. Participants with SNHL had a higher number of components of MetS (P<0.001 for all components).

CONCLUSION

Our results demonstrated that an association possibly exists between different components of MetS (obesity, hypertension, hypertriglyceridemia, high fasting glucose levels, and waist circumference) and SNHL in a population of West Azerbaijan drivers. Therefore, it is important to schedule periodic checkups for drivers to detect and avoid the increase in MetS components at an early stage in this population.

Health impact and noise exposure assessment in the cricket bat industry of Kashmir, India

AIM

The aim of the present study was to identify and evaluate predominant noise sources in the cricket bat industry of Kashmir, India.

METHODS

Sound levels were measured at operator's ear level in the working zone of the workers of seven cricket bat factories. The impact assessment was made through personal interviews with each worker separately during their period of rest.

RESULTS

On average, 62.5% of the workers reported difficulty in hearing and 24.1% of the workers have become patients for hypertension. Only 58.1% of the workers complained of headache due to high noise level.

CONCLUSIONS

The workers engaged in the cricket bat industry of Kashmir are exposed to high noise levels. It is suggested that personal protective equipment like ear plugs and ear muffs be used by these workers as a protection against this hazard.

Is it reasonable to use 1 and 8 kHz anchor points in the medico-legal diagnosis and estimation of noise-induced hearing loss?

BACKGROUND

In the United Kingdom, use of 1 and 8 kHz as anchor point frequencies has been recommended for the medico-legal diagnosis and estimation of noise-induced hearing loss. There appear to be four assumptions behind the use of 1 and 8 kHz anchor point approach: (i) The frequencies of 1 and 8 kHz are not damaged by noise; therefore, the measured hearing thresholds at the said frequencies solely reflect age-related hearing loss, even in the noise-exposed; (ii) The hearing thresholds at 1 and 8 kHz are a valid predictor of the likely age-related hearing loss thresholds at the other frequencies; (iii) Age and noise damage are always completely additive; (iv) Individual's susceptibility to age and noise damage is not proportionate. Doubts have been expressed in the medical circles about the legitimacy and validity of their use as anchor points.

OBJECTIVE OF REVIEW

Is it reasonable to use 1 and 8 kHz anchor points in the medico-legal diagnosis and estimation of noise-induced hearing loss?

TYPE OF REVIEW

Medico-legal.

SEARCH STRATEGY

Literature search; Medline, Embase, Internet, and medico-legal records.

EVALUATION METHOD

Equating and comparing the assumptions in the anchor point approach with the information in medical literature.

RESULTS

Based upon the information in medical literature, technical reports, and professional statements, the assumptions behind the use of anchor point approach cannot be reliably substantiated.

CONCLUSIONS

'Carte Blanche' use of 1 and 8 kHz anchor points is probably unreasonable and may well be unsafe in the medico-legal diagnosis and estimation of noise-induced hearing loss.

Heart Rate, Stress, and Occupational Noise Exposure among Electronic Waste Recycling Workers

Electronic waste (e-waste) is a growing occupational and environmental health issue around the globe. E-waste recycling is a green industry of emerging importance, especially in low-and middle-income countries where much of this recycling work is performed, and where many people's livelihoods depend on this work. The occupational health hazards of e-waste recycling have not been adequately explored. We performed a cross-sectional study of noise exposures, heart rate, and perceived stress among e-waste recycling workers at a large e-waste site in Accra, Ghana. We interviewed 57 workers and continuously monitored their individual noise exposures and heart rates for up to 24 h. More than 40% of workers had noise exposures that exceeded recommended occupational (85 dBA) and community (70 dBA) noise exposure limits, and self-reported hearing difficulties were common. Workers also had moderate to high levels of perceived stress as measured via Cohen's Perceived Stress Scale, and reported a variety of symptoms that could indicate cardiovascular disease. Noise exposures were moderately and significantly correlated with heart rate (Spearman's ρ 0.46, p < 0.001). A mixed effects linear regression model indicated that a 1 dB increase in noise exposure was associated with a 0.17 increase in heart rate (p-value = 0.01) even after controlling for work activities, age, smoking, perceived stress, and unfavorable physical working conditions. These findings suggest that occupational and non-occupational noise exposure is associated with elevations in average heart rate, which may in turn predict potential cardiovascular damage.

Analysis of plasma microRNA expression profiles in male textile workers with noise-induced hearing loss

BACKGROUND

Circulating microRNAs (miRNAs) have attracted interests as non-invasive biomarkers of physiological and pathological conditions, which may be applied in noise-induced hearing loss (NIHL). However, no epidemiology studies have yet examined the potential effects of NIHL or noise exposure on miRNA expression profiles.

OBJECTIVES

We sought to identify permanent NIHL-related miRNAs and to predict the biological functions of the putative genes encoding the indicated miRNAs.

METHODS

In the discovery stage, we used a microarray assay to detect the miRNA expression profiles between pooled plasma samples from 10 noise-exposed individuals with normal hearing and 10 NIHL patients. In addition, we conducted a preliminary validation of six candidate miRNAs in the same 20 workers. Subsequently, three miRNAs were selected for expanded validation in 23 non-exposed individuals with normal hearing and 46 noise-exposed textile workers which including 23 noise-exposed workers with normal hearing and 23 NIHL patients. Moreover, we predicted the biological functions of the putative target genes using a Gene Ontology (GO) function enrichment analysis.

RESULTS

In the discovery stage, compared with the noise exposures with normal hearing, 73 miRNAs demonstrated at least a 1.5-fold differential expression in the NIHL patients. In the preliminary validation, compared with the noise exposures, the plasma levels of miR-16-5p, miR-24-3p, miR-185-5p and miR-451a were all upregulated (P < 0.001) in the NIHL patients. In the expanded validation stage, compared with the non-exposures, the plasma levels of miR-24, miR-185-5p and miR-451a were all significantly downregulated (P < 0.001) in the exposures. And compared with the noise exposures, the plasma levels of miR-185-5p and miR-451a were slightly elevated (P < 0.001) in the NIHL patients, which were consistent with the results of preliminary validation and microarray analysis.

CONCLUSION

The two indicated plasma miRNAs may be biomarkers of indicating responses to noise exposure. However, further studies are necessary to prove the causal association between miRNAs changes and noise exposure, and to determine whether these two miRNAs are clear biomarkers to noise exposure.

Prevalence of hearing problems and associated factors in an agricultural company in southern Brazil

OBJECTIVE

To describe the prevalence and to analyze the factors associated with hearing problems in an agricultural company.

METHODS

This was a cross-sectional study, and the participants consisted entirely of employees of an agricultural company in southern Brazil. The workforce of the company was composed of several different occupations. The research instrument was a semi-structured questionnaire administered by interview.

RESULTS

Of the 326 workers of the company, there were 273 (83.8%) respondents, and the prevalence of hearing problems was n = 42 (15.4%) among the participants of the study. The hearing problems were associated with lower schooling, with the operating occupational group, the technical assistance group and the general services group. The self-reported health conditions associated with hearing problems were depression and nervousness or irritation. The occupational exposures associated with hearing problems were noise, dust, vibration, oils and solvents, and toxic gases.

CONCLUSION

There was an intermediate prevalence of hearing problems in relation to other studies. It was possible to observe the need to implement strategies aiming at the prevention of hearing problems that primarily contemplate modifiable aspects, such as the use of personal protective equipment, as well as improvements in the conditions, organization and work environment.

Does tinnitus, hearing asymmetry, or hearing loss predispose to occupational injury risk?

OBJECTIVE

To determine the relative contributions of tinnitus, asymmetrical hearing loss, low frequency hearing loss (pure tone average of 0.5, 1, 2, 3 kHz; PTA.5123), or high frequency hearing loss (pure tone average of 4, 6 kHz; PTA46), to acute injury risk among a cohort of production and maintenance workers at six aluminum manufacturing plants, adjusting for ambient noise exposure and other recognized predictors of injury risk.

DESIGN

Retrospective analysis.

STUDY SAMPLE

The study considered 9920 workers employed during 2003 to 2008. The cohort consisted of 8818 workers (89%) whose complete records were available.

RESULTS

Adjusting for noise exposure and other recognized injury predictors, a 25% increased acute injury risk was observed among workers with a history of tinnitus in conjunction with high-frequency hearing loss (PTA46). Low frequency hearing loss may be associated with minor, yet less serious, injury risk. We did not find evidence that asymmetry contributes to injury risk.

CONCLUSION

These results provide evidence that tinnitus, combined with high-frequency hearing loss, may pose an important safety threat to workers, especially those who work in high-noise exposed environments. These at risk workers may require careful examination of their communication and hearing protection needs.

Acoustic Noise Levels of Dental Equipments and Its Association with Fear and Annoyance Levels among Patients Attending Different Dental Clinic Setups in Jaipur, India

BACKGROUND

Noise is a source of pervasive occupational hazard for practicing dentists and the patients. The sources of dental sounds by various dental equipments can pose as a potential hazard to hearing system and add to the annoyance levels of the patients. The aim of the study was to analyze the noise levels from various equipments and evaluate the effect of acoustic noise stimulus on dental fear and annoyance levels among patients attending different dental clinic setups in Jaipur, India.

METHODOLOGY

The sampling frame comprised of 180 patients, which included 90 patients attending 10 different private clinics and 90 patients attending a Dental College in Jaipur. The levels of Acoustic Noise Stimulus originating from different equipments were determined using a precision sound level meter/decibulometer. Dental fear among patients was measured using Dental Fear Scale (DFS).

RESULTS

Statistical analysis was performed using chi square test and unpaired t-test. The mean background noise levels were found to be maximum in the pre-clinical setup/ laboratory areas (69.23+2.20). Females and the patients attending dental college setup encountered more fear on seeing the drill as compared to the patients attending private clinics (p<0.001).

CONCLUSION

The sources of dental sounds can pose as a potential hazard to hearing system. It was analyzed that the environment in the clinics can directly have an effect on the fear and annoyance levels of patients. Hence it is necessary control the noise from various dental equipments to reduce the fear of patients from visiting a dental clinic.

Interventions to prevent occupational noise-induced hearing loss: a Cochrane systematic review

OBJECTIVE

To assess the effectiveness of interventions for preventing occupational noise exposure or hearing loss compared to no intervention or alternative interventions.

DESIGN

We searched biomedical databases up to 25 January 2012 for randomized controlled trials (RCT), controlled before-after studies and interrupted time-series of hearing loss prevention among workers exposed to noise.

STUDY SAMPLE

We included 19 studies with 82 794 participants evaluating effects of hearing loss prevention programs (HLPP). The overall quality of studies was low to very low, as rated using the GRADE approach.

RESULTS

One study of stricter legislation showed a favorable effect on noise levels. Three studies, of which two RCTs, did not find an effect of a HLPP. Four studies showed that better use of hearing protection devices in HLPPs decreased the risk of hearing loss. In four other studies, workers in a HLPP still had a 0.5 dB greater hearing loss at 4 kHz (95% CI - 0.5 to 1.7) than non-exposed workers. In two similar studies there was a substantial risk of hearing loss in spite of a HLPP.

CONCLUSIONS

Stricter enforcement of legislation and better implementation of HLPPs can reduce noise levels in workplaces. Better evaluations of technical interventions and long-term effects are needed.

Noise exposure and hearing impairment among Chinese restaurant workers and entertainment employees in Hong Kong

Background

Noise-induced hearing loss (NIHL) is a major concern in the non-manufacturing industries. This study aimed to investigate the occupational noise exposure and the NIHL among Chinese restaurant workers and entertainment employees working in the service industry in Hong Kong.

Methods

This cross-sectional survey involved a total of 1,670 participants. Among them, 937 were randomly selected from the workers of Chinese restaurants and 733 were selected from workers in three entertainment sectors: radio and television stations; cultural performance halls or auditoria of the Leisure and Cultural Services Department (LCSD); and karaoke bars. Noise exposure levels were measured in the sampled restaurants and entertainment sectors. Each participant received an audiometric screening test. Those who were found to have abnormalities were required to take another diagnostic test in the health center. The “Klockhoff digit” method was used to classify NIHL in the present study.

Results

The main source of noise inside restaurants was the stoves. The mean hearing thresholds showed a typical dip at 3 to 6 KHz and a substantial proportion (23.7%) of the workers fulfilled the criteria for presumptive NIHL. For entertainment sectors, employees in radio and television stations generally had higher exposure levels than those in the halls or auditoria of the LCSD and karaoke bars. The mean hearing thresholds showed a typical dip at 6 KHz and a substantial proportion of the employees fulfilled the criteria for presumptive NIHL (38.6%, 95%CI: 35.1–42.1%). Being male, older, and having longer service and daily alcohol consumption were associated with noise-induced hearing impairment both in restaurant workers and entertainment employees.

Conclusion

Excessive noise exposure is common in the Chinese restaurant and entertainment industries and a substantial proportion of restaurant workers and entertainment employees suffer from NIHL. Comprehensive hearing conservation programs should be introduced to the service industry in Hong Kong.

Relative risk of elevated hearing threshold compared to ISO1999 normative populations for Royal Australian Air Force male personnel

OBJECTIVE

This paper introduces a new method to calculate relative risks of elevated hearing thresholds, at various ages and frequencies, between a study population and ISO1999:2003: Annex A Screened, Annex B Unscreened and ISO1999 Section 5.3 adjustment for noise exposure using Annex A Screened data. We demonstrate this method on a study population of male Royal Australian Air Force personnel.

STUDY DESIGN

Using a retrospective cohort design, hearing thresholds were assessed in 583 F-111 aircraft maintenance personnel, 377 technical-trade comparisons and 492 non-technical comparisons using pure-tone audiometry. A quantile regression model was used determine whether an association exists between median hearing thresholds and F-111 maintenance, adjusting for possible confounders. The new method involves using quantile regression models with bootstrapped standard errors to estimate percentiles for the study population and thus determine the probability of a greater than 25 dB hearing threshold. This was done for the three ISO datasets as follows; for the ISO1999 Annex A screened population data the formula provided allows the calculation of these probabilities. ISO1999 Annex B unscreened population data only provides the values for the 10th, 50th and 90th percentiles at ages 30, 40, 50 and 60 only, therefore it was necessary to fit a curve to these values in order to estimate the probabilities. For ISO1999 Section 5.3 adjustment for noise exposure population we used the Annex A screened population data plus the formula. The probabilities were then divided to give the relative risks of a greater than 25 dB hearing threshold, at various ages and frequencies.

RESULTS

While no difference was observed between the three groups, the model identified a number of significant confounders, namely tinnitus, smoking, diabetes and the use of anti-depressant medications. Relative risks were high at frequencies 2 kHz and less for the study population of all ages compared to ISO A screened data. The increased relative risks at 4 and 6 kHz give the appearance of a "noise notch" for ages 30 and 40 years. The comparison with the ISO B unscreened data are significantly less than one for frequencies above 2 kHz, particularly for young men and greater than one less than 2 kHz. The relative risks for the comparison to the ISO A screened data with ISO 5.3 adjustments, are highest for young men decreasing with age, with the highest relative risk are at frequencies less than 2 kHz.

CONCLUSIONS

This paper demonstrates a new method for quantifying the probability of a clinically relevant hearing loss and the relative risk of the loss due to a risk factor. Prior to this, researchers were reduced to simplistic methods such as visual comparison of deciles which did not enable the estimation of risk. The new method can use all observed hearing thresholds per study participant, adjust for known confounding factors such age and gender, and calculate the relative risk of a clinically relevant increase in hearing threshold due to a risk factor of interest.

Noise frequency components and the prevalence of hypertension in workers

Epidemiological studies have demonstrated a relationship between noise exposure and hypertension, but the association between hypertension and noise frequency components remains unclear. This cross-sectional study investigated the association between noise exposure at different frequencies and the prevalence of hypertension in 188 screw-manufacturing workers. Participants were divided into one high-noise-exposure group (≥80 A-weighted decibel, [dBA]; n=68) and two reference groups, including 68 low-noise-exposure workers (75.8±3.2 dBA) and 52 office workers (61.5±0.5dBA). Personal noise exposure and environmental octave-band analyses were performed at work. Multiple logistic regression models were used to estimate odds ratios (ORs) for hypertension between different noise-exposure categories after adjustment for potential confounders. Male workers exposed to noise levels at high frequencies of 2000, 4000 or 8000Hz had a higher but non-significant risk of hypertension. Those exposed to ≥80dBA for 2-4years, 4-6years and more than 6years had a 4.43-fold (95% CI=1.21-16.15), 1.21-fold (95% CI=0.35-4.21) and 0.95-fold (95% CI=0.16-5.60) risk of hypertension, respectively, compared with reference workers. A significant association was only observed in male workers exposed to ≥70dBA at 4000Hz for 2-4years (adjusted OR=4.22; 95% CI=1.15-15.49) and was not found at other frequencies for any periods. These findings suggest that occupational noise exposure above 80dBA for specific periods may be associated with hypertension, and noise frequency at 4000Hz may have the greatest effect on hypertension.

Hearing effects from intermittent and continuous noise exposure in a study of Korean factory workers and firefighters

Background

South Korea and surrounding countries in East Asia are believed to have the highest proportion in the world of high frequency hearing loss due to occupational noise exposure, yet there has been limited information published in international journals, and limited information for control of noise in local workplaces beyond strategies from western countries. We exploit medical surveillance information from two worker groups to enhance local knowledge about noise-induced hearing loss and explore the possible importance of shift work to risk.

Methods

Four-years of hearing data were evaluated for 81 male farm machine factory workers and 371 male firefighters who had successfully completed a health examination and questionnaires for the duration of the study period. The averages of hearing thresholds at 2, 3, and 4 kHz were used as the primary end-point for comparison. Repeat measure analysis adjusted for age, exposure duration and smoking status was used to measure the difference in hearing threshold between the two groups.

Results

Noise levels were measured in the factory at a mean of 82 dBA, with a range of 66-97. No concurrent measurements were taken for the firefighters, but historic comparison values showed a wider range but a similar mean of 76-79 dBA. Although losses during follow-up were negligible, the factory workers had significantly (P < 0.0001) more hearing loss at the baseline of the study than the firefighters in both ears at 2, 3, and 4 kHz, adjusted for age, duration of employment and smoking status. Among those with 10 years of employment, mean losses at these frequencies among the factory workers fell into the impairment range (> 25 dB loss). Firefighters also showed increased losses associated with longer exposure duration, but these were significantly less marked. Losses at lower frequencies (< or = 1 kHz) were negligible in both groups.

Conclusions

Korean work environments with continuous noise exposure in the measured range should consider implementation of a hearing conservation program. Further evaluation of hearing loss in workers exposed to irregular or intermittent high noise levels, such as firefighters, is also warranted.

High-frequency hearing loss, occupational noise exposure and hypertension: a cross-sectional study in male workers

BACKGROUND

The association between occupational noise exposure and hypertension is inconsistent because of an exposure bias caused by outer-ear measurements of noise levels among workers. This study used hearing loss values (HLVs) measured at 4 kHz and 6 kHz in both ears as a biomarker to investigate the chronic effects of noise exposure on hypertension in 790 aircraft-manufacturing workers.

METHODS

Participants were divided into a high hearing loss (HL) group (n = 214; average HLVs ≥ 30 decibel [dB] at 4 kHz or 6 kHz bilaterally; 83.1 ± 4.9 A-weighted decibel [dBA]), a median HL group (n = 302; 15 ≤ average HLVs < 30 dB at 4 kHz or 6 kHz bilaterally; 83.1 ± 4.4 dBA) and a low HL group (n = 274; average HLVs < 15 dB at 4 kHz or 6 kHz bilaterally; 82.2 ± 5.1 dBA) based on the results of pure tone audiometry. Multivariate logistic regressions were used to estimate the risk of hypertension between groups.

RESULTS

The prevalence rates of hypertension were significantly higher in the high HL (43.5%; p = 0.021) and median HL (42.1%; p = 0.029) groups than in the low HL group (33.2%). The high HL and median HL workers had 1.48-fold (95% confidence interval [95%CI] = 1.02-2.15; p = 0.040) and 1.46-fold (95%CI = 1.03-2.05; p = 0.031) higher risks of hypertension relative to the low HL workers. Employment duration was significantly and positively correlated with the risk of hypertension among workers with average HLVs ≥ 15 dB at 4 kHz (p < 0.001) and 6 kHz (p < 0.001) bilaterally.

CONCLUSIONS

Our findings suggest that high-frequency hearing loss is a good biomarker of occupational noise exposure and that noise-induced hearing loss may be associated with the risk of hypertension.

Cortical tonotopic map plasticity and behavior

Central topographic representations of sensory epithelia have a genetic basis, but are refined by patterns of afferent input and by behavioral demands. Here we review such experience-driven map development and plasticity, focusing on the auditory system, and giving particular consideration to its adaptive value and to the putative mechanisms involved. Recent data have challenged the widely held notion that only the developing auditory brain can be influenced by changes to the prevailing acoustic environment, unless those changes convey information of behavioral relevance. Specifically, it has been shown that persistent exposure of adult animals to random, bandlimited, moderately loud sounds can lead to a reorganization of auditory cortex not unlike that following restricted hearing loss. The mature auditory brain is thus more plastic than previously supposed, with potentially troubling consequences for those working or living in noisy environments, even at exposure levels considerably below those presently considered just-acceptable.

A retrospective analysis of noise-induced hearing loss in the Dutch construction industry

Purpose

Noise exposure is an important and highly prevalent occupational hazard in the construction industry. This study examines hearing threshold levels of a large population of Dutch construction workers and compares their hearing thresholds to those predicted by ISO-1999.

Methods

In this retrospective study, medical records of periodic occupational health examinations of 29,644 construction workers are analysed. Pure-tone audiometric thresholds of noise-exposed workers are compared to a non-exposed control group and to ISO-1999 predictions. Regression analyses are conducted to explore the relationship between hearing loss and noise intensity, noise exposure time and the use of hearing protection.

Results

Noise-exposed workers had greater hearing losses compared to their non-noise-exposed colleagues and to the reference population reported in ISO-1999. Noise exposure explained only a small proportion of hearing loss. When the daily noise exposure level rose from 80 dB(A) towards 96 dB(A), only a minor increase in hearing loss is shown. The relation of exposure time and hearing loss found was similar to ISO-1999 predictions when looking at durations of 10 years or more. For the first decade, the population medians show poorer hearing than predicted by ISO-1999.

Discussion

Duration of noise exposure was a better predictor than noise exposure levels, probably because of the limitations in noise exposure estimations. In this population, noise-induced hearing loss was already present at the beginning of employment and increased at the same rate as is predicted for longer exposure durations.

Hearing impairment in F-111 maintenance workers: the study of health outcomes in aircraft maintenance personnel (SHOAMP) general health and medical study

BACKGROUND

We sought to examine hearing loss in a group from the Royal Australian Air Force who undertook fuel tank maintenance on F-111 aircraft, with exposure to formulations containing ototoxins, relative to two different comparison groups.

METHODS

Using pure-tone audiometry, hearing thresholds were assessed in 614 exposed personnel, 513 technical-trade comparisons (different base, same job), and 403 non-technical comparisons (same base, different job). We calculated percentage loss of hearing (PLH) and used regression models to examine whether there was an association between PLH and F-111 fuel tank maintenance, adjusting for possible confounders. In addition, the difference between the observed hearing thresholds and the expected thresholds based on an otologically normal population (ISO-7029-2003) was determined.

RESULTS

The PLH ranged from nil to 96 (median 1.5, quartiles 0.3, 5.5). A logistic regression model showed no statistically significant difference in PLH among the three exposure groups (exposed vs. non-technical controls 1.1: 95% CI 0.7, 2.0 and exposed vs. technical OR 0.9: 95% CI 0.6, 1.3). The model also highlighted a number of other risk factors for PLH including age, tinnitus, smoking, depression, and use of depression medications. However, at all eight frequencies measured, all populations had lower than expected hearing thresholds based on published ISO-7029 medians.

CONCLUSIONS

Although there was no difference in PLH between the three exposure groups, the study did reveal a high degree of hearing loss between the 3 groups and a normal population.

Hearing problems among a cohort of nationally certified EMS professionals

PURPOSE

The objectives of this study were to estimate the prevalence of hearing problems among a national cohort of emergency medical service (EMS) professionals, determine factors associated with hearing problems, and estimate the percentage of EMS professionals who utilize hearing protection.

METHODS

Utilizing results from a questionnaire, individuals who reported hearing problems were compared to individuals who had not. Multivariable logistic regression was performed to identify variables associated with hearing problems. Finally, items regarding use of hearing protection were assessed to estimate the percentage of usage among EMS professionals.

RESULTS

In total, 1,058 (57%) participants responded to the questionnaire. Of those, 1,024 (97%) who completed the hearing problems question were utilized for analysis. There were 153 (14.9%) cases of self-reported hearing problems. The final logistic regression model included lifetime occupational noise exposure 0.99 (95% CI = 0.9997-1.0002), report of previous back problems (odds ratio (OR) = 2.74, 95% CI = 1.8340-4.1042), large community size (OR = 1.67, 95% CI = 1.1211-2.4843), and minority status (OR = 0.61, 95% CI = 0.3719-0.9867). Finally, 213 (20.8%) individuals reported utilizing some form of hearing protection at their main EMS job.

CONCLUSION

The results from this analysis are the first national estimates of the prevalence of self reported hearing problems among EMS professionals. This study was also the first to estimate the percentage of EMS professionals who self reported the utilization of hearing protection.

Occupational performance: Comparing normally-hearing and hearing-impaired employees using the Amsterdam Checklist for Hearing and Work

This study compares the occupational performance of employees with and without hearing impairment, and aims to identify occupational difficulties specifically related to hearing loss. The Amsterdam Checklist for Hearing and Work was administered to 150 hearing-impaired employees and 60 normally-hearing colleagues. A multivariate analysis of variance was performed to test group effects, and to examine differences between means. Factors predicting sick-leave were identified by regression analyses. A significant group effect (p < 0.01) was found. Hearing-impaired employees differed from normally-hearing colleagues in their perception of 'environmental noise', 'job control' and the 'necessity to use hearing activities' at work. Also, sick-leave due to distress occurred significantly more often in the hearing impaired group (p < 0.05). 'Hearing impairment', 'job demand', and the requirement to 'recognize/distinguish between sounds' were the strongest risk-factors for stress related sick-leave. The importance of hearing functions besides speech communication is discussed. Implications for rehabilitation are suggested. In future research, hearing loss should be considered as a risk factor for fatigue and mental distress which may lead to sick-leave.