Is occupational noise associated with arthritis? Cross-sectional evidence from US population

BACKGROUND

The impact of occupational noise exposure on various diseases, including ear and cardiovascular diseases, has been studied extensively. Nevertheless, the connection between osteoarthritis (OA) and rheumatoid arthritis (RA) and occupational noise exposure remains largely unexplored in real-world scenarios. This study assessed the association between occupational noise exposure and the prevalence of two types of arthritis.

METHODS

This study used database data from 2005 to 2012 and 2015-March 2020 from the prepandemic National Health and Nutrition Examination Survey (NHANES) related to occupational noise exposure and arthritis. Multivariate logistic regression analysis was used to estimate the association between occupational noise exposure and RA/OA, adjusting for age, gender, race, education level, marital status, the ratio of family income to poverty, trouble sleeping, smoking status, alcohol consumption, diabetes, hypertension, body mass index (BMI), metabolic equivalents (METs), and thyroid disease.

RESULTS

This study included 11,053 participants. Multivariate logistic regression analysis demonstrated that previous exposure to occupational noise was positively associated with self-reported RA (OR = 1.43, 95% CI = 1.18-1.73) and OA (OR = 1.25, 95% CI = 1.07-1.46). Compared to individuals without a history of occupational noise exposure, those with an exposure duration of 1 year or greater exhibited higher odds of prevalent RA, though there was no apparent exposure response relationship for noise exposure durations longer than 1 year. The results of our subgroup analyses showed a significant interaction between age and occupational noise exposure on the odds of self-reported prevalent OA.

CONCLUSIONS

Our findings suggest an association between occupational noise exposure and the prevalence of RA and OA. Nevertheless, further clinical and basic research is warranted to better explore their associations.

A history of occupational noise exposure is associated with steep-slope audiograms and poorer self-reported hearing-aid outcomes

OBJECTIVE

To investigate the effects of previous occupational noise exposure in older adults with hearing loss on (1) audiometric configuration and acoustic reflex (AR) thresholds and (2) self-reported hearing abilities and hearing aid (HA) effectiveness.

DESIGN

A prospective observational study.

STUDY SAMPLE

The study included 1176 adults (≥60 years) with bilateral sensorineural hearing loss. Pure-tone audiometry, AR thresholds, and responses to the abbreviated version of the Speech, Spatial, and Qualities of Hearing Scale (SSQ12) and the International Outcome Inventory for Hearing Aids (IOI-HA) questionnaire were obtained, along with information about previous occupational noise exposure.

RESULTS

Greater occupational noise exposure was associated with a higher prevalence of steeply sloping audiograms in men and women and a 0.32 (95% CI: -0.57; -0.06) scale points lower mean SSQ12 total score among noise-exposed men. AR thresholds did not show a significant relation to noise-exposure status, but hearing thresholds at a given frequency were related to elevated AR thresholds at the same frequency.

CONCLUSIONS

A noise exposure history is linked to steeper audiograms in older adults with hearing loss as well as to poorer self-reported hearing abilities in noise-exposed men. More attention to older adults with previous noise exposure is warranted in hearing rehabilitation.

The rate of occupational noise-induced hearing loss among male workers in Israel and implication on hearing surveillance frequency

OBJECTIVES

To investigate the annual rate of NIHL in Israel, a modern economy with relatively low industrial hazardous noise exposure. To review international protocols of hearing surveillance. To recommend an effective, efficient, hearing screening frequency protocol.

METHODS

A historical cohort study was conducted. Audiometric surveillance data from the Jerusalem occupational medicine registry of male employees in various industries from 2006 to 2017 were used. Mean individual annual threshold shifts simulating 1-8 checkup interval years were calculated. Joinpoint regression analysis was used to assess the interval in which the slope of the calculated ATS variability moderates significantly.

RESULTS

A total of 263 noise-exposed workers and 93 workers in the comparison group produced 1913 audiograms for analysis. Among the noise-exposed workers, using the 1-4 kHz average, threshold shifts stabilized from 3 years onwards at around 1 dB per year in all age groups and 0.83 dB in the stratum younger than 50 years. No enhanced decline was detected in the first years of exposure.

CONCLUSION

Although most countries conduct annual hearing surveillance, hearing threshold shifts of noise-exposed workers become more accurate and show less variability when calculated at 3-year checkup intervals onwards than shorter intervals. Since margins of errors of the test method are much larger than the annual shift found, screening schedule that enables each subsequent test to identify a real deterioration in hearing is necessary. Triennial audiometric screening would be a better surveillance frequency for noise-exposed workers younger than 50 years of age in the category of 85-95 dBL_Aeq,8 h without other known risk factors.

Association between Simultaneous Occurrence of Occupational Noise-Induced Hearing Loss and Noise-Induced Vestibular Dysfunction: A Systematic Review

Background

Background: Because of functional and structural similarities between the cochlea and vestibular sensory receptors, vestibular dysfunction could be accompanied by noise-induced hearing loss (NIHL) due to occupational noise exposure. We aimed to evaluate the occurrence of vestibular dysfunction (VD) in individuals with NIHL and occupational noise exposure.

Methods

A systematic literature research was carried out within the databases of PubMed, Scopus, Science Direct, and Web of Science for published articles between 1980 and Jan 5, 2023 using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The methodological quality of the included systematic reviews was assessed with the Joanna Briggs Institute (JBI) checklist. Vestibular system dysfunction parameters were considered as primary outcomes in subjects with NIHL.

Results

We reviewed the evidence (from 19 eligible articles) for VD from noise-induced damage to peripheral vestibular structures. VD can occur after occupational noise exposure or concomitantly with NIHL. Furthermore, this study showed that the saccular organ has a higher susceptibility to noise damage than the vestibular organs of the utricle and semicircular canals (SCCs).

Conclusion

Our results support the role of occupational noise exposure and NIHL as risk factors for developing VD. Further research is needed to investigate the association between the occurrence of VD due to occupational noise exposure or concomitantly with NIHL.

Speech ABR Findings in Auto Rickshaw Drivers Exposed to Occupational Noise

Most of the persons with noise exposure will have clinically normal hearing threshold while experiencing reduced speech comprehension. The motive of this study is to assess the impact of occupational noise on the encoding of speech stimuli in the auditory system in the auto-rickshaw drivers and compare the auditory brainstem responses (ABR) using speech stimuli with that of controls. The study was done in experimental design, where speech evoked ABR was measured in 21 auto-drivers who were continuously exposed to higher levels of occupational noise, and they were compared to the results of 37 individuals who were not exposed to noise. Speech ABR was administered in both the groups and the absolute latencies and amplitudes of the peaks V, A, C, D, E, F and O were compared. The results revealed that there is a statistically significant difference (p < 0.05) in the latency of peak V (F(1,32) = 6.13, p < 0.05, η p 2  = 0.12) and peak A (F(1,32) = 4.03, p < 0.05, η p 2  = 0.08) between the control and experimental group. Similarly, there was a statistically significant difference seen in the amplitude of peak D (F(1,32) = 6.38, p < 0.05, η p 2  = 0.12) and peak F (F(1,32) = 7.97, p < 0.05, η p 2  = 0.15). Acknowledging how the speech signals are coded in the brainstem may aid in the timely detection and intervention of hearing-related issues, even in individuals having normal hearing acuity. The results indicate that there is damage at the level of the brainstem which will lead to poor speech understanding in those who are exposed to occupational noise. These indicators are present even before routine audiometry indicates a hearing loss.

A comprehensive finite-element human ear model to estimate noise-induced hearing loss associated with occupational noise exposure

BACKGROUND AND OBJECTIVE

Noise is a common occupational and environmental hazard; however, little is known about the use of computational tools to quantitively analyze data on basilar membrane (BM) damage in noise-induced hearing loss (NIHL). Here, we established a comprehensive three-dimensional finite-element human ear model to quantify the impact of noise exposure on BM and perilymph fluid.

METHODS

We used auditory risk units (ARUs) to evaluate the BM damage for subjects (3 men and 5 women; mean age, 32.75 ± 8.86 years; age range, 24-44 years). A 90-dB sound pressure level (SPL) was normally applied at the external auditory canal (EAC) entrance to simulate sound transmission from the EAC to the cochlea at frequencies of 0.2-10.0 kHz.

RESULTS

The pressure distribution of perilymph fluid is totally different on frequency responses under low and high sound-evoked (0.013-10.0 kHz). The highest ARUs were 18.479% at the distance of 1 mm from the base, and the second-highest to fourth-highest ARUs occurred at distances of 5-7 mm from the base, where their ARUs were 9.749%, 9.176%, and 11.231%. The total of the ARUs reached 81.956% at external frequencies' sounds of 3.2-5.0 kHz. Among these, the 3.8-kHz and 3.6-kHz frequencies yielded the highest and second-highest ARUs of 20.325% and 19.873%, respectively.

CONCLUSIONS

This study would inform our understanding of NIHL associated with occupational noise exposure. We present a FE modelling and describe how it might provide a unique way to unravel mechanisms that drive NIHL due to loud noises.

Noise exposure and mental workload: Evaluating the role of multiple noise exposure metrics among surface miners in the US Midwest

This study examined associations between metrics of noise exposure and mental workload. In this cross-sectional study, five occupational noise metrics computed from full-shift dosimetry were evaluated among surface mine workers in the US Midwest. Mental workload was evaluated using a modified, raw NASA-TLX and clustered with a k-means clustering algorithm. Mixed effects logistic regression and Bayesian Kernel Machine Regression (BKMR) was utilized for analysis. Average noise exposure, the difference between peak and mean noise exposure, and the number of peaks >135 dB were each strongly associated with mental workload, while the kurtosis and standard deviation of noise throughout a shift were not. An exposure-response relationship between average noise exposure and mental workload may exist, with elevated risk of high mental workload beginning at 80 dBA. These results suggest that high noise exposure may be an independent risk factor of high mental workload, and impulse events and the difference between the peak and mean noise exposure may have interactive effects with average noise exposure.

[Investigation of occupational noise exposure and hearing loss among automobile manufacturing workers]

Objective: To investigation the situation of occupational noise exposure and hearing loss among workers in automobile manufacturing enterprise during 2017-2019 in Wuhan. Methods: Workers in automobile manufacturing who underwent physical examination in Wuhan Hospital for the Prevention and Treatment of Occupational Diseases from 2017 to 2019 were included as subjects in the cross-sectional survey. Questionnaire survey, noise detection and pure tone threshold test were used. Excluding individuals with working time less than 3 years and information deficiency, 3 948 individuals were finally included in the study. Results: Among 3 948 workers, 128 workers had hearing loss and the rate of hearing loss was 3.24%, among which 101 workers had high-frequency hearing loss and 27 workers were diagnosed as occupational noise deafness. The prevalence of hearing loss among workers previously exposed to noise was significantly higher than that without prior exposure (12.10%, 0.96%, P<0.05) . The prevalence of hearing loss among workers with occupational noise exposure <80 dB (A) , 80~<85 dB (A) and ≥85 dB (A) was 1.83%, 2.69% and 5.09%, respectively. The prevalence of high frequency hearing loss was 1.60%, 2.05% and 3.71%, respectively. The prevalence of occupational noise deafness was 0.23%, 0.64% and 1.38%, respectively. The prevalence of hearing loss and high frequency hearing loss among workers exposed to different occupational noise was statistically significant (P<0.05) , while the prevalence of occupational noise deafness was not statistically significant (P>0.05) . There were statistically significant differences in the prevalence of hearing loss (2.88%, 4.45%) and occupational noise deafness (0.46%, 1.41%) between those who used protective equipment and those who did not (P<0.05) . Compared with workers exposed to occupational noise <80 dB (A) , workers exposed to occupational noise ≥85 dB (A) had A 3.16-fold increased risk of hearing loss (OR=3.16, 95%CI: 1.44~6.95, P<0.05) . Compared to workers using hearing protective equipment, the risk of hearing loss (OR=1.96, 95%CI: 1.25~3.06, P<0.05) and occupational noise deafness (OR=3.46, 95%CI: 1.51-7.96, P<0.05) significantly increased among those without using hearing protective equipment. Conclusion: The risk of hearing loss in automobile manufacturing workers is significantly associated with occupational noise exposure and the use of hearing protective equipment. Good hearing protection may reduce the risk of occupational noise-induced hearing loss and occupational noise deafness.

Occupational noise exposure and the prevalence of dyslipidemia in a cross-sectional study

BACKGROUND

Occupational noise exposure was related to cardiovascular disease, of which dyslipidemia was an important inducement. This study investigated the relationship between occupational noise exposure and dyslipidemia.

METHODS

Four hundred ninety-two occupational noise-exposed workers and 664 non-exposed workers were recruited to conduct environmental noise tests and personal occupational physical examinations. A lasso-logistic regression model was used to estimate the relative risk of dyslipidemia. A restricted cubic spline was used to estimate the association between noise exposure years and dyslipidemia after adjusting for potential confounding factors.

RESULTS

A crude association was observed between the occupational noise exposure (75-85 dB(A)) and dyslipidemia. After adjusting for confounding factors, there was a non-linear relationship between noise exposure years and dyslipidemia (P for non-linearity =0.01). Workers exposed to 75-85 dB(A) for 11 to 24.5 years had a higher risk of dyslipidemia than non-exposed workers.

CONCLUSIONS

A positive and non-linear exposure-response relationship was found in workers exposed to 75-85 dB(A) whose exposure years were between 11 and 24.5. Workers had the highest risk of dyslipidemia when exposed for 13.5 years.

Sex differences in noise-induced hearing loss: a cross-sectional study in China

BACKGROUND

Significant sex differences exist in hearing physiology, while few human studies have investigated sex differences in noise-induced hearing loss (NIHL), and the sex bias in previous studies resulted in inadequate female data. The study aims to investigate sex differences in the characteristics of NIHL to provide insight into sex-specific risk factors, prevention strategies and treatment for NIHL.

METHODS

This cross-sectional study included 2280 industrial noise-exposed shipyard workers (1140 males and 1140 females matched for age, job and employment length) in China. Individual noise exposure levels were measured to calculate the cumulative noise exposure (CNE), and an audiometric test was performed by an experienced technician in a soundproof booth. Sex differences in and influencing factors of low-frequency (LFHL) and high-frequency hearing loss (HFHL) were analyzed using logistic regression models stratified by age and CNE.

RESULTS

At comparable noise exposure levels and ages, the prevalence of HFHL was significantly higher in males (34.4%) than in females (13.8%), and males had a higher prevalence of HFHL (OR = 4.19, 95% CI 3.18 to 5.52) after adjusting for age, CNE, and other covariates. Sex differences were constant and highly remarkable among subjects aged 30 to 40 years and those with a CNE of 80 to 95 dB(A). Alcohol consumption might be a risk factor for HFHL in females (OR = 3.12, 95% CI 1.10 to 8.89).

CONCLUSIONS

This study indicates significant sex differences in NIHL. Males are at higher risk of HFHL than females despite equivalent noise exposure and age. The risk factors for NIHL might be different in males and females.

A Comparative Study of the Methods to Assess Occupational Noise Exposures of Fish Harvesters

Background

Noise-induced hearing loss is a well-known occupational disease that affects many fish harvesters from many fisheries worldwide, whose risk factor is prolonged exposure to hazardous noise levels. To date, academic research activities and regulatory bodies have not provided any comparative analysis among the existing methods to assess noise exposure levels of fish harvesters. This paper provides a comparison of four relevant assessment methods of noise exposure, examining the results of a measurement campaign performed onboard small fishing vessels from Newfoundland and Labrador.

Methods

We traveled onboard 11 vessels engaged in multiple fisheries from Newfoundland and Labrador and performed extensive noise exposure surveys using the simplified International Maritime Organization method, the full-day measurement method, and the two methods provided by ISO 9612:2009, the task-based method and job-based method (JBM).

Results

The results showed that the four methods yield similar values when the noise components are dominated by the engine and auxiliaries (steady-state sources); when noise components are dominated by the fishing gear, task-based method and the simplified International Maritime Organization method estimates are less accurate than JBM, using full-day measurements as baseline.

Conclusion

The JBM better assesses noise exposure in small-scale fisheries, where noise exposure has significant variance and uncertainties on the exposure levels are higher.

Occupational noise and age: A longitudinal study of hearing sensitivity as a function of noise exposure and age in South African gold mine workers

Background

A relationship exists between occupational noise exposure and age, which remains poorly understood.

Objectives

The aim of this study was to establish the relationship between hearing loss and age over time.

Method

Audiological data from 2583 mine workers in South Africa were utilised. Data were received from a non-noise exposed group (NNEG) (n = 951) and a noise exposed group (NEG) (≥85 dBA) (n = 1632). Data comprised a low-frequency average (LFA512) (average of audiological thresholds for 0.5 kHz, 1 kHz and 2 kHz) and high-frequency average (HFA346) (average of audiological thresholds for 3 kHz, 4 kHz and 6 kHz). Data were compared by using mixed-effects regression analysis.

Results

Base threshold values were higher for the NEG than for the NNEG across frequencies. All year-to-year increases in mean hearing thresholds were statistically significant (p < 0.01). When correcting for age, increases in mean hearing thresholds were higher for the NEG than for the NNEG for HFA346 (3.5 dB vs. 2.9 dB decline over a 4-year period) but similar for LFA512 (0.6 dB vs. 0.7 dB decline). Uncorrected for age, increases in mean hearing thresholds were higher than when age was corrected for.

Conclusion

Age and occupational noise exposure influence hearing thresholds over time. The continued increase in hearing thresholds of the NEG above that of the NNEG can be related to ineffective noise management programmes and/or the fact that early noise exposure leads to a higher burden of hearing loss over time – even after noise exposure had stopped.

Relationship between time-varying exposure to occupational noise and incident hypertension: A prospective cohort study

BACKGROUND

Exposure to occupational noise might increase the risk of hypertension. However, limited cohort studies have investigated the relationship between time-varying exposure to occupational noise and the development of hypertension.

METHODS

We conducted a 17-year cohort study involving 2459 workers to assess the relationship between time-varying exposure to occupational noise and incident hypertension in the aerospace industry. We performed an extended Cox proportional hazard model considering occupational noise exposure as time-varying covariates. Furthermore, we employed the distributed lag nonlinear models (DLNMS) to examine the exposure-response relationship.

RESULTS

In the extended Cox proportional model, as workers were exposed to noise over 80 dBA, the hazard ratios (HRs) of hypertension significantly increased with a noise increase of 5 dBA (HR = 1.16, 95% CI: 1.04-1.29). In exposure-response associations, the HRs of hypertension steadily increased between noise levels of 82 and 106 dBA (HRs ranged from 1.04 to 1.46). After additionally adjusting for personal protection equipment (PPE), the HRs decreased dramatically between 107 and 124 dBA (HRs ranged from 1.45 to 1.00).

CONCLUSIONS

Our study refined the exposure assessment by integrating time-varying exposures to occupational noise and taking work history into consideration. Our findings suggested that workers exposed to noise levels between 82 and 106 dBA for 3-17 years may increase the risk of hypertension with a non-linear exposure-response pattern. We further provided evidence that workers wearing PPE could effectively reduce noise exposure and avoid the development of hypertension.

Will daytime occupational noise exposures induce nighttime sleep disturbance?

BACKGROUND

Nighttime environmental noise affects sleep quality. However, the effects of daytime occupational noise remain unclear.

METHODS

A quasi-experiment of 48 participants who had been employed for at least six months in two hospital cafeterias. The participants were randomly designated to be assessed on high- and low-noise workdays for 8 h or low- and high-noise workdays, separated by a washout period of 14 days. Subsequently, pure tone audiometry, autonomic nervous system (ANS) function tests, serum cortisol tests, and polysomnography were conducted.

RESULTS

For the 40 participants in the study, the 8-h time-weighted average of personal noise exposed on high- and low-noise workdays was 76.8 dBA (standard deviation, SD: 6.2) and 61.0 dBA (SD: 7.1), respectively. Participants with higher personal noise exposure during the day were found to have a lower percentage of slow wave sleep (percent change of mean value: -1.287%; 95% CI: -2.602%, -0.037%) and lower sleep efficiency (-0.267%; 95% CI: -0.525%, -0.008%). In addition, after work, personal noise exposure was revealed to be related to increased serum cortisol levels (1.698%; 95% CI: 0.887%, 2.528%), and sympathetic activity as measured by low frequency/high frequency (3.000%; 95% CI: 1.294%, 4.706%) and blood pressures by cold pressor test (systolic: 5.163%; 95% CI: 2.780%, 7.537%) (diastolic: 3.109%; 95% CI: 1.604%, 4.614%).

CONCLUSIONS

Daytime occupational noise exposure had sustained effects on nighttime sleep quality, specifically on slow wave sleep and sleep efficiency. These disturbances could be partially explained by post-shift elevated cortisol and ANS activity. The psychosocial and metabolic consequences of poorer sleep quality induced by occupational noise exposure warrant further investigation.

Feasibility of a low-cost hearing screening in rural Indiana

Background

Hearing loss remains a neglected public health issue in the rural and agricultural communities in the United States and therefore, promotion of a low-cost hearing screening may be important for these underserved populations. The major objectives of our study were to assess feasibility of a low-cost telephone-administered hearing test in rural Indiana and to identify the challenges, barriers and viable implementation strategies associated with this test. Also, we evaluated whether a focus group session could change the hearing health attitude of rural residents.

Methods

We recruited 126 adults from six rural Indiana counties who participated in study activities in the following order: 1) a pre-focus group demographic, knowledge and attitude survey, 2) a focus group for discussing the feasibility of a telephone-administered hearing screening, 3) a post focus group attitude survey and 4) hearing was screened using an audiometer and self-assessment scale. These activities generated both qualitative and quantitative data, which were subsequently analyzed.

Results

Hearing impairment was perceived as an important public health issue. Many participants expressed interests to try the low-cost National Hearing Test (NHT). However, participants recommended NHT to be facilitated by community organizations to provide access to landline phones. The focus group turned out to be an excellent awareness building activity producing significant improvement in hearing health attitudes. Comparison of self and audiometric evaluations indicated underestimation of hearing handicap in our rural study population.

Conclusions

The study results underscore the urgent need for an effective strategy to promote low-cost hearing screening in rural US communities.

Noise exposure in occupational setting associated with elevated blood pressure in China

Background

Hypertension is the primary out-auditory adverse outcome caused due to occupational noise exposure. This study investigated the associations of noise exposure in an occupational setting with blood pressure and risk of hypertension.

Methods

A total of 1,390 occupational noise-exposed workers and 1399 frequency matched non-noise-exposed subjects were recruited from a cross-sectional survey of occupational noise-exposed and the general population, respectively. Blood pressure was measured using a mercury sphygmomanometer following a standard protocol. Multiple logistic regression was used to calculate the odds ratio (OR) and 95% confidence interval (CI) of noise exposure adjusted by potential confounders.

Results

Noise-exposed subjects had significantly higher levels of systolic blood pressure(SBP) (125.1 ± 13.9 mm Hg) and diastolic blood pressure (DBP) (77.6 ± 10.7 mm Hg) than control subjects (SBP: 117.2 ± 15.7 mm Hg, DBP: 70.0 ± 10.5 mm Hg) (P < 0.001). Significant correlations were found between noise exposure and blood pressure (SBP and DBP) (P < 0.001). However, the linear regression coefficients with DBP appeared larger than those with SBP.

The prevalence of hypertension was 17.8% in subjects with noise exposure and 9.0% in control group (P < 0.001). Compared with the control group, the subjects with noise exposure had the risk of hypertension with an OR of 1.941 (95% CI = 1.471– 2.561) after adjusting for age, sex, smoking, and drinking status. Dose–response relationships were found between noise intensity, years of noise exposure, cumulative noise exposure and the risk of hypertension (all P values < 0.05). No significant difference was found between subjects wearing an earplug and those not wearing an earplug, and between steady and unsteady noise categories (P > 0.05).

Conclusions

Occupational noise exposure was associated with higher levels of SBP, DBP, and the risk of hypertension. These findings indicate that effective and feasible measures should be implemented to reduce the risk of hypertension caused by occupational noise exposure.

Noise-induced hearing loss in a longitudinal study of Norwegian railway workers

OBJECTIVE

The aim of this study was to analyse longitudinal data to assess the risk of noise-induced hearing loss (NIHL) in Norwegian railway workers.

DESIGN

Longitudinal.

SETTING

A major Norwegian railway company.

METHODS

We examined data from the first and last audiograms for the period 1991-2014, from 9640 railway workers with varying occupational noise exposure and with an average observation period of 10 years. The course of hearing acuity in seven groups of railway workers (train drivers, conductors, bus drivers, traffic controllers, train maintenance workers, track maintenance workers and others) were compared with each other and with ISO standards (ISO 1999).

RESULTS

The change in hearing threshold during the observation period was 2-3 dB in the 0.5-4 kHz range and 6-7 dB in the 3-6 kHz range adjusted for age and sex, for all occupational groups, which is slightly less than expected (8 dB) according to ISO 1999.

CONCLUSIONS

The risk of NIHL in Norwegian railway workers during the period 1991-2014 has been negligible.

The influence of hearing impairment on sleep quality among workers exposed to harmful noise

OBJECTIVE

To assess connections between sleeping quality and hearing impairment due to prolonged exposure to industrial noise.

DESIGN

Observational cross-sectional study.

SETTING

Occupational clinic of the Clalit Health Services in Israel.

PARTICIPANTS

298 male volunteers occupationally exposed to harmful noise, who had an audiometric examination performed by an occupational nurse as a part of the national workers health supervision programs.

MEASUREMENTS AND RESULTS

The participants underwent an audiometric testing, and their sleep quality was measured by a validated Mini Sleep Questionnaire (MSQ). Participants with hearing loss greater than 25 dBA in the range of 1000-4000 Hz were defined as the research group (n = 99) and were compared to those with no hearing impairment (n = 199). Sleeping disorders were age related (30% higher MSQ score among workers above 50 years, P = 0.003). Tinnitus was the highest sleep disturbing factor, with 75% higher score among those affected, P = 0.001. In multiple linear regression analysis, tinnitus was the leading sleep-disturbing factor (regression coefficient B = 8.66, P < 0.001) followed by hearing impairment (regression coefficient B = 2.42, P = 0.084), adjusted for age (or years of exposure) and coffee drinking. A part of the MSQ, related to insomnia, was further evaluated using logistic regression models. Tinnitus was again the leading sleep disturbing factor [OR = 11.91; CI95% (1.56-91.2)], followed by hearing impairment [OR = 3.051; CI95% (1.18-7.86)].

CONCLUSION

Although tinnitus was the main sleep disrupting factor, hearing impairment among workers occupationally exposed to harmful noise, independently contributed to sleep impairment, especially to insomnia, regardless of age and years of exposure.

Sensorineural hearing loss associated with occupational noise exposure: effects of age-corrections

Noise-induced permanent threshold shifts (NIPTS) were computed from retrospective audiometric analyses by subtracting aging effects on hearing sensitivity in sixty-eight patients with bilateral sensorineural hearing loss who reported significant occupational noise exposure histories. There were significant effects of age on NIPTS but no significant gender- or ear- differences in terms of NIPTS. The NIPTS at 2,000 Hz was found to be significantly greater than NIPTS at frequencies 500 Hz, 1,000 Hz, 4,000 Hz, and 8,000 Hz. Defined noise notches were seen in the audiograms of 38/136 (27%) ears with SNHL. Results support models that suggest interactive effects of aging and noise on sensorineural hearing loss in ears with occupational noise exposure.