An overview of occupational noise-induced hearing loss among workers: epidemiology, pathogenesis, and preventive measures

Global trends and burden of age-related hearing loss: 32-year study

BACKGROUND

Age-related hearing loss (ARHL) is a major cause of disability and diminished quality of life in older adults. This study uses data from the 2021 Global Burden of Disease (GBD) study to assess global ARHL.

METHODS

We evaluated ARHL prevalence, DALYs (Disability-Adjusted Life Years), ASPR (Age-Standardized Prevalence Rate), and ASDR (Age-Standardized DALYs Rate). Trend analysis was conducted using Estimated Annual Percentage Change (EAPC), with projections to 2050.

RESULT

From 1990 and 2021, global ARHL prevalence cases and DALYs increased by 109 %, reaching 1.55 billion and 44.45 million, respectively. The ASPR increased from 17,106.88 to 18,070.26, while the crude prevalence rate significantly from 13,890.66 to 19,587.14. Both ASPR and ASDR demonstrated significant age-related increases, particularly for moderate and moderately severe ARHL, with EAPC values of 1.39 and 1.49 for ASDR, respectively. Among individuals aged over 85 years, the ASPR of ARHL is expected to reach 80 %. Prevalence cases peaked in the 55-69 age group, with the highest number of cases (179.43 million) observed in the 55-59 subgroup. High-middle SDI regions and East Asia exhibited the most rapid growth. By 2050, ARHL cases are projected to reach 2.31 billion, with ASPR and ASDR expected to continue rising.

CONCLUSION

ARHL has increased globally over the past three decades, largely due to population aging. The burden is most severe in middle SDI regions, East Asia, and the 55-69 age group, primarily due to their substantial population bases. Addressing this escalating challenge requires enhanced public awareness, early screening initiatives, and targeted interventions.

Investigating the effects of construction industry noise on workers' cognitive performance and learning efficiency

Despite growing industrialization, the cognitive and psychological impacts of construction noise on workers remain inadequately addressed in empirical research. This study examines the impact of different noise types and intensities on the cognitive performance and learning efficiency of construction workers, using electroencephalogram (EEG) and behavioral data. Specifically, it analyzes the effects of complex noise and steady noise on workers' attention, mental workload, mental fatigue, and mental stress. The results indicate that complex noise significantly reduces learning efficiency, notably impairing accuracy and reaction time relative to steady noise. This adverse effect is attributed to the unpredictability and variability of complex noise, which disrupts workers' cognitive processing and heightens mental fatigue. In contrast, although steady noise does not significantly impact mental workload, it induces greater mental fatigue and mental stress than complex noise, especially at high noise levels. The findings also reveal that workers develop some level of adaptation to continuous noise, mitigating its overall impact on learning efficiency. However, elevated noise levels, regardless of type, consistently lead to significant declines in attention and increases in mental stress and mental fatigue. This research makes an original contribution by providing evidence-based insights into the interaction between noise characteristics and worker cognition, offering practical implications for targeted noise management strategies to improve learning efficiency and well-being in construction environments.

Inflection points in hearing deterioration: clinical characteristics of NIHL from steady-state noise exposure

OBJECTIVES

To explore the clinical characteristics of noise-induced hearing loss (NIHL) caused by long-term exposure to steady-state noise and find a possible inflection point time leading to hearing deterioration.

MATERIAL AND METHODS

Subjects exposed to steady-state noise were selected as the noise-exposed group and matched with a control group of individuals not exposed to noise. Both groups underwent pure-tone audiometry (PTA) and distortion product otoacoustic emissions (DPOAE), and their hearing conditions were analyzed. The time inflection point with the most significant disparities in NIHL between early and late exposure was evaluated. The noise-exposed subjects were divided into 2 groups based on cumulative exposure time: the early exposure group (group A) and the late exposure group (group B). Retrospective analyses of clinical characteristics of hearing loss were conducted.

RESULTS

The noise-exposed group exhibited significantly higher hearing thresholds and reduced otoacoustic emissions compared to the control group, with high-frequency hearing loss being the most prominent. The most significant disparity in high-frequency hearing loss in PTA was observed before and after 5 years of cumulative steady-state noise exposure. Among the 78 noise-exposed subjects, 37 were in group A (≤5 years) and 41 in group B (>5 years). In DPOAE, the most significant disparity occurred before and after 4 years of acexposure, with 33 subjects in group A (≤4 years) and 45 in group B (>4 years). Distortion product otoacoustic emissions identified the time inflection point of significant hearing deterioration 1 year earlier than PTA.

CONCLUSIONS

Hearing loss caused by long-term exposure to steady-state noise showed evident deterioration after 4-5 years. The DPOAE can illustrate the inflection point of hearing deterioration 1 year earlier than PTA. Int J Occup Med Environ Health. 2025;38(1):57-69.

Noise-induced hearing loss in farmworkers: a scoping review

Objective

Farmworkers who have prolonged exposure to loud noise are at risk for disabling hearing loss. The objectives of this scoping review are to (1) identify and summarize the evidence on noise-induced hearing loss in farmworkers, (2) describe instruments used to evaluate hearing loss outcomes, (3) describe testing approaches and limitations, and (4) provide recommendations for future studies that seek to quantify hearing loss in this population.

Methods

We performed a systematic search of three electronic databases, PubMed, CINAHL, and Scopus, to identify articles related to noise-related hearing loss in farmworkers. Our search was guided by Arksey and O'Malley's methodological framework and PRISMA-ScR guidelines.

Results

A total of 57 articles met inclusion criteria. The majority of studies were undertaken in North America (n = 32, 56%), and most were in the midwestern United States. Farmworkers tended to be white, male, and work in crop agriculture. A total of 47 studies (82%) used audiometry to measure farmworkers' hearing sensitivity, among which testing was carried out at various locations, including hospitals, clinics, farmworkers' homes, and worksites. The criteria for defining hearing loss varied across studies making it difficult to summarize results. Among 14 studies that used a cutoff point greater than 25 decibels, the prevalence of hearing loss ranged between 46 and 98%. Subjective outcomes (used in 14 studies) were typically assessed using a variety of researcher-developed questions. The prevalence of hearing difficulties in this category was as high as 87%.

Conclusion

Hearing loss is prevalent across studies and does not appear to decrease over the years. Our findings call for more research among diverse farmworker populations. Further, given the high prevalence of hearing loss in many of the studies reviewed, there is clearly a need to develop strategies to protect farmworkers from noise exposure and noise-induced hearing loss.

Noise exposure, hearing loss and cognitive impairment: a cross-sectional study based on an occupational health surveillance cohort in China

BACKGROUND

High-intensity noise is associated with noise-induced hearing loss (NIHL). There is also evidence that noise exposure is related to cognitive impairment. This research aimed to analyze the associations and potential pathways of cumulative noise exposure (CNE), hearing loss and cognitive impairment.

METHODS

A total of 560 research subjects were included in this research from May 2021 to April 2022 in western China. The demographic features, occupational features, and CNE were investigated and examined. Hearing loss was evaluated according to the National standard GB/T 7583-1987 of China. The Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were used to assess cognitive function. Structural equation modeling (SEM) was used to analyze the potential pathways and specific effect sizes of CNE, hearing loss and cognitive impairment.

RESULTS

The mean age of the research subjects was 34.3 (SD, 9.89). Men accounted for 96.4% (540/560) and women accounted for 3.6% (20/560). A total of 62.3% (349/560) held a college degree or above. The regression analysis showed that high dose CNE was related to MMSE (β = -1.069 (-1.539, -0.600)) and MoCA (β = -1.040 (-1.726, -0.355)) scores. The monaural threshold weighted value of the right ear (MTWVR) greater than 40 dB was associated with both MMSE (β = -1.183 (-2.033, -0.333)) and MoCA (β = -1.420 (-2.647, -0.193)) scores. The monaural threshold weighted value of the left ear (MTWVL) greater than 40 dB was also associated with MMSE (β = -1.540 (-2.389, -0.690)) and MoCA (β = -1.685 (-2.915, -0.456)) scores. The SEM result (Model C) showed that the standard effect of CNE- hearing loss path, CNE-MMSE path, and hearing loss-MMSE path were 0.142 (p < 0.001), -0.151 (p < 0.001), and -0.030 (p = 0.376). The Model D showed that the standard effect of CNE- hearing loss path, CNE- MoCA path, and hearing loss- MoCA path were 0.143 (p < 0.001), -0.048 (p = 0.267), and - 0.050 (p = 0.047). The CNE had only a direct effect on the MMSE score. Conversely, the CNE had only an indirect effect on the MoCA score, while hearing loss was borderline associated with MoCA. The total effects of CNE on MMSE and MoCA scores were -0.151 and -0.007, respectively.

CONCLUSION

Job-related noise exposure is not only associated with NIHL but also with early cognitive impairment in occupational groups. However, there is not enough evidence indicating that NLHL mediates the associations.

A scoping review of the prevalence of musicians' hearing loss

Introduction

Hearing loss is the most commonly recognized occupational disease in Germany. Musicians are also affected, as playing classical music can expose them to high or very high sound volumes. With this scoping review, we aimed to assess the prevalence of noise-induced hearing loss among professional musicians and evaluate its characteristics.

Methods

The databases such as MEDLINE, Embase, Cochrane Library, and Google Scholar were searched using the terms (hearing loss OR hearing impairment OR hearing difficulties OR acoustic trauma) AND (musician) on 14 August 2023 and 2 January 2025. Only original studies with audiometric examination results were included.

Results

A total of 79 studies were retrieved for descriptive analysis. The median number of participants was 52 (IQR 30-109). The majority of the retrieved studies included participants with at least 5 years of experience as practicing musicians. The proportion of men was significantly higher than that of women, with the medianmen portion of 69% (IQR 53-83%). Students were a common study population, indicating that the data on older and retired musicians were either rare or missing. As a result, the lifetime prevalence of hearing loss in musicians could not be determined. The data analysis showed an increased risk of hearing loss >15-20 dB in the frequency range of 4,000-6,000 Hz among participants in the classical genre group. Studies with participants having normal hearing were also found within that genre. Rock, pop, and jazz musicians had an increased risk of hearing loss >20 dB in the frequency range of 3,000-8,000 Hz. The data for military and marching band music and traditional music genres were limited. The retrieved studies indicated a higher risk of hearing loss >20 dB in the frequency range of 4,000-6,000 Hz. A total of 17 studies adjusted the audiogram results for age, 2 did not, and 59 had no report. Data extraction yielded a prevalence of notch configurations in 20-50% of the classical musicians, with hearing loss affecting 5-70% of them. Up to 40% of rock, pop, and jazz musicians showed notch configurations, with 20-60% experiencing hearing loss.

Conclusion

Overall, a definitive assessment of the prevalence of musicians' hearing loss cannot be drawn from the available data. Prospective, longitudinal studies with reliable sample sizes and representative populations are essential. A multicenter study would also be valuable.

The protective effect of wearing hearing protection devices in noise-induced hearing loss and its potential influencing factors in the Chinese adult population

BACKGROUND

Noise is a threat to human auditory system, hearing protection devices (HPDs) are widely used to prevent noise-induced hearing loss (NIHL). However, the role of wearing HPDs on NIHL and the complex relationship between them are still unclear. This study aims to explore such relationship and identify the associated influencing pathways. Providing the important targets for hearing health interventions.

METHODS

We tested audiometry and Personal Attenuation Ratings (PARs) in 862 participants, recording HPDs usage and fitting actions. Furthermore, an intervention, the comfort survey and the insertion depth measuring of foam earplugs were conducted with 455 participants. Using structural equation models to assess the association among these variables.

RESULTS

There were 18.1 % of participants who wore HPDs had NIHL in our study, and their baseline PARs were lower (p < 0.001). Then we found proper fitting actions and continuous use of HPDs led to higher PARs, with "roll" and "pull" being crucial for foam earplugs. In addition, baseline PARs (OR = 0.783; 95 % Cl: 0.644, 0.953) and HPDs wearing frequency (OR = 0.131; 95 % Cl: 0.079, 0.218) were the protective factors of NIHL. Moreover, both proper fitting actions (β = 0.237; 95 % Cl, 0.070, 0.404) and continuous wearing foam earplugs (β = 0.018; 95 % Cl: 0.010, 0.025) could moderate NIHL through baseline PARs, and they also had indirect effect on NIHL. HPDs wearing comfort and insertion depth could mediate the link between wearing HPDs and baseline PARs. The mediation effect of insertion depth on baseline PARs accounted for 35.5 %.

CONCLUSIONS

Our study found that people who wore HPDs improperly in noisy environments had a risk of suffering from NIHL. Highlighting the important role of proper fitting actions and continuously wearing HPDs in improving PARs and preventing NIHL, especially roll and pull actions for foam earplugs. Proposing that the insertion depth might be an auxiliary indicator to help screen workers that need to be focused on for identification and intervention.

The Role of Connexin26 and Connexin30 in the Mouse Cochlea of Noise-Induced Hearing Loss

OBJECTIVE

We aimed to explore the role of connexin26 (Cx26) and connexin30 (Cx30) in the cochlea in noise-induced permanent threshold shifts (PTS) and temporary threshold shift (TTS).

STUDY DESIGN

Prospective, controlled.

SETTING

Laboratory.

METHODS

A mouse model of noise-induced PTS and TTS was constructed. Western blots were used to detect the expression of Cx26 and Cx30 in the cochlea. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used to assess the potential biological pathways.

RESULTS

Both the expression of Cx26 and Cx30 showed a trend of first rising and then falling in noise-induced PTS. The expression of Cx26 increased greatly in the 24 hours noise exposure (P < .05) and reached the highest level in the 4 hours after noise exposure (P < .05), then decreased gradually and returned to the control level on the seventh day after the noise exposure, when compared with the control group. The expression of Cx30 showed a similar trend in noise-induced PTS. However, both the expression of Cx26 and Cx30 showed a trend of first falling and then rising in noise induced TTS. The expression of Cx26/Cx30 reached its lowest level in the 4 hours after noise exposure (P < .05), and then increased to the control level on the second day after noise exposure (P > .05), compared with the control group. The first KEGG and GO pathway may be related with oxidative phosphorylation.

CONCLUSION

Cx26 and Cx30 may have an effect in noise induced PTS and TTS. Future studies are needed to confirm the results.

Wearing Hearing Protection Makes Me Worse at My Job: Impacts of Hearing Protection Use on Sensorimotor Tracking Performance

OBJECTIVES

Occupational hearing loss is a significant problem worldwide despite the fact that it can be mitigated by the wearing of hearing protection devices (HPDs). When surveyed, workers frequently report that worsened work performance while wearing HPDs is one reason why they choose not to wear them. However, there have been few studies to supplement these subjective reports with objective measures. Where they do exist, assessed performance measures have mostly characterized auditory situational awareness in gross terms (e.g., average speech comprehension scores over an entire session). The temporal dynamics of performance and HPD impacts on nonauditory aspects of work performance are largely unknown. In the present study, we aimed to fill this gap in the literature by measuring how HPD usage impacted sensorimotor tracking performance in relation to ongoing auditory events.

DESIGN

In two experiments, listeners heard commands sourced from the coordinate response measure (CRM) corpus (i.e., sentences of the form "Ready go to now"). These commands informed listeners of which of nine moving on-screen objects to track with a computer mouse (e.g., "blue four" refers the listener to a blue square). The commands were presented in background street noise and were heard under either "No HPD" or "HPD" conditions. In experiment 1, HPD wearing was simulated with a digital filter designed to mimic the attenuation profile of a passive HPD. In experiment 2, actual HPDs were worn by listeners. Continuous recording of tracking error allowed us to simultaneously examine how HPD wearing impacted speech comprehension, the accuracy of tracking, and how tracking accuracy varied as a function of time on task and ongoing auditory events (e.g., the presentation of a critical CRM sentence).

RESULTS

In both experiments, listeners spent less time tracking the correct object in the HPD condition. After trimming data to those time points in which the target object was known, worse performance was exhibited by the HPD condition than the No HPD condition. In the examination of the temporal dynamics of tracking error, it was apparent that differences arose strongly during the presentation of CRM sentences.

CONCLUSIONS

Workers' complaints of poorer performance while wearing HPDs are justified and extend beyond just diminished auditory situational awareness. The negative impact on nonauditory aspects of work performance may be strongest around critical listening periods. Addressing these aspects of performance will be an important part of addressing HPD nonuse in occupational settings.

Nationwide Hearing Loss Trends Over Two Decades

OBJECTIVES

Hearing loss (HL) is one of the most common chronic health conditions in the United States (US). This study aims to evaluate trends in HL prevalence among US adults over the past two decades.

METHODS

Audiometric data of adults from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018 were analyzed in 2-year intervals to evaluate changes in HL (defined as pure tone average greater than 25 dB in at least one ear) over time in using odds ratios (ORs). Multivariate logistic regression was used to control for age and sex, and linear regression was used to evaluate trends in HL prevalence over time.

RESULTS

The study included 13,468 participants. In adult participants (20-69 years old), HL remained stable over time, with some fluctuations ranging from 14.8% to 16.8%. In elderly participants (70-years and older), HL remained stable over time, with some fluctuations ranging from 71.7% to 77.1%. Based on univariate and linear regression analysis, there were no differences in HL rates in the adult and elderly cohorts. Subjects 40-49 years old and adults with education level of less than high school had significant downward trends in HL prevalence over two decades (p < 0.001 and p = 0.029).

CONCLUSIONS

HL prevalence may be declining in the adult population when correcting for age and gender; however, there has not been a significant downward trend for the elderly population. HL may be decreasing over time among adults 40-49 years old and with shorter education backgrounds.

LEVEL OF EVIDENCE

4 Laryngoscope, 135:277-285, 2025.

Epidemiological Characteristics and Diagnostic Outcomes of Suspected Occupational Noise-Induced Deafness - Guangdong Province, China, 2014-2023

Introduction

Suspected occupational noise-induced deafness (ONID) represents the most prevalent suspected occupational disease in Guangdong Province and is among the most frequently reported nationwide. Given its public health significance, we conducted a systematic investigation of suspected ONID cases in Guangdong from 2014 to 2023, analyzing their epidemiological characteristics and diagnostic outcomes to inform evidence-based policies for ONID prevention and management.

Methods

Data on suspected ONID cases reported in Guangdong Province from 2014 to 2023 were extracted from the "Occupational Diseases and Health Hazard Factors Monitoring Information System." Cases were analyzed using descriptive epidemiological methods, with joinpoint regression analysis employed to assess long-term trends.

Results

From 2014 to 2023, 16,987 suspected ONID cases were reported in Guangdong Province, comprising 65.22% of all suspected occupational disease cases (26,044). Cases exhibited a significant increasing trend (Average annual percentage change: 11.8%, 95% CI: 2.9%-22.3%, P = 0.013). The Pearl River Delta region accounted for 87.9% of all cases, with manufacturing being the predominant industry (90.1%). Within manufacturing, the metal products industry represented the highest proportion (15.2%). Males constituted 87.7% (14,905/16,987) of cases. Analysis of diagnostic outcomes from 2020 to 2023 revealed an overall diagnostic procedure initiation rate of 45.1%, with a subsequent confirmation rate of 48.9%.

Conclusions

Guangdong Province demonstrates high occurrence patterns of suspected ONID cases, particularly concentrated in the Pearl River Delta region and manufacturing sectors. The low rates of diagnostic procedure initiation and confirmation highlight the urgent need for enhanced regulatory oversight of diagnostic procedures and the development of expert consensus on suspected ONID identification criteria to improve diagnostic confirmation rates.

Investigation of Noise Induced Hearing Loss Among Power Loom Industry Workers in Tamil Nadu, India

Noise-induced hearing loss remains a prevalent occupational concern across various industries. This study aimed to address several key objectives regarding noise exposure and hearing impairment among power loom workers in Tamil Nadu, India. The major objectives were to assess the levels of noise exposure in the power loom industry and to determine the prevalence of hearing loss among the workers. The minor objectives included identifying the specific factors associated with hearing loss and proposing measures to mitigate noise exposure. A cross-sectional study was carried out at a Power Loom Industry in the Erode District of Tamil Nadu between September and November 2023. A total of 123 workers from weaving sections were randomly selected to participate in face-to-face interviews using a structured questionnaire. Noise exposure levels were measured using a noise meter, while hearing loss was assessed using a pure tone audiometer. Logistic regression analysis was conducted to identify factors associated with hearing loss. Among the workers, 88.5% were exposed to noise levels of ≥ 95 dB (A), and the prevalence of hearing loss was 71.6%. Factors positively associated with hearing loss included age between 31-50 years and over 50 years, lack of literacy, experiencing hearing difficulties or earaches, hypertension, and more than 15 years of service in the power loom industry. To mitigate noise exposure levels, there is a need for enhanced occupational hazard education and stricter enforcement of safety regulations. Regular audiometry tests should be implemented to monitor hearing threshold shifts. Employers should establish and enforce hearing conservation programs in workplaces where noise exposure exceeds or reaches 95 dB (A).

Application of the occupational health risk assessment model in predicting the risk of noise-induced hearing loss in noise-polluted manufacturers in southern China

Objective. This study aimed to evaluate the correlation between occupational noise-induced hearing loss (ONIHL) and noise exposure in different positions within manufacturing facilities that primarily produce electronic devices, wooden furniture and hardware machinery in southern China and to investigate the practical application of the risk assessment model. Methods. Noise exposure data were collected from 115 workers in 10 manufacturing industries in southern China through on-site investigation. Subsequently, sample testing was conducted in accordance with Chinese standards. The 31 job positions investigated were classified into two similar exposure groups (SEGs). The occupational health risk assessment (OHRA) model was used to evaluate the risks of ONIHL in various job positions. Results. More than half of the positions in both groups had noise levels exceeding 85 dB. In both SEGs, male workers exhibited similar risk patterns of acquiring hearing impairment, with a more pronounced and earlier risk of hearing loss compared to female workers. Age was also found to be a risk factor for hearing impairments. Conclusion. The ORHA model demonstrated a positive correlation between noise exposure levels and NIHL. This model can help employers assess job management with noise exposure and take measures to implement an effective risk management system.

Developing and validating a risk assessment method for noise-induced hearing loss in workers

Various risk factors can affect noise-induced hearing loss (NIHL) among employees. This research sought to establish and validate a risk assessment method for NIHL using these risk factors. This cross-sectional research was carried out with 220 workers from a steel manufacturing facility. At first, their demographic characteristics and information related to the studies' items were gathered by the researcher-made questionnaire. In the next step, the noise exposure values of the participants were measured by the sound pressure level meter based on the ISO 9612 standard. Moreover, a pure tone audiometric test of bone and air conduction was used to measure hearing loss in people. Ultimately, a new index for risk assessment was created. Indirect effect coefficients of individual factors such as work experience, age, smoking, and effective diseases were 0.266, 0.227, 0.056, and 0.064, respectively. The coefficients of noise exposure items including occupational noise and leisure noise were obtained as 0.687 and 0.660. The personal protective equipment (PPE) items including use of PPE, noise reduction rating of PPE, and awareness of PPE were 0.194, 0.147, and 0.127, respectively. These coefficients were utilized to create a new index. The overall score of the index was divided into four categories using optimal cut-off values of 4.85, 6.84, and 7.59. According to the findings, the OHLRA methods were able to account for 74 percent of the hearing loss values. The results showed that the novel index for risk assessment had proper validity in the prediction of NIHL.

Epidemiological Characteristics and Spatiotemporal Analysis of Occupational Noise-Induced Deafness From 2006 to 2022 in Guangdong, China: Surveillance Study

Background

Occupational noise-induced deafness (ONID) has replaced occupational poisoning as the second most common occupational disease in China since 2015. However, there is a limited number of articles on epidemiological characteristics of legally diagnosed ONID.

Objective

We conducted a comprehensive analysis of the epidemiological and spatiotemporal characteristics of ONID in Guangdong Province from 2006 to 2022, with the aim of providing a scientific foundation for policy formulation and health resource allocation.

Methods

Surveillance data of ONID cases in Guangdong Province from 2006 to 2022 were obtained from the "Occupational Diseases and Health Hazard Factors Monitoring Information System." Joinpoint regression analysis was applied to assess the long-term trends in cases of ONID from 2006 to 2022. Global spatial autocorrelation analysis was performed to measure the overall degree of similarity of the attribute values of spatially adjacent or neighboring regional units. The local indicators of spatial autocorrelation (LISA) plots were then used to identify the local clusters of ONID in Guangdong.

Results

There were 3761 ONID cases in Guangdong Province from 2006 to 2022, showing a significantly increased trend in cases across the entire study period (average annual percentage change 21.9, 95% CI 18.7-35.1). The Moran's I values for the period of 2006 to 2022 ranged from 0.202 to 0.649 (all P<.001), indicating a positive spatial correlation of ONID across regions each year in Guangdong Province. A total of 15 high-high clusters were notably concentrated in specific counties within the Pearl River Delta.

Conclusions

Significant spatiotemporal patterns of ONID in Guangdong Province from 2006 to 2022 were identified, characterized by a dramatic increase followed by stabilization in case numbers. ONID predominantly occur in manufacturing industries, domestically funded enterprises, among males, individuals aged 40-49 years, and those with 5+ years of occupational noise exposure. Spatial analysis demonstrated significant clustering in the Pearl River Delta region, with consistent positive spatial autocorrelation across years. These results could help prioritize the allocation of resources for targeted prevention and control measures for ONID.

Optimizing a Classification Model to Evaluate Individual Susceptibility in Noise-Induced Hearing Loss: Cross-Sectional Study

Background

Noise-induced hearing loss (NIHL), one of the leading causes of hearing loss in young adults, is a major health care problem that has negative social and economic consequences. It is commonly recognized that individual susceptibility largely varies among individuals who are exposed to similar noise. An objective method is, therefore, needed to identify those who are extremely sensitive to noise-exposed jobs to prevent them from developing severe NIHL.

Objective

This study aims to determine an optimal model for detecting individuals susceptible or resistant to NIHL and further explore phenotypic traits uniquely associated with their susceptibility profiles.

Methods

Cross-sectional data on hearing loss caused by occupational noise were collected from 2015 to 2021 at shipyards in Shanghai, China. Six methods were summarized from the literature review and applied to evaluate their classification performance for susceptibility and resistance of participants to NIHL. A machine learning (ML)-based diagnostic model using frequencies from 0.25 to 12 kHz was developed to determine the most reliable frequencies, considering accuracy and area under the curve. An optimal method with the most reliable frequencies was then constructed to detect individuals who were susceptible versus resistant to NIHL. Phenotypic characteristics such as age, exposure time, cumulative noise exposure, and hearing thresholds (HTs) were explored to identify these groups.

Results

A total of 6276 participants (median age 41, IQR 33-47 years; n=5372, 85.6% men) were included in the analysis. The ML-based NIHL diagnostic model with misclassified subjects showed the best performance for identifying workers in the NIHL-susceptible group (NIHL-SG) and NIHL-resistant group (NIHL-RG). The mean HTs at 4 and 12.5 kHz showed the highest predictive value for detecting those in the NIHL-SG and NIHL-RG (accuracy=0.78 and area under the curve=0.81). Individuals in the NIHL-SG selected by the optimized model were younger than those in the NIHL-RG (median 28, IQR 25-31 years vs median 35, IQR 32-39 years; P<.001), with a shorter duration of noise exposure (median 5, IQR 2-8 years vs median 8, IQR 4-12 years; P<.001) and lower cumulative noise exposure (median 90, IQR 86-92 dBA-years vs median 92.2, IQR 89.2-94.7 dBA-years; P<.001) but greater HTs (4 and 12.5 kHz; median 58.8, IQR 53.8-63.8 dB HL vs median 8.8, IQR 7.5-11.3 dB HL; P<.001).

Conclusions

An ML-based NIHL diagnostic model with misclassified subjects using the mean HTs of 4 and 12.5 kHz was the most reliable method for identifying individuals susceptible or resistant to NIHL. However, further studies are needed to determine the genetic factors that govern NIHL susceptibility.

The impact of noise-induced hearing loss on individual job performance: exploring the role of aggression and work-related quality of life

BACKGROUND

Noise-Induced Hearing Loss (NIHL) may have a significant effect on individual job performance (IJP). These effects may exert through aggression and work-related quality of life (WRQoL). Hence, the present study was conducted to investigate the modeling of the impact of NIHL on IJP by exploring the role of aggression and WRQoL.

METHODS

In 2022, a comprehensive study was carried out on 335 industrial workers in Kaveh Industrial Town, Saveh, Iran. The study encompassed a range of assessments, including a questionnaire-based survey that included the IJP questionnaire, WRQoL questionnaire, and Aggression questionnaire, as well as a pure tone audiometry test. The data gathered from these assessments were analyzed using structural equation modeling, providing a robust framework for understanding the complex relationships between variables.

RESULTS

Based on Spearman correlation test there is a negative correlation between NIHLtotal and WRQoL and IJP, with coefficients of -0.459 (P-value < 0.01) and - 0.575 (P-value < 0.01), respectively. Additionally, there is a positive correlation between NIHLtotal and aggression, with a coefficient of 0.374 (P-value < 0.05). The direct effect coefficients for the impact of NIHLtotal on WRQoL, aggression, and IJP were - 0.412, 0.453, and - 0.128, respectively. Moreover, the indirect effect coefficients of NIHLtotal on the IJP through aggression, through WRQoL, and through both aggression and WRQoL were - 0.057, -0.275, and - 0.078, respectively.

CONCLUSION

Overall, the results indicate that NIHL had a negative and positive association with WRQoL and aggression among workers, respectively. Furthermore, IJP was found to be directly and indirectly influenced by NIHL, through reduced WRQoL and aggressive behavior as negative consequences of NIHL.

From sound waves to molecular and cellular mechanisms: Understanding noise‑induced hearing loss and pioneering preventive approaches (Review)

Noise-induced hearing loss (NIHL) is a significant and urgent global public health concern, arising from prolonged exposure to elevated levels of noise. This auditory impairment harms delicate inner ear structures, particularly the essential hair cells transmitting auditory signals to the brain. Recognized by the World Health Organization as a major contributor to worldwide hearing loss, NIHL requires a comprehensive examination of its molecular and cellular mechanisms. Animal models emerge as indispensable tools for unraveling these intricacies, allowing researchers to simulate and study the impact of noise exposure on auditory structures, shedding light on the interplay of oxidative stress, inflammation and immune responses-crucial factors in NIHL progression. The present review focuses on elucidating the molecular mechanisms of NIHL, with a specific emphasis on findings derived from animal models, alongside the exploration of thorough preventive strategies, including protective measures and probing potential interventions. Understanding the molecular underpinnings not only provides insight into targeted treatment approaches, but also unlocks pathways for exploring and implementing preventive actions. This approach not only deepens the current comprehension of NIHL, but also has the potential to influence the shaping of public health policies, offering a nuanced perspective on this prevalent auditory disorder.

Associations of GST Gene Polymorphisms and GST Enzyme Activity with the Development of Noise-Induced Hearing Loss in Chinese Han Males

INTRODUCTION

In noise-induced hearing loss (NIHL), glutathione S-transferases (GSTs) play a pivotal role as antioxidants in cochlear protection. Nevertheless, the variability in population and environmental factors complicates the interpretation of research findings on the association among GST gene polymorphism, GST enzyme activity, and NIHL, leading to inconsistent results. To explore the potential correlation between them, we took a cross-sectional survey.

METHODS

For workers with NIHL, standard 1:1 propensity score matching was applied to create a highly comparable control group. Multiplex PCR was used to detect GSTT1 and GSTM1 gene deletions, PCR-restriction fragment length polymorphism was used to detect the GSTP1 rs1695 gene polymorphism, and a GST assay kit was used to measure total plasma GST activity. Furthermore, we analyzed the relationship among GST gene polymorphism, GST enzyme activity, and NIHL.

RESULTS

This study included 144 workers with NIHL and 144 workers with normal hearing. The GSTM1 null genotype was significantly higher among workers with NIHL than controls (64.6% vs. 49.3%), regression analysis revealed a significant correlation between GSTM1 null genotype and elevated susceptibility to NIHL (p = 0.013). Workers with NIHL had significantly lower GST activity than healthy controls (p < 0.05). GST enzymes were not affected by GSTT1, GSTM1, or GSTP1 polymorphisms.

CONCLUSION

GSTM1 null genotype but not GSTM1 alone may confer susceptibility to NIHL, and serum GST enzyme activity is linked to NIHL.

Comparison of the risk of noise-induced hearing loss between male police officers and male non-police officers: a nationwide cohort study using propensity score matching in South Korea

BACKGROUND

Police officers are at a high risk of noise-induced hearing loss (NIHL) owing to the nature of their work. Therefore, this study aimed to compare the risk of NIHL in police officers and controls.

METHODS

This study used the National Health Insurance claims data of workers aged 25-65 years obtained from 2005 to 2015. The case group comprised police officers, while the control group comprised general workers and public officers. The study followed a three-phase cohort design. The standardized incidence ratio (SIR) was calculated using an indirect standardization method based on age. Propensity score matching was performed using the greedy matching method, with a police officer-to-control group ratio of 1:3. Cox regression analysis was performed for each matched control group. Statistical significance was determined by a lower limit of greater than 1, based on the 95% confidence interval (CI).

RESULTS

The SIR values for police officers were 1.62 (95% CI: 1.44-1.82) compared with general workers and 1.78 (95% CI: 1.66-1.73) compared with public officers. Police officers exhibited an increased risk of NIHL compared with general workers (hazard ratio (HR): 1.71, 95% CI: 1.49-1.98) and public officers (HR: 2.19, 95% CI: 1.88-2.56).

CONCLUSIONS

It is necessary to prevent NIHL by reducing occupational noise exposure through measures such as wearing earplugs, improving shooting training methods, and improving the shift work system.

Analysis of the positive influence of hyperbaric oxygen therapy on the prognosis and hearing control of patients with noise-induced hearing loss

OBJECTIVE

In this study, the research team aimed to explore the therapeutic effectiveness of hyperbaric oxygen therapy (HBOT) for noise-induced hearing loss (NIHL), its influence on patient prognosis, and its impact on hearing to provide valuable clinical evidence.

METHODS

Ninety-four patients with NIHL admitted to The First People's Hospital of Changde City, Hunan, China, from May 2021 to January 2023 were selected for this retrospective analysis. Among them, 43 were given conventional treatment (control group) and 51 were given HBOT (observation group). The clinical efficacy, symptom improvement, and pure-tone hearing thresholds (PTHTs) at different frequencies were detected. All cases were followed up for 12 months to record the NIHL recurrence rates and hearing (hearing threshold), and their quality of life was investigated.

RESULTS

The observation group had higher total effective rate and excellent rate and lower incidence of insomnia, tinnitus, and other symptoms than the control group (P < 0.05). PTHTs were lower in the observation group than in the control group at different frequencies (P < 0.05). Follow-up analysis showed no notable intergroup difference in the NHL recurrence rate (P > 0.05), but the hearing threshold was lower and the quality of life was better in the observation group than in the control group (P < 0.05).

CONCLUSIONS

Compared to conventional treatment, HBOT is effective in treating NIHL and can improve the hearing and coagulation function of patients and provide a reliable guarantee for their prognostic health.

Calcitriol alleviates noise-induced hearing loss by regulating the ATF3/DUSP1 signalling pathway

BACKGROUND

Calcitriol (Cal) is the most active metabolite of vitamin D and has antioxidant and anti-inflammatory properties. The aim of this study was to investigate the role of Cal in noise-induced hearing loss (NIHL) to further elucidate the mechanism of noise-induced oxidative stress in the mouse cochlea.

METHODS

C57BL/6 J mice were given six intraperitoneal injections of Cal (500 ng/kg/d). After 14 days of noise exposure, auditory brainstem response (ABR) thresholds, and the cochlear outer hair cell loss rate were analysed to evaluate auditory function. Real-time fluorescence quantitative PCR, immunofluorescence and western blotting were performed in vitro after the treatment of cochlear explants with 100 µM tert-butyl hydroperoxide (TBHP) for 2.5 h and HEI-OC1 cells with 250 µM TBHP for 1.5 h.

RESULTS

In vivo experiments confirmed that Cal pretreatment mitigated NIHL and outer hair cell death. The in vitro results demonstrated that Cal significantly reduced TBHP-induced cochlear auditory nerve fibre degradation and spiral ganglion neuron damage. Moreover, treatment with Cal inhibited the expression of oxidative stress-related factors (3-NT and 4-HNE) and DNA damage-related factors (γ-H2A.X) and attenuated TBHP-induced apoptosis in cochlear explants and HEI-OC1 cells. A total of 1479 upregulated genes and 1443 downregulated genes were screened in cochlear tissue 1 h after noise exposure. The level of transcription factor 3 (ATF3) was significantly elevated in HEI-OC1 cells after TBHP stimulation. Gene Transcription Regulation Database （GTRD）and Cistrome database analyses revealed that the downstream target gene of ATF3 is dual specificity phosphatase 1 (DUSP1). Cistrome DB Toolkit database results showed that the transcription factor of DUSP1 was ATF3. In addition, the ChIP-PCR results indicated that ATF3 might be a direct transcription factor of DUSP1.

CONCLUSION

The results of our study suggest that Cal attenuates NIHL and inhibits noise-induced apoptosis by regulating the ATF3/DUSP1 signalling pathway.

Role of Nursing in Managing Noise-Related Hearing Loss in Children: A Retrospective Study of Earmuffs as a Protective Intervention

BACKGROUND

Noise-induced hearing loss (NIHL) in children is a growing public health concern due to increased exposure to high noise levels in various environments. Early intervention is crucial to prevent long-term developmental and social impacts. This study evaluates the effectiveness of earmuffs as a protective intervention in managing NIHL in children.

METHODS

A prospective study was conducted involving 120 paediatric patients aged 5-12 years diagnosed with NIHL. Patients were divided into an intervention group (n = 60), who received standard treatment plus earmuffs, and a control group (n = 60), who received standard treatment only. Pure-tone audiometry tests were used to assess hearing thresholds at baseline and post-intervention. Family satisfaction was also assessed using a self-administered questionnaire.

RESULTS

Hearing thresholds substantially improved in the intervention group compared with those in the control group. After the intervention, hearing thresholds in the intervention group reduced by 7.31 decibels (dB) at 500 Hertz (Hz), 6.73 dB at 1000 Hz, 6.66 dB at 2000 Hz and 6.92 dB at 4000 Hz (P < 0.05). In the control group, reductions were 3.74, 3.72, 3.64 and 3.80 dB, respectively (P < 0.05). Family satisfaction was significantly higher in the intervention group, with 91.7% expressing satisfaction, compared with 65.0% in the control group (P = 0.030).

CONCLUSION

This study demonstrates the effectiveness of earmuffs in preventing NIHL in children, showing improvements in hearing thresholds and increased family satisfaction. These findings suggest that earmuffs could be beneficial as part of standard preventive measures for paediatric patients exposed to high noise levels and highlight their potential practical and clinical value.

Individual and combined effects of noise exposure and diabetes mellitus on hearing

Hearing loss (HL) is a prevalent health concern with a significant impact on society and the economy. Several factors contribute to the development of hearing impairment, with noise overexposure being the primary culprit. Diabetes mellitus (DM) is also a factor in hearing impairment, and studies have shown a positive correlation between DM and HL; however, the exact causal relationship and pathogenesis remain contentious. Given the ubiquity of noise exposure and the high incidence of DM, individuals may develop diabetes while being chronically exposed to noise. It is particularly important to explore the independent and combined effects of noise and DM on hearing, which can help healthcare professionals understand the potential risks posed by these factors and inspire prevention strategies and potential interventions for hearing impairment. This review summarizes the current research advancements in noise-induced HL and diabetes-related HL and discusses their characteristics and potential mechanisms. Furthermore, this review focuses on the combined effects of noise exposure and DM on hearing, setting the stage for further research and development of intervention strategies to address HL.

Occupational noise exposure and its effects among mill workers: A narrative review

There are many possibilities for noise exposure in industrial workplaces, including sectors that extensively use heavy machinery in processing each product. Various studies indicate a causal relationship between noise exposure and auditory/nonauditory effects among workers. Noise exposure poses risks to health and workers' hearing acuity and safety. This review paper aims to identify and summarize occupational noise exposure by examining the auditory and nonauditory effects among mill workers. The mills included in the study are palm oil, lumber, textiles, rice, sugarcane, flour, paper, and sawmills. A two-step methodology was used to achieve the aims of this narrative review. The literature search was conducted by gathering PubMed and Google Scholar papers, focusing on occupational noise in different occupational mill environments. Grey's literature was conducted by screening the worldwide national standard for the laws, guidelines, and other related information based on this topic. A total of 22 articles published have been included. The content of each publication was subsequently summarized. Most of the machine areas within the mills emitted high level of noise. The auditory effects of occupational noise exposure among mill workers were noise-induced hearing loss and hearing impairment. Hypertension, stress, communication disturbance, cardiovascular disease, and headache were the nonauditory effects experienced by workers. The recommendations provided in this review for mitigating noise exposure are derived from the hierarchy of control. Overall, most mill workers are exposed to a high noise level exceeding the standard noise exposure limit. Preventive actions should be taken to address and reduce work-related injuries among mill workers worldwide.

Exploring delivery systems for targeted nanotechnology-based gene therapy in the inner ear

Hearing loss places a significant burden on our aging population. However, there has only been limited progress in developing therapeutic techniques to effectively mediate this condition. This review will outline several of the most commonly utilized practices for the treatment of sensorineural hearing loss before exploring more novel techniques currently being investigated via both in vitro and in vivo research. This review will place particular emphasis on novel gene-delivery technologies. Primarily, it will focus on techniques used to deliver genes that have been shown to encourage the proliferation and differentiation of sensory cells within the inner ear and how these technologies may be translated into providing clinically useful results for patients.

A Study of Hearing Acuity and the Health of the External Auditory Canal Among Earphone Users in Central India

Background and objective The pervasive use of earphones has raised concerns about its potential impact on hearing acuity and the health of the external auditory canal (EAC). This study aimed to investigate these effects in a sample of individuals in Central India to better understand the associated risks. Materials and methods This observational cross-sectional study was conducted in the Department of Otorhinolaryngology, Acharya Vinoba Bhave Rural Hospital, Sawangi Wardha. A total of 130 participants aged 15-35 years were divided into two groups: 65 earphone users and 65 non-earphone users. The data collection involved medical histories, clinical examinations, and audiometric testing, including pure-tone audiometry (PTA), impedance audiometry, and otoacoustic emissions (OAE). Participants completed a questionnaire on earphone usage, and EAC health was assessed via physical examinations and photographic documentation. Statistical analyses included descriptive and inferential statistics, with significance set at p<0.05. Results Among earphone users, 45 (69.23%) exhibited hearing loss compared to 11 (16.92%) in non-users (p<0.00001). Noise-canceling earphones were associated with fewer cases of hearing loss (6/45, 13.33%) than non-noise-canceling types (39/45, 86.67%) (p<0.00001). EAC issues were more prevalent in earphone users, with 39 (60%) showing normal conditions versus 52 (80%) in non-users. Impactions of wax, otomycosis, and otitis externa were observed more frequently among earphone users. Conclusions The study highlights a significant association between earphone use and increased risk of hearing loss and EAC issues. Noise-canceling earphones may offer some protective benefits. These findings underscore the need for raising awareness and implementing preventive measures to mitigate potential risks associated with prolonged earphone use.

Effects of Occupational Noise Exposure on Hearing Loss: Regulatory Effect of Mediterranean Diet

OBJECTIVE

To assess regulatory effect of Mediterranean diet for occupational noise exposure and hearing loss. Methods: This cross-sectional study included 4757 individuals. Weighted logistic regression model was adopted to explore the association of occupational noise exposure and Mediterranean diet with hearing loss, and regulatory effects of the Mediterranean diet for the relationship of occupational noise exposure and hearing loss. Results: Occupational noise exposure was associated with an increased odds of hearing loss. Under low adherence to the Mediterranean diet, the occupational noise exposure group was related to increased odds of hearing loss. Under high adherence to the Mediterranean diet, no significant difference was observed between occupational noise exposure and hearing loss, and adjusted effect size was reduced accordingly. Conclusion: Mediterranean diet may moderate this relationship of occupational noise exposure and hearing loss to some degree.

The Working Environment in Primary Healthcare Outpatient Facilities: Assessment of Physical Factors and Health Professionals' Perceptions of Working Environment Conditions

The objectives of this study were to assess the adequacy of physical parameters/factors (temperature, relative humidity, noise, and illuminance levels) of the work environment in PHC facilities, to evaluate the association between the adequacy of these measured physical parameters and the physical characteristics of the PHC facilities and their surroundings and to assess the association between health professionals' perceptions about exposure to physical risks in the PHC work environment and the adequacy of physical parameters measured in the same facilities. The study monitored 23 PHC facilities in southern Brazil and interviewed 210 health professionals. Data analysis involved Pearson's chi-square, Fisher's exact test, Spearman's correlation, and multivariate linear regression analysis was used to control for confounding factors. The significance level was set at 5% (p ≤ 0.05). The combination of temperature and relative humidity presented thermal comfort levels outside the adopted criteria for adequacy in consultation (outdoor relative humidity, p = 0.013) and procedure rooms (front door open, p = 0.034). Inadequate sound comfort (noise) levels in the morning shift were found in the vaccination (front door open, p = 0.021) and consultation rooms (movement of people, p = 0.016). In PHC facilities where reception rooms had insufficient lighting, internal curtains were opened less frequently (p = 0.047). The analysis of health professionals' perceptions of physical factors demonstrated that physicians more frequently perceive the physical risk of temperature and humidity (p = 0.044). The higher the number of nurses (p = 0.004) and oral health technicians in the PHC facilities (p = 0.031), the greater the general percentage of adequacy of monitored physical parameters. It was also confirmed that the higher the perception of moderate or severe physical risk among health professionals, the lower the general percentage of the adequacy of the physical parameters of the work environment of the PHC facilities evaluated (rs = -0.450, p = 0.031). This study's evidence contributes to a better understanding of physical conditions and future occupational interventions to ensure the comfort, safety, and well-being of PHC workers.

Association of socioeconomic position with sensory impairment among Chinese population: a nationally representative cohort and Mendelian randomization study

Aims

To investigate the association between socioeconomic position (SEP) and sensory impairments (SIs).

Methods

We used data from the China Health and Retirement Longitudinal Study (CHARLS) (2015). Logistic regressions estimated the odds ratio for associations of SEP with SIs. In addition, Mendelian randomization (MR) analysis was conducted to assess the causal relationship between them with the inverse variance weighting (IVW) estimator. MR-Egger, simple median, weighted median, maximum likelihood, and robust adjusted profile score were employed for sensitivity analyses.

Results

In the observational survey, we enrolled 19,690 individuals aged 45 and above. SEP was negatively associated with SIs. Adjusted odds of vision impairment were higher for illiterate (1.50; 95%CI: 1.19, 1.91), less than elementary school diploma (1.76; 95%CI: 1.39, 2.25), middle school diploma (1.53; 95%CI: 1.21, 1.93) and lower income (all p < 0.001). The odds of hearing impairment were significantly higher for people with less than a high school diploma than those with a college degree or higher diploma, for agricultural workers than non-agricultural workers, and for people in low-income families (p < 0.01). The MR analysis also showed that occupation was associated with HI (1.04, 95%CI: 1.01, 1.09, p < 0.05) using IVW.

Conclusion

We found that both observational and causal evidence supports the theory that SEP can result in SIs and that timely discovery, targeted management, and education can prevent SIs among middle-aged and older adults.

The influencing factors of hearing protection device usage among noise-exposed workers in Guangdong Province: a structural equation modeling-based survey

BACKGROUND

There are numerous complex barriers and facilitators to continuously wearing hearing protection devices (HPDs) for noise-exposed workers. Therefore, the present study aimed to investigate the relationship between HPD wearing behavior and hearing protection knowledge and attitude, HPD wearing comfort, and work-related factors.

METHOD

A cross-sectional study was conducted with 524 noise-exposed workers in manufacturing enterprises in Guangdong Province, China. Data were collected on hearing protection knowledge and attitudes, HPD wearing comfort and behavior, and work-related factors through a questionnaire. Using structural equation modeling (SEM), we tested the association among the study variables.

RESULTS

Among the total workers, 69.47% wore HPD continuously, and the attitudes of hearing protection (26.17 ± 2.958) and total HPD wearing comfort (60.13 ± 8.924) were satisfactory, while hearing protection knowledge (3.54 ± 1.552) was not enough. SEM revealed that hearing protection knowledge had direct effects on attitudes (β = 0.333, p < 0.01) and HPD wearing behavior (β = 0.239, p < 0.01), and the direct effect of total HPD wearing comfort on behavior was β = 0.157 (p < 0.01). The direct effect also existed between work shifts and behavior (β=-0.107, p < 0.05). Indirect relationships mainly existed between other work-related factors, hearing protection attitudes, and HPD wearing behavior through knowledge. Meanwhile, work operation had a direct and negative effect on attitudes (β=-0.146, p < 0.05), and it can also indirectly and positively affect attitudes through knowledge (β = 0.08, p < 0.05).

CONCLUSION

The behavior of wearing HPD was influenced by hearing protection knowledge, comfort in wearing HPD, and work-related factors. The results showed that to improve the compliance of noise-exposed workers wearing HPD continuously when exposed to noise, the HPD wearing comfort and work-related factors must be taken into consideration. In addition, we evaluated HPD wearing comfort in physical and functional dimensions, and this study initially verified the availability of the questionnaire scale of HPD wearing comfort.

Unveiling the Role of Oxidative Stress in Cochlear Hair Cell Death: Prospective Phytochemical Therapeutics against Sensorineural Hearing Loss

Hearing loss represents a multifaceted and pervasive challenge that deeply impacts various aspects of an individual's life, spanning psychological, emotional, social, and economic realms. Understanding the molecular underpinnings that orchestrate hearing loss remains paramount in the quest for effective therapeutic strategies. This review aims to expound upon the physiological, biochemical, and molecular aspects of hearing loss, with a specific focus on its correlation with diabetes. Within this context, phytochemicals have surfaced as prospective contenders in the pursuit of potential adjuvant therapies. These compounds exhibit noteworthy antioxidant and anti-inflammatory properties, which hold the potential to counteract the detrimental effects induced by oxidative stress and inflammation-prominent contributors to hearing impairment. Furthermore, this review offers an up-to-date exploration of the diverse molecular pathways modulated by these compounds. However, the dynamic landscape of their efficacy warrants recognition as an ongoing investigative topic, inherently contingent upon specific experimental models. Ultimately, to ascertain the genuine potential of phytochemicals as agents in hearing loss treatment, a comprehensive grasp of the molecular mechanisms at play, coupled with rigorous clinical investigations, stands as an imperative quest.

Auditory Changes in Occupational Health Associated With Metabolic Diseases in Adult Workers

INTRODUCTION

The most common hearing losses in the population are associated with genetic conditions, use of ototoxic substances or medications, infectious diseases, metabolic diseases and chronic ear diseases and the association of exposure to occupational risks or the natural aging process.

OBJECTIVE

Verify the association between hearing loss in workers and metabolic diseases.

METHOD

Retrospective cross-sectional study with analysis of secondary data of subjects exposed to occupational noise and undergoing drug treatment for metabolic disease, attended in two occupational health clinics (C1 and C2) from January 2020 to December 2022, considering the data of reference examinations from the year 2005.

RESULTS

Of the n = 97 subjects evaluated, 73.20% were male, exposed to occupational noise (64.90%), with medication use for treating cardiovascular diseases (89.70%). The most recurrent auditory complaint was tinnitus (28.90%), n = 53 subjects presented sensorineural hearing loss with a statistical association between the decline of hearing loss and medications used for metabolic and hormonal regulation.

CONCLUSION

Here was a higher frequency in the use of medications for treating cardiovascular diseases with a risk of triggering or worsening hearing loss in these subjects and greater impairment and decline of hearing thresholds were observed in the results of C2.

Hearing Loss: Self-Reported Onset and Etiology Among Older Adults in the United States

This study investigated self-reported age of onset and etiology of hearing loss among older adults in the United States. Study cohort included older adult (≥70 years) survey respondents from the 2017 to 2020 National Health and Nutrition Examination Survey (n = 797). Overall, 51.1% [95% confidence interval [CI]: 46.1-56.1] of older adults self-reported hearing loss. Among older adults who reported hearing loss, the most reported age of onset was age 70 or older (41.7% [95% CI: 38.1%-45.3%]), followed by sequentially younger age brackets including ages 60 to 69 years (27.3% [95% CI: 23.6%-31.3%]) and ages 40 to 59 years (15.7% [95% CI: 12.9%-19.0%]). The most common etiology of hearing loss was aging (66.3% [95% CI: 60.8%-71.4%]) followed by loud long-term noise (30.3% [95% CI: 26.2%-34.9%]) and loud brief noise (13.8% [95% CI: 10.3%-18.4%]). Our study describes the most common age of onset and etiologies of hearing loss among a representative sample of United States older adults.

A Comprehensive Review of Auditory and Non-Auditory Effects of Noise on Human Health

OBJECTIVE

Excessive noise is unpleasant and induces several physiological and psychological effects. Noise pollution is a potential threat to humans, particularly those continuously exposed for extended periods throughout the day over many years. This review aims to examine the various auditory and non-auditory outcomes associated with prolonged exposure to noise pollution.

MATERIALS AND METHODS

The review utilized a combination of relevant keywords to search the electronic databases. After screening based on the applied selection criteria for title, abstract, and full text, 44 articles were finally selected for critical review.

RESULTS

We identified and analyzed research findings related to noise-induced hearing loss, tinnitus, and sleep disturbances along with non-auditory issues such as annoyance, cognitive impairments, and mental stress associated with cardiovascular disorders. Furthermore, the existing studies were compared and collated to highlight the unique challenges and significance of noise pollution as a distinctive environmental concern and to explore the ongoing efforts in its research and prevention, including the early detection and potential reversal of noise-induced hearing loss.

CONCLUSION

The fundamental health consequences of noise pollution underscore the need for extensive research encompassing emerging noise sources and technologies to establish a health management system tailored to address noise-related health concerns and reduce noise exposure risk among populations. Finally, further research is warranted to ensure improved measurement of noise exposure and related health outcomes, especially in the context of occupational noise.

The synergetic impact of digital campaigns and economic incentives on environmental performance: the mediating role of household indoor and outdoor activities

The primary goal of this research is to look into the impact of digital campaigns for environmental and economic incentives on environmental performance, with indoor and outdoor activities of households taken as mediating variables. PLS-SEM was used to evaluate and quantify the novel and complex model to meet the study's goals. Furthermore, data were gathered from 1542 Pakistani households using convenient sampling techniques. The study's findings show that digital campaigns and economic incentives significantly increase household's participation in indoor and outdoor activities, which improves environmental performance. This study contributes to the literature on environmental performance by examining digital campaigns and economic incentives as resilient influencers. Furthermore, this study assists authorities in developing an effective and efficient policy that promotes environmental savaging information while providing economic incentives to encourage the activities. At the same time, it emphasizes environmental concerns and how they can be addressed.

Risk of noise-induced hearing loss in the spine surgeon

Background

Occupation-related noise-induced hearing loss (NIHL) has both negative economic and quality of life implications. The risk spine surgeons undertake in regards to NIHL during operative intervention is unknown. Governing bodies, including the National Institute for Occupational Safety and Health, have recommended exposure limits not to exceed 85 decibels (dB) over 8 hours. The purpose of this study is to characterize noise exposure to spine surgeons in the operating room (OR).

Methods

Prospective collection of intraoperative recordings of spinal surgeries (cervical and thoracic/lumbar) was undertaken. Data gathered included procedure, operative duration, presence of background music, and noise information. Noise information included maximum decibel level (MDL), Peak level (LCPeak), Equivalent continuous sound pressure level, time weighted average (TWA), dose, and projected dose. Noise measurements were compared with baseline controls with and without music (empty ORs).

Results

Two hundred seven noise recordings were analyzed. One hundred eighteen of those being spinal surgeries, 49 baseline recordings without music, and 40 with music. Maximum decibel level reached a maximum value of 111.5 dBA, with an average amongst surgical recordings of 103 dBA. Maximum decibel level exceeded 85 dBA in 100% of cases and was greater than 100 dBA in 78%. The maximum LCPeak recorded was 132.9 dBC with an average of 120 dBC. Furthermore, the average dose was 7.8% with an average projected dose of 26.5%. The highest dose occurred during a laminectomy at 72.9% of daily allowable noise. Maximum projected dose yielded 156% during a 3-level anterior cervical discectomy and fusion.

Conclusions

Spine surgeons are routinely exposed to damaging noise levels (>85 dBA) during operative intervention. With spine surgeons often performing multiple surgeries a day, the cumulative risk of noise exposure cannot be ignored. The synergistic effects of continuous and impact noise places spine surgeons at risk for the development of occupation-related NIHL.

Microglial activation in the lateral amygdala promotes anxiety-like behaviors in mice with chronic moderate noise exposure

BACKGROUND

Long-term non-traumatic noise exposure, such as heavy traffic noise, can elicit emotional disorders in humans. However, the underlying neural substrate is still poorly understood.

METHODS

We exposed mice to moderate white noise for 28 days to induce anxiety-like behaviors, measured by open-field, elevated plus maze, and light-dark box tests. In vivo multi-electrode recordings in awake mice were used to examine neuronal activity. Chemogenetics were used to silence specific brain regions. Viral tracing, immunofluorescence, and confocal imaging were applied to define the neural circuit and characterize the morphology of microglia.

RESULTS

Exposure to moderate noise for 28 days at an 85-dB sound pressure level resulted in anxiety-like behaviors in open-field, elevated plus maze, and light-dark box tests. Viral tracing revealed that fibers projecting from the auditory cortex and auditory thalamus terminate in the lateral amygdala (LA). A noise-induced increase in spontaneous firing rates of the LA and blockade of noise-evoked anxiety-like behaviors by chemogenetic inhibition of LA glutamatergic neurons together confirmed that the LA plays a critical role in noise-induced anxiety. Noise-exposed animals were more vulnerable to anxiety induced by acute noise stressors than control mice. In addition to these behavioral abnormalities, ionized calcium-binding adaptor molecule 1 (Iba-1)-positive microglia in the LA underwent corresponding morphological modifications, including reduced process length and branching and increased soma size following noise exposure. Treatment with minocycline to suppress microglia inhibited noise-associated changes in microglial morphology, neuronal electrophysiological activity, and behavioral changes. Furthermore, microglia-mediated synaptic phagocytosis favored inhibitory synapses, which can cause an imbalance between excitation and inhibition, leading to anxiety-like behaviors.

CONCLUSIONS

Our study identifies LA microglial activation as a critical mediator of noise-induced anxiety-like behaviors, leading to neuronal and behavioral changes through selective synapse phagocytosis. Our results highlight the pivotal but previously unrecognized roles of LA microglia in chronic moderate noise-induced behavioral changes.

Occupational noise and hypertension in Southern Chinese workers: a large occupational population-based study

INTRODUCTION

An increasing number of original studies suggested that occupational noise exposure might be associated with the risk of hypertension, but the results remain inconsistent and inconclusive. In addition, the attributable fraction (AF) of occupational noise exposure has not been well quantified. We aimed to conduct a large-scale occupational population-based study to comprehensively investigate the relationship between occupational noise exposure and blood pressure and different hypertension subtypes and to estimate the AF for hypertension burden attributable to occupational noise exposure.

METHODS

A total of 715,135 workers aged 18-60 years were included in this study based on the Key Occupational Diseases Surveillance Project of Guangdong in 2020. Multiple linear regression was performed to explore the relationships of occupational noise exposure status, the combination of occupational noise exposure and binaural high frequency threshold on average (BHFTA) with systolic and diastolic blood pressure (SBP, DBP). Multivariable logistic regression was used to examine the relationshipassociation between occupational noise exposure status, occupational noise exposure combined with BHFTA and hypertension. Furthermore, the attributable risk (AR) was calculated to estimate the hypertension burden attributed to occupational exposure to noise.

RESULTS

The prevalence of hypertension among occupational noise-exposed participants was 13·7%. SBP and DBP were both significantly associated with the occupational noise exposure status and classification of occupational noise exposure combined with BHFTA in the crude and adjusted models (all P < 0·0001). Compared with workers without occupational noise exposure, the risk of hypertension was 50% greater among those exposed to occupational noise in the adjusted model (95% CI 1·42-1·58). For participants of occupational noise exposed with BHFTA normal, and occupational noise exposed with BHFTA elevated, the corresponding risks of hypertension were 48% (1·41-1·56) and 56% (1·46-1·63) greater than those of occupational noise non-exposed with BHFTA normal, respectively. A similar association was found in isolated systolic hypertension (ISH) and prehypertension. Subgroup analysis by sex and age showed that the positive associations between occupational noise exposure and hypertension remained statistically significant across all subgroups (all P < 0.001). Significant interactions between occupational noise status, classification of occupational noise exposure combined with BHFTA, and age in relation to hypertension risk were identified (all P for interaction < 0.001). The associations of occupational noise status, classification of occupational noise exposure combined with BHFTA and hypertension were most pronounced in the 18-29 age groups. The AR% of occupational noise exposure for hypertension was 28·05% in the final adjusted model.

CONCLUSIONS

Occupational noise exposure was positively associated with blood pressure levels and the prevalence of hypertension, ISH, and prehypertension in a large occupational population-based study. A significantly increased risk of hypertension was found even in individuals with normal BHFTA exposed to occupational noise, with a further elevated risk observed in those with elevated BHFTA. Our findings provide epidemiological evidence for key groups associated with occupational noise exposure and hypertension, and more than one-fourth of hypertension cases would have been prevented by avoiding occupational noise exposure.

Cross-Modal Sensory Boosting to Improve High-Frequency Hearing Loss: Device Development and Validation

Background

High-frequency hearing loss is one of the most common problems in the aging population and with those who have a history of exposure to loud noises. This type of hearing loss can be frustrating and disabling, making it difficult to understand speech communication and interact effectively with the world.

Objective

This study aimed to examine the impact of spatially unique haptic vibrations representing high-frequency phonemes on the self-perceived ability to understand conversations in everyday situations.

Methods

To address high-frequency hearing loss, a multi-motor wristband was developed that uses machine learning to listen for specific high-frequency phonemes. The wristband vibrates in spatially unique locations to represent which phoneme was present in real time. A total of 16 participants with high-frequency hearing loss were recruited and asked to wear the wristband for 6 weeks. The degree of disability associated with hearing loss was measured weekly using the Abbreviated Profile of Hearing Aid Benefit (APHAB).

Results

By the end of the 6-week study, the average APHAB benefit score across all participants reached 12.39 points, from a baseline of 40.32 to a final score of 27.93 (SD 13.11; N=16; P=.002, 2-tailed dependent t test). Those without hearing aids showed a 10.78-point larger improvement in average APHAB benefit score at 6 weeks than those with hearing aids (t14=2.14; P=.10, 2-tailed independent t test). The average benefit score across all participants for ease of communication was 15.44 (SD 13.88; N=16; P<.001, 2-tailed dependent t test). The average benefit score across all participants for background noise was 10.88 (SD 17.54; N=16; P=.03, 2-tailed dependent t test). The average benefit score across all participants for reverberation was 10.84 (SD 16.95; N=16; P=.02, 2-tailed dependent t test).

Conclusions

These findings show that vibrotactile sensory substitution delivered by a wristband that produces spatially distinguishable vibrations in correspondence with high-frequency phonemes helps individuals with high-frequency hearing loss improve their perceived understanding of verbal communication. Vibrotactile feedback provides benefits whether or not a person wears hearing aids, albeit in slightly different ways. Finally, individuals with the greatest perceived difficulty understanding speech experienced the greatest amount of perceived benefit from vibrotactile feedback.

Noise-induced hearing loss and hearing protection: Attitudes at a South African coal mine

BACKGROUND

 Negative attitudes and beliefs are major contributing factors to the rising numbers of noise-induced hearing loss (NIHL) cases in coal mines both locally and internationally. International literature confirms limited knowledge surrounding employees' attitudes and beliefs regarding NIHL and hearing protection devices (HPDs), hence the need for the study.

OBJECTIVES

 To ascertain the attitudes and beliefs about NIHL and HPD use among employees at a large scale underground coal mine in Mpumalanga.

METHOD

 A descriptive and exploratory cross-sectional study was conducted using a self-administered questionnaire, developed by the National Institute for Occupational Safety and Health (NIOSH) on Beliefs about Hearing Protection and Hearing Loss (BHPHL). Participants (n = 241) included employees from a coal mine in Mpumalanga, South Africa.

RESULTS

 Out of 241 completed surveys, this study found that 84% were aware of when to replace earmuffs; 95% believed wearing HPDs could prevent hearing loss in noisy environments; 83% felt their hearing was impacted by loud noise. Additionally, 86% mentioned discomfort from earmuff pressure; 95% emphasised HPD importance; and 95% used HPDs around loud sounds. Moreover, 98% knew how to properly wear earplugs, while lower education levels were linked to higher susceptibility to NIHL.

CONCLUSION

 The study identified positive attitudes towards NIHL and HPD use, but existing NIHL cases must be acknowledged. Organisations can use the findings to develop tailored hearing conservation programmes (HCP), including education, involving employees in protection decisions and promoting diligent HPD usage.Contribution: This study contributes to the limited literature on noise perceptions, NIHL, and HPD use in mining, emphasising the impact attitude has on HPD use and assessing the effect of miners NIHL knowledge on compliance. The findings, unique to coal mining, hold significance for enhancing hearing conservation and reducing NIHL.

NcRNA: key and potential in hearing loss

Hearing loss has an extremely high prevalence worldwide and brings incredible economic and social burdens. Mechanisms such as epigenetics are profoundly involved in the initiation and progression of hearing loss and potentially yield definite strategies for hearing loss treatment. Non-coding genes occupy 97% of the human genome, and their transcripts, non-coding RNAs (ncRNAs), are widely participated in regulating various physiological and pathological situations. NcRNAs, mainly including micro-RNAs (miRNAs), long-stranded non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), are involved in the regulation of cell metabolism and cell death by modulating gene expression and protein-protein interactions, thus impacting the occurrence and prognosis of hearing loss. This review provides a detailed overview of ncRNAs, especially miRNAs and lncRNAs, in the pathogenesis of hearing loss. We also discuss the shortcomings and issues that need to be addressed in the study of hearing loss ncRNAs in the hope of providing viable therapeutic strategies for the precise treatment of hearing loss.

The sound of safety: exploring the determinants of prevention intention in noisy industrial workplaces

Occupational noise exposure is a pervasive issue in many industries, leading to a range of health issues and sleep disturbances among workers. Additionally, there is a strong desire among these workers to prevent industrial accidents. This study, aimed at enhancing worker health and well-being, utilized a survey distributed by the Korean Confederation of Trade Unions to field workers. Data from 1285 workers were collected and analyzed using partial least squares structural equation modeling (PLS-SEM) to identify and understand the factors affecting prevention intention in noisy work environments. Our findings indicate that health problems resulting from occupational noise exposure significantly influence insomnia, perceived severity of potential accidents, perceived benefits of preventive measures, and perceived barriers. Perceived severity was significantly correlated with prevention intention, emphasizing the role of risk perception in motivating preventive behaviors. Perceived benefits were also significantly associated with prevention intention, highlighting the importance of positive outcomes in influencing workers' behaviors. Additionally, perceived barriers showed a significant relationship with prevention intention, suggesting that overcoming these barriers is crucial in promoting preventive behaviors. Demographic factors such as gender displayed a significant association with prevention intention, while age did not. This study provides valuable insights into the multifaceted factors influencing workers' intention to prevent industrial accidents in noisy environments, underlining the importance of comprehensive data collection tools in understanding these dynamics.

Effect of noise and hand-transmitted vibration exposure on hearing and equilibrium under a simulated work environment with building tools

BACKGROUND

Construction workers are exposed to hand-transmitted vibration (HTV) and/or noise caused by vibrating hand tools in the work environment.

OBJECTIVE

The present study aims to investigate the effects of exposure to HTV and/or noise on workers' hearing loss and body balance.

METHODS

Forty construction workers were exposed to HTV (10 m/s2 rms, 31.5 Hz) and/or typical construction noise (90 dBA) in three simulated experiment scenarios with the vibrating hand-held tool for 30 minutes over three days. The hearing loss from 1000 to 6000 Hz and the body balance were determined before and after each exposure scenario.

RESULTS

Separate noise exposure at all frequencies except for 1000 Hz could significantly affect hearing threshold levels (p-value<0.05). Separate exposure to HTV cannot lead to a remarkable effect on hearing loss (p-value>0.05); however, it can synergistically increase the effect of noise on hearing loss. Also, the affected frequency range in concurrent exposure has been greater than in separate noise exposure. The separate effects of exposure to HTV and noise on the subjects' body balance were not statistically significant (p-value>0.05); however, these effects became significant in concurrent exposure (p-value<0.05). Based on the estimated effect sizes, noise could synergistically increase the observed effect of HTV on body balance.

CONCLUSION

There is a synergistic interaction between HTV and noise on hearing loss and body balance. It seems necessary to pay attention to the risk evaluation of simultaneous exposure to noise and HTV when setting the occupational action limit values.

Quantitative levels of noise exposure and 20-year hearing decline: findings from a prospective cohort study (the HUNT Study)

OBJECTIVE

We aimed to assess the association between occupational noise exposure and long-term hearing decline.

DESIGN

This prospective cohort study used linear regression to investigate the association between occupational noise exposure and 20-year hearing decline, adjusted for important confounders.

STUDY SAMPLE

The Norwegian cohort (N = 4,448) participated in two population-based health studies with pure-tone audiometry; HUNT2 1996-1998 and HUNT4 2017-2019. Exposure assessments included a quantitative job exposure matrix (JEM) and questionnaires.

RESULTS

The participants (40.2% men, 20-39 years at baseline) had a mean 20-year decline (3-6 kHz) of 11.3 ± 9.8 decibels (dB). There was a positive association between 20-year logarithmic average noise level (JEM-based, LEX,20y) and 20-year hearing decline among men. Compared with no exposure ≥80 dB during follow-up, minimum 5 years of exposure ≥85 dB (JEM-based) predicted 2.6 dB (95% CI: 0.2-5.0) larger 20-year decline for workers aged 30-39 years at baseline, and -0.2 dB (95% CI: -2.2 to 1.7) for workers aged 20-29 years. Combining JEM information with self-reported noise exposure data resulted in stronger associations.

CONCLUSION

This large longitudinal study shows an association between JEM-based noise exposure level and increased 20-year hearing decline among men. Contrary to expectations, the associations were weaker among younger workers, which might reflect a latency period.

Prevalence and correlates of occupational noise-induced hearing loss among workers in the steel industry

BACKGROUND

The steel industry is one of the noisiest industries, which can predispose workers to hearing loss. In Egypt, the demand for steel is increasing due to the construction of new infrastructures as bridges, flyover roads, buildings, and towers; however, little is known about the prevalence of occupational noise-induced hearing loss (NIHL) among steel workers. Understanding the distribution of the affected workers is crucial for planning prevention strategies. This study aimed to estimate the prevalence of occupational NIHL among Egyptian steel workers and identify its correlates.

METHODS

This study was conducted at two steel factories in Egypt in November 2021. It involved an initial retrospective review of the factory medical records of the latest periodic medical examination conducted on workers from July to September in the year 2021 representing workers' health status in that year. Then, a case-control approach analysis was carried out. Eligible workers (n = 606) were enrolled and divided into two groups: noise-exposed workers (n = 396) and unexposed workers (n = 210). Univariate and multivariate regression analyses were performed.

RESULTS

Occupational exposure to hazardous A-weighted equivalent noise level (> 85 dB) was associated with higher hearing thresholds at all frequencies (highest at 4 kHz followed by 6 kHz), particularly in younger workers below the age of 40 years. Nearly 71% of noise-exposed workers had hearing impairment, and 47% had NIHL compared with unexposed workers (45.7% and 11.9%, respectively). The probability of NIHL in noise-exposed workers was 6.55 times higher than that in unexposed workers (OR = 6.55, 95%CI = 4.13, 10.40; p < 0.001). In noise-exposed workers, age and tinnitus were independent predictors of hearing thresholds, while tinnitus was found to be an independent predictor of NIHL after adjusting for age and job duration (OR = 2.06, 95%CI = 1.01, 4.20; p = 0.045).

CONCLUSION

Almost half of noise-exposed workers had NIHL. Tinnitus was found to be an independent predictor of NIHL. Decreasing noise exposure levels in steel plants is recommended to reduce hearing loss. Future research is required to study the effect of tinnitus on audiometry measurements among workers with NIHL.

Antioxidant Therapy as an Effective Strategy against Noise-Induced Hearing Loss: From Experimental Models to Clinic

Cochlear redox unbalance is the main mechanism of damage involved in the pathogenesis of noise-induced-hearing loss. Indeed, the increased free radical production, in conjunction with a reduced efficacy of the endogenous antioxidant system, plays a key role in cochlear damage induced by noise exposure. For this reason, several studies focused on the possibility to use exogenous antioxidant to prevent or attenuate noise-induce injury. Thus, several antioxidant molecules, alone or in combination with other compounds, have been tested in both experimental and clinical settings. In our findings, we tested the protective effects of several antioxidant enzymes, spanning from organic compounds to natural compounds, such as nutraceuticals of polyphenols. In this review, we summarize and discuss the strengths and weaknesses of antioxidant supplementation focusing on polyphenols, Q-Ter, the soluble form of CoQ10, Vitamin E and N-acetil-cysteine, which showed great otoprotective effects in different animal models of noise induced hearing loss and which has been proposed in clinical trials.

The Combined Effect of Elevated Blood Pressure and Occupational Noise Exposure on Bilateral High-Frequency Hearing Loss: Evidence From a Large Sample Cross-sectional Study

BACKGROUND

Combined effect of elevated blood pressure and occupational noise exposure on hearing loss have rarely been evaluated among Chinese population.

METHODS

This cross-sectional study was conducted in 242,811 participants. Logistic regression model was performed to estimate the independent and combined associations.

RESULTS

Compared with participants without occupational noise exposure, the risk of bilateral high-frequency hearing loss (BHFHL) was significantly higher for noise exposure 10 years or more (odds ratio [OR] = 1.29, 95% confidence interval [95% CI] = 1.23-1.35). Compared with no hypertension, participants with grade 1 hypertension had higher risk of BHFHL in all age groups (OR, 1.14; 95% CI, 1.09-1.20). As to the combined effect, the highest BHFHL risk was found in males (OR, 1.51; 95% CI, 1.37-1.67), especially among participants with grade 1 hypertension older than 50 years (OR, 1.65; 95% CI, 1.46-1.88).

CONCLUSIONS

Elevated blood pressure may synergistically influence hearing loss combined with occupational noise exposure.

Noise-Induced Hearing Loss

Noise-induced hearing loss (NIHL) is the second most common cause of sensorineural hearing loss, after age-related hearing loss, and affects approximately 5% of the world's population. NIHL is associated with substantial physical, mental, social, and economic impacts at the patient and societal levels. Stress and social isolation in patients' workplace and personal lives contribute to quality-of-life decrements which may often go undetected. The pathophysiology of NIHL is multifactorial and complex, encompassing genetic and environmental factors with substantial occupational contributions. The diagnosis and screening of NIHL are conducted by reviewing a patient's history of noise exposure, audiograms, speech-in-noise test results, and measurements of distortion product otoacoustic emissions and auditory brainstem response. Essential aspects of decreasing the burden of NIHL are prevention and early detection, such as implementation of educational and screening programs in routine primary care and specialty clinics. Additionally, current research on the pharmacological treatment of NIHL includes anti-inflammatory, antioxidant, anti-excitatory, and anti-apoptotic agents. Although there have been substantial advances in understanding the pathophysiology of NIHL, there remain low levels of evidence for effective pharmacotherapeutic interventions. Future directions should include personalized prevention and targeted treatment strategies based on a holistic view of an individual's occupation, genetics, and pathology.

Effects of coexposure to noise and mixture of toluene, ethylbenzene, xylene, and styrene (TEXS) on hearing loss in petrochemical workers of southern China

Many harmful factors existing simultaneously with noise are reported to induce hearing impairment, such as organic solvents. However, the existing hearing safety limits and current risk assessment for hearing loss rely on single noise exposure. It is urgent to clarify the combined effect of noise and other harmful factors on hearing loss. Petrochemical workers are always exposed to noise and organic solvents, mainly benzene, toluene, ethylbenzene, xylene, and styrene (BTEXS), while the combined effect of their coexposure on hearing remains unclear. Herein we conducted a cross-sectional survey, measuring pure-tone audiometry of 1496 petrochemical workers in southern China. Participants exposed to BTEXS were 569, 524, 156, 452, and 177 respectively. Individual cumulative noise exposure (CNE) levels and BTEXS exposure were assessed. The average CNE was 93.27 ± 4.92 dB(A)·years, and the concentrations of BTEXS were far below the occupational exposure limits of China. Logistic regression analyses showed that CNE was consistently positively associated with hearing loss (HL) and high-frequency hearing loss (HFHL) but not related to speech-frequency hearing loss (SFHL). Compared with participants in the lowest quartile of CNE, those in the highest quartile showed an OR of 5.229 (95% CI: 3.179, 8.598) for HFHL. Two-pollutant model analysis indicated that TEXS exposure was positively associated with HL (OR 1.679, 95%CI 1.086, 2.597), SFHL (OR 2.440, 95%CI 1.255, 4.744), and HFHL (OR 1.475, 95%CI 1.077, 2.020). However, no interactions were observed between CNE and TEXS coexposure on hearing loss. In our study, covariates including smoking and drinking status, body mass index (BMI), ear protection and personal protective equipment, and use of earphone/headphone were adjusted. In conclusion, coexposure to noise and low-level TEXS could induce more severe damage on hearing function than exposure to each alone, especially SFHL. Therefore, petrochemical workers simultaneously exposed to noise and TEXS, even at low-level, should be included in hearing protection programs.