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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Music as a unique source of noise-induced hearing loss

Music is among the most important artistic, cultural, and entertainment modalities in any society. With the proliferation of music genres and the technological advances that allow people to consume music in any location and at any time, music over-exposure has become a significant public health issue. Music-induced hearing loss has a great deal in common with noise-induced hearing loss. However, there are important differences that make music a unique insult to the auditory system and a unique threat to public health. Its unique properties also make it a potentially valuable asset in sound conditioning paradigms. This review discusses hearing loss from noise and music, comparing and contrasting the two. Recent research on music-induced hearing loss is reviewed, followed by discussion of the differences in music-induced hearing loss between performers and consumers. The review concludes with a discussion of the potential of music as a sound conditioning stimulus to protect against acquired hearing loss.

Classification of audiograms in the prevention of noise-induced hearing loss: A clinical perspective

Background

Noise induced hearing loss (NIHL) is a major contributor to disabling hearing loss. Engineering controls are superior to hearing protection devices (HPDs) in prevention of occupational noise induced hearing loss (ONIHL), although the latter are more commonly used. Effective use of audiometry requires quick categorization of audiograms. The UK Health and Safety Executive (UKHSE) scheme for the categorization of audiograms is a tool that accomplishes this.

Objectives

The objective of this paper is to provide an overview of the classification of audiograms and build a case for the preferential use of the UKHSE’s scheme to achieve this.

Method

The author provides a literature review of methods of classification for audiograms and uses a case study in a Tanzanian mining company to demonstrate how the UKHSE scheme was successfully used to enhance the existing hearing protection program.

Results

The literature review identified several methods of classification based on a variation of threshold shifts from baseline. The difference was in the frequency and level of threshold shift used to determine hearing loss, and the recommended course of action once hearing loss is detected. The UKHSE scheme is simple and provides guidance on steps to be taken thereafter. This was demonstrated in a case study among miners in a mining company in Tanzania.

Conclusion

The UKHSE audiogram classification scheme has the advantage of providing a straightforward, easy to determine classification that allows for intervention appropriate to the findings.

Effect of Mastoid Drilling on Hearing of the Contralateral Normal Ear in Mastoidectomy

To evaluate hearing of the contralateral normal ear before and after mastoidectomy in a longitudinal manner and to assess whether the hearing loss is transient or permanent and to find out the duration of temporary hearing loss. This was a clinical longitudinal observational study involving 50 patients with unilateral chronic suppurative otitis media requiring mastoidectomy operation over a period of 18 months after satisfying the inclusion criteria. During the part of the mastoidectomy surgery involving drilling of the mastoid bone, noise levels were recorded at multiple points in the surgery using a digital sound level meter. Postoperatively, beginning from Day 1 to Day 7, PTA and OAE of the contralateral ear were recorded for all patients. The patients were then followed up at 1, 3 and 6 months postoperatively, at which times PTA and OAE were repeated. There is an increase in the absence of High Frequency DPOAEs on the first and second postoperative days, but this increase is higher than that of Low Frequency DPOAEs and gradually returns to normal by 72 h. OAEs were found to be more sensitive at diagnosing and tracking the progress of affected patients. All affected ears only had a temporary postoperative hearing loss, primarily affecting the higher frequencies and returning to normal within 72 h. Drill-generated noise and vibration during mastoidectomy operation is associated with a significant temporary shift in hearing thresholds of the contralateral normal ear in susceptible individuals, affecting the higher frequencies, and is best evaluated using DPOAEs.

Evaluation of geranylgeranylacetone against cisplatin-induced ototoxicity by auditory brainstem response, heat shock proteins and oxidative levels in guinea pigs

This study aims to assess whether geranylgeranylacetone (GGA) could reduce ototoxicity induced by cisplatin through upregulation of not only heat shock protein(HSP)-70, but also HSP-27 and HSP-40, and to study if GGA would reduce cisplatin-induced increase in oxidative stress. 48 guinea pigs were used in this study and treated with the following regimen: 0.5% CMC (sodium carboxymethyl cellulose) control for 7days, GGA (600mg/kg/d) for 7days, a combination of GGA (600mg/kg) for 7days and then one dose of 10mg/kg cisplatin (GGA+Cis), and a combination of CMC for 7days and then 10mg/kg cisplatin (cisplatin group). Auditory brainstem response (ABR) measurement was performed in each animal at time before treatment and 7days after the last dose. Additionally, HSPs, nitric oxide (NO), and lipid peroxidation (LPO) levels in cochlear membranous tissues were assessed. The mean ABR thresholds in the cisplatin group were significantly (p<0.05) increased when compared to the other three groups. In guinea pigs receiving both GGA and cisplatin, the mean threshold shift (TS) were smaller (p<0.05) than those of the cisplatin group, but larger (p<0.05) than those of the CMC control or GGA only group with statistical significance. Compared to the GGA only group or the group treated with GGA+Cis, the cisplatin group had the highest (p<0.05) oxidative stress (NO and LPO levels), and the lowest (p<0.05) mean HSPs expression levels. It can be concluded that GGA attenuate ototoxicity induced by cisplatin through upregulation of HSP-27, -40, and -70. Moreover, increased oxidative stress induced by cisplatin in the cochlea membranous tissue could be reduced by pre-treatment of GGA.

Offshore Dredger Sounds: Source Levels, Sound Maps, and Risk Assessment

The underwater sound produced during construction of the Port of Rotterdam harbor extension (Maasvlakte 2) was measured, with emphasis on the contribution of the trailing suction hopper dredgers during their various activities: dredging, transport, and discharge of sediment. Measured source levels of the dredgers, estimated source levels of other shipping, and time-dependent position data from a vessel-tracking system were used as input for a propagation model to generate dynamic sound maps. Various scenarios were studied to assess the risk of possible effects of the sound from dredging activities on marine fauna, specifically on porpoises, seals, and fish.

The role of genetic factors for hearing deterioration across 20 years: a twin study

BACKGROUND

Hearing deterioration at advanced ages is associated with environmental exposures (eg, to noise and solvents) and genetic influences may also be important. Little is known about the role of genetic influences on hearing when evaluated longitudinally. We sought to investigate longitudinal hearing loss in a cohort of adult male twins to evaluate the importance of genetic and environmental factors for hearing deterioration over time.

METHODS

Hearing using conventional clinical audiometry was assessed in 583 male twins (128 monozygotic twin pairs and 111 dizygotic twin pairs) aged 34-79 at baseline and again two decades later. The hearing thresholds at two time points were compared at each frequency and in two different frequency regions. Genetic analyses were based on structural equation models. Bivariate Cholesky decomposition was used for longitudinal analysis.

RESULTS

The prevalence of hearing loss increased over time in better and worse ear. The hearing threshold shift was more pronounced in the high-frequency region, especially at 8000 Hz. Genetic influences were moderate (heritability: 53%-65%) for pure-tone averages at both lower and higher frequencies, and were of equal magnitude at baseline and follow-up. In contrast, environmental influences were of substantial importance (55%-88%) for rate of change of the hearing threshold over the 18-year period.

CONCLUSIONS

Genetic factors are of considerable importance for level of hearing acuity, but environmental factors are more important for rate of change over an 18-year period.

The effect of celecoxib, a cyclooxygenase-2 inhibitor on noise- induced hearing loss

OBJECTIVE(S)

Noise-induced hearing loss (NIHL) is the major cause of acquired hearing loss. Celecoxib, a cyclooxygenase-2 (COX-2) inhibitor, is a non- steroidal anti- inflammatory drug (NSAID) with known antioxidant and antineoplastic activity. Therefore, we monitored the extent of temporary noise- induced threshold shifts (TTS) and cochlear damage caused by high level 4- kHz noise exposure to verify the differences with those pretreated with celecoxib.

MATERIALS AND METHODS

Ten male albino guinea pigs (300-350 g in weight) were randomly allocated into two groups: the primal group was exposed to 4- kHz octave band noise at 102 dB SPL for 3 hrs (group 1, n=5); the latter pretreated with 50 mg/ kg celecoxib for 3 days, then exposed to noise (group 2, n=5). Before exposure and one hr after noise exposure, threshold shifts were evaluated with auditory brainstem responses (ABR) and finally the animals were euthanized for histological evaluation.

RESULTS

Comparing the threshold shifts before/after noise exposure with those pretreated, we found out that TTS caused by noise exposure did not show significant mitigation by celecoxib. By observing the organ of Corti at lower middle turn of cochlea in celecoxib pretreated group, considerable hair cell loss was discovered.

CONCLUSION

The current study clearly confirmed that celecoxib had no attenuation against temporary noise-induced hearing loss.