A cross-sectional study of hearing thresholds among 4627 Norwegian train and track maintenance workers.
ABSTRACT: OBJECTIVE:Railway workers performing maintenance work of trains and tracks could be at risk of developing noise-induced hearing loss, since they are exposed to noise levels of 75-90?dB(A) with peak exposures of 130-140?dB(C). The objective was to make a risk assessment by comparing the hearing thresholds among train and track maintenance workers with a reference group not exposed to noise and reference values from the ISO 1999. DESIGN:Cross-sectional. SETTING:A major Norwegian railway company. PARTICIPANTS:1897 and 2730 male train and track maintenance workers, respectively, all exposed to noise, and 2872 male railway traffic controllers and office workers not exposed to noise. OUTCOME MEASURES:The primary outcome was the hearing threshold (pure tone audiometry, frequencies from 0.5 to 8?kHz), and the secondary outcome was the prevalence of audiometric notches (Coles notch) of the most recent audiogram. RESULTS:Train and track maintenance workers aged 45?years or older had a small mean hearing loss in the 3-6?kHz area of 3-5?dB. The hearing loss was less among workers younger than 45?years. Audiometric notches were slightly more prevalent among the noise exposed (59-64%) group compared with controls (49%) for all age groups. They may therefore be a sensitive measure in disclosing an early hearing loss at a group level. CONCLUSIONS:Train and track maintenance workers aged 45?years or older, on average, have a slightly greater hearing loss and more audiometric notches compared with reference groups not exposed to noise. Younger (<45?years) workers have hearing thresholds comparable to the controls.
Project description:The aim of this study was to investigate the association between insomnia and hearing impairment among workers exposed to occupational noise.This study included 809 male workers exposed to occupational noise. The participants underwent audiometric testing, and their insomnia was examined based on the Insomnia Severity Index test. Hearing impairment was defined as hearing threshold >25 dB hearing level in the range of 1-4 kHz.According to analysis of covariance, it was observed that pure tone audiometry thresholds at 1-2 kHz in the right ear and at 1 kHz in the left ear were significantly higher among workers with insomnia compared to those with no insomnia. Multiple logistic regression analysis of insomnia for hearing impairments was performed, which showed the odds ratio was 1.806 (95% confidence intervals: 1.022-3.188, p = 0.042) after adjustment for age, working period, noise level, snoring, use of protection devices, diabetes mellitus, hypertension, smoking, alcohol consumption, regular exercise, waist circumference, total cholesterol, triglyceride and high density lipoprotein cholesterol.Insomnia could be associated with hearing impairment in workers who are exposed to occupational noise. Additionally, insomnia may be associated with decreased hearing at low frequencies. Especially, more efforts are required to improve the quality of sleep for workers who are exposed to loud occupational noise. Further well- designed prospective studies are needed to clarify the relationship between insomnia and hearing impairment.
Project description:Importance:Portable music player use may have harmful effects on hearing. The magnitude and effect of frequent music exposure, especially at younger ages, on hearing are unclear. Objectives:To examine the prevalence of noise-induced hearing loss in a 9- to 11-year-old population and associations with portable music player use and sociodemographic factors. Design, Setting, and Participants:A cross-sectional study within an ongoing, prospective, birth cohort study within Rotterdam, the Netherlands was conducted. Between ages 9 and 11 years, 5355 children underwent their first audiometric evaluation. Children were excluded if they had missing or failed tympanometry results. The study was conducted from April 16, 2012, to October 25, 2015. Exposures:Portable music player (PMP) use and sociodemographic factors assessed via parental questionnaires. Main Outcomes and Measures:Hearing acuity measured by pure-tone audiometry at 0.5 to 8 kHz. Possible noise-induced hearing loss was contingent on a high-frequency notch and/or high-frequency hearing loss in the audiogram, or reported hearing-related symptoms. Results:The final sample included 3116 participants who were a mean (interquartile range) age of 9.7 (9.6-9.9) years and equally distributed between boys (1550 [49.7%]) and girls (1566 [50.3%]). Of these, 1244 (39.9%) reported no PMP use, 577 (18.5%) reported use 1 or 2 days per week, 254 (8.2%) reported use 3 or more days per week, and for 1041 (33.4%), PMP use was not reported. Audiometric notches and high-frequency hearing loss were present in 443 (14.2%) of all children; 140 (4.5%) fulfilled the criteria of a notch, 238 (7.6%) of high-frequency hearing loss, and 65 (2.1%) of both. Of the cohort, 52 (1.7%) showed bilateral impairment. Hearing-related symptoms were reported for 232 (11.3%) of the respondents, and 831 (40.0%) of the respondents used portable music players. Portable music player use was associated with high-frequency hearing loss (odds ratio [OR], 2.88; 95% CI, 1.36-6.980 for 1 or 2 days per week and OR, 2.74; 95% CI, 1.22-6.96 for ?3 days per week), but listening time and duration were not. There was no association of music exposure with high-frequency notches. Conclusions and Relevance:In this study, 14.2% of school-aged children showed audiometric notches or high-frequency hearing loss. This hearing impairment is already present prior to exposure to known noise hazards, such as club and concert attendance, and may have lifelong consequences. Repeated measurements are needed to confirm the association of portable music player use with hearing impairment in children.
Project description:Obtaining reliable and objective data on certain working conditions is necessary to analyse the causes and variables that can influence the development of hearing loss amongst the working population. Objective occupational data have been collected from a heterogeneous sample of 1418 workers in Spain, see "How activity type, time on the job and noise level on the job affect the hearing of the working population. Using Bayesian networks to predict the development of hipoacusia" (Barrero et al., 2018) . Among the main factors analysed are the noise levels to which these workers are exposed, measured at their respective workstations, and the assessment of their hearing status, evaluated by audiometric medical tests. These factors provide information to predict the development of hypoacusia.
Project description:We assessed the reliability of a hearing risk factor screening survey used by hearing conservation programmes for noise-exposed workers.We compared workers' answers from the screening survey to their answers to a confidential research questionnaire regarding hearing loss risk factors. We calculated kappa statistics to test the correlation between yes/no questions in the research questionnaire compared to answers from 1 and 5 years of screening surveys.We compared the screening survey and research questionnaire answers of 274 aluminum plant workers.Most of the questions in the in-company screening survey showed fair to moderate agreement with the research questionnaire (kappa range: -0.02, 0.57). Workers' answers to the screening survey had better correlation with the research questionnaire when we compared 5 years of screening answers. For nearly all questions, workers were more likely to respond affirmatively on the research questionnaire than the screening survey.Hearing conservation programmes should be aware that workers may underreport hearing loss risk factors and functional hearing status on an audiometric screening survey. Validating company screening tools could help provide more accurate information on hearing loss and risk factors.
Project description:OBJECTIVE: To investigate whether single nucleotide polymorphisms (SNPs) in the Mn-superoxide dismutase gene (SOD2) underlie the susceptibility to noise-induced hearing loss (NIHL). METHODS: Audiometric data from 2400 Chinese Han workers who exposed to occupational noise were analyzed. DNA samples were collected from the 10% most susceptible and the 10% most resistant individuals, and five SNPs (SOD2 rs2842980, rs5746136, rs2758331, rs4880 and rs5746092) were genotyped by Taqman SNP Genotyping Kits. The SNP main effects and interactions between noise exposure and SNP were analyzed using logistic regression. Haplotypes were analyzed by using Haploview software. RESULTS: The CT genotype of rs4880 (SOD2 V16A SNP) was associated with a higher risk of NIHL (covariates-adjusted OR, 2.18; 95% CI, 1.34-3.54, P=0.002). Haplotype analysis revealed that the frequency of AGCCG at the five SNP loci was significantly higher in the susceptible group (P=0.020). With AGCTG as the reference, the OR (95% CI) was 2.63 (1.14, 6.06). The rs4880 polymorphisms imposed larger effects when the carriers were exposed to higher levels of noise, indicating the interaction between SNP and noise exposure. CONCLUSIONS: Our results suggest that SOD2 V16A SNP in the mitochondrial targeting sequence is associated with noise induced hearing loss in Chinese workers, and this effect was enhanced by higher levels of noise exposure.
Project description:Rail transport is a key stepping stone in the EU's transport policy and is pinpointed for investment and growth over the coming decades. This expanding infrastructure implies increased exposure to environmental stressors, such as noise and ground-borne vibrations. Little is known about the health impacts of exposure to these vibrations. The aim of this paper is to examine the association between annoyance from rail vibrations and the distance of residential dwelling from the railway. It reports the first results of a large epidemiological study, EpiVib, which was designed to investigate the long-term health effects of exposure to rail vibrations. The first part of this study examines a self-reported questionnaire. In total, 6894 individuals aged between 18 and 80 living within 1 km of a railway in west Sweden participated. Results presented here examine the association between distance to the railway and annoyance from vibrations and are stratified by train type. A positive association between closer distance and increased annoyance is seen. After adjustment for important modifiers, results showed that vibrations from freight trains and maintenance operations are reported to be moderately and highly annoying at distances of up to 400 m from the railway and diesel up to 300 m. Vibration from passenger and fast trains are significantly annoying up to 200 m from the track. Vibration from freight trains and maintenance operations were considered highly annoying up to 300 m from the track, diesel up to 400 m. Vibration from passenger and fast trains are not reported to be highly annoying after adjustment. Heavier, slower moving locomotives, in the form of diesel and freight trains, appear to be the source of annoyance at distances further from the railway compared to passenger and fast trains. This has implications in terms of property, transport, and infrastructure planning.
Project description:BACKGROUND: Noise exposure is a well-known contributor to work-related hearing loss. Recent biological evidence suggests that exposure to ototoxic chemicals such as organic solvents and heavy metals may be additional contributors to hearing loss. However, in industrial settings, it is difficult to determine the risks of hearing loss due to these chemicals in workplaces accompanied by excessive noise exposure. A few studies suggest that the effect of noise may be enhanced by ototoxic chemicals. Therefore, this study investigated whether co-exposure to organic solvents and/or heavy metals in the workplace modifies the risk of noise exposure on hearing loss in a background of excessive noise. METHODS: We examined 30,072 workers nationwide in a wide range of industries from the Korea National Occupational Health Surveillance 2009. Data on industry-based exposure (e.g., occupational noise, heavy metals, and organic solvents) and subject-specific health outcomes (e.g., audiometric examination) were collected. Noise was measured as the daily 8-h time-weighted average level. Air conduction hearing thresholds were measured from 0.5 to 6 kHz, and pure-tone averages (PTA) (i.e., means of 2, 3, and 4 kHz) were computed. RESULTS: In the multivariate linear model, PTA increment with occupational noise were 1.64-fold and 2.15-fold higher in individuals exposed to heavy metals and organic solvents than in unexposed individuals, respectively. CONCLUSION: This study provides nationwide evidence that co-exposure to heavy metals and/or organic solvents may exacerbate the effect of noise exposure on hearing loss in workplaces. These findings suggest that workers in industries dealing with heavy metals or organic solvents are susceptible to such risks.
Project description:Agricultural workers who have concurrent exposure to pesticides and noise are at increased risk of hearing loss. We recruited 163 Thai conventional and 172 organic farmers to answer our questionnaires about personal demographics, agricultural activities, and pesticide and agricultural machinery use. This information was used to calculate the years of conventional (pesticide use) farming and the years of agricultural noise exposure, and to estimate semiquantitative metrics for pesticide exposure (cumulative intensity score-years) and cumulative noise exposure (dB(A)-years) for each conventional farmer. All participants underwent pure tone audiometric testing. The mean hearing threshold in the low-frequency band (0.5-2 kHz) and high-frequency band (3-6 kHz) were used for analysis. Years involved in conventional farming and years using agricultural machinery were associated with an increase in the average hearing threshold for the high-frequency band after controlling for age, ever exposed to industrial noise and cigarette smoking. The highest category of cumulative insecticide exposure (score-years), cumulative organophosphates exposure (score-years) and cumulative noise exposure (dB(A)-years) were also associated with an increased high-frequency band hearing threshold among conventional farmers. Results from the full cohort and the subcohort of conventional farmers support each other and the hypothesis that pesticide and noise have an additive effect on hearing, since no model interactions were significant.
Project description:To estimate the short-term variability and correlates of variability in pure-tone thresholds obtained using audiometric equipment designed for occupational use, and to examine the justification for excluding 8 kHz as a mandatory threshold in occupational hearing conservation programs.Pure-tone thresholds and other hearing-related tests (e.g. noise dosimetry, otoscopy, middle-ear assessment) were conducted with a group of 527 adults between 20 and 69 years of age. Five measurement visits were completed by participants within 14 days.The 50% critical difference boundaries were - 5 and 0 dB at 4 kHz and below and - 5 and 5 dB at 6 and 8 kHz. The likelihood of spurious notches due to test-retest variability was substantially lower than the likelihood of failing to detect a notched configuration when present. Correlates of variability included stimulus frequency, baseline threshold, acoustic reflectance of the ear, average noise exposure during the previous eight hours, age, and the tester's level of education in audiology.The short-term variability in 8-kHz pure-tone thresholds obtained with the TDH-39P earphone was slightly greater than at other frequencies, but this difference was not large enough to justify the disadvantages stemming from the inability to detect a 6-kHz notch.
Project description:The aim of this study is to compare vibration exposure to noise exposure from railway traffic in terms of equal annoyance, i.e., to determine when a certain noise level is equally annoying as a corresponding vibration velocity. Based on questionnaire data from the Train Vibration and Noise Effects (TVANE) research project from residential areas exposed to railway noise and vibration, the dose response relationship for annoyance was estimated. By comparing the relationships between exposure and annoyance for areas both with and without significant vibration exposure, the noise levels and vibration velocities that had an equal probability of causing annoyance was determined using logistic regression. The comparison gives a continuous mapping between vibration velocity in the ground and a corresponding noise level at the facade that are equally annoying. For equivalent noise level at the facade compared to maximum weighted vibration velocity in the ground the probability of annoyance is approximately 20% for 59 dB or 0.48 mm/s, and about 40% for 63 dB or 0.98 mm/s.