Noise-exposed Workers Research Articles

Hypertension in noise-exposed sawmill workers: a cohort study

Objective:To investigate the hypothesised association between exposure to high levels of noise and risk of hypertension using quantitative exposure assessment and administrative health data.Methods:This study followed a cohort of 10...

The risk of tinnitus following occupational noise exposure in workers with hearing loss or normal hearing

The purpose was to investigate the relationship between noise exposure and tinnitus among workers with normal hearing and hearing loss, respectively. We conducted a cross-sectional survey of 752 workers employed at 91 workplaces, that were investigated by means of full work-shift noise levels, questionnaire data, and bilateral pure-tone audiometry. Tinnitus was not associated with the present noise level, the duration of noise exposure, or the cumulative noise exposure if participants had normal hearing. As expected, such trends were demonstrated if participants had a hearing handicap. Based on these data, we will be cautious in ascribing tinnitus to noise exposure in our patients’ workplaces if they have a normal audiogram. Furthermore our data indicates no risk of noise-induced tinnitus at exposure levels where no hearing loss would be expected, e.g. as usually encountered in non-industrial workplaces.

Noise exposure in oil mills

Context:Noise of machines in various agro-based industries was found to be the major occupational hazard for the workers of industries. The predominant noise sources need to be identified and the causes of high noise need to be studied to undertake the appropriate measures to reduce the noise level in one of the major agro-based industries, oil mills.Aims:To identify the predominant noise sources in the workrooms of oil mills. To study the causes of noise in oil mills. To measure the extent of noise exposure of oil mill workers. To examine the response of workers towards noise, so that appropriate measures can be undertaken to minimize the noise exposure.Settings and Design:A noise survey was conducted in the three renowned oil mills of north-eastern region of India.Materials and Methods:Information like output capacity, size of power source, maintenance condition of the machines and workroom configurations of the oil mills was collected by personal observations and enquiry with the owner of the mill. Using a Sound Level Meter (SLM) (Model-824, Larson and Davis, USA), equivalent SPL was measured at operator's ear level in the working zone of the workers near each machine of the mills. In order to study the variation of SPL in the workrooms of the oil mill throughout its operation, equivalent SPL was measured at two appropriate locations of working zone of the workers in each mill. For conducting the noise survey, the guidelines of Canadian Centre for Occupational Health and Safety (CCOHS) were followed. Grid points were marked on the floor of the workroom of the oil mill at a spacing of 1 m × 1 m. SPL at grid points were measured at about 1.5 m above the floor. The direction of the SLM was towards the nearby noisy source. To increase accuracy, two replications were taken at each grid point. All the data were recorded for 30 sec. At the end of the experiment, data were downloaded to a personal computer. With the help of utility software of Larson and Davis, USA, equivalent SPL and noise spectrum at each reading was obtained. Noise survey map of equivalent SPL was drawn for each oil mill by drawing contour lines on the sketch of the oil mill between the points of equal SPL. The floor area in the oil mill where SPL exceeded 85 dBA was identified from the noise survey map of each oil mill to determine the causes of high level of noise. Subjective assessment was done during the rest period of workers and it was assessed with personal interview with each worker separately. Demographic information, nature of work, working hours, rest period, experience of working in the mill, degree of noise annoyance, activity interference, and psychological and physiological effects of machine noise on the worker were asked during the interview. These details were noted in a structured form.Statistical Analysis Used:Nil.Results:The noise survey conducted in three renowned oil mills of north-eastern region of India revealed that about 26% of the total workers were exposed to noise level of more than 85 dBA. Further, 10% to 30% floor areas of workrooms, where oil expellers are provided have the SPL of more than 85 dBA. The noise in the oil mills was dominated by low frequency noise. The predominant noise sources in the oil mills were seed cleaner and power transmission system to oil expellers. Poor maintenance of machines and use of bamboo stick to prevent the fall of belt from misaligned pulleys were the main reason of high noise. Noise emitted by the electric motor, table ghani and oil expellers in all the oil mills was well within 85 dBA. Subjective response indicated that about 63% of the total workers felt that noise interfered with their conversation. About 16% each were of the opinion that noise interfered in their work and harmed their hearing. About 5% of workers stated that the workroom noise gave them headaches.Conclusions:The workers engaged in the workrooms of the oil mills are exposed to high noise, which will have detrimental effect on their health. The poor maintenance of drive system was found to be the main reason for high noise level.

Iris pigmentation and susceptibility to noise-induced hearing loss

The purpose of this retrospective study is to examine the possible association between iris pigmentation and susceptibility to noise-induced hearing loss in 2407 noise-exposed workers. The workers were between 16 to 65 years of age and were exposed to 2 to 42 years of work-related noise. Results demonstrated that dark-eyed workers presented a greater percentage of normal pure-tone thresholds than fair-eyed workers. Fair-eyed workers had threshold averages of 25.1 dB (right ear) and 26.0 dB (left ear) at 3, 4, and 6 kHz, which were significantly worse than workers with dark irises, with threshold averages of 15.8 dB and 17.2 dB in the right and left ear, respectively (p<0.01). Fair-eyed workers with less than 10 years of noise exposure had the same audiometric pattern as the dark-eyed workers exposed for more than 10 years. Workers not exposed to noise did not present significant differences in their audiometric pattern as a function of eye colour. These results suggest that iris pigmentation may be an additional indication of susceptibility to noise-induced hearing loss.

Blood Pressure and Serum Lipids in Industrial Workers under Intense Noise and a Hot Environment

The aim of the study was to follow the rate of high blood pressure and dyslipidemia in industrial workers in relation to experience under intense noise and a hot environment. We studied 545 male industrial workers comprising 271 subjects working under intense noise (86 to 92 dba), 159 subjects exposed to heat [wet bulb globe temperature of 35.4 degrees C (28.4-41.7 degrees C)], and a control group of 115 subjects with experience of <9; 10-19, or >20 y, which paralleled the age groups of young (< 32 y); middle-aged (33-45 y), and aged workers (> 46 y). Arterial pressure, anthropometric variables, lipid status, smoking, and alcohol use were monitored. The rate of blood pressure > 140/90 mmHg was significantly higher in noise-exposed middle-aged workers and in both exposed groups of aged workers (p < .05). The rate of dyslipidemia was significantly higher in heat-exposed middle-aged workers and in both exposed groups of aged workers (p < .05). Summing up, our data suggest that long-term work under intensive noise or in a hot environment is associated with a greater chance of becoming hypertensive and dyslipidemic. Exposure to noise was related to elevated blood pressure, whereas heat exposure was related to deviations in serum lipids.

Associations of blood pressure and arterial compliance with occupational noise exposure in female workers of textile mill

There are few studies on the arterial compliance of noise exposure. The purpose of this study was to understand the relationship between hearing loss, blood pressure and arterial compliance of female workers who exposed to occupational noise in a textile mill. The noise levels in the workplace were measured with a HS6288 sound level meter. Cumulated noise exposure (CNE) was calculated according to the noise intensity and the exposure period. Hearing ability and arterial compliance were measured in 618 noise exposed workers. The database was set up with EpiData and the statistical analysis was performed with SAS software 9.1.3. The noise levels were 80.1dB (A) to 113.5dB (A), of which the levels at 92.5% of the noise monitoring sites were over the national standard. The incidence of high frequency hearing loss (HFHL) was 24.43% and language frequency hearing impairment (LFHI) was 0.81%. The incidence of hypertension was 7.93%. Both systolic blood pressure (SBP) and diastolic blood pressure (DBP) in the high frequency hearing loss group were significantly higher than those in the normal hearing group (P < 0.05), while C(1) (large artery compliance) and C(2) (small artery compliance) were significantly lower (P < 0.05). The high frequency hearing threshold (HFHT) of the hypertension group was significantly higher than in the normal blood pressure group (P < 0.05), while C(1) and C(2) were significantly lower (P < 0.05). C(1) and C(2) had a negative correlation with HFHT, SBP, DBP, mean of arterial pressure (MAP), pulse pressure (PP) and pulse rate (PR) (P < 0.05). The multiple regression analyses showed that blood pressure and PR were the main influencing factors on C(1) and C(2). LFHT was an influence on C(2) and HFHT on C(1). Textile mill noise pollution is very serious and has an obvious influence on worker's auditory function. The female workers with low artery compliance or with high blood pressure might be suffering from hearing loss; those with noise induced hearing loss might be suffering from hypertension if she is constantly exposed to loud industrial noise.

Deterioration of noise-induced hearing loss among bottling factory workers

Repeated exposure to excessive noise will eventually lead to an irreversible increase in hearing thresholds. In theory, the damage reflects both the intensity of the noise and the duration of exposure. This is not linear with respect to duration of exposure; rather, the worker may experience a disproportionate loss in the early years of exposure. A prospective study surveying workers of the production section (i.e. most noise-exposed area) of a bottling factory was carried out in December 2003 and in December 2005. A self-administered questionnaire was used to extract information about worker's demographic characteristics, drug intake, and medical and occupational history, as well as information on the use of hearing protection devices. Noise mapping of the various departments of the factory was carried out. Otological examination, tympanometry and audiometry were also carried out on selected subjects. Eighty-four workers, 76 (90.5 per cent) men and eight (9.5 per cent) women, were studied. Their mean age was 33.0 +/- 7.6 years in 2003 and 35.0 +/- 7.6 years in 2005. The recorded noise levels in the factory production section ranged between 91.5 and 98.7 dBA. The prevalence of sensorineural hearing loss among workers was noted to be 64.9 and 86.9 per cent for test one (2003) and test two (2005), respectively. The degree of hearing deterioration within the two years of this study was 1.0-3.2 dB for the right ear and 1.6-3.4 dB for the left ear. This deterioration was at discrete frequencies. More than half (53.6 per cent) of the workers did not have a hearing protection device. Of the 46.4 per cent who did, only 38.5 per cent claimed to have used it regularly. These findings showed that there was a high prevalence of mild sensorineural hearing loss and significant hearing deterioration among workers, due to exposure to excessive noise over a two-year period. The study demonstrates the practical importance of serial audiometry for noise-exposed workers as a means of monitoring hearing deterioration. It is necessary to enforce existing occupational health laws in our industries in order to prevent noise-induced hearing loss, since it is eminently preventable.

Measurement and analysis of personal noise exposure in a city metro

To measure and analyze the personal noise exposure of city metro station workers by using noise dosimeter. According to job category and work type, all workers were divided into 4 groups. The workers from each group were selected as subjects for personal noise exposure measurement. CEL-320 dosimeters were worn by each subject and noise data collected by a phone fixed at collar. All subjects were asked to take notes about their working activities when they were wearing CEL-320 dosimeters. Each worker's one workday LAeq, geometric mean and range of each group were computed. There were many noise sources in the metro station, and the noise exposure was unstable. The varieties of personal noise levels were recorded among 48 workers, the highest LAeq work type was of the instrument room, (81.8 +/- 2.5) dB (A), and the biggest LAeq rang was of the hall, 8.1 dB (A). The lowest LAeq was of the station control room (68.7 +/- 1.8) dB (A) and the lowest LAeq rang also was there, 4.0 dB (A). The personal noise exposure of metro station should be implicated. Measuring personal noise exposure individually with dosimeters might obtain the noise exposure level more integrally in the complicated environment.

Environmental noise-exposed workers: Event-related potentials, neuropsychological and mood assessment

Prolonged environmental noise exposure can induce pathogenic effects on various physical and psychosocial responses. The first aim of this study was to investigate whether long-term occupational noise exposure could affect neurophysiological, neuropsychological and emotional statuses, with particular respect to attention and working memory. The second aim was to evaluate the effects on the tactile P300 of a specific stressor (background traffic noise) vs a non-specific stress inductor (Stroop test). The comparison between a group of noise-exposed workers (traffic police officers), and a control group (office employees) did not show marked differences in cognitive and emotional profiles. The amplitude of the baseline cognitive potential (P300), recorded during a tactile (electric) discrimination task, resulted higher in noise-exposed workers than in controls, and this enhancement was associated with a lower level of trait anxiety and better mood profiles. Moreover, we found a wider P300 amplitude reduction in traffic police officers than in controls, under noisy conditions due to traffic. The effect of the Stroop test as a stress inductor was negligible and similar in the two groups. The wider amplitude of the non-auditory P300 in traffic police officers in the baseline condition could be a sign of cross-modal cerebral plasticity enhancing attentive processes in the ‘stress-free’ sensory channel. In addition, noise-exposed workers presented a higher cerebral sensitivity to stress selectively when they were exposed to the habitual environmental stressor.

Worker noise exposures from diesel and electric surface coal mining machinery

A comparative study of noise produced from diesel and electric mining machinery in an opencast coal mine was made. It was found that the diesel machines produced higher environmental noise than the electric machines. The projected and measured operator's noise dose for 8-hour also showed that the diesel machines produced higher noise than the electric machines. The recorded sound levels and the noise dose for different machines and the crusher house were compared with the regulatory limits. With electric drill machines, drilling in hard rock produced higher noise levels than drilling in soft rock. This can be used to characterize the rock for blast designs.

Survey of noise in coal preparation plants

In response to the continuing problem of noise induced hearing loss (NIHL) among mine workers, the National Institute for Occupational Safety and Health (NIOSH) has conducted numerous noise surveys in coal preparation plants. The research, consisting of worker dose monitoring, task observations, and equipment noise profiling, was completed in eight separate preparation plants. Worker dose monitoring was conducted for three shifts in most cases. Workers experiencing higher than allowable doses were task-observed for one full shift to correlate dose to noise source(s). Finally, noise levels on all floors, and in lunch rooms and control rooms, were characterized. Results indicate that only workers who routinely spend a significant portion of their shift in the plants (away from the control rooms) are susceptible to overexposure from noise. Certain pieces of equipment (screens, centrifuges, sieve bends) are the loudest primary noise sources responsible for the worker noise exposures.

Audiogram Notches in Noise-Exposed Workers

Diagnostic criteria for noise-induced hearing loss include the audiometric notch, yet no standardized definition exists. This study tested whether objective notch metrics could match the clinical judgments of an expert panel. A panel of occupational physicians, otolaryngologists, and audiologists reviewed audiograms of noise-exposed workers. In a two-sample process, the panel judged whether a notch was present and whether hearing loss had progressed in a notch pattern. Quantitative notch metrics were compared against expert decisions. At least five of six experts agreed about notch identification in 71 and 72% of the cases in the two samples, and agreement about notch progression was 61 and 67%. Notch depth and professional specialty appeared to affect notch judgments. Despite this variability, a notch metric showed excellent agreement with expert notch consensus in each sample (94.7 and 96.6%; kappa = 0.88 and 0.92). Audiogram notch metrics can agree with expert clinical consensus and assist in the surveillance of noise-exposed workers.

Influence of source directivity on noise levels in industrial halls: Simulation and experiments

Noise exposure of workers in industrial halls is mainly induced by noisy machines whose acoustical features are often globally known by Sound Pressure Level. The evaluation of the directivity of these noise sources can help to anticipate specific solutions for noise reduction. This study shows how the directivities of three wood-working machines have been characterized. Some characterisations have been achieved with a simple and fast acoustical intensity mapping which meets the constraints of industrial areas. When source directivity is evaluated, its influence on the noise field in industrial halls can be assessed. Some simulations and some experiments allowed the estimation of the noise field induced in workshops by both directional and omnidirectional sources. Comparison of the fields prove that the noise distribution is influenced by the source directivity if the halls are empty. As soon as the halls contain scattering objects, the directivity effect is reduced a lot and the noise field remains nearly the same far from the source whatever source used. Nevertheless, workers close to a machine are exposed to noise according to their position with respect to the machine. Exposure at the workplace can vary from 4 to 8 dB(A) according to the directivity of machines such as those measured in the trials.

The contribution of genes involved in potassium-recycling in the inner ear to noise-induced hearing loss

Noise-induced hearing loss (NIHL) is one of the most important occupational diseases and, after presbyacusis, the most frequent cause of hearing loss. NIHL is a complex disease caused by an interaction between environmental and genetic factors. The various environmental factors involved in NIHL have been relatively extensively studied. On the other hand, little research has been performed on the genetic factors responsible for NIHL. To test whether the variation in genes involved in coupling of cells and potassium recycling in the inner ear might partly explain the variability in susceptibility to noise, we performed a case-control association study using 35 SNPs selected in 10 candidate genes on a total of 218 samples selected from a population of 1,261 Swedish male noise-exposed workers. We have obtained significant differences between susceptible and resistant individuals for the allele, genotype, and haplotype frequencies for three SNPs of the KCNE1 gene, and for the allele frequencies for one SNP of KCNQ1 and one SNP of KCNQ4. Patch-clamp experiments in high K+-concentrations using a Chinese hamster ovary (CHO) cell model were performed to investigate the possibility that the KCNE1-p.85N variant (NT_011512.10:g.21483550G>A; NP_00210.2:p.Asp85Asn) was causative for high noise susceptibility. The normalized current density generated by KCNQ1/KCNE1-p.85N channels, thus containing the susceptibility variant, differed significantly from that from wild-type channels. Furthermore, the midpoint potential of KCNQ1/KCNE1-p.85N channels (i.e., the voltage at which 50% of the channels are open) differed from that of wild-type channels. Further genetic and physiological studies will be necessary to confirm these findings.

Measurement of personal noise exposure in a cold rolling mill

To measure and evaluate the personal noise exposure of cold rolling mill workers by using noise dosimeter. According to job category and work type, all workers were divided into 11 groups. 3 to 5 day shift (8:00 to 16:00) workers from each group were selected as subjects for personal noise exposure measurement. SH-126 dosimeters were worn by each subject and collect noise data by a phone fix at collar. All subjects were asked to take notes about their working activities when they were wearing SH-126 dosimeters. Each worker's L(A)(eq) of 8 hours, geometric mean and range of each group were computed. There were many noise sources in the workshop. Recorded data showed that noise exposure of cold rolling mill was unstable. The varieties of personal noise levels were quite large. Among 53 workers, the highest noise exposure level was 100.0 dB (A), the lowest was 81.2 dB (A); the highest work type was of the foreside welders [94.20 dB (A)], and the lowest was of the straight-cutters [89.02 dB (A)]; quality checkers had the biggest rang [16.3 dB (A)], and primary rolling workers had the lest [2.3 dB (A)]. Noise exposure of all the 11 groups were more than 85 dB (A). Noise protection of these workers should be improved. It suggested that measuring personal noise exposure individually with dosimeters might obtain the noise exposure level more integrally in the complicated environment.

Audiological findings in workers exposed to styrene alone or in concert with noise

Audiological testing, interviews and exposure measurements were used to collect data on the health effects of styrene exposures in 313 workers from fiberglass and metal-product manufacturing plants and a mail terminal. The audiological test battery included pure-tone audiometry, distortion product otoacoustic emissions (DPOAE), psychoacoustic modulation transfer function, interrupted speech, speech recognition in noise and cortical response audiometry (CRA). Workers exposed to noise and styrene had significantly poorer pure-tone thresholds in the high-frequency range (3 to 8 kHz) than the controls, noise-exposed workers and those listed in a Swedish age-specific database. Even though abnormalities were noted on DPOAE and CRA testing, the interrupted speech and speech recognition in noise tests were the more sensitive tests for styrene effects. Further research is needed on the underlying mechanisms to understand the effects of styrene and on audiological test batteries to detect changes in populations exposed to solvents.

Total non-occupational noise exposure of construction workers

Total non-occupational noise exposure of construction workers

Associação entre perda auditiva induzida pelo ruído e zumbidos

The objective of this study was to verify an association between noise-induced hearing loss (NIHL) and tinnitus in workers exposed to occupational noise. Workers with a history of work noise exposure who attended two audiology outpatient clinics were interviewed and evaluated. The statistical association between NIHL and tinnitus was evaluated using an adjusted linear regression model, with tinnitus as the dependent variable and NIHL, classified into six levels, as the independent variable, with age and length of noise exposure as covariates. Data were collected from 284 workers between April and October, 2003, in Bauru, São Paulo State, Brazil. Tinnitus was observed to increase with the progression of auditory damage, controlled by age and length of noise exposure. These results suggest that investment in hearing conservation programs is needed, especially for source noise emission control and for intervention in hearing loss progression that is caused by noise exposure, in order to maintain auditory health and reduce the associated symptoms.

Working in Noise with a Hearing Loss: Perceptions from Workers, Supervisors, and Hearing Conservation Program Managers

Workers with hearing loss face special problems, especially when working in noise. However, conventional hearing conservation practices do not distinguish between workers with normal hearing versus impaired hearing. This study collected information from workers with self-reported noise exposure and hearing loss, supervisors of such workers, and hearing conservation program managers through focus groups and in-depth interviews to evaluate their perspectives on the impact of hearing loss on safety and job performance, the use of hearing protection, and information needed to appropriately manage hearing-impaired workers who work in noisy environments. Concerns about working in noise with a hearing loss could be grouped into the following 10 categories: impact on job performance, impact on job safety, impaired ability to hear warning signals, impaired ability to monitor equipment, interference with communication, stress and/or fatigue, impaired communication caused by hearing protector use, reduced ability to monitor the environment as the result of hearing protector use, concerns about future quality of life, and concerns about future employability. Mostly, there was an agreement between the perceptions of workers, supervisors, and hearing conservation program managers regarding difficulties associated with hearing loss and consequent needs. These findings suggest that noise-exposed workers with hearing loss face many of the same problems reported in the literature by noise-exposed workers with normal hearing, with additional concerns primarily about job safety as the result of a reduced ability to hear environmental sounds, warning signals, and so forth. The study outlines potential challenges regarding job safety and hearing conservation practices for noise-exposed, hearing-impaired workers. Awareness of these issues is a necessary first step toward providing appropriate protective measures for noise-exposed, hearing-impaired workers.

Total Non-Occupational Noise Exposure of Construction Workers

Total non-occupational noise exposure levels were estimated for a group of 266 construction apprentices participating in a longitudinal study of noise and hearing loss. Subjects were interviewed regarding their exposure to “episodic” activities (e.g., concert attendance), and noise levels for these activities were obtained from a literature review. “Routine” activities were assessed using a combination of self-reported activity logs and non-occupational noise dosimetry measurements. Routine and episodic activity exposures were combined into estimated annual Leq exposure levels for the 6760 nominal non-occupational hours in a year (LAeq6760h). The LAeq6760h levels were then transformed into equivalent levels for a 2000 hour exposure period (LA2000hn), which allowed direct comparison to occupational risk criteria. The median LAeq6760h was 73 dBA, and the median LA2000hn was 78 dBA. Nineteen percent of LA2000hn non-occupational exposures exceeded 85 dBA, the generally recommended occupational limit. Firearms use could not be incorporated into the total noise exposure estimates. However, firearms users reported more exposure to other noisy non-occupational activities than did non-shooters, and had higher estimated exposure levels even without including their firearms exposure. Non-occupational noise exposures among most construction workers present little additional exposure when compared to their occupational exposures. However, they may contribute significantly to overall exposure in the subset of workers who frequently participate in selected noisy activities.