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Variability and Determinants of Occupational Noise Exposure Among Iron and Steel Factory Workers in Tanzania.

ABSTRACT: Background:Machines, processes, and tasks in the iron and steel factories may produce noise levels that are harmful to hearing if not properly controlled. Studies documenting noise exposure levels and related determinants in sub-Saharan Africa, including Tanzania are lacking. The aim of this study was to document noise exposure and to identify determinants of noise exposure with a view to establishing an effective hearing conservation programme. Methods:A walk-through survey was conducted to describe the working environment in terms of noise sources in four metal factories (A-D) in Tanzania. Noise measurements were conducted by both personal, full-shift noise measurements (8 h) using dosimeters and area measurements (10-s measurements) using a sound level meter. A total of 163 participants had repeated personal noise measurements (Factory A: 46 participants, B: 43, C: 34, and D: 40). Workers were randomly selected and categorized into 13 exposure groups according to their job. Linear mixed effects models were used to identify significant determinants of noise exposure in the furnace section and the rolling mill section. Results:The average personal noise exposure in the four factories was 92.0 dB(A) (range of job group means; 85.4-96.2 dB(A)) (n = 326). Personal exposure was significantly higher in the rolling mill section (93.0 dB(A)) than in the furnace section (89.6 dB(A)). Among the job groups, the cutters located in the rolling mill section had the highest noise exposure (96.2 dB(A)). In the furnace section, furnace installation (below the ground floor), manual handling of raw materials/billets/crowbars, and billet weighing/transfer were significant determinants explaining 40% of the total variance in personal noise exposure. In the rolling mill section, the size of the cutting machine, steel billet weight and feeding re-heating furnace explained 46% of the total variance in personal noise exposure. The mean noise level of the area measurements was 90.5 dB(A) (n = 376). Conclusion:Workers in the four iron and steel factories in Tanzania were exposed to average noise of 92.0 dB(A), without using hearing protection, implying a high risk of developing hearing loss. Task and factory level determinants were identified in the furnace and the rolling mill sections of the plant, which can inform noise control in factories with similar characteristics.

SUBMITTER: Nyarubeli IP

PROVIDER: S-EPMC6231025 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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Variability and Determinants of Occupational Noise Exposure Among Iron and Steel Factory Workers in Tanzania.

Nyarubeli Israel P IP Tungu Alexander M AM Bråtveit Magne M Sunde Erlend E Kayumba Akwilina V AV Moen Bente E BE

Annals of work exposures and health 20181101 9

<h4>Background</h4>Machines, processes, and tasks in the iron and steel factories may produce noise levels that are harmful to hearing if not properly controlled. Studies documenting noise exposure levels and related determinants in sub-Saharan Africa, including Tanzania are lacking. The aim of this study was to document noise exposure and to identify determinants of noise exposure with a view to establishing an effective hearing conservation programme.<h4>Methods</h4>A walk-through survey was c ...[more]

PMID: 30113644

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Project description:BackgroundThe 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.MethodsThis 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.ResultsOccupational 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).ConclusionAlmost 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.

Project description:BackgroundOccupational respiratory disorders are a major global public health concern among workers exposed to dust particles in dust-generating workplaces. Despite fragmented research findings on the magnitude of respiratory problems and the lack of a national occupational respiratory disease recording and reporting system at the Ethiopian factory, the prevalence of respiratory symptoms among factory workers were unknown. Therefore, the aim of this meta-analysis was to summarize and pool estimates from studies that reported the prevalence of respiratory symptoms and predictors among Ethiopian factory workers who worked in dusty environments.MethodsA systematic literature searches were conducted using electronic databases (PubMed, Science Direct, African Journals Online, and Web of Science). The primary and secondary outcomes were prevalence of respiratory symptoms and predictors, respectively. The STATA version 17 was used to analyze the data. A random effect meta-analysis model was used. Eggers test with p-value less than 5%, as well as the funnel plot, were used to assess publication bias.ResultsThe searches yielded 1596 articles, 15 of which were included in the systematic review and meta-analysis. The pooled prevalence of respiratory symptoms among Ethiopian factory workers was 54.96% [95% confidence interval (CI):49.33-60.59%]. Lack of occupational health and safety (OSH) training [Odds Ratio (OR) = 2.34, 95%CI:1.56-3.52], work experience of over 5 years [OR = 3.19, 95%CI: 1.33-7.65], not using personal protective equipment (PPE) [OR = 1.76, 95%CI:1.30-2.39], and working more than eight hours per day [OR = 1.89, 95%CI:1.16-3.05] were all significant predictors of respiratory symptoms.ConclusionThe prevalence of respiratory symptom was found to be high in Ethiopian factory workers. To prevent workers from being exposed to dust, regular provision and monitoring of PPE use, workers OSH training, and adequate ventilation in the workplace should be implemented.

Project description:BackgroundSouth Korea and surrounding countries in East Asia are believed to have the highest proportion in the world of high frequency hearing loss due to occupational noise exposure, yet there has been limited information published in international journals, and limited information for control of noise in local workplaces beyond strategies from western countries. We exploit medical surveillance information from two worker groups to enhance local knowledge about noise-induced hearing loss and explore the possible importance of shift work to risk.MethodsFour-years of hearing data were evaluated for 81 male farm machine factory workers and 371 male firefighters who had successfully completed a health examination and questionnaires for the duration of the study period. The averages of hearing thresholds at 2, 3, and 4 kHz were used as the primary end-point for comparison. Repeat measure analysis adjusted for age, exposure duration and smoking status was used to measure the difference in hearing threshold between the two groups.ResultsNoise levels were measured in the factory at a mean of 82 dBA, with a range of 66-97. No concurrent measurements were taken for the firefighters, but historic comparison values showed a wider range but a similar mean of 76-79 dBA. Although losses during follow-up were negligible, the factory workers had significantly (P < 0.0001) more hearing loss at the baseline of the study than the firefighters in both ears at 2, 3, and 4 kHz, adjusted for age, duration of employment and smoking status. Among those with 10 years of employment, mean losses at these frequencies among the factory workers fell into the impairment range (> 25 dB loss). Firefighters also showed increased losses associated with longer exposure duration, but these were significantly less marked. Losses at lower frequencies (< or = 1 kHz) were negligible in both groups.ConclusionsKorean work environments with continuous noise exposure in the measured range should consider implementation of a hearing conservation program. Further evaluation of hearing loss in workers exposed to irregular or intermittent high noise levels, such as firefighters, is also warranted.

Project description:The aim was to assess the risk of hyperacusis in relation to occupational noise exposure among female workers in general, and among women working in preschool specifically. A retrospective longitudinal study was performed. Survey data were collected in 2013 and 2014 from two cohorts: randomly selected women from the population in region Västra Götaland, Sweden, and women selected based on having received a preschool teacher degree from universities in the same region. The final study sample included n = 8328 women born between 1948 and 1989. Occupational noise exposure was objectively assigned to all time periods from the first to the last reported occupation throughout working life, using the Swedish Job-Exposure Matrix (JEM) with three exposure intervals: <75 dB(A), 75 to 85 dB(A), and >85 dB(A). The JEM assigns preschool teachers to the 75 to 85 dB(A) exposure interval. The outcome hyperacusis was assessed by self-report using one question addressing discomfort or pain from everyday sounds. In the main analysis, a hyperacusis event was defined by the reported year of onset, if reported to occur at least a few times each week. Additional sensitivity analyses were performed using more strict definitions: (a) at least several times each week and (b) every day. The risk (hazard ratio, HR) of hyperacusis was analyzed in relation to years of occupational noise exposure, using survival analysis with frailty regression modeling accounting for individual variation in survival times which reflect, for example, noise exposure during years prior to onset. Occupational noise exposure was defined by the occupation held at year of hyperacusis onset, or the occupation held at the survey year if no event occurred. Models were adjusted for confounders including age, education, income, family history of hearing loss, and change of jobs due to noise. In total, n = 1966 hyperacusis events between 1960 and 2014 were analyzed in the main analysis. A significantly increased risk of hyperacusis was found among women working in any occupation assigned to the 75 to 85 dB(A) noise exposure group [HR: 2.6, 95% confidence interval (CI): 2.4-2.9], compared with the reference group <75 dB(A). The risk was tripled among preschool teachers specifically (HR: 3.4, 95% CI: 3.0-3.7), with the crude Kaplan-Meier curve showing a higher rate of onset early in the working life in preschool teachers compared with all the other exposure groups. The risk was increased, but not statistically significant in the main analysis, for the highest exposure group >85 dB(A), where only six hyperacusis events were identified (HR: 1.4, 95% CI: 0.6-3.1). In the sensitivity analysis, where hyperacusis was defined as occurring every day, the HR was significant also in the highest exposure group (HR: 3.8, 95% CI: 1.4-10.3), and generally slightly higher in the other exposure groups compared to the main analysis. This study indicates increased risk of hyperacusis already below the permissible occupational noise exposure limit in Sweden (85 dB LAeq,8h) among female workers in general, and in particular among preschool teachers. Prospective studies and less wide exposure intervals could confirm causal effects and assess dose-response relationships, respectively, although this study at present suggest a need for risk assessment, improved hearing prevention measures, and noise abatement measures in occupations with noise levels from 75 dB(A). The results could also have implications for management of occupational disability claims.

Project description:IntroductionAn 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.MethodsA 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.ResultsThe 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.ConclusionsOccupational 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.

Dataset Information

Variability and Determinants of Occupational Noise Exposure Among Iron and Steel Factory Workers in Tanzania.

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Variability and Determinants of Occupational Noise Exposure Among Iron and Steel Factory Workers in Tanzania.

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