Occupational Noise Exposure and the Risk of Stroke

MiRNA-92a-3p mediated the association between occupational noise exposure and blood pressure among Chinese adults

Evidence on the association between occupational noise exposure and blood pressure is inconsistent, and the underlying mechanism remains unknown. This study aimed to evaluate the association between occupational noise exposure and blood pressure, and explore the potential role of miRNAs in the association. A total of 894 subjects from two companies in Wuhan, China were included. Occupational noise exposure was assessed using cumulative noise exposure (CNE), and six candidate plasma miRNAs (miR-92a-3p, miR-21-5p, miR-200a-3p, miR-200b-3p, miR-200c-3p, and miR-1-3p) which were not only associated with blood pressure/hypertension but also related to oxidative stress were selected according to previous studies and tested. A linear dose-response relationship was found between occupational noise exposure and blood pressure, including systolic blood pressure (SBP) and diastolic blood pressure (DBP). Each 1-unit increase in CNE levels was significantly associated with a 0.130 (95 % confidence interval [CI] = 0.026, 0.234) unit increase in SBP and a 0.141 (95 % CI = 0.063, 0.219) unit increase in DBP. However, the association between occupational noise and hypertension is not statistically significant (P > 0.05). In the meanwhile, occupational noise exposure was negatively associated with miRNA-92a-3p (β = -0.019, 95 % CI = -0.032, -0.006) and miRNA-21-5p (β = -0.031, 95 % CI = -0.052, -0.010), and miRNA-92a-3p mediated 24.66 % of the association between occupational noise exposure and DBP. In addition, bilateral high-frequency hearing loss was not only positively associated with occupational noise exposure (OR = 1.974, 95 % CI = 1.084, 3.702) but also DBP (β = 2.546, 95 % CI = 0.160, 4.932). Our study suggests that occupational noise exposure is positively associated with SBP and DBP, and miRNA-92a-3p partially mediate the association between occupational noise exposure and DBP.

Occupational Risk Factors for Stroke: A Comprehensive Review

For primary prevention, it is important for public health and clinical medicine to identify and characterize modifiable risk factors of stroke. In existing literature, the impact of occupational variables on ischemic and hemorrhagic stroke has been extensively studied. This review summarizes the available data on the significance of occupational variables in stroke. The results of this review suggest that there is sufficient evidence for the relationship between increased risk of stroke and job stress, working in extreme temperatures, long working hours, and/or shift work. The association between long working hours and occupational exposure to noise and chemicals remains inconclusive although several studies have reported this finding. This review will act as a step toward future research and provide information that may serve as a baseline for developing targeted interventions to prevent stroke in the working population.

Occupational exposure to noise and dust in Swedish soft paper mills and mortality from ischemic heart disease and ischemic stroke: a cohort study

OBJECTIVE

To elucidate whether occupational noise exposure increases the mortality from ischemic heart disease (IHD) and stroke, and if exposure to paper dust modified the risks.

METHODS

We studied 6686 workers from soft paper mills, with occupational noise exposure, < 85 dBA, 85-90 dBA and > 90 dBA, and high (> 5 mg/m3) exposure to paper dust. Person-years 1960-2019 were stratified according to gender, age, and calendar-year. Expected numbers of deaths were calculated using the Swedish population as the reference and standardized mortality ratios (SMR) with 95% confidence intervals (95% CI) were assessed.

RESULTS

SMR for IHD was 1.12 (95% CI 0.88-1.41) for noise < 85 dBA, 1.18 (95% CI 0.90-1.55) for 85-90 dBA, and 1.27 (95% CI 1.10-1.47) among workers exposed > 90 dBA. Joint exposure to high noise exposure and high exposure to paper dust resulted in slightly higher IHD mortality (SMR 1.39, 95% CI 1.15-1.67). SMR for ischemic stroke was 0.90 (95% CI 0.37-2.15) for noise < 85 dBA, 1.08 (95% CI 0.45-2.59) for 85-90 dBA, and 1.48 (95% CI 0.99-2.00) among workers exposed > 90 dBA. High noise exposure and high exposure to paper dust resulted in higher ischemic stroke mortality (SMR 1.83, 95% CI 1.12-2.98).

CONCLUSION

Noise levels > 90 dBA was associated with increased IHD mortality. Combined exposures of noise and paper dust may further increase the risks. Our results do not provide support for a causal relationship for ischemic stroke. Residual confounding from smoking has to be considered. Workers need to be protected from occupational noise levels exceeding 90 dBA.

Occupational noise exposure and risk of incident stroke: a pooled study of five Scandinavian cohorts

OBJECTIVES

To investigate the association between occupational noise exposure and stroke incidence in a pooled study of five Scandinavian cohorts (NordSOUND).

METHODS

We pooled and harmonised data from five Scandinavian cohorts resulting in 78 389 participants. We obtained job data from national registries or questionnaires and recoded these to match a job-exposure matrix developed in Sweden, which specified the annual average daily noise exposure in five exposure classes (LAeq8h): <70, 70-74, 75-79, 80-84, ≥85 dB(A). We identified residential address history and estimated 1-year average road traffic noise at baseline. Using national patient and mortality registers, we identified 7777 stroke cases with a median follow-up of 20.2 years. Analyses were conducted using Cox proportional hazards models adjusting for individual and area-level potential confounders.

RESULTS

Exposure to occupational noise at baseline was not associated with overall stroke in the fully adjusted models. For ischaemic stroke, occupational noise was associated with HRs (95% CI) of 1.08 (0.98 to 1.20), 1.09 (0.97 to 1.24) and 1.06 (0.92 to 1.21) in the 75-79, 80-84 and ≥85 dB(A) exposure groups, compared with <70 dB(A), respectively. In subanalyses using time-varying occupational noise exposure, we observed an indication of higher stroke risk among the most exposed (≥85 dB(A)), particularly when restricting analyses to people exposed to occupational noise within the last year (HR: 1.27; 95% CI: 0.99 to 1.63).

CONCLUSIONS

We found no association between occupational noise and risk of overall stroke after adjustment for confounders. However, the non-significantly increased risk of ischaemic stroke warrants further investigation.

The effect of occupational exposure to noise on ischaemic heart disease, stroke and hypertension: A systematic review and meta-analysis from the WHO/ILO Joint Estimates of the Work-Related Burden of Disease and Injury

BACKGROUND

The World Health Organization (WHO) and the International Labour Organization (ILO) are developing joint estimates of the work-related burden of disease and injury (WHO/ILO Joint Estimates), with contributions from a large number of individual experts. Evidence from mechanistic data suggests that occupational exposure to noise may cause cardiovascular disease (CVD). In this paper, we present a systematic review and meta-analysis of parameters for estimating the number of deaths and disability-adjusted life years from CVD that are attributable to occupational exposure to noise, for the development of the WHO/ILO Joint Estimates.

OBJECTIVES

We aimed to systematically review and meta-analyse estimates of the effect of any (high) occupational exposure to noise (≥85 dBA), compared with no (low) occupational exposure to noise (<85 dBA), on the prevalence, incidence and mortality of ischaemic heart disease (IHD), stroke, and hypertension.

DATA SOURCES

A protocol was developed and published, applying the Navigation Guide as an organizing systematic review framework where feasible. We searched electronic academic databases for potentially relevant records from published and unpublished studies up to 1 April 2019, including International Trials Register, Ovid MEDLINE, PubMed, Embase, Lilacs, Scopus, Web of Science, and CISDOC. The MEDLINE and Pubmed searches were updated on 31 January 2020. We also searched grey literature databases, Internet search engines and organizational websites; hand-searched reference lists of previous systematic reviews and included study records; and consulted additional experts.

STUDY ELIGIBILITY AND CRITERIA

We included working-age (≥15 years) workers in the formal and informal economy in any WHO and/or ILO Member State but excluded children (<15 years) and unpaid domestic workers. We included randomized controlled trials, cohort studies, case-control studies and other non-randomized intervention studies with an estimate of the effect of any occupational exposure to noise on CVD prevalence, incidence or mortality, compared with the theoretical minimum risk exposure level (<85 dBA).

STUDY APPRAISAL AND SYNTHESIS METHODS

At least two review authors independently screened titles and abstracts against the eligibility criteria at a first stage and full texts of potentially eligible records at a second stage, followed by extraction of data from qualifying studies. We prioritized evidence from cohort studies and combined relative risk estimates using random-effect meta-analysis. To assess the robustness of findings, we conducted sensitivity analyses (leave-one-out meta-analysis and used as alternative fixed effects and inverse-variance heterogeneity estimators). At least two review authors assessed the risk of bias, quality of evidence and strength of evidence, using Navigation Guide tools and approaches adapted to this project.

RESULTS

Seventeen studies (11 cohort studies, six case-control studies) met the inclusion criteria, comprising a total of 534,688 participants (39,947 or 7.47% females) in 11 countries in three WHO regions (the Americas, Europe, and the Western Pacific). The exposure was generally assessed with dosimetry, sound level meter and/or official or company records. The outcome was most commonly assessed using health records. We are very uncertain (low quality of evidence) about the effect of occupational exposure to noise (≥85 dBA), compared with no occupational exposure to noise (<85 dBA), on: having IHD (0 studies); acquiring IHD (relative risk (RR) 1.29, 95% confidence interval (95% CI) 1.15 to 1.43, two studies, 11,758 participants, I² 0%); dying from IHD (RR 1.03, 95% CI 0.93-1.14, four studies, 198,926 participants, I² 26%); having stroke (0 studies); acquiring stroke (RR 1.11, 95% CI 0.82-1.65, two studies, 170,000 participants, I² 0%); dying from stroke (RR 1.02, 95% CI 0.93-1.12, three studies, 195,539 participants, I² 0%); having hypertension (0 studies); acquiring hypertension (RR 1.07, 95% CI 0.90-1.28, three studies, four estimates, 147,820 participants, I² 52%); and dying from hypertension (0 studies). Data for subgroup analyses were missing. Sensitivity analyses supported the main analyses.

CONCLUSIONS

For acquiring IHD, we judged the existing body of evidence from human data to provide "limited evidence of harmfulness"; a positive relationship is observed between exposure and outcome where chance, bias, and confounding cannot be ruled out with reasonable confidence. For all other included outcomes, the bodies of evidence were judged as "inadequate evidence of harmfulness". Producing estimates for the burden of CVD attributable to occupational exposure to noise appears to not be evidence-based at this time.

PROTOCOL IDENTIFIER

10.1016/j.envint.2018.09.040.

PROSPERO REGISTRATION NUMBER

CRD42018092272.

Association of occupational noise exposure, bilateral hearing loss with atherosclerotic cardiovascular disease risk in Chinese adults

We aimed to explore the association of occupational noise exposure with atherosclerotic cardiovascular disease (ASCVD) risk in Chinese adults. We included 21,412 participants from the Dongfeng-tongji Cohort Study, occupational noise exposure was evaluated through workplace noise level and/or the job titles, hearing loss was defined as a pure-tone mean of 25 dB or higher at 0.5, 1, 2, and 4 kHz in any ear. Compared with participants without occupational noise exposure, the 10-year ASCVD risk was significantly higher for noise exposure duration ≥20 years (OR = 1.20, 95%CI = 1.05-1.32) after adjusting for potential confounders. In the subgroup analysis, the association was only statistically significant in males (OR = 1.86, 95%CI = 1.12-3.14) and participants aged equal to or over 60 years old (OR = 1.20, 95%CI = 1.05-1.33), but not in females (OR = 1.15, 95%CI = 0.71-1.92) and aged below 60 (OR = 1.51, 95%CI = 0.75-2.85). In the subsample analyses (N = 10,165), bilateral hearing loss was associated with a higher risk of 10-year ASCVD (OR = 1.72, 95%CI = 1.30-2.30), especially for participants who were males (OR = 2.40, 95%CI = 1.61-3.42) and aged equal to or over 60 (OR = 1.85, 95%CI = 1.40-2.44). The present study suggests that occupational noise exposure may be a potential risk factor for ASCVD, especially for males and older participants.

Association between exposure to noise and risk of hypertension: a meta-analysis of observational epidemiological studies

OBJECTIVE

An increasing amount of original studies suggested that exposure to noise could be associated with the risk of hypertension, but the results remain inconsistent and inconclusive. We aimed to synthesize available epidemiological evidence about the relationship between various types of noise and hypertension, and to explore the potential dose-response relationship between them in an up-to-date meta-analysis.

METHODS

We conducted a literature search of PubMed and Embase from these databases' inception through December 2016 to identify observational epidemiological studies examining the association between noise and risk of hypertension. A random effects model was used to combine the results of included studies. Dose-response meta-analysis was conducted to examine the potential dose-response relationship.

RESULTS

In total, 32 studies (five cohort studies, one case-control study, and 26 cross-section studies) involving 264 678 participants were eligible for inclusion. Pooled result showed that living or working in environment with noise exposure was significantly associated with increased risk of hypertension (odds ratio 1.62; 95% confidence interval: 1.40-1.88). We found no evidence of a curve linear association between noise and risk of hypertension. A dose-response analysis suggested that, for an increment of per 10 dB(A) of noise, the combined odds ratio of hypertension was 1.06 (95% confidence interval: 1.04-1.08).

CONCLUSION

Integrated epidemiological evidence supports the hypothesis that exposure to noise may be a risk factor of hypertension, and there is a positive dose-response association between them.

Longitudinal study of occupational noise exposure and joint effects with job strain and risk for coronary heart disease and stroke in Swedish men

OBJECTIVES

The aims were to investigate whether occupational noise increased the risk for coronary heart disease (CHD) and stroke and to elucidate interactions with stressful working conditions in a cohort of Swedish men.

DESIGN

This is a prospective cohort study on CHD and stroke in Swedish men followed until death, hospital discharge or until 75 years of age, using Swedish national registers on cause of death and hospital discharges. Baseline data on occupation from 1974 to 1977 were used for classification of levels of occupational noise and job demand-control. Cox regression was used to analyse HRs for CHD and stroke.

SETTING

Swedish men born in 1915-1925.

PRIMARY AND SECONDARY OUTCOME MEASURES

CHD and stroke.

PARTICIPANTS

The participants of the study were men from the Primary Prevention Study, a random sample of 10 000 men born in 1915-1925 in Gothenburg. Subjects with CHD or stroke at baseline or were not employed were excluded. The remaining subjects with complete baseline data on occupation, weight, height, hypertension, diabetes, serum cholesterol and smoking constituted the study sample (5753 men).

RESULTS

There was an increased risk for CHD in relation to noise levels 75-85 dB(A) and >85 dB(A) compared with <75 dB(A) (HR 1.15, 95% CI 1.01 to 1.31, and HR 1.27, 95% CI 0.99 to 1.63, respectively). Exposure to noise peaks also increased the risk for CHD (HR 1.19, 95% CI 1.03 to 1.38). Among those with high strain (high demands and low control) combined with noise >75 dB(A), the risk for CHD further increased (HR 1.80, 95% CI 1.19 to 2.73). There was no significantly increased risk for stroke in any noise category.

CONCLUSIONS

Exposure to occupational noise was associated with an increased risk for CHD and the risk further increased among those with concomitant exposure to high strain. None of the analysed variables were related to increased risk for stroke.

Ambient and at-the-ear occupational noise exposure and serum lipid levels

OBJECTIVES

Occupational and residential noise exposure has been related to increased risk of cardiovascular disease. Alteration of serum lipid levels has been proposed as a possible causal pathway. The objective of this study was to investigate the relation between ambient and at-the-ear occupational noise exposure and serum levels of total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, and triglycerides when accounting for well-established predictors of lipid levels.

METHODS

This cross-sectional study included 424 industrial workers and 84 financial workers to obtain contrast in noise exposure levels. They provided a serum sample and wore portable dosimeters that every 5-s recorded ambient noise exposure levels during a 24-h period. We extracted measurements obtained during work and calculated the full-shift mean ambient noise level. For 331 workers who kept a diary on the use of a hearing protection device (HPD), we subtracted 10 dB from every noise recording obtained during HPD use and estimated the mean full-shift noise exposure level at the ear.

RESULTS

Mean ambient noise level was 79.9 dB (A) [range 55.0-98.9] and the mean estimated level at the ear 77.8 dB (A) [range 55.0-94.2]. Ambient and at-the-ear noise levels were strongly associated with increasing levels of triglycerides, cholesterol-HDL ratio, and decreasing levels of HDL-cholesterol, but only in unadjusted analyses that did not account for HPD use and other risk factors.

CONCLUSION

No associations between ambient or at-the-ear occupational noise exposure and serum lipid levels were observed. This indicates that a causal pathway between occupational and residential noise exposure and cardiovascular disease does not include alteration of lipid levels.

ICBEN review of research on the biological effects of noise 2011-2014

The mandate of the International Commission on Biological Effects of Noise (ICBEN) is to promote a high level of scientific research concerning all aspects of noise-induced effects on human beings and animals. In this review, ICBEN team chairs and co-chairs summarize relevant findings, publications, developments, and policies related to the biological effects of noise, with a focus on the period 2011-2014 and for the following topics: Noise-induced hearing loss; nonauditory effects of noise; effects of noise on performance and behavior; effects of noise on sleep; community response to noise; and interactions with other agents and contextual factors. Occupational settings and transport have been identified as the most prominent sources of noise that affect health. These reviews demonstrate that noise is a prevalent and often underestimated threat for both auditory and nonauditory health and that strategies for the prevention of noise and its associated negative health consequences are needed to promote public health.