Occupational noise exposure and ischaemic heart disease mortality

Occupational and Environmental Noise Exposure and Extra-Auditory Effects on Humans: A Systematic Literature Review

Noise is a common harmful factor in our work and the environment. Most studies have investigated the auditory effects of noise exposure; however, few studies have focused on the extra-auditory effects of exposure to occupational or environmental noise. This study aimed to systematically review published studies on the extra-auditory effects of noise exposure. We reviewed literature from PubMed and Google Scholar databases up to July 2022, using the Patient, Intervention, Comparison, and Outcome criteria and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify studies that reported extra-auditory effects of occupational or environmental noise exposure. Studies were evaluated utilizing validated reporting tools (CONSORT, STROBE) appropriate to study design. A total of 263 articles were identified, of which 36 were finally selected and reviewed. Upon conducting a review of the articles, exposure to noise can elicit a variety of extra-auditory effects on humans. These effects include circulatory effects linked to higher risk of cardiovascular disease and decreased endothelial function, nervous system effects correlated with sleep disturbance, cognitive impairment, and mental health problems, immunological and endocrinal effects connected to increased physiological stress response and metabolic disorders, oncological and respiratory effects associated with an elevated risk of acoustic neuroma and respiratory disorders, gastrointestinal effects linked to an increased risk of gastric or duodenal ulcer, and obstetric effects connected to the risk of preterm birth. Our review suggests that there are numerous extra-auditory effects of noise exposure on human, and further investigations are needed to fully understand these effects.

Association of noise exposure, plasma microRNAs with arterial stiffness among Chinese workers

Long-term noise exposure is reported to damage cardiovascular system, but the relationship between occupational noise exposure and arterial stiffness (AS) and the underlying mechanism is still unclear. We aimed to investigate the association of occupational noise exposure with arterial stiffness (AS), and further explore the mediation roles of microRNAs (miRNAs). A total of 838 workers were recruited from two companies in Wuhan, Hubei, China. Cumulative occupational noise exposure (CNE) was assessed through noise level of job title and work years in occupational noise. The AS for the participants were evaluated using brachial-ankle pulse wave velocity (baPWV) measured by an oscillometric device. Each 1-unit increase in CNE levels was significantly associated with a 0.002 (95% confidence interval (CI) = 0.001-0.003) unit increase in ln-transformed values of baPWV. In the sex-specific analysis, the association was significant in males (β = 0.002, 95%CI = 0.001-0.003). Meanwhile, the risk of bilateral hearing loss at high frequency was significantly higher in the high-exposed group than non-exposed group (OR = 1.895, 95%CI = 1.024-3.508), and participants with bilateral hearing loss at high frequency had a significantly higher level of ln-transformed baPWV (β = 0.032, 95%CI = 0.003-0.061). Occupational noise exposure and AS were both negatively associated with plasma miR-92a-3p and miR-21-5p, and the two miRNAs mediated 15.0% and 16.8% of the association of occupational noise with AS (P < 0.05). Our findings suggest that occupational noise exposure is positively associated with AS, and plasma miR-92a-3p and miR-21-5p may partly mediate such association.

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.

Quantitative Bias Analysis of the Association between Occupational Radiation Exposure and Ischemic Heart Disease Mortality in UK Nuclear Workers

The scientific question of whether protracted low-dose or low-dose-rate exposure to external radiation is causally related to the risk of circulatory disease continues to be an important issue for radiation protection. Previous analyses of a matched case-control dataset nested in a large cohort of UK nuclear fuel cycle workers indicated that there was little evidence that observed associations between external radiation dose and ischemic heart disease (IHD) mortality risk [OR = 1.35 (95% CI: 0.99-184) for 15-year-lagged exposure] could alternatively be explained by confounding from pre-employment tobacco smoking, BMI or blood pressure, or from socioeconomic status or occupational exposure to excessive noise or shiftwork. To improve causal inference about the observed external radiation dose and IHD mortality association, we estimated the potential magnitude and direction of non-random errors, incorporated sensitivity analyses and simulated bias effects under plausible scenarios. We conducted quantitative bias analyses of plausible scenarios based on 1,000 Monte Carlo samples to explore the impact of exposure measurement error, missing information on tobacco smoking, and unmeasured confounding, and assessed whether observed associations were reliant on the inclusion of specific matched pairs using bootstrapping with 10% of matched pairs randomly excluded in 1,000 samples. We further explored the plausibility that having been monitored for internal exposure, which was an important confounding factor in the case-control analysis for which models were adjusted, was indeed a confounding factor or whether it might have been the result of some form of selection bias. Consistent with the broader epidemiological evidence-base, these analyses provide further evidence that the dose-response association between cumulative external radiation exposure and IHD mortality is non-linear in that it has a linear shape plateauing at an excess risk of 43% (95% CI: 7-92%) on reaching 390 mSv. Analyses of plausible scenarios of patterns of missing data for tobacco smoking at start of employment indicated that this resulted in relatively little bias towards the null in the original analysis. An unmeasured confounder would have had to have been highly correlated (rp > 0.60) with cumulative external radiation dose to importantly bias observed associations. The confounding effect of "having been monitored for internal dose" was unlikely to have been a true confounder in a biological sense, but instead may have been some unknown factor related to differences over time and between sites in selection criteria for internal monitoring, possibly resulting in collider bias. Plausible patterns of exposure measurement error negatively biased associations regardless of the modeled scenario, but did not importantly change the shape of the observed dose-response associations. These analyses provide additional support for the hypothesis that the observed association between external radiation exposure and IHD mortality may be causal.

Occupational noise exposure and the prevalence of dyslipidemia in a cross-sectional study

BACKGROUND

Occupational noise exposure was related to cardiovascular disease, of which dyslipidemia was an important inducement. This study investigated the relationship between occupational noise exposure and dyslipidemia.

METHODS

Four hundred ninety-two occupational noise-exposed workers and 664 non-exposed workers were recruited to conduct environmental noise tests and personal occupational physical examinations. A lasso-logistic regression model was used to estimate the relative risk of dyslipidemia. A restricted cubic spline was used to estimate the association between noise exposure years and dyslipidemia after adjusting for potential confounding factors.

RESULTS

A crude association was observed between the occupational noise exposure (75-85 dB(A)) and dyslipidemia. After adjusting for confounding factors, there was a non-linear relationship between noise exposure years and dyslipidemia (P for non-linearity =0.01). Workers exposed to 75-85 dB(A) for 11 to 24.5 years had a higher risk of dyslipidemia than non-exposed workers.

CONCLUSIONS

A positive and non-linear exposure-response relationship was found in workers exposed to 75-85 dB(A) whose exposure years were between 11 and 24.5. Workers had the highest risk of dyslipidemia when exposed for 13.5 years.

Impact of exposure to noise on the risk of hypertension: A systematic review and meta-analysis of cohort studies

OBJECTIVE

We aimed to synthesize available cohorts about the relationship between various types of noise and hypertension, and to explore the potential dose-response relationship between them in an updated meta-analysis.

METHODS

PubMed and Embase were searched through October 2019 to identify cohort studies that met predetermined inclusion criteria. 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

Eleven cohort studies involving 224,829 participants were included in this systematic review. Pooled result showed that living or working in environment with noise exposure was significantly associated with increased risk of hypertension (RR: 1.18; 95% CI: 1.06 to 1.32), with low heterogeneity (P = 0.098, I² = 42.1%). We found no evidence of a nonlinear association of elevated noise with hypertension risk (P = 0.443). The summary risk ratio of hypertension for an increment of per 10 dB(A) of noise was 1.13 (95% CI: 0.99 to 1.28), with moderate heterogeneity (P = 0.003, I² = 72.1%).

CONCLUSIONS

Integrated evidence from cohort studies supports the hypothesis that exposure to noise may be a risk factor of hypertension.

The GoAudio Quantitative Mobile Audiology Test Enhances Access to Clinical Hearing Assessments

Purpose Hearing loss is a common impairment of the human senses with an estimated 48 million American adults reporting some trouble hearing; however, access to hearing health care is limited. Detection of hearing loss through a mobile, handheld tool can provide an important access point and potentially expedited access to the continuum of hearing health care. Here, we determined that GoAudio, a portable, automated hearing assessment tool, can be used to identify individuals who require additional hearing evaluation in a clinical workflow. Method This initial study included 24 adults, ages 18-65 years (M = 50, SD = 12), tested with GoAudio versus "gold-standard" clinical audiometry for eight frequencies to evaluate "real-world" applications. Participants utilized noise-canceling headphones combined with a tablet-based application for the GoAudio assessment. Results The primary study outcome measurements were the comparison of hearing thresholds (dB HL) from clinical audiometry and GoAudio. Results suggest that GoAudio is comparable to clinical audiometry for the identification of hearing loss at most frequencies (except 1 kHz for both ears and 2 kHz in the right ear). Upon stratifying data based on age, we identified that GoAudio is capable of identifying suspected age-related hearing loss or hearing thresholds greater than 30 dB HL at higher frequencies in both ears. Conclusion The study results support that GoAudio can be used effectively in clinical practice workflows as a reliable hearing assessment tool for the identification of hearing loss at the majority of frequencies outside a sound-treated booth and can detect characteristics of age-related hearing loss. Supplemental Material https://doi.org/10.23641/asha.13087682.

Short-term exposure to noise on stroke volume and left ventricular contractility: A repeated-measure study

Prolonged exposure to noise has been associated with cardiovascular disease, but the possible mechanism for its influence on cardiac activity is unknown. This study investigated the acute effects of noise exposure on 24-h ambulatory cardiac parameters among male workers. We recruited 75 volunteers in an aviation-industry cohort in 2009. Personal noise-exposure levels and individual cardiac parameters, including stroke volume (SV) and left ventricular contractility (LVC), were measured simultaneously over 24 h on working and nonworking days. Linear mixed-effects regression models were used to estimate transient and sustained effects on ambulatory SV and LVC among high-noise-exposure (≥80 A-weighted decibels [dBA]), low-noise-exposure (<80 dBA) and office workers. Every 1-dBA increase in noise exposure was significantly associated with transient changes of -1.50 (95% confidence interval [CI]: -2.18, -1.03) ml/beat in SV and -1.76 (-2.99, -1.03) L/sec in LVC at work on working days only among high-exposure workers. The 1-dBA increase in nocturnal noise exposure was also significantly associated with transiently decreased SV among high-exposure (-1.62 [-2.15, -1.22] ml/beat), low-exposure (-1.27 [-1.57, -1.03] ml/beat) and office workers (-1.09 [-1.18, -1.00] ml/beat), but only the high-exposure group had the transiently reduced LVC (-1.70, [-2.37, -1.22] L/sec) after the current noise exposure on nonworking days. Such decreasing effects persisted to become sustained decreases in 24-h ambulatory SV in high-exposure (-1.10 [-1.20, -1.01] ml/beat) and office workers (-1.13 [-1.22, -1.05] ml/beat) on working days and in all three groups (-1.19 [-1.36, -1.04]; -1.15 [-1.31, -1.02]; -1.08 [-1.13, -1.02] ml/beat, respectively) on nonworking days. No significant effect on 24-h ambulatory LVC was found in any group on working or nonworking days. Occupational and nocturnal noise exposure may have acute effects on 24-h ambulatory SV among male workers, directly influencing the cardiac function related to cardiovascular disease.

Occupational noise exposure and its association with incident hyperglycaemia: a retrospective cohort study

Noise pollution is reported to be associated with diabetes, but few studies have elucidated the associations between noise frequency characteristics. We aimed to evaluate the relationships between different noise frequency components and incident hyperglycaemia. An industry-based cohort of 905 volunteers was enrolled and followed up to 2012. Octave-band frequencies of workstation noise and individual noise levels were measured in 2012 to classify subjects' exposures retrospectively. We applied Cox regression models to estimate the relative risk (RR) of hyperglycaemia. An increased RR for hyperglycaemia of 1.80 (95% confidence interval [CI]: 1.04, 3.10) was found among subjects exposed to ≥ 85 A-weighted decibels (dBA) compared with those exposed to < 70 dBA. The high-exposure groups at frequencies of 31.5, 63, 125, 250, 500, 1000, and 2000 Hz had a significantly higher risk of hyperglycaemia (all p values < 0.050) than the low-exposure groups. A 5-dB increase in noise frequencies at 31.5, 63, 125, 250, 500 Hz, and 1000 Hz was associated with an elevated risk of hyperglycaemia (all p values < 0.050), with the highest value of 1.27 (95% CI: 1.10, 1.47) at 31.5 Hz (p = 0.001). Occupational noise exposure may be associated with an increased incidence of hyperglycaemia, with the highest risk observed at 31.5 Hz.

A statistical downscaling approach for generating high spatial resolution health risk maps: a case study of road noise and ischemic heart disease mortality in Melbourne, Australia

Introduction

Road traffic noise increases the risk of mortality from ischemic heart disease (IHD). Because noise is highly localized, high resolution maps of exposures and health outcomes are key to urban planning interventions that are informed by health risks. In Australia, publicly accessible IHD deaths data are only available at the coarse spatial aggregation level of local government area (LGA), in which about 130,000 people reside. Herein, we addressed this limitation of health data using statistical downscaling and generated environmental health risk maps for noise at the meshblock level (MB; ~ 90 people).

Methods

We estimated noise exposures at the MB level using a model of road traffic noise in Melbourne, Australia, from 2011. As recommended by the World Health Organization, a non-linear exposure–response function for traffic noise and IHD was used to calculate odds ratios for noise related IHD in all MBs. Noise attributable risks of IHD death were then estimated by statistically downscaling LGA-level IHD rates to the MB level.

Results

Noise levels of 80 dB were recorded in some MBs. From the given noise maps, approximately 5% of the population was exposed to traffic noise above the risk threshold of 55 dB. Maps of excess risk at the MB level identified areas in which noise levels and exposed populations are large. Attributable rates of IHD deaths due to noise were generally very low, but some were as high as 5–10 per 100,000, and in extremely noisy and populated MBs represented more than 8% excess risk of IHD death. We presented results as interactive maps of excess risk due to noise at the small neighbourhood scale.

Conclusion

Our method accommodates low-resolution health data and could be used to inform urban planning and public health decision making for various environmental health concerns. Estimated noise related IHD deaths were relatively few in Melbourne in 2011, likely because road traffic is one of many noise sources and the current noise model underestimates exposures. Nonetheless, this novel computational framework could be used globally to generate maps of noise related health risks using scant health outcomes data.

Questionnaire-based algorithm for assessing occupational noise exposure of construction workers

Objectives

Occupational noise exposure is a major cause of hearing loss worldwide. In order to inform preventative strategies, we need to further understand at a population level which workers are most at risk.

Methods

We have developed a new questionnaire-based algorithm that evaluates an individual worker’s noise exposure. The questionnaire and supporting algorithms are embedded into the existing software platform, OccIDEAS. Based on the tasks performed by a worker during their most recent working shift and using a library of task-based noise exposure levels, OccIDEAS estimates whether a worker has exceeded the full-shift workplace noise exposure limit (LAeq,8h≥85 dBA). We evaluated the validity of the system in a sample of 100 construction workers. Each worker wore a dosimeter for a full working shift and was then interviewed using the OccIDEAS software.

Results

The area under the receiver operating characteristic curve was 0.81 (95% CI 0.72 to 0.90) indicating that the ability of OccIDEAS to identify construction workers with an LAeq,8h≥85 dBA was excellent.

Conclusion

This validated noise questionnaire may be useful in epidemiological studies and for workplace health and safety applications.

Blood Pressure of Jordanian Workers Chronically Exposed to Noise in Industrial Plants

BACKGROUND

Occupational studies investigating the association between blood pressure and noise exposure are almost lacking in the Eastern Mediterranean Region countries.

OBJECTIVE

To determine the association between occupational exposure to high level of noise and blood pressure among a group of workers in Jordan.

METHODS

All workers who had been exposing to noise for at least 3 years in 3 plants in Madaba governorate in Jordan were included in this cross-sectional study. A structured questionnaire was used to collect data. The occupational noise level was measured with a portable calibrated sound meter.

RESULTS

We studied 191 male workers, of whom 145 (75.9%) were exposed to a noise level higher than the permissible limit of 85 dBA. The mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) and the prevalence of hypertension were significantly higher among those exposed to higher noise level. In multivariate analysis, workers exposed to high level of noise had a significantly higher odds of hypertension compared to those exposed to noise level lower than the permissible limit (OR 4.7, 95% CI 1.6 to 13.8). The odds of hypertension increased by 17% (95% CI 10% to 30%) for each dB increase in noise intensity.

CONCLUSION

Exposure to high level of noise is associated with elevated blood pressure.

Occupational noise and ischemic heart disease: A systematic review

Noise exposure might be a risk factor for ischemic heart disease (IHD). Unlike residential exposure, however, evidence for occupational noise is limited. Given that high-quality quantitative synthesis of existing data is highly warranted for occupational safety and policy, we aimed at conducting a systematic review and meta-analysis of the risks of IHD morbidity and mortality because of occupational noise exposure. We carried out a systematic search in MEDLINE, EMBASE, and on the Internet since April 2, 2015, in English, Spanish, Russian, and Bulgarian. A quality-scoring checklist was developed a priori to assess different sources of methodological bias. A qualitative data synthesis was performed. Conservative assumptions were applied when appropriate. A meta-analysis was not feasible because of unresolvable methodological discrepancies between the studies. On the basis of five studies, there was some evidence to suggest higher risk of IHD among workers exposed to objectively assessed noise >75–80 dB for <20 years (supported by one high, one moderate, and one low quality study, opposed by one high and one moderate quality study). Three moderate and two low quality studies out of six found self-rated exposure to be associated with higher risk of IHD, and only one moderate quality study found no effect. Out of four studies, a higher mortality risk was suggested by one moderate quality study relying on self-rated exposure and one of high-quality study using objective exposure. Sensitivity analyses showed that at higher exposures and in some vulnerable subgroups, such as women, the adverse effects were considerably stronger. Despite methodological discrepancies and limitations of the included studies, occupational noise appeared to be a risk factor for IHD morbidity. Results suggested higher risk for IHD mortality only among vulnerable subgroups. Workers exposed to high occupational noise should be considered at higher overall risk of IHD.

Occupational Noise Frequencies and the Incidence of Hypertension in a Retrospective Cohort Study

Occupational noise exposure is associated with cardiovascular disease, but little is known about the contributions of noise frequency components. This retrospective study investigated the relationship between exposure to different noise frequencies and the incidence of hypertension. A cohort of 1,002 volunteers from 4 machinery and equipment manufacturing companies in Taichung, Taiwan, was followed from 1973 to 2012. Personal noise measurements and environmental octave-band analyses were performed to divide subjects into different exposure groups. Cox regression models were used to estimate the relative risk of hypertension. Participants exposed to ≥80 A-weighted decibels (dBA) over 8 years had a higher relative risk of hypertension (relative risk = 1.38, 95% confidence interval: 1.02, 1.85) compared with those exposed to <75 dBA. Significant exposure-response patterns were observed between incident hypertension and stratum of noise exposure at frequencies of 250 Hz, 1 kHz, 2 kHz, 4 kHz, and 8 kHz. The strongest effect was found at 4 kHz; a 20-dBA increase in noise exposure at 4 kHz was associated with a 34% higher risk of hypertension (relative risk = 1.34, 95% confidence interval: 1.01, 1.77). Occupational noise exposure may be associated with an increased risk of hypertension, and the 4 kHz component of occupational noise exposure may have the strongest relationship with hypertension.

Exposure to loud noise, bilateral high-frequency hearing loss and coronary heart disease

OBJECTIVES

Bilateral high-frequency hearing loss is an indicator for chronic exposure to loud noise. This study aimed to examine the association between bilateral high-frequency hearing loss and the presence of coronary heart disease (CHD).

METHODS

This study included 5223 participants aged 20-69 years who participated in the audiometry examination of the National Health and Nutrition Examination Survey 1999-2004. Bilateral high-frequency hearing loss was defined as the average high-frequency (3, 4 and 6 kHz) hearing threshold ≥25 dB in both ears. CHD was defined as self-reported diagnoses by doctors or other health professionals.

RESULTS

Compared with those with normal high-frequency hearing, participants with bilateral high-frequency hearing loss were more likely to have CHD (OR 1.91; 95% CI 1.28 to 2.85) after adjustment for various covariates. This association was particularly strong for currently employed workers who were exposed to loud occupational noise (OR 4.23; 95% CI 1.32 to 13.55). For this subgroup, there was no significant association of CHD with unilateral high-frequency hearing loss, and unilateral or bilateral low-frequency hearing loss. Furthermore, there was no significant association of CHD with any types of hearing loss for participants who were not exposed to loud noise. Stratified analyses for participants exposed to loud noise showed that the observed association was particularly strong for those who were less than 50 years of age, less educated and current smokers.

CONCLUSIONS

On the basis of an objective indicator for personal chronic exposure to loud noise, this study confirmed that exposure to loud occupational noise is associated with the presence of CHD.

Cardiovascular disease mortality among retired workers chronically exposed to intense occupational noise

OBJECTIVE

The aim of this study, conducted among retired workers (≥65 years), is to estimate the association between long-term risk of cardiovascular disease (CVD) death and (1) duration of occupational noise exposure in career and (2) noise-induced hearing loss (NIHL), the latter being used as an indicator of adverse effects for long-term exposure to occupational noise.

METHODS

Data from screening activities of occupational NIHL were paired to data from death records and were used for this study. A nested case-control analysis was performed. Each case was matched with three controls for length of follow-up and economic sector. A total of 161 CVD deaths occured during an average follow-up of 6.8 years. Conditional logistic regression models were used to estimate the risk (OR) of CVD death by tertiles of duration of noise exposure and of NIHL.

RESULTS

Conditional logistic regression models indicated that prolonged duration of noise exposure (≥36.5 years) (3rd tertile) was associated with an increased risk of CVD death (OR 1.70; 95 % CI 1.10-2.62), as compared with shorter duration (<27 years) (first tertile). Moderate NIHL (2nd tertile) (OR 1.64; 95 % CI 1.04-2.6) and severe NIHL (3rd tertile) (OR 1.66; 95 % CI 1.06-2.60) were also associated with an increase in risk of CVD death.

CONCLUSIONS

Results are consistent with recent findings on the chronic effects of occupational noise exposure persisting after retirement although it is less than during active working life.

Occupational noise exposure and incident hypertension in men: a prospective cohort study

The associations between occupational noise exposure and hypertension remain controversial because of the differences in study designs, exposure assessments, and confounding controls. This prospective study investigated the relationship between noise exposure and the 10-year risk of hypertension. A cohort of 578 male workers in Taiwan was followed from 1998 to 2008. All subjects were divided into high-, intermediate-, and low-exposure groups on the basis of noise exposure assessment. Cox regression models were used to estimate the relative risks of hypertension after adjustment for potential confounders. During the 7,805 person-years of follow-up, 141 hypertension cases were identified. Significant increases of 3.2 (95% confidence interval (CI): 0.2, 6.2) mm Hg in systolic blood pressure and 2.5 (95% CI: 0.1, 4.8) mm Hg in diastolic blood pressure between the baseline and follow-up measurements were observed in the high-exposure group. Participants exposed to ≥85 A-weighted decibels (dBA) had a 1.93-fold (95% CI: 1.15, 3.22) risk of hypertension compared with those exposed to <80 dBA. There was a significant exposure-response pattern (P = 0.016) between the risk of hypertension and the stratum of noise exposure. Prolonged exposure to noise levels ≥85 dBA may increase males' systolic and diastolic blood pressure levels. This association may translate into a higher incidence of hypertension.

Mass transit ridership and self-reported hearing health in an urban population

Information on prevalence and risk factors associated with self-reported hearing health among mass transit riders is extremely limited, even though evidence suggests mass transit may be a source of excessive exposure to noise. Data on mass transit ridership were collected from 756 study participants using a self-administered questionnaire. Hearing health was measured using two symptom items (tinnitus and temporary audiometric threshold shift), two subjective measures (self-rated hearing and hearing ability), and two medical-related questions (hearing testing and physician-diagnosed hearing loss). In logistic regression analyses that controlled for possible confounders, including demographic variables, occupational noise exposure, nonoccupational noise exposure (including MP3 player use) and use of hearing protection, frequent and lengthy mass transit (all forms) ridership (1,100 min or more per week vs. 350 min or less per week) was the strongest predictor of temporary threshold shift symptoms. Noise abatement strategies, such as engineering controls, and the promotion of hearing protection use should be encouraged to reduce the risk of adverse impacts on the hearing health of mass transit users.

Noise-induced hearing loss and associated factors among vector control workers in a Malaysian state

This study aims to determine the prevalence and associated factors of noise-induced hearing loss (NIHL) among vector control workers in the state of Negeri Sembilan, Malaysia. This was an analytical cross-sectional study conducted on 181 vector control workers who were working in district health offices in a state in Malaysia. Data were collected using a self-administered questionnaire and audiometry. Prevalence of NIHL was 26% among this group of workers. NIHL was significantly associated with the age-group of 40 years and older, length of service of 10 or more years, current occupational noise exposure, listening to loud music, history of firearms use, and history of mumps/measles infection. Following logistic regression, age of more than 40 years and noise exposure in current occupation were associated with NIHL with an odds ratio of 3.45 (95% confidence interval = 1.68-7.07) and 6.87 (95% confidence interval = 1.54-30.69), respectively, among this group of vector control workers.

Exposure to workplace noise and the risk of cardiovascular disease events and mortality among older adults

BACKGROUND

We aimed to examine whether cross-sectional (prevalence) and longitudinal relationships (5-year incidence and 10-year mortality) exist between workplace noise exposure and cardiovascular diseases (CVD).

METHODS

2942 participants aged 55+years of the Blue Mountains Eye Study, Australia (1997-9 and 2002-4). Participants self-reported workplace noise exposure, hearing protector use and physician diagnosed CVD. CVD deaths were confirmed using the Australian National Death Index.

RESULTS

133 and 937 participants self-reported workplace noise exposure, and use or non-use of hearing protection devices, respectively. After multivariate adjustment, those who did not use hearing protection devices were 53% and 75% more likely to have prevalent CVD and angina, respectively, compared to those never exposed to workplace noise. Exposure to severe workplace noise for less than 1 to 5 years versus no exposure was associated with incident stroke OR 3.44 (95% CI 1.11-10.63). The mortality rate of CVD was 0.94% per year in people unexposed to workplace noise. Participants reporting less than 1 to 5 years versus those with no workplace noise exposure had a higher risk of CVD mortality, hazard ratio, HR, 1.60 (95% CI 1.10-2.33).

DISCUSSION

These data highlight the public health impact of workplace noise exposure on the vascular health of older adults.

The Magnitude of Mortality from Ischemic Heart Disease Attributed to Occupational Factors in Korea - Attributable Fraction Estimation Using Meta-analysis

Objectives

Ischemic heart disease (IHD) is a major cause of death in Korea and known to result from several occupational factors. This study attempted to estimate the current magnitude of IHD mortality due to occupational factors in Korea.

Methods

After selecting occupational risk factors by literature investigation, we calculated attributable fractions (AFs) from relative risks and exposure data for each factor. Relative risks were estimated using meta-analysis based on published research. Exposure data were collected from the 2006 Survey of Korean Working Conditions. Finally, we estimated 2006 occupation-related IHD mortality.

Results

For the factors considered, we estimated the following relative risks: noise 1.06, environmental tobacco smoke 1.19 (men) and 1.22 (women), shift work 1.12, and low job control 1.15 (men) and 1.08 (women). Combined AFs of those factors in the IHD were estimated at 9.29% (0.3-18.51%) in men and 5.78% (-7.05-19.15%) in women. Based on these fractions, Korea's 2006 death toll from occupational IHD between the age of 15 and 69 was calculated at 353 in men (total 3,804) and 72 in women (total 1,246).

Conclusion

We estimated occupational IHD mortality of Korea with updated data and more relevant evidence. Despite the efforts to obtain reliable estimates, there were many assumptions and limitations that must be overcome. Future research based on more precise design and reliable evidence is required for more accurate estimates.

Predictive validity of a retrospective measure of noise exposure

AIMS

To investigate the validity of measures of noise exposure derived retrospectively for a cohort of nuclear energy workers for the period 1950-98, by investigating their ability to predict hearing loss.

METHODS

Subjects were men aged 45-65 chosen from a larger group of employees--assembled for a nested case-control study of noise and death from ischaemic heart disease--who had had at least one audiogram after at least five years' work. Average hearing loss, across both ears and the frequencies 0.5, 1, 2, and 4 kHz, was calculated from the last audiogram for each man. Previous noise exposure at work was assessed retrospectively by three hygienists using work histories, noise survey records from 1965-98, and judgement about use of hearing protection devices. Smoking and age at the time of the audiogram were extracted from records. Differences in hearing loss between men categorised by cumulative noise exposure were assessed after controlling for age, smoking, year of test, and previous test experience.

RESULTS

There were 186 and 150 eligible subjects at sites A and B of the company respectively who were employed for an average of 20 years. Compared to men with less than one year's exposure to levels of 85dB(A) or greater, hearing loss was greater by 3.7 dB (90% CI -2.6 to 10.1), 3.8 dB (90% CI -2.6 to 10.3), 7.0 dB (90% CI 1.1 to 12.9) and 10.1 dB (90% CI 4.2 to 16.0) in the lowest to highest categories of cumulative noise exposure at site B. In contrast, at site A, the corresponding figures were -2.2 dB, -2.4 dB, -1.8 dB, and -4.4 dB, with no confidence interval excluding zero.

CONCLUSIONS

Noise estimation at one site was shown to have predictive validity in terms of hearing loss, but not at the other site. Reasons for the differences between sites are discussed.