Occupational noise and ischemic heart disease: A systematic review

The experience of noise in communication-intense workplaces: A qualitative study

OBJECTIVE

The aim of the study was to explore and describe how workers in communication-intense workplaces in health care and preschools experience the sound environment. The dependence on vocal communication and social interaction poses a challenge using hearing protection in these working environments.

METHOD

A qualitative method was used, more specifically inductive thematic analysis was used, as this approach was deemed suitable to explore the staff's experiences of the sound environment. Data were collected by interviews and to increase trustworthiness, several researchers were involved in the data collection and analysis.

STUDY SAMPLE

Workers from two preschools, one obstetrics ward and one intensive care unit took part in the study.

RESULTS

Four main themes emerged from the thematic analysis: A challenging and harmful sound environment; Health-related effects of a challenging and harmful sound environment; A good sound environment is not prioritised; and Resourceful and motivated staff.

CONCLUSIONS

Workers in communication-intense workplaces in preschools, obstetrics care and intensive care reported that there was a relationship between the sound environment and negative health effects. In addition, the results suggests that the high motivation for change among staff should be utilised together with an increased prioritization from the management to reach innovative context specific improvements to the sound environment in communication intense working environments.

Environmental noise-induced cardiovascular, metabolic and mental health disorders: a brief review

BACKGROUND

Environmental noise is a pervasive pollutant that is one of the greatest environmental threats to mental, physiological and psychological well-being and has a significant global health burden associated with it. Many epidemiological studies indicate long-term relationship of noise pollution with wide range of metabolic, cardio-vascular and respiratory disorders and diseases.

OBJECTIVE

The goal of this study was to thoroughly analyse available literature on public health implications and various underlying biological mechanisms associated with ambient noise exposure, taking into account both objective and subjective measures of noise exposure.

METHODS

A search of literature for review on environmental noise and associated cardiovascular, mental health and metabolic implications on human health was done using Web of Science, Google Scholar and PubMed databases.

DISCUSSION

Experimental studies indicate that noise exposure leads to endocrine effects, increased incidence of diabetes, impairment of cognitive performance, sleep disturbance and annoyance. Epidemiological evidence indicates that high levels of noise, particularly at night, may cause arterial hypertension and endothelial dysfunction due to higher level of stress hormones and oxidative stress. An increased incidence of cardio-vascular diseases like myocardial infarction, heart rate, ischemic heart disease, stroke and heart failure is associated with noise-induced mental stress. Furthermore, psychological and mental health issues like anxiety and depression are also related with exposure to noise pollution.

CONCLUSION

This article summarises a comprehensive and systematic knowledge established in recent noise research with the spotlight on cardiovascular, metabolic and mental health disorders of environmental noise, providing unique understanding into underlying mechanisms.

Ischaemic Heart Disease and Occupational Exposures: A Longitudinal Linkage Study in the General and Māori Populations of New Zealand

OBJECTIVES

This study assessed associations between occupational exposures and ischaemic heart disease (IHD) for males and females in the general and Māori populations (indigenous people of New Zealand).

METHODS

Two surveys of the general adult [New Zealand Workforce Survey (NZWS); 2004-2006; n = 3003] and Māori population (Māori NZWS; 2009-2010; n = 2107), with information on occupational exposures, were linked with administrative health data and followed-up until December 2018. Cox proportional hazards regression (adjusted for age, deprivation, and smoking) was used to assess associations between organizational factors, stress, and dust, chemical and physical exposures, and IHD.

RESULTS

Dust [hazard ratio (HR) 1.6, 95%CI 1.1-2.4], smoke or fumes (HR 1.5, 1.0-2.3), and oils and solvents (HR 1.5, 1.0-2.3) were associated with IHD in NZWS males. A high frequency of awkward or tiring hand positions was associated with IHD in both males and females of the NZWS (HRs 1.8, 1.1-2.8 and 2.4, 1.1-5.0, respectively). Repetitive tasks and working at very high speed were associated with IHD among NZWS females (HRs 3.4, 1.1-10.4 and 2.6, 1.2-5.5, respectively). Māori NZWS females working with vibrating tools and those exposed to a high frequency of loud noise were more likely to experience IHD (HRs 2.3, 1.1-4.8 and 2.1, 1.0-4.4, respectively). Exposure to multiple dust and chemical factors was associated with IHD in the NZWS males, as was exposure to multiple physical factors in males and females of the NZWS.

CONCLUSIONS

Exposures associated with an elevated IHD risk included dust, smoke or fumes, oils and solvents, awkward grip or hand movements, carrying out repetitive tasks, working at very high speed, loud noise, and working with tools that vibrate. Results were not consistently observed for males and females and between the general and Māori populations.

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.

Experimental Rodent Models of Cardiovascular Diseases

Cardiovascular diseases, as the most common non-communicable disease in the world, cause a high mortality rate today and bring a serious medical burden to countries worldwide, especially in low- and middle-income countries. Experimental rodent models are widely used for cardiovascular diseases researches due to the effective simulation of human cardiovascular diseases, strong reproductive ability, and easy detection. Herein, we will summarize the pathological manifestations of common cardiovascular diseases and illustrate the establishment of corresponding experimental rodent models in detail.

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.

The Association of Occupational Noises and the Prevalence of Metabolic Syndrome

Objectives

Previous studies have shown the association of exposure to noise with cardiovascular diseases such as hypertension, however, it is not well known whether the exposure has any effect on metabolic syndrome (MetS). This study aimed to quantify and clarify the association between noise exposure and the prevalence of MetS.

Methods

This cross-sectional study was conducted in 2017 among 518 workers in a thermal power plant industry. According to types of work and 8-h equivalent A-weighted sound pressure level (8-h LAeq), the participants were divided into the following groups: office workers and line-production workers exposed to &lt; 85, 90 to &lt;95, 95 to &lt;100, and ≥100 dBA. We used the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) criteria to identify subjects with MetS. The logistic regression was used to determine the odds of MetS among study groups.

Results

We observed the significant differences in the number (%) of subjects with high blood pressure in line-production workers who exposed to noise ≥100 (12 [19.7%]) versus &lt;85 dBA (7 [7.1%]) and office (10 [4.7%]) groups. For the waist circumference (&gt;102 cm), there was a significant difference in the ≥100 dBA group (12 [19.7%]) compared with office group (21 [9.8%]). Obtained results indicated only the significant difference in the prevalence of MetS in ≥100 versus &lt;85 dBA groups (10 [16.4%] versus 6 [6.1%]). The unadjusted and adjusted odds ratios and 95% confidence intervals of MetS in ≥100 versus &lt;85 dBA groups were estimated 3.01 (1.03, 8.75) and 3.24 (1.01, 10.42), respectively.

Conclusions

This study indicated the significant association between noise exposure and MetS in line-production workers. However, more studies are needed to confirm our results.

Occupational exposure to noise and cold environment and the risk of death due to myocardial infarction and stroke

Purpose

The present study examined a possible association between occupational exposure to noise, working and living in cold conditions, and the risk of mortality in myocardial infarction and stroke.

Methods

The present cohort study consists of 194,501 workers in the Swedish construction industry that participated in health examinations between 1971 and 1993. Noise exposure was defined on a job-exposure matrix based on a survey of the working conditions carried out during the mid 1970s. All workers were categorised into three main regions of Sweden, differing in temperature: Reference (Götaland), colder (Svealand), and coldest (Norrland). Relative risks (RR) were analysed by negative binomial regression adjusting for age, BMI, and smoking habits.

Results

Moderate and high noise exposure was associated with increased risk of myocardial infarction (RR 1.10–1.13 with 95% CI over unit) and stroke mortality (RR 1.15 to 1.19 with 95% CI over unit). There was an increased risk for myocardial infarction (RR 1.10, 95% CI 1.01–1.20), but not for stroke mortality (RR 1.09, 95% CI 0.94–1.25) associated with living and working in the coldest region. There was an interaction on the risk of myocardial infarction mortality between different regions and noise exposure (p = 0.016), but not for stroke mortality (p = 0.88).

Conclusions

The study indicates an interaction between working at hazardous noise levels and living and working in cold conditions for increased mortality in myocardial infarction.

Electronic supplementary material

The online version of this article (10.1007/s00420-019-01513-5) contains supplementary material, which is available to authorized users.

Occupational noise exposure: A review of its effects, epidemiology, and impact with recommendations for reducing its burden

Exposure to hazardous noise is one of the most common occupational risks, both in the U.S. and worldwide. Repeated overexposure to noise at or above 85 dBA can cause permanent hearing loss, tinnitus, and difficulty understanding speech in noise. It is also associated with cardiovascular disease, depression, balance problems, and lower income. About 22 million U.S. workers are currently exposed to hazardous occupational noise. Approximately 33% of working-age adults with a history of occupational noise exposure have audiometric evidence of noise-induced hearing damage, and 16% of noise-exposed workers have material hearing impairment. While the Mining, Construction, and Manufacturing sectors typically have the highest prevalence of noise exposure and hearing loss, there are noise-exposed workers in every sector and every sector has workers with hearing loss. Noise-induced hearing loss is preventable. Increased understanding of the biological processes underlying noise damage may lead to protective pharmacologic or genetic therapies. For now, an integrated public health approach that (1) emphasizes noise control over reliance on hearing protection, (2) illustrates the full impact of hearing loss on quality of life, and (3) challenges the cultural acceptance of loud noise can substantially reduce the impact of noise on worker health.

Hearing loss is associated with increased CHD risk and unfavorable CHD-related biomarkers in the Dongfeng-Tongji cohort

BACKGROUND AND AIMS

The association between hearing loss and coronary heart disease (CHD) is inconsistent. We aimed to investigate the association of hearing loss with prevalent CHD and CHD-related biomarkers among a middle aged and elderly Chinese population.

METHODS

We included 14,755 Chinese aged 64.6 years from the Dongfeng-Tongji Cohort in 2013. Hearing loss was classified into normal, mild, moderate or greater levels by the pure tone average (PTA) at low frequency and high frequency, respectively. Logistic regression models were used to estimate the odds ratios (ORs) of CHD risk in relation to hearing loss. Linear regression models were used to evaluate the effect of hearing loss on CHD-related biomarkers.

RESULTS

The adjusted ORs for prevalent CHD increased gradually with the increasing hearing loss levels. Compared with normal hearing, individuals having mild- and moderate or greater-hearing loss had a higher CHD risk of 19% and 20% at low frequency, and 33% and 41% at high frequency, respectively (all p for trend < 0.05). The associations were more evident among subjects who were females, overweight, exposed to occupational noise and with hyperglycemia, hypertension or dyslipidemia at low frequency, and those with hyperglycemia at high frequency. Meanwhile, moderate or greater hearing loss combined with overweight, hyperglycemia, hypertension or dyslipidemia had joint effects on CHD. In addition, the majority of CHD-related biomarkers worsened with increasing hearing loss levels.

CONCLUSIONS

There may be a dose-response relationship between hearing loss and CHD prevalence, and the association could partially be explained by intermediate CHD-related biomarkers.

WHO/ILO work-related burden of disease and injury: Protocol for systematic reviews of exposure to occupational noise and of the effect of exposure to occupational noise on cardiovascular disease

BACKGROUND

The World Health Organization (WHO) and the International Labour Organization (ILO) are developing a joint methodology for estimating the national and global work-related burden of disease and injury (WHO/ILO joint methodology), with contributions from a large network of experts. In this paper, we present the protocol for two systematic reviews of parameters for estimating the number of deaths and disability-adjusted life years from cardiovascular disease attributable to exposure to occupational noise, to inform the development of the WHO/ILO joint methodology.

OBJECTIVES

We aim to systematically review studies on exposure to occupational noise (Systematic Review 1) and systematically review and meta-analyse estimates of the effect of occupational noise on cardiovascular diseases (Systematic Review 2), applying the Navigation Guide systematic review methodology as an organizing framework, conducting both systematic reviews in tandem and in a harmonized way.

DATA SOURCES

Separately for Systematic Reviews 1 and 2, we will search electronic academic databases for potentially relevant records from published and unpublished studies, including Medline, EMBASE, Web of Science and CISDOC. We will also search electronic grey literature databases, Internet search engines and organizational websites; hand search reference list of previous systematic reviews and included study records; and consult additional experts.

STUDY ELIGIBILITY AND CRITERIA

We will include working-age (≥15 years) workers in the formal and informal economy in any WHO and/or ILO Member State, but exclude children (<15 years) and unpaid domestic workers. The eligible risk factor will be occupational noise. Eligible outcomes will be hypertensive heart disease, ischaemic heart disease, stroke, cardiomyopathy, myocarditis, endocarditis and other circulatory diseases. For Systematic Review 1, we will include quantitative prevalence studies of exposure to occupational noise (i.e., low: <85 dB(A) and high: ≥85 dB(A)) stratified by country, sex, age and industrial sector or occupation. For Systematic Review 2, we will include randomized controlled trials, cohort studies, case-control studies and other non-randomized intervention studies with an estimate of the relative effect of high exposure to occupational noise on the prevalence of, incidence of or mortality due to cardiovascular disease, compared with the theoretical minimum risk exposure level (i.e., low exposure).

STUDY APPRAISAL AND SYNTHESIS METHODS

At least two review authors will independently screen 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. At least two review authors will assess risk of bias and the quality of evidence, using the most suited tools currently available. For Systematic Review 2, if feasible, we will combine relative risks using meta-analysis. We will report results using the guidelines for accurate and transparent health estimates reporting (GATHER) for Systematic Review 1 and the preferred reporting items for systematic reviews and meta-analyses guidelines (PRISMA) for Systematic Review 2. PROSPERO registration number: CRD42018092272.

Hearing loss is associated with increased stroke risk in the Dongfeng-Tongji Cohort

BACKGROUND AND AIMS

The evidence concerning the association between hearing loss and stroke is limited. We aimed to investigate the association of hearing loss with risk of stroke and its subtypes among the middle-aged and older Chinese population.

METHODS

We included 19,238 participants aged 64.6 years from the Dongfeng-Tongji Cohort in 2013. Hearing loss was classified into normal, mild, moderate, severe or greater levels by the pure tone average at speech frequency and high frequency, respectively. We calculated the odds ratios of hearing loss and stroke by logistic regression models.

RESULTS

With the increase of hearing loss level, the prevalence risk of stroke has gradually increased. Compared with normal hearing, participants having severe or greater hearing loss had a higher stroke risk of 76% and 39% at speech frequency and at high frequency, respectively. Similarly, individuals with severe or greater hearing loss had an increased risk of ischemic stroke of 69% and 52% at speech frequency and high frequency, respectively; while severe or greater hearing loss was associated with about a 2-fold risk of hemorrhagic stroke than normal hearing only at speech frequency. Stratified analysis suggested that some high cardiovascular risk participants such as male, age ≥65, exposed to occupational noise, smoker and with diabetes, hypertension or hyperlipidemia had higher risk of stroke. Furthermore, severe or greater hearing loss combined with age, diabetes, hypertension and hyperlipidemia had joint effects on stroke.

CONCLUSIONS

The results have suggested a dose-response relationship between hearing loss and stroke risk in middle-aged and older adults.

Associations between Positive Health-Related Effects and Soundscapes Perceptual Constructs: A Systematic Review

In policy-making and research alike, environmental sounds are often considered only as psychophysical stressors, leading to adverse health effects. The soundscape approach, on the other hand, aims to extend the scope of sound-related research to consider sounds as resources, promoting healthy and supportive environments. The ISO 12913-1 standard defined soundscapes as acoustic environments "as perceived by people, in context." The aim of this study was assessing associations between positive soundscapes (e.g., pleasant, calm, less annoying) and positive health-related effects (e.g., increased restoration, reduced stress-inducing mechanisms, etc.). Studies collecting data about individual responses to urban acoustic environments, and individual responses on psychophysical well-being were selected, looking at cases where positive effects were observed. The Web of Science, Scopus and PubMed databases were searched for peer-reviewed journal papers published in English between 1 January 1991 and 31 May 2018, with combinations of the keywords "soundscape" and at least one among "health", "well-being" or "quality of life." An additional manual search was performed on the reference lists of the retrieved items. Inclusion criteria were: (1) including at least one measure of soundscape dimensions as per the ISO 12913-1 definition; (2) including at least one health-related measure (either physiological or psychological); (3) observing/discussing a "positive" effect of the soundscape on the health-related outcome. The search returned 130 results; after removing duplicates, two authors screened titles and abstracts and selected 19 papers for further analysis. Seven studies were eventually included, with 2783 participants in total. Each study included at least a valence-related soundscape measure. Regarding the health-related measures, four studies included physiological monitoring and the remaining three included self-reported psychological measures. Positive soundscapes were associated with faster stress-recovery processes in laboratory experiments, and better self-reported health conditions in large-scale surveys. Due to the limited number of items and differences in measures across studies, no statistical analysis was performed, and a qualitative approach to data synthesis was sought. Results support the claim that, in contrast with looking at noise only as an environmental stressor, sound perception can act as an enhancer of the human experience in the urban realm, from a health-related point of view.

Cardiovascular conditions, hearing difficulty, and occupational noise exposure within US industries and occupations

BACKGROUND

The purpose of this study was to estimate the prevalence of occupational noise exposure, hearing difficulty and cardiovascular conditions within US industries and occupations, and to examine any associations of these outcomes with occupational noise exposure.

METHODS

National Health Interview Survey data from 2014 were examined. Weighted prevalence and adjusted prevalence ratios of self-reported hearing difficulty, hypertension, elevated cholesterol, and coronary heart disease or stroke were estimated by level of occupational noise exposure, industry, and occupation.

RESULTS

Twenty-five percent of current workers had a history of occupational noise exposure (14% exposed in the last year), 12% had hearing difficulty, 24% had hypertension, 28% had elevated cholesterol; 58%, 14%, and 9% of these cases can be attributed to occupational noise exposure, respectively.

CONCLUSIONS

Hypertension, elevated cholesterol, and hearing difficulty are more prevalent among noise-exposed workers. Reducing workplace noise levels is critical. Workplace-based health and wellness programs should also be considered.

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.

Association between Noise Pollution and Prevalent Ischemic Heart Disease

Background:Noise pollution is considered a risk factor for ischemic heart disease (IHD). Both are highly prevalent in Bulgaria, but their association has not been studied sufficiently.

Aim:The aim of the present study was to examine the risk of IHD associated with road traffic (Lden) and lifetime occupational noise exposure (LONE) in a Bulgarian sample.

Materials and methods:A cross-sectional survey was carried out among 513 residents of Plovdiv, Bulgaria. A questionnaire asked about doctor-diagnosed IHD, LONE and confounding factors. Ldenwas derived from official noise map after geocoding participants’ addresses. In log-link Poisson regressions we investigated the relative risks of prevalent IHD. Sensitivity analyses examined subgroup differences.

Results:Lden≥ 65 dB was associated with higher risk (RR=1.84, 95% CI: 0.61, 5.57) of IHD in long-term residents (≥ 20 years). LONE was associated with RR=1.76 (0.82, 3.78) for ever-exposed; and RR=2.35 (1.00, 5.52) for 15 - 47 years exposure.

Conclusions:Exposure to Lden≥65 dB was associated with non-significantly higher risk of IHD. Longer LONE was consistently associated with higher risk. In some subgroups the effect of noise was more pronounced.