Occupational stress and subclinical atherosclerosis: a systematic review

Abstract

Background:

Stress is a common hazard in the work environment and is associated with multiple adverse health effects. The association between work-related stress (WRS) and cardiovascular disease has been established in a number of epidemiological studies.

Methods:

A systematic review was conducted according to the PRISMA statement of the English literature involving WRS and carotid artery intima media thickness (CIMT).

Results:

Four cohorts and six cross-sectional studies of occupational stress and CIMT were identified. All cohorts and five of the cross-sectional studies reported a significant positive association, while one reported an inverse association of WRS and CIMT.

Discussion:

The weight of the evidence that we were able to identify suggests that occupational stress results in an increased risk of atherosclerosis, assessed via CIMT. Studies that include longitudinal measures of stress and intermediate cardiac endpoints, with adequate accounting for confounders, are needed. Interventional studies should also be conducted to determine whether CIMT progression can be prevented with workplace stress reduction.     

Air Pollution and Atherosclerosis: A Cross-Sectional Analysis of Four European Cohort Studies in the ESCAPE Study

Background:

In four European cohorts, we investigated the cross-sectional association between long-term exposure to air pollution and intima-media thickness of the common carotid artery (CIMT), a preclinical marker of atherosclerosis.

Methods:

Individually assigned levels of nitrogen dioxide, nitrogen oxides, particulate matter ≤ 2.5 μm (PM_2.5), absorbance of PM_2.5 (PM_2.5abs), PM₁₀, PM_coarse, and two indicators of residential proximity to highly trafficked roads were obtained under a standard exposure protocol (European Study of Cohorts for Air Pollution Effects—ESCAPE study) in the Stockholm area (Sweden), the Ausburg and Ruhr area (Germany), and the Girona area (Spain). We used linear regression and meta-analyses to examine the association between long-term exposure to air pollution and CIMT.

Results:

The meta-analysis with 9,183 individuals resulted in an estimated increase in CIMT (geometric mean) of 0.72% (95% CI: –0.65%, 2.10%) per 5-μg/m³ increase in PM_2.5 and 0.42% (95% CI: –0.46%, 1.30%) per 10^–5/m increase in PM_2.5abs. Living in proximity to high traffic was also positively but not significantly associated with CIMT. Meta-analytic estimates for other pollutants were inconsistent. Results were similar across different adjustment sets and sensitivity analyses. In an extended meta-analysis for PM_2.5 with three other previously published studies, a 0.78% (95% CI: –0.18%, 1.75%) increase in CIMT was estimated for a 5-μg/m³ contrast in PM_2.5.

Conclusions:

Using a standardized exposure and analytical protocol in four European cohorts, we found that cross-sectional associations between CIMT and the eight ESCAPE markers of long-term residential air pollution exposure did not reach statistical significance. The additional meta-analysis of CIMT and PM_2.5 across all published studies also was positive but not significant.

Citation:

Perez L, Wolf K, Hennig F, Penell J, Basagaña X, Foraster M, Aguilera I, Agis D, Beelen R, Brunekreef B, Cyrys J, Fuks KB, Adam M, Baldassarre D, Cirach M, Elosua R, Dratva J, Hampel R, Koenig W, Marrugat J, de Faire U, Pershagen G, Probst-Hensch NM, de Nazelle A, Nieuwenhuijsen MJ, Rathmann W, Rivera M, Seissler J, Schindler C, Thiery J, Hoffmann B, Peters A, Künzli N. 2015. Air pollution and atherosclerosis: a cross-sectional analysis of four European cohort studies in the ESCAPE Study. Environ Health Perspect 123:597–605; http://dx.doi.org/10.1289/ehp.1307711     

Occupational benzene exposure and the risk of lymphoma subtypes: a meta-analysis of cohort studies incorporating three study quality dimensions

Background

The use of occupational cohort studies to assess the association of benzene and lymphoma is complicated by problems with exposure misclassification, outcome classification, and low statistical power.

Objective

We performed meta-analyses of occupational cohort studies for five different lymphoma categories: Hodgkin lymphoma (HL), non-Hodgkin lymphoma (NHL), multiple myeloma (MM), acute lymphocytic leukemia (ALL), and chronic lymphocytic leukemia (CLL).

Data extraction

We assessed three study quality dimensions to evaluate the impact of study quality variations on meta-relative risks (mRRs): stratification by the year of start of follow-up, stratification by the strength of the reported acute myelogenous leukemia association, and stratification by the quality of benzene exposure assessment.

Data synthesis

mRRs for MM, ALL, and CLL increased with increasing study quality, regardless of the study quality dimension. mRRs for NHL also increased with increasing study quality, although this effect was less pronounced. We observed no association between occupational benzene exposure and HL.

Conclusions

Our meta-analysis provides support for an association between occupational benzene exposure and risk of MM, ALL, and CLL. The evidence for an association with NHL is less clear, but this is likely complicated by the etiologic heterogeneity of this group of diseases. Further consideration of the association between benzene and NHL will require delineation of risks by NHL subtype.     

A Systematic Review and Meta-analysis of Childhood Leukemia and Parental Occupational Pesticide Exposure

Objectives

We conducted a systematic review and meta-analysis of childhood leukemia and parental occupational pesticide exposure.

Data sources

Searches of MEDLINE (1950–2009) and other electronic databases yielded 31 included studies.

Data extraction

Two authors independently abstracted data and assessed the quality of each study.

Data synthesis

Random effects models were used to obtain summary odds ratios (ORs) and 95% confidence intervals (CIs). There was no overall association between childhood leukemia and any paternal occupational pesticide exposure (OR = 1.09; 95% CI, 0.88–1.34); there were slightly elevated risks in subgroups of studies with low total-quality scores (OR = 1.39; 95% CI, 0.99–1.95), ill-defined exposure time windows (OR = 1.36; 95% CI, 1.00–1.85), and exposure information collected after offspring leukemia diagnosis (OR = 1.34; 95% CI, 1.05–1.70). Childhood leukemia was associated with prenatal maternal occupational pesticide exposure (OR = 2.09; 95% CI, 1.51–2.88); this association was slightly stronger for studies with high exposure-measurement-quality scores (OR = 2.45; 95% CI, 1.68–3.58), higher confounder control scores (OR = 2.38; 95% CI, 1.56–3.62), and farm-related exposures (OR = 2.44; 95% CI, 1.53–3.89). Childhood leukemia risk was also elevated for prenatal maternal occupational exposure to insecticides (OR = 2.72; 95% CI, 1.47–5.04) and herbicides (OR = 3.62; 95% CI, 1.28–10.3).

Conclusions

Childhood leukemia was associated with prenatal maternal occupational pesticide exposure in analyses of all studies combined and in several subgroups. Associations with paternal occupational pesticide exposure were weaker and less consistent. Research needs include improved pesticide exposure indices, continued follow-up of existing cohorts, genetic susceptibility assessment, and basic research on childhood leukemia initiation and progression.     

Gynecologic pain related to occupational stress among female factory workers in Tianjin,China

Background:

Dysmenorrhea, dyspareunia, and non-cyclic pelvic pain are health concerns for factory workers in China and may be increased by occupational stress.

Objectives:

To estimate the prevalence and demographic and occupational factors associated with three types of gynecologic pain among female factory workers in Tianjin.

Methods:

The study included 651 female workers from three factories in Tianjin, China. Logistic regression models were estimated to determine associations between occupational stress and gynecologic pain.

Results:

Occupational stress including high job strain, exhaustion, and stress related to working conditions was a risk factor for gynecologic pain. High job strain and poor job security were associated with an increased risk for dysmenorrhea. Compulsory overtime and exhaustion were associated with increased non-cyclic pelvic pain. Working overtime and exhaustion were associated with increased dyspareunia.

Conclusions:

As China’s population of female factory workers grows, research on the reproductive health of this population is essential.     

Social capital and health: a review of prospective multilevel studies

Background

This article presents an overview of the concept of social capital, reviews prospective multilevel analytic studies of the association between social capital and health, and discusses intervention strategies that enhance social capital.

Methods

We conducted a systematic search of published peer-reviewed literature on the PubMed database and categorized studies according to health outcome.

Results

We identified 13 articles that satisfied the inclusion criteria for the review. In general, both individual social capital and area/workplace social capital had positive effects on health outcomes, regardless of study design, setting, follow-up period, or type of health outcome. Prospective studies that used a multilevel approach were mainly conducted in Western countries. Although we identified some cross-sectional multilevel studies that were conducted in Asian countries, including Japan, no prospective studies have been conducted in Asia.

Conclusions

Prospective evidence from multilevel analytic studies of the effect of social capital on health is very limited at present. If epidemiologic findings on the association between social capital and health are to be put to practical use, we must gather additional evidence and explore the feasibility of interventions that build social capital as a means of promoting health.Key words: health, literature review, multilevel analysis, prospective study, social capital     

More evidence of unpublished industry studies of lead smelter/refinery workers

Background

Lead smelter/refinery workers in the US have had significant exposure to lead and are an important occupational group to study to understand the health effects of chronic lead exposure in adults. Recent research found evidence that studies of lead smelter/refinery workers have been conducted but not published. This paper presents further evidence for this contention.

Objectives

To present further evidence of industry conducted, unpublished epidemiologic studies of lead smelter/refinery workers and health outcomes.

Methods

Historical research relying on primary sources such as internal industry documents and published studies.

Results

ASARCO smelter/refinery workers were studied in the early 1980s and found to have increased risk of lung cancer and stroke in one study, but not in another.

Conclusions

Because occupational lead exposure is an on-going concern for US and overseas workers, all epidemiologic studies should be made available to evaluate and update occupational health and safety standards.     

Association between occupational heat stress and kidney disease among 37,816 workers in the Thai Cohort Study (TCS)

Background

We examined the relationship between self-reported occupational heat stress and incidence of self-reported doctor-diagnosed kidney disease in Thai workers.

Methods

Data were derived from baseline (2005) and follow-up (2009) self-report questionnaires from a large national Thai Cohort Study (TCS). Analysis was restricted to full-time workers (n = 17 402 men and 20 414 women) without known kidney disease at baseline. We used logistic regression models to examine the association of incident kidney disease with heat stress at work, after adjustment for smoking, alcohol drinking, body mass index, and a large number of socioeconomic and demographic characteristics.

Results

Exposure to heat stress was more common in men than in women (22% vs 15%). A significant association between heat stress and incident kidney disease was observed in men (adjusted odds ratio [OR] = 1.48, 95% CI: 1.01–2.16). The risk of kidney disease was higher among workers reporting workplace heat stress in both 2005 and 2009. Among men exposed to prolonged heat stress, the odds of developing kidney disease was 2.22 times that of men without such exposure (95% CI 1.48–3.35, P-trend <0.001). The incidence of kidney disease was even higher among men aged 35 years or older in a physical job: 2.2% exposed to prolonged heat stress developed kidney disease compared with 0.4% with no heat exposure (adjusted OR = 5.30, 95% CI 1.17–24.13).

Conclusions

There is an association between self-reported occupational heat stress and self-reported doctor-diagnosed kidney disease in Thailand. The results indicate a need for occupational health interventions for heat stress among workers in tropical climates.Key words: occupational heat stress, kidney disease, Thai Cohort Study, Thailand     

Cutaneous exposure scenarios for engineered nanoparticles used in semiconductor fabrication: a preliminary investigation of workplace surface contamination

Background:

Numerous studies are ongoing in the fields of nanotoxicology and exposure science; however, gaps remain in identifying and evaluating potential exposures from skin contact with engineered nanoparticles in occupational settings.

Objectives:

The aim of this study was to identify potential cutaneous exposure scenarios at a workplace using engineered nanoparticles (alumina, ceria, amorphous silica) and evaluate the presence of these materials on workplace surfaces.

Methods:

Process review, workplace observations, and preliminary surface sampling were conducted using microvacuum and wipe sample collection methods and transmission electron microscopy with elemental analysis.

Results:

Exposure scenarios were identified with potential for incidental contact. Nanoparticles of silica or silica and/or alumina agglomerates (or aggregates) were identified in surface samples from work areas where engineered nanoparticles were used or handled.

Conclusions:

Additional data are needed to evaluate occupational exposures from skin contact with engineered nanoparticles; precautionary measures should be used to minimize potential cutaneous exposures in the workplace.     

Impact of a physical activity program on the anxiety,depression, occupational stress and burnout syndrome of nursing professionals

Objective

to assess the effects of a workplace physical activity (WPA) program on levels of anxiety, depression, burnout, occupational stress and self-perception of health and work-related quality of life of a nursing team in a palliative care unit.

Methods

the WPA was conducted five days per week, lasting ten minutes, during three consecutive months. Twenty-one nursing professionals were evaluated before and after the intervention, with the Hospital Anxiety and Depression Scale, the Maslch Burnout Inventory, and the Job Stress Scale. The changes in self-perceived health and work-related quality of life were measured using a semi-structured questionnaire.

Results

the WPA did not yield significant results on the levels of anxiety, depression, burnout or occupational stress. However, after the intervention, participants reported improved perceptions of bodily pain and feeling of fatigue at work.

Conclusion

the WPA did not lead to beneficial effects on occupational stress and psychological variables, but it was well accepted by the nursing professionals, who reported improvement in perceptions of health and work-related quality of life.     

Occupational and non-occupational factors associated with work-related injuries among construction workers in the USA

Background:

Many factors contribute to occupational injuries. However, these factors have been compartmentalized and isolated in most studies.

Objective:

To examine the relationship between work-related injuries and multiple occupational and non-occupational factors among construction workers in the USA.

Methods:

Data from the 1988–2000 National Longitudinal Survey of Youth, 1979 cohort (N = 12,686) were analyzed. Job exposures and health behaviors were examined and used as independent variables in four multivariate logistic regression models to identify associations with occupational injuries.

Results:

After controlling for demographic variables, occupational injuries were 18% (95% CI: 1.04–1.34) more likely in construction than in non-construction. Blue-collar occupations, job physical efforts, multiple jobs, and long working hours accounted for the escalated risk in construction. Smoking, obesity/overweight, and cocaine use significantly increased the risk of work-related injury when demographics and occupational factors were held constant.

Conclusions:

Workplace injuries are better explained by simultaneously examining occupational and non-occupational characteristics.     

Relationship Quality and Patient-Assessed Quality of Care in VA Primary Care Clinics: Development and Validation of the Work Relationships Scale

PURPOSE

Efforts to better understand the impact of clinic member relationships on care quality in primary care clinics have been limited by the absence of a validated instrument to assess these relationships. The purpose of this study was to develop and validate a scale assessing relationships within primary care clinics.

METHODS

The Work Relationships Scale (WRS) was developed and administered as part of a survey of learning and relationships among 17 Department of Veterans Affairs (VA) primary care clinics. A Rasch partial-credit model and principal components analysis were used to evaluate item performance, select the final items for inclusion, and establish unidimensionality for the WRS. The WRS was then validated against semistructured clinic member interviews and VA Survey of Healthcare Experiences of Patients (SHEP) data.

RESULTS

Four hundred fifty-seven clinicians and staff completed the clinic survey, and 247 participated in semistructured interviews. WRS scores were significantly associated with clinic-level reporting for 2 SHEP variables: overall rating of personal doctor/nurse (r² =0.43, P <.01) and overall rating of health care (r²= 0.25, P <.05). Interview data describing relationship characteristics were consistent with variability in WRS scores across low-scoring and high-scoring clinics.

CONCLUSIONS

The WRS shows promising validity as a measure assessing the quality of relationships in primary care settings; moreover, primary care clinics with lower WRS scores received poorer patient quality ratings for both individual clinicians and overall health care. Relationships play an important role in shaping care delivery and should be assessed as part of efforts to improve patient care within primary care settings.     

Occupational sunlight exposure, polymorphism of glutathione S-transferase M1, and senile cataract risk

Background

The pathogenesis of cataract is influenced by a number of factors including oxidative stress. Glutathione S‐transferase (GST) catalyses the nucleophilic addition of the thiol of GST to electrophilic acceptors. It is important for detoxification of xenobiotics in order to protect tissues from oxidative damage.

Objectives

To examine whether the interaction of polymorphism of GSTM1 gene and occupational sunlight exposure modulate the risk of cataract.

Methods

Blood samples from 95 subjects with cataract and 95 age and sex matched healthy persons were collected. The genotypes of GSTM1 were determined using PCR.

Results

The null genotype of GSTM1 was associated with an increase in cataract risk in the indoor workplace, but this association was not significant in the outdoor subjects.

Conclusion

The active genotype of GSTM1 has lost its protective role in persons who work outdoors. It is suggested that activity of the GSTμ enzyme may be inhibited in the human lens after occupational exposure to UV light.     

Measuring Effort–Reward Imbalance in School Settings: A Novel Approach and Its Association With Self-Rated Health

Background

We attempted to apply the model of effort–reward imbalance (ERI) to school settings in order to measure students’ psychosocial stress and analyze its association with self-rated health in adolescents.

Methods

A cross-sectional survey was conducted in Kunming, China among 1004 Chinese students (468 boys and 536 girls) in grades 7 through 12, using a 19-item effort–reward imbalance questionnaire.

Results

Satisfactory internal consistencies for the scales for effort and reward were obtained; the value for the scale for overcommitment was acceptable. Factor analysis replicated the theoretical structure of the ERI construct in this sample of Chinese students. All 3 scales were associated with an elevated odds ratio for diminished self-rated health, and the effect was strongest for the effort–reward ratio, as predicted by the theory. Sex and grade differences were also observed.

Conclusions

The ERI questionnaire is a valid instrument for identifying sources of stressful experience, in terms of effort–reward imbalance, among adolescents in school settings.Key words: effort–reward imbalance, psychosocial school stress, self-rated health, adolescents     

A Nonparametric Statistical Method That Improves Physician Cost of Care Analysis

Objective

To develop a compositing method that demonstrates improved performance compared with commonly used tests for statistical analysis of physician cost of care data.

Data Source

Commercial preferred provider organization (PPO) claims data for internists from a large metropolitan area.

Study Design

We created a nonparametric composite performance metric that maintains risk adjustment using the Wilcoxon rank-sum (WRS) test. We compared the resulting algorithm to the parametric observed-to-expected ratio, with and without a statistical test, for stability of physician cost ratings among different outlier trimming methods and across two partially overlapping time periods.

Principal Findings

The WRS algorithm showed significantly greater within-physician stability among several typical outlier trimming and capping methods. The algorithm also showed significantly greater within-physician stability when the same physicians were analyzed across time periods.

Conclusions

The nonparametric algorithm described is a more robust and more stable methodology for evaluating physician cost of care than commonly used observed-to-expected ratio techniques. Use of such an algorithm can improve physician cost assessment for important current applications such as public reporting, pay for performance, and tiered benefit design.     

Malondialdehyde–Deoxyguanosine Adducts among Workers of a Thai Industrial Estate and Nearby Residents

Background

Humans living near industrial point emissions can experience high levels of exposures to air pollutants. Map Ta Phut Industrial Estate in Thailand is the location of the largest steel, oil refinery, and petrochemical factory complexes in Southeast Asia. Air pollution is an important source of oxidative stress and reactive oxygen species, which interact with DNA and lipids, leading to oxidative damage and lipid peroxidation, respectively.

Objective

We measured the levels of malondialdehyde–deoxyguanosine (dG) adducts, a biomarker of oxidative stress and lipid peroxidation, in petrochemical workers, nearby residents, and subjects living in a control district without proximity to industrial sources.

Design

We conducted a cross-sectional study to compare the prevalence of malondialdehyde-dG adducts in groups of subjects experiencing various degrees of air pollution.

Results

The multivariate regression analysis shows that the adduct levels were associated with occupational and environmental exposures to air pollution. The highest adduct level was observed in the steel factory workers. In addition, the formation of DNA damage tended to be associated with tobacco smoking, but without reaching statistical significance. A nonsignificant increase in DNA adducts was observed after 4–6 years of employment among the petrochemical complexes.

Conclusions

Air pollution emitted from the Map Ta Phut Industrial Estate complexes was associated with increased adduct levels in petrochemical workers and nearby residents. Considering the mutagenic potential of DNA lesions in the carcinogenic process, we recommend measures aimed at reducing the levels of air pollution.     

Research Recommendations for Selected IARC-Classified Agents

Objectives

There are some common occupational agents and exposure circumstances for which evidence of carcinogenicity is substantial but not yet conclusive for humans. Our objectives were to identify research gaps and needs for 20 agents prioritized for review based on evidence of widespread human exposures and potential carcinogenicity in animals or humans.

Data sources

For each chemical agent (or category of agents), a systematic review was conducted of new data published since the most recent pertinent International Agency for Research on Cancer (IARC) Monograph meeting on that agent.

Data extraction

Reviewers were charged with identifying data gaps and general and specific approaches to address them, focusing on research that would be important in resolving classification uncertainties. An expert meeting brought reviewers together to discuss each agent and the identified data gaps and approaches.

Data synthesis

Several overarching issues were identified that pertained to multiple agents; these included the importance of recognizing that carcinogenic agents can act through multiple toxicity pathways and mechanisms, including epigenetic mechanisms, oxidative stress, and immuno- and hormonal modulation.

Conclusions

Studies in occupational populations provide important opportunities to understand the mechanisms through which exogenous agents cause cancer and intervene to prevent human exposure and/or prevent or detect cancer among those already exposed. Scientific developments are likely to increase the challenges and complexities of carcinogen testing and evaluation in the future, and epidemiologic studies will be particularly critical to inform carcinogen classification and risk assessment processes.