Development and psychometric evaluation of a Total Worker Health® practice scale

OBJECTIVE

Occupational Safety and Health (OSH) professionals increasingly need to assess and mitigate a broad scope of worker safety, health, and well-being concerns that extend beyond traditional OSH training curricula. Work-related and non-work-related psychosocial hazards, chronic physical and mental health conditions, and changing work arrangements call for an integrative, public health approach to occupational risk management; this approach has been called, "Total Worker Health®" by United States public health authorities (Schulte et al. 2019). OSH professionals need education to ensure that Total Worker Health (TWH) practice approaches are consistently and effectively applied. This study sought to develop a valid, reliable scale that could be used to assess TWH skills gaps that can be addressed with tailored, competency-based curricula.

METHOD

We developed a survey scale to assess professional competency for specific TWH practice approaches described in prior literature (Lee et al. 2016; Punnett et al. 2020). The scale contained 11 statements and used a 5-point scale (not skilled to highly skilled) to rate the level of competency. We pre-tested and refined the statements for face validity then administered the scale with a convenience sample of 258 professionals from mixed OSH disciplines. A total of 210 OSH professionals (31% safety, 17% industrial hygiene, 12% occupational nurses, 11% occupational physicians, 29% other) who completed 50% or more of the questions were included in the analysis. Scale reliability was assessed with a Cronbach's alpha test. Scale validity and structure were assessed with exploratory factor analysis (EFA).

RESULTS

The 11-item scale had high internal consistency (Cronbach's α = 0.92). The initial EFA solution suggested 2 factors that explained 65.3% of variance, with one cross-loaded question. A final 10-item, 2-factor scale was developed that accounted for 66.0% of variance with no cross-loaded items (Cronbach's alpha α = 0.91). Factor 1 (6 items) contributed to 55.5% of the variance and captured skills related to TWH program leadership (e.g. leader commitment, integrating program systems, engaging with other program leaders and workers). Factor 2 (4 items) contributed to 10.5% of the variance and captured technical skills related to hazard identification and control (e.g. identifying hazards, designing work to reduce hazards). Internal consistency was very good for both TWH program leadership (Cronbach α = 0.89) and TWH risk assessment and control (Cronbach α = 0.80) subscales.

CONCLUSION

A novel 10-item TWH skill scale to assess specific TWH practice approaches was developed with very good reliability. Factor analysis revealed 2 latent constructs: TWH leadership skills and TWH risk assessment and control skills. This study offers an evidence-based tool to assess competency for specific TWH practices among OSH professionals. The results of this study contribute to the broader research base needed to formalize a TWH competency framework, as advocated by other scholars interested in TWH workforce education (Newman et al. 2020).

Life satisfaction and job and personal resources among public workers with non-standard work schedules

BACKGROUND

While the link between non-standard work schedules and poor health outcomes is established, few studies have examined how resources both in and outside of work can support the well-being of workers with non-standard work schedules.

METHODS

Using a cross-sectional survey, we assessed the association between one facet of well-being, life satisfaction, and job and personal resources. In 2019, an electronic survey was administered to two unionized, public service populations who work non-standard work schedules: transportation maintainers and correctional supervisors. We assessed life satisfaction with a 10-item scale; a broad set of job resources (reward satisfaction, supervisor support, co-worker support, schedule satisfaction, and working hours fit); and a broad set of personal resources (health status, sleep, physical activity, and finances). We used log-binomial regression models to estimate prevalence ratios and 95% confidence intervals among statistically significant univariate predictors.

RESULTS

Of the 316 workers surveyed, the majority were male (86%), White (68%), and reported positive life satisfaction (56%). In multivariate models, the prevalence of positive life satisfaction was higher in workers reporting reward satisfaction (PR:1.35, 95% CI: 1.11, 1.65; p = 0.003), good work schedule fit (PR:1.43, 95% CI: 1.12, 1.83; p = 0.004), good health (PR:2.92, 95% CI: 1.70, 4.99; p < 0.0001), and good finances (PR:1.32, 95% CI: 1.01, 1.72; p = 0.04).

CONCLUSION

Employers should consider increasing work recognition, as well as improving schedule fit, financial well-being, and overall good health in support of worker life satisfaction and ultimately well-being.

Impact of work schedule characteristics on teacher mental health and burnout symptoms while remote working

BACKGROUND

During the COVID-19 pandemic, teachers quickly shifted to remote teaching with many teachers experiencing increased work demands with limited resources, affecting both mental health and work.

METHODS

Within a cross-sectional study, we evaluated the relationship between one type of work demand, non-standard work schedule characteristics, and depressive and burnout symptoms in kindergarten through 8th grade U.S. teachers working remotely in May 2020. We further assessed the impact of COVID-19 and work resources. Work schedule characteristics were self-assessed across six domains on a 5-point frequency scale from always (1) to never (5). We used multilevel Poisson models to calculate prevalence ratios (PRs) and 95% confidence intervals (CIs).

RESULTS

In fully adjusted models, frequently working unexpectedly was associated with a higher prevalence of depressive symptoms (PR = 1.18, 95% CI = 1.07-1.31, p < 0.01), high emotional exhaustion (PR = 1.17, 95% CI = 1.05-1.30, p < 0.01), and high depersonalization (PR = 1.40, 95% CI = 1.02-1.92, p = 0.03). Remote work resources were significantly associated with a lower prevalence of depressive symptoms (PR = 0.88, 95% CI = 0.79-0.98, p = 0.02). There was a linear association between low coworker support and a low sense of personal accomplishment (PR = 0.68, 95% CI = 0.53-0.87, p < 0.01).

CONCLUSIONS

Frequently having to work unexpectedly while remote teaching was associated with symptoms of depression and burnout during the COVID-19 pandemic. Workplaces should support predictable working times to lessen the disruption caused by unexpected work to promote worker well-being.

Qualitative Assessment of Perceived Organizational Support for Employed Breast Cancer Survivors

OBJECTIVE

A more detailed understanding of unmet organizational support needs and workplace-based best practices for supporting cancer survivors is needed.

METHODS

Ninety-four working breast cancer survivors responded to an open-ended survey question regarding the desired types of organizational support that were and were not received during early survivorship. We performed content-analysis of qualitative data.

RESULTS

Major themes included instrumental support, emotional support, and time-based support. The need for flexible arrangements and reduced workloads was mostly met. Unmet needs included navigation/coordination, understanding/empathy, and time off for treatment and recovery.

CONCLUSIONS

Organizational support can help cancer survivors manage their health and work roles, diminishing work-health conflict and turnover intent. Study findings can be used to design targeted interventions to fulfill cancer survivors' unmet organizational support needs, which may also apply to workers with other chronic health conditions.

Associations between observed time sitting at work and musculoskeletal symptoms: a repeated-measures study of manufacturing workers

Time sitting at work is known to affect health overall, but its specific effects on musculoskeletal symptoms are unclear. We evaluated the relationship between observed time sitting at work and self-reported musculoskeletal symptoms among 195 manufacturing workers. Longer time sitting at work was significantly associated with lower prevalence of neck/shoulder (prevalence ratio [PR] = 0.70, 95% confidence interval [CI] [0.68, 0.72]; p < 0.001) and arm/wrist/hand (PR = 0.46, 95% CI [0.31, 0.69]; p < 0.001) musculoskeletal symptoms. Associations remained largely unchanged after adjusting for job type or occupational postures and load. Time sitting at work was associated with musculoskeletal symptoms, and should be taken into consideration as part of interventions to prevent musculoskeletal disorders (MSDs) and promote health of manufacturing workers.

Participatory design of a sleep intervention with correctional supervisors using a root causes approach

BACKGROUND

After a Design Team (DT) conducted a workforce health assessment of correctional supervisors, they selected sleep as an intervention priority, given its numerous health and work consequences. Existing workplace sleep interventions are designed with little worker input, but participatory solutions that incorporate workers' lived experiences and root causes of poor sleep may be more relevant, appropriate, and acceptable to end-users, resulting in better uptake.

METHODS

The DT met bi-monthly to complete the Intervention Design and Analysis Scorecard (IDEAS) tool to brainstorm interventions that address root causes of poor sleep, and evaluate, rank, and select interventions for implementation. We conducted a qualitative review of meeting notes and worksheets from each IDEAS step, and present our findings on root causes and prioritized solutions.

RESULTS

The DT consisted of two university researchers and seven members of a correctional supervisors' union, with 5-9 participants attending each meeting. IDEAS Steps 1-5 were completed in eight meetings over six months. Root causes of poor sleep included mind/body and environmental disruptions, and insufficient time. Three solutions were proposed: training on sleep hygiene, meditation, and sleep debt management; a sleep-tracking smartphone app; and a shared overtime policy based on splitting one 8-hour shift between two supervisors.

CONCLUSIONS

This is the first known application of IDEAS to address sleep, and targeting root causes may result in more efficacious interventions for sleep improvement. Moreover, because IDEAS guides DTs in selecting solutions with the greatest perceived health benefits, reach, cost-effectiveness, and feasibility, it may result in more successful implementation.

The development and initial validation of a new working time scale for full-time workers with non-standard schedules

BACKGROUND

Working time characteristics have been used to link work schedule features to health impairment; however, extant working time exposure assessments are narrow in scope. Prominent working time frameworks suggest that a broad range of schedule features should be assessed to best capture non-standard schedules. The purpose of this study was to develop a multi-dimensional scale that assesses working time exposures and test its reliability and validity for full-time workers with non-standard schedules.

METHODS

A cross-sectional study was conducted using full-time, blue-collar worker population samples from three industries - transportation (n = 174), corrections (n = 112), and manufacturing (n = 99). Using a multi-phased approach including the review of scientific literature and input from an advisory panel of experts, the WorkTime Scale (WTS) was created and included multiple domains to characterize working time (length, time of day, intensity, control, predictability, and free time). Self-report surveys were distributed to workers at their workplace during company time. Following a comprehensive scale development procedure (Phase 1), exploratory factor analysis (EFA) (Phase 2) and, confirmatory factor analysis (CFA) (Phase 3; bivariate correlations were used to identify the core components of the WTS and assess the reliability and validity (Phase 4) in three samples.

RESULTS

Phase 1 resulted in a preliminary set of 21 items that served as the basis for the quantitative analysis of the WTS. Phase 2 used EFA to yield a 14-item WTS measure with two subscales ("Extended and Irregular Work Days (EIWD)" and "Lack of Control (LOC)"). Phase 3 used CFA to confirm the factor structure of the WTS, and its subscales demonstrated good internal consistency: alpha coefficients were 0.88 for the EIWD factor and 0.76-0.81 for the LOC factor. Phase 4 used bivariate correlations to substantiate convergent, discriminant, and criterion (predictive) validities.

CONCLUSIONS

The 14-item WTS with good reliability and validity is an effective tool for assessing working time exposures in a variety of full-time jobs with non-standard schedules.

Participatory Assessment and Selection of Workforce Health Intervention Priorities for Correctional Supervisors

OBJECTIVE

A team of academics and unionized correctional supervisors collaborated to assess workforce health and determine intervention priorities using participatory methods and tools.

METHODS

Correctional supervisors took a web-based survey. Univariate and bivariate tests examined attitudes/behaviors, exposures, and outcomes most strongly associated with health; risk based on rank within chain-of-command; and health behaviors amenable to change. We used a voting process tool to prioritize intervention topics.

RESULTS

Some health behaviors and outcomes were poor (89% overweight/ obese, 41% poor-quality sleep). We also found favorable health behaviors (annual check-ups) and psychosocial conditions (meaningful work). Some health risks (excessive overtime) were not amenable to change or resisted acknowledgment (poor mental health). The team voted to develop interventions on sleep, mental health, and obesity.

CONCLUSIONS

Comprehensive health assessment informed the prioritization process, enabling the team to quickly reach consensus on intervention priorities.

Scale-out of a Total Worker Health® approach for designing interventions to reduce teacher stress: pilot implementation evaluation

BACKGROUND

Teachers have high rates of daily stress and the majority of available interventions are focused at the teacher-level. Yet, best practices in Total Worker Health® approaches indicate organization-level interventions identified using a participatory approach are most effective. We conducted an exploratory scale-out pilot study to examine the adoption of the Healthy Workplace Participatory Program (HWPP), an evidence-based, Total Worker Health approach to engage employees (e.g., teachers) and supervisory personnel (e.g., administrators) in the design and implementation of workplace well-being interventions within two elementary schools.

METHODS

We evaluated the program both quantitatively and qualitatively collecting implementation outcome data (i.e., fidelity, acceptability, understanding, feasibility, system alignment) as well as data-driven adaptations using the Framework for Reporting Adaptations and Modifications-Expanded. Data from the first school informed scale-out adaptation of the HWPP intervention, HWPP-Education, within the second school. We compared implementation outcomes between Pilot Schools 1 and 2 to evaluate improvements in the adapted HWPP.

RESULTS

Adaptations to HWPP program content and process were suggested to increase feasibility and contextual fit. Acceptability, understanding, and feasibility ratings showed statistically significant improvements comparing School 1 to School 2 which implemented the improved HWPP-Education. Furthermore, users reported adaptations including shorter meeting design and faster process were feasible within their work context.

CONCLUSION

This pilot study is the first attempt to scale out the HWPP to educators, and while not intended to confirm efficacy, it showed promising results for scale-out. Results from Pilot Schools 1 and 2 suggest systematic use of quantitative and qualitative implementation data can effectively inform scale-out efforts that increase critical outcomes such as fidelity, acceptability, understanding, feasibility, system alignment, and leader engagement as well as decrease the extent of system resources needed. As such, this scale-out process may be a feasible approach on which to base large-scale implementation efforts of the HWPP among educators.

GuLF DREAM: A Model to Estimate Dermal Exposure Among Oil Spill Response and Clean-up Workers

Tens of thousands of individuals performed oil spill response and clean-up (OSRC) activities following the 'Deepwater Horizon' oil drilling rig explosion in 2010. Many were exposed to oil residues and dispersants. The US National Institute of Environmental Health Sciences assembled a cohort of nearly 33 000 workers to investigate potential adverse health effects of oil spill exposures. Estimates of dermal and inhalation exposure are required for those individuals. Ambient breathing-zone measurements taken at the time of the spill were used to estimate inhalation exposures for participants in the GuLF STUDY (Gulf Long-term Follow-up Study), but no dermal measurements were collected. Consequently, a modelling approach was used to estimate dermal exposures. We sought to modify DREAM (DeRmal Exposure Assessment Method) to optimize the model for assessing exposure to various oil spill-related substances and to incorporate advances in dermal exposure research. Each DREAM parameter was reviewed in the context of literature published since 2000 and modified where appropriate. To reflect the environment in which the OSRC work took place, the model treatment of evaporation was expanded to include vapour pressure and wind speed, and the effect of seawater on exposure was added. The modified model is called GuLF DREAM and exposure is estimated in GuLF DREAM units (GDU). An external validation to assess the performance of the model for oils, tars, and fuels was conducted using available published dermal wipe measurements of heavy fuel oil (HFO) and dermal hand wash measurements of asphalt. Overall, measured exposures had moderate correlations with GDU estimates (r = 0.59) with specific correlations of -0.48 for HFO and 0.68 for asphalt. The GuLF DREAM model described in this article has been used to generate dermal exposure estimates for the GuLF STUDY. Many of the updates made were generic, so the updated model may be useful for other dermal exposure scenarios.

The effects of a new seat suspension system on whole body vibration exposure and driver low back pain and disability: Results from a randomized controlled trial in truck drivers

Through a randomized controlled trial, we evaluated the effects of an electro-magnetic active seat suspension that reduces exposure of a long-haul truck driver to whole body vibration (WBV) on low back pain (LBP) and disability. Among 276 drivers recruited from six trucking terminals of a major US trucking company, 135 eligible drivers were assigned to either having an Active Seat (Intervention: n = 70) - the BoseRide® electro-magnetic active seat - or Passive Seat (reference: n = 65) - a new version of their current seat (passive air suspension seat) - installed in their truck via block (terminal) randomization. Low back pain (LBP) severity, on a 0-10 scale and the Oswestry LBP Disability Index were collected before and 3-, 6-, 12-, 18-, and 24-months post seat installation. LBP severity and LBP disability scores were significantly lower post seat installation in both groups. At 3 months, LBP severity decreased -1.4 [95% CI: -2.1 to -0.7: n = 46] for drivers in the Active Seat arm, and -1.5 [95% CI: -2.3 to -0.8: n = 41] for drivers in the Passive Seat arm. In a subset of drivers, WBV exposures were collected before and after the seat installation. WBV exposures significantly decreased post seat installation for Active Seat (p < 0.01) but not for Passive Seat (p = 0.15). While the new seat-suspension technology reduced WBV exposures, LBP appeared to be improved by multiple factors. These results were limited by the secondary prevention approach and the longer-term loss to follow up due to large rates of driver turnover typical for the industry.

Precarious Work Schedules and Sleep: A Study of Unionized Full-Time Workers

Unlike precarious employment which is temporary and insecure, with inadequate pay, benefits, and legal protections, precarious work schedules can affect workers with permanent full-time jobs in sectors where employment has historically been secure, well-compensated, and even unionized. Precarious work schedules - characterized by long shifts, non-daytime hours, intensity and unsocial work hours - are increasingly prevalent. Relations between precarious work schedules and poor health are not well understood, and less is known about how to attenuate this relation. We examined the indirect effects of precarious work schedules on fatigue and depressive symptoms through sleep quantity. Two moderators - schedule flexibility and sleep quality - were examined as buffers of these associations. Workers from the Departments of Correction and Transportation in a northeast state (N = 222) took surveys and reported on demographics, work schedule characteristics, schedule flexibility, sleep quality and quantity, fatigue, and depressive symptoms. Results revealed that precarious work schedules had indirect effects on fatigue and depressive symptoms through sleep quantity. Schedule flexibility moderated the relation between precarious work schedules and sleep quantity, such that workers with greater schedule flexibility had more hours of sleep. Sleep quality moderated the association between sleep quantity and fatigue and depressive symptoms, such that workers reported greater fatigue and depressive symptoms when they had poorer sleep quality. Findings have direct applicability for developing initiatives that enhance Total Worker Health® through individual and organizational changes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41542-022-00114-y.

Evaluation of the HearWell Pilot Program: A Participatory Total Worker Health® Approach to Hearing Conservation

Our objective was to pilot test HearWell, an intervention created to preserve hearing among highway maintainers, by using a participatory Total Worker Health^® (TWH) approach to designing, implementing and evaluating interventions. Regional maintenance garages were randomized to control (n = 6); HearWell (n = 4) or HearWell Design Team (n = 2) arms. Maintainer representatives from the HearWell Design Team garages identified barriers to hearing health and collaborated to design interventions including a safety leadership training for managers, a noise hazard management scheme to identify noise levels and indicate the hearing protection device (HPD) needed, and a comprehensive HearWell training video and protocol. These worker-designed interventions, after manager input, were delivered to the HearWell Design Team and the HearWell garages. Control garages received standard industry hearing conservation training. Periodic surveys of workers in all 12 garages collected information on the frequency of HPD use and a new hearing climate measure to evaluate changes in behaviors and attitudes over the study period and following interventions. An intention-to-treat approach was utilized; differences and trends in group HPD use and hearing climate were analyzed using a mixed-effects model to account for repeated measures from individual participants. The HearWell Design Team maintainers reported the highest frequency of HPD use. Hearing climate improved in each group 6 months following intervention implementation, with the largest increase and highest value for the HearWell Design Team workers. The HearWell pilot intervention showed promising results in improving HPD use through a participatory TWH approach to hearing conservation. Furthermore, results suggest that employee participation in hearing conservation programs may be necessary for maximal effectiveness.

Exposure, health effects, sensing, and remediation of the emerging PFAS contaminants - Scientific challenges and potential research directions

Per- and polyfluoroalkyl substances (PFAS) make up a large group of persistent anthropogenic chemicals which are difficult to degrade and/or destroy. PFAS are an emerging class of contaminants, but little is known about the long-term health effects related to exposure. In addition, technologies to identify levels of contamination in the environment and to remediate contaminated sites are currently inadequate. In this opinion-type discussion paper, a team of researchers from the University of Connecticut and the University at Albany discuss the scientific challenges in their specific but intertwined PFAS research areas, including rapid and low-cost detection, energy-saving remediation, the role of T helper cells in immunotoxicity, and the biochemical and molecular effects of PFAS among community residents with measurable PFAS concentrations. Potential research directions that may be employed to address those challenges and improve the understanding of sensing, remediation, exposure to, and health effects of PFAS are then presented. We hope our account of emerging problems related to PFAS contamination will encourage a broad range of scientific experts to bring these research initiatives addressing PFAS into play on a national scale.

Leisure-Time Physical Activity and General Health Mitigate Effects of Job Demands on Nonrestorative Sleep: CDC National Healthy Worksite Project

OBJECTIVE

We sought to determine if leisure-time physical activity (LTPA) modified the adverse relationship between high job demands and nonrestorative sleep (NRS).

METHODS

We conducted a multivariate logistic regression analysis among workers from the cross-sectional National Healthy Worksite Project (n = 4683) using self-report Likert-Scale data on psychological and physical demands of jobs, LTPA and general health in relation to NRS.

RESULTS

Not engaging in LTPA was associated with NRS for workers with jobs at the lowest or highest levels of the physical demand scale (OR 1.64, 95% CI: 0.96-2.81, OR 2.06, 95% CI: 0.95-4.45; respectively) in comparison to those who met LTPA recommendations. When assessing psychological demands, poor general health was associated with NRS at all levels of the scale independent of LTPA.

CONCLUSIONS

LTPA may reduce NRS for workers with jobs at either extreme of physical demands.

Working Time Characteristics and Mental Health among Corrections and Transportation Workers

OBJECTIVES

Mental health disorders are a leading cause of work disability and while the psychosocial workplace environment plays a critical role, working time characteristics are also implicated. We sought to examine the association between working time characteristics and mental health in a cohort of two unionized, full-time worker populations, correctional supervisors, and transportation maintainers.

METHODS

Using a cross-sectional study design, we surveyed workers on working time characteristics across seven domains including length of the shift, the intensity or proximity of sequential shifts, the time of day, and social aspects of work hours including predictability, variability, control, and free time. Burnout symptoms (Oldenburg Burnout Inventory) and depressive symptoms (eight-item Centers for Epidemiologic Studies Depression Scale) were assessed along with the psychosocial work environment and health behaviors. We used log-binomial regression models to estimate prevalence ratios and 95% confidence intervals after adjusting for age, gender, and company.

RESULTS

A total of 318 workers were surveyed. The majority (72%) of workers reported a fixed shift. The prevalence of burnout symptoms was higher among workers reporting more frequent shift intensity (working 6 or more days in a row) (PR: 1.15, 95% CI: 1.01, 1.31; P = 0.04). Low psychological demands and high worker social support were associated with fewer burnout symptoms, independent of working time characteristics. The prevalence of depressive symptoms was higher in workers reporting more frequent unpredictable work (PR: 1.17, 95% CI: 1.01, 1.35; P = 0.04) and was lower among workers reporting increased schedule control (PR: 0.86, 95% CI: 0.77, 0.96; P = 0.01). Higher worker social support as well as sufficient sleep and adequate exercise were associated with fewer depressive symptoms, independent of working time characteristics.

CONCLUSIONS

Different working time characteristics were associated with work-related mental health (i.e. burnout) as well as general mental health (i.e. depressive symptoms). Work intensity was associated with the prevalence of burnout symptoms and the results suggest that the mechanism may be through the need for recovery from the psychosocial exposures of work. Both schedule control and predictability were associated with depressive symptoms and the results suggest that work-life imbalance and lack of recovery may be implicated. Comprehensive prevention policies that consider work organization along with the psychosocial work environment and work-life balance may help to improve workers' mental health.

Participatory survey design of a workforce health needs assessment for correctional supervisors

INTRODUCTION

The correctional workforce experiences persistent health problems, and interventions designed with worker participation show favorable outcomes. However, participatory intervention research often leaves workers out of the health needs assessment, the basis of interventions subsequently developed. This omission risks failure to detect factors contributing to the health and is less likely to result in primary prevention interventions.

METHODS

Partnering with a correctional supervisors' union, we followed Schulz and colleagues' community-based participatory research (CBPR) methods for participatory survey design and used Healthy Workplace Participatory Program (HWPP) tools to develop a tailored survey to assess workforce health and contributing factors. Utilizing the HWPP Focus Group Guide, we generated key themes to adapt the HWPP All Employee Survey, a generic workforce health assessment, to become thorough and contextually-relevant for correctional supervisors.

RESULTS

Content analysis of focus group data revealed 12 priority health concerns and contributors, including organizational culture, masculinity, work-family conflict, family support, trauma, positive job aspects, health literacy and efficacy, health/risk behaviors, sleep, obesity, and prioritizing work and income over health. Twenty-six measures were added to the generic survey, mainly health-related antecedents including knowledge, attitudes, norms, and motivation.

CONCLUSION

Findings yielded new insights about supervisors' lived experiences of work and health, and resulted in a customized workforce survey. CBPR methods and HWPP tools allowed us to identify health issues that we would not have detected with conventional methods, and provide opportunities for interventions that address root causes of poor health. We share challenges faced and lessons learned using CBPR with the correctional workforce.

Perceptions of clinical support for employed breast cancer survivors managing work and health challenges

PURPOSE

A substantial portion of breast cancer survivors are active in the workforce, yet factors that allow survivors to balance work with cancer management and to return to work are poorly understood. We examined breast cancer survivors' most valued/desired types of support in early survivorship.

METHODS

Seventy-six employed breast cancer survivors answered an open-ended survey question assessing the most valued/desired support to receive from healthcare providers during early survivorship to manage work and health. Cutrona's (Journal of Social and Clinical Psychology 9:3-14, 1990) optimal matching theory and House's (1981) conceptualization of social support types informed our analyses. Data were content-analyzed to identify themes related to support, whether needed support was received or not, and the types of healthcare providers who provided support.

RESULTS

We identified six themes related to types of support. Informational support was valued and mostly received by survivors, but they expected more guidance related to work. Emotional support was valued but lacking, attributed mainly to providers' lack of personal connection and mental health support. Instrumental (practical) support was valued but received by a small number of participants. Quality of life support to promote well-being and functionality was valued and often received. Other themes included non-specific support and non-support.

CONCLUSIONS

This study expands our understanding of how breast cancer survivors perceive work-related support from healthcare professionals. Findings will inform targeted interventions designed to improve the support provided by healthcare professionals.

IMPLICATIONS FOR CANCER SURVIVORS

Breast cancer survivors managing work and health challenges may benefit by having their unmet support needs fulfilled.

Investigating the relationship between working time characteristics on musculoskeletal symptoms: a cross sectional study

How working hours are organized can have a substantial effect on workers' health. Using a questionnaire and cross-sectional study design, we evaluated the relationship between working time characteristics, job demands, and health behaviors on musculoskeletal symptoms among 316 Department of Transportation (N = 174) and Department of Corrections (N = 142) workers. Low schedule control was associated with neck/shoulder musculoskeletal symptoms (prevalence ratio: 1.20, 95% confidence interval: 1.06-1.34, p < 0.01), and working long (>48 hours per week) hours more frequently was associated with leg/foot musculoskeletal symptoms (prevalence ratio: 1.26 95% confidence interval: 1.06-1.50, p = 0.02). Some working time characteristics were associated with musculoskeletal symptoms, and should be taken into consideration as part of interventions to prevent musculoskeletal disorders and promote health of workers.

Development and application of a noise-hazard scheme for road maintainers

BACKGROUND

Transportation road maintenance and repair workers, or "maintainers," are exposed to hazardous and variable noise levels and often rely on hearing protection devices (HPD) to reduce noise-exposure levels. We aimed to improve upon HPD use as part of the HearWell program that used a Total Worker Health, participatory approach to hearing conservation.

METHODS

Full-shift, personal noise sampling was performed during the routine task of brush cutting. Work activities and equipment were recorded and combined with 1-min noise measures to summarize personal noise-exposure levels by equipment. Using noise-monitoring results, HPD noise reduction ratings, and input from worker-based design teams, a noise-hazard scheme was developed and applied to the task and equipment used during brush cutting.

RESULTS

Average (standard deviation) and maximum L_eq 1-minute, personal noise-exposure levels recorded during brush cutting included chainsaws at 92.1 (7.6) and max of 111 dBA, leaf blowers at 91.2 (7.5) and max 107 dBA, and wood chipper at 90.3 (7.3) and max of 104 dBA. The worker-designed noise-hazard scheme breaks down noise exposures into one of three color bands and exposure ranges: red (over 105 dBA), orange (90-105 dBA), or yellow (85-90 dBA). The scheme simplifies the identification of noise levels, assessment of noise-hazard, and choice of appropriate hearing protection for workers.

CONCLUSION

Combining noise-exposure assessment with intervention development using participatory methods, we characterized noise exposure and developed an intervention to educate and assist in protecting workers as they perform noisy tasks.

Defining 'Integration' for Total Worker Health®: A New Proposal

The effects of work and the conditions of employment on health behaviors and intermediate health conditions have been demonstrated, to the extent that these relationships should be addressed in efforts to prevent chronic disease. However, conventional health promotion practice generally focuses on personal risk factors and individual behavior change. In an effort to find solutions to the myriad of health challenges faced by the American workforce, the U.S. National Institute for Occupational Safety and Health (NIOSH) established the Total Worker Health® (TWH) program. Originally organized around the paradigm of integrating traditional occupational safety and health protections with workplace health promotion, TWH has evolved to a broader emphasis on workplace programs for enhancing worker safety, health, and well-being. Among the research programs and approaches developed by investigators at NIOSH Centers of Excellence for TWH and elsewhere, definitions of 'integration' in workplace interventions vary widely. There is no consensus about which organizational or individual outcomes are the most salient, how much to emphasize organizational contexts of work, or which program elements are necessary in order to qualify as 'Total Worker Health'. Agreement about the dimensions of integration would facilitate comparison of programs and interventions which are self-defined as TWH, although diverse in content. The specific criteria needed to define integration should be unique to that concept-i.e. distinct from and additive to conventional criteria for predicting or evaluating the success of a workplace health program. We propose a set of four TWH-specific metrics for integrated interventions that address both program content and process: (i) coordination and interaction of workplace programs across domains; (ii) assessment of both work and non-work exposures; (iii) emphasis on interventions to make the workplace more health-promoting; and (iv) participatory engagement of workers in pivotal ways during intervention prioritization and planning to develop self-efficacy in addressing root causes, skill transfer, building program ownership, empowerment, and continuous improvement. Thus we find that integration requires organizational change, both to engage two managerial functions with different goals, legal responsibilities, and (often) internal incentives & resources, and also to orient the organization toward salutogenesis. Examples from research activity within the Center for the Promotion of Health in the New England Workplace illustrate how these criteria have been applied in practice.

Safety climate, hearing climate and hearing protection device use among transportation road maintainers

BACKGROUND

It is important to understand workplace factors including safety climate that influence hearing protection device (HPD) use. We sought to investigate the association between HPD use, safety climate, and hearing climate, a new measure specific to hearing.

METHODS

A survey was developed and distributed among transportation "maintainers" who perform road maintenance and repair. A new hearing climate measure was designed by adapting a safety climate measure. HPD use was assessed by asking workers how often they wear HPD while in noise. The differences in safety climate and hearing climate were compared by the frequency of HPD use using analysis of variance.

RESULTS

Among 166 maintainers, 54% reported always or almost always wearing HPD while noise exposed. High-frequency HPD users reported a statistically significant higher safety climate (P = 0.004) and hearing climate (P = 0.003).

CONCLUSIONS

Hearing climate predicts the frequency of HPD use and may be a useful measure when assessing and improving hearing conservation programs.

The Characterization of Polycyclic Aromatic Hydrocarbons in Northeastern US Trucking Terminals

In recent years, significant attention has been given to polycyclic aromatic hydrocarbons (PAHs) exposures given their mutagenic and carcinogenic properties. However, levels of exposure and the key determinants of exposure are not well defined for the trucking industry. We measured ultrafine particle characteristics at 10 trucking terminals of varying operating size and location in the Northeast region of the United States using particle concentration counter and a surface area analyzer. Multivariate mixed-effects linear regression models were used to assess determinants of the concentration of total bound PAHs (tPAH), the total aerosol active surface area (AS), and the ratio tPAH/AS overall and individually within docks, trucking cabs, and administrative offices. Associations between PAH measures with integrated measures of elemental carbon (EC), organic carbon (OC), and particulate matter (PM)2.5 were assessed by Spearman rank correlation. In adjusted models, tPAH, AS, and tPAH/AS average concentrations (95% confidence interval) were significantly higher in truck cabs compared to office locations (1.26 (ng m-3) (1.18, 1.35); 0.99 (mm2 mm-3) (0.91, 1.08); 0.26 (ng mm-2) (0.18, 0.33), respectively). In the loading dock, AS concentrations were significantly higher than in the office (0.67 (0.61, 0.71), while the tPAH/AS was not (-0.63 (-0.67, -0.58). In each location, average tPAH concentrations were moderately but significantly correlated with EC (r = 0.47-0.63) and with tPAH/AS (r = 0.34-0.40) in the truck cabs and loading docks. In conclusion, key predictors of tPAH, AS, and tPAH/AS within the trucking industry are work location (in particular truck cabs and terminal docks) and terminal characteristics (size). The association of tPAH and tPAH/AS with EC concentrations in dockworkers and pick-up and delivery drivers is consistent with occupational exposure attributable to vehicle exhaust. Therefore, measurement of tPAH, AS, and tPAH/AS to characterize ultrafine particles and bound PAH concentrations provide additional information regarding exposures in the trucking industry not captured by integrated measures by EC, OC, and PM2.5.

Spatial and temporal determinants of A-weighted and frequency specific sound levels-An elastic net approach

BACKGROUND

Urban sound levels are a ubiquitous environmental stressor and have been shown to be associated with a wide variety of health outcomes. While much is known about the predictors of A-weighted sound pressure levels in the urban environment, far less is known about other frequencies.

OBJECTIVE

To develop a series of spatial-temporal sound models to predict A-weighted sound pressure levels, low, mid, and high frequency sound for Boston, Massachusetts.

METHODS

Short-term sound levels were gathered at n = 400 sites from February 2015 - February 2016. Spatial and meteorological attributes at or near the sound monitoring site were obtained using publicly available data and a portable weather station. An elastic net variable selection technique was used to select predictors of A-weighted, low, mid, and high frequency sound.

RESULTS

The final models for low, mid, high, and A-weighted sound levels explained 59 - 69% of the variability in each measure. Similar to other A-weighted models, our sound models included transportation related variables such as length of roads and bus lines in the surrounding area; distance to road and rail lines; traffic volume, vehicle mix, residential and commercial land use. However, frequency specific models highlighted additional predictors not included in the A-weighted model including temperature, vegetation, impervious surfaces, vehicle mix, and density of entertainment establishments and restaurants.

CONCLUSIONS

Building spatial temporal models to characterize sound levels across the frequency spectrum using an elastic net approach can be a promising tool for noise exposure assessments within the urban soundscape. Models of sound's character may give us additional important sound exposure metrics to be utilized in epidemiological studies.

Application of linear mixed-effects model with LASSO to identify metal components associated with cardiac autonomic responses among welders: a repeated measures study

Background

Environmental and occupational exposure to metals is ubiquitous worldwide, and understanding the hazardous metal components in this complex mixture is essential for environmental and occupational regulations.

Objective

To identify hazardous components from metal mixtures that are associated with alterations in cardiac autonomic responses.

Methods

Urinary concentrations of 16 types of metals were examined and ‘acceleration capacity’ (AC) and ‘deceleration capacity’ (DC), indicators of cardiac autonomic effects, were quantified from ECG recordings among 54 welders. We fitted linear mixed-effects models with least absolute shrinkage and selection operator (LASSO) to identify metal components that are associated with AC and DC. The Bayesian Information Criterion was used as the criterion for model selection procedures.

Results

Mercury and chromium were selected for DC analysis, whereas mercury, chromium and manganese were selected for AC analysis through the LASSO approach. When we fitted the linear mixed-effects models with ‘selected’ metal components only, the effect of mercury remained significant. Every 1 µg/L increase in urinary mercury was associated with −0.58 ms (−1.03, –0.13) changes in DC and 0.67 ms (0.25, 1.10) changes in AC.

Conclusion

Our study suggests that exposure to several metals is associated with impaired cardiac autonomic functions. Our findings should be replicated in future studies with larger sample sizes.

An epigenome-wide association analysis of cardiac autonomic responses among a population of welders

DNA methylation is one of the potential epigenetic mechanisms associated with various adverse cardiovascular effects; however, its association with cardiac autonomic dysfunction, in particular, is unknown. In the current study, we aimed to identify epigenetic variants associated with alterations in cardiac autonomic responses. Cardiac autonomic responses were measured with two novel markers: acceleration capacity (AC) and deceleration capacity (DC). We examined DNA methylation levels at more than 472,506 CpG probes through the Illumina Infinium HumanMethylation450 BeadChip assay. We conducted separate linear mixed models to examine associations of DNA methylation levels at each CpG with AC and DC. One CpG (cg26829071) located in the GPR133 gene was negatively associated with DC values after multiple testing corrections through false discovery rate. Our study suggests the potential functional importance of methylation in cardiac autonomic responses. Findings from the current study need to be replicated in future studies in a larger population.

Differences in the prevalence of musculoskeletal symptoms among female and male custodians

BACKGROUND

The prevalence of musculoskeletal symptoms among custodians is high. We sought to compare musculoskeletal symptoms between female and male custodians and to explore how task might affect this relationship.

METHODS

A cross-sectional study was performed among 712 custodians who completed a survey assessing upper extremity, back, and lower extremity musculoskeletal symptoms and exposure to cleaning tasks. Chi-square tests and logistic regression analyses were used to test for associations between gender, cleaning tasks, and musculoskeletal symptoms.

RESULTS

Gender was significantly (P < 0.05) associated with musculoskeletal symptoms in χ(2) tests and multivariate analyses. The prevalence ratio of symptoms among women was roughly 50% higher than men, regardless of the tasks that workers performed.

CONCLUSIONS

The prevalence of musculoskeletal symptoms differed for female and male custodians and appeared to be consistent across a range of job tasks. Am. J. Ind. Med. 59:841-852, 2016. © 2016 Wiley Periodicals, Inc.

Cardiovascular and stress responses to short-term noise exposures-A panel study in healthy males

BACKGROUND

While previous epidemiological studies report adverse effects of long-term noise exposure on cardiovascular health, the mechanisms responsible for these effects are unclear. We sought to elucidate the cardiovascular and stress response to short-term, low (31.5-125Hz) and high (500-2000Hz) frequency noise exposures.

METHODS

Healthy male (n=10) participants were monitored on multiple visits during no noise, low- or high-frequency noise exposure scenarios lasting 40min. Participants were fitted with an ambulatory electrocardiogram (ECG) and blood pressure measures and saliva samples were taken before, during and after noise exposures. ECGs were processed for measures of heart rate variability (HRV): high-frequency power (HF), low-frequency power (LF), the root of the mean squared difference between adjacent normal heart beats (N-N) intervals (RMSSD), and the standard deviation of N-N intervals (SDNN). Systolic blood pressure (SBP), diastolic blood pressure (DPB), and pulse were reported and saliva was analyzed for salivary cortisol and amylase. Multivariate mixed-effects linear regression models adjusted for age were used to identify statistically significant difference in outcomes by no noise, during noise or after noise exposure periods and whether this differed by noise frequency.

RESULTS

A total of 658, 205, and 122, HRV, saliva, and blood pressure measurements were performed over 41 person days. Reductions in HRV (LF and RMSSD) were observed during noise exposure (a reduction of 19% (-35,-3.5) and 9.1% (-17,-1.1), respectively). After adjusting for noise frequency, during low frequency noise exposure, HF, LF, and SDNN were reduced (a reduction of 32% (-57,-6.2), 34% (-52,-15), and 16% (-26,-6.1), respectively) and during high frequency noise exposure, a 21% (-39,-2.3) reduction in LF, as compared to during no noise exposure, was found. No significant (p<0.05) changes in blood pressure, salivary cortisol, or amylase were observed.

CONCLUSIONS

These results suggest that exposure to noise, and in particular, to low-frequency noise, negatively impacts HRV. The frequencies of noise should be considered when evaluating the cardiovascular health impacts of exposure.

Time Course of Heart Rate Variability Response to PM2.5 Exposure from Secondhand Smoke

Purpose: Exposure to secondhand smoke (SHS) has been associated with decreased heart rate variability (HRV). However, the time course of this association is unclear. Therefore, the objective of this study was to investigate the association between 15–240 minute SHS-related fine particulate matter (PM_2.5) moving averages and indices of HRV. Methods: With a panel study design, we used personal monitors to continuously measure PM_2.5 and HRV of 35 participants who were exposed to SHS for approximately 6 hours. Results: We observed negative, significant associations between 5-minute HRV indices and 15 minute PM_2.5 moving averages and 240 minute PM_2.5 moving averages: there was a significant (p<0.01) 7.5% decrease in the 5-minute square root of the mean squared differences of successive normal heart beats associated with (RMSSD), and a significant (p<0.01) 14.7% decrease in the 5-minute high frequency (HF) power associated with the 15 minute PM_2.5 moving averages; there was also a significant (p<0.01) 46.9% decrease in the 5-minute RMSSD, and a significant (p<0.01) 77.7% decrease in the 5-minute high frequency (HF) power associated with the 240 minute PM_2.5 moving averages. Conclusions: Our findings that exposure to SHS related PM_2.5 was associated with HRV support the hypothesis that SHS can affect the cardiovascular system. The negative associations reported between short and longer term PM_2.5 and HRV indicate adverse effects of SHS on the cardiovascular system.

Environmental and occupational particulate matter exposures and ectopic heart beats in welders

OBJECTIVES

Links between arrhythmias and particulate matter exposures have been found among sensitive populations. We examined the relationship between personal particulate matter ≤2.5 µm aerodynamic diameter (PM2.5) exposures and ectopy in a panel study of healthy welders.

METHODS

Simultaneous ambulatory ECG and personal PM2.5 exposure monitoring with DustTrak Aerosol Monitor was performed on 72 males during work and non-work periods for 5-90 h (median 40 h). ECGs were summarised hourly for supraventricular ectopy (SVE) and ventricular ectopy (VE). PM2.5 exposures both work and non-work periods were averaged hourly with lags from 0 to 7 h. Generalised linear mixed-effects models with a random participant intercept were used to examine the relationship between PM2.5 exposure and the odds of SVE or VE. Sensitivity analyses were performed to assess whether relationships differed by work period and among current smokers.

RESULTS

Participants had a mean (SD) age of 38 (11) years and were monitored over 2993 person-hours. The number of hourly ectopic events was highly skewed with mean (SD) of 14 (69) VE and 1 (4) SVE. We found marginally significant increases in VE with PM2.5 exposures in the sixth and seventh hour lags, yet no association with SVE. For every 100 μg/m(3) increase in sixth hour lagged PM2.5, the adjusted OR (95% CI) for VE was 1.03 (1.00 to 1.05). Results persisted in work or non-work exposure periods and non-smokers had increased odds of VE associated with PM2.5 as compared with smokers.

CONCLUSIONS

A small increase in the odds of VE with short-term PM2.5 exposure was observed among relatively healthy men with environmental and occupational exposures.

Short-term metal particulate exposures decrease cardiac acceleration and deceleration capacities in welders: a repeated-measures panel study

OBJECTIVE

Acceleration (AC) and deceleration (DC) capacities measure heart rate variability during speeding up and slowing down of the heart, respectively. We investigated associations between AC and DC with occupational short-term metal PM2.5 exposures.

METHODS

A panel of 48 male welders had particulate matter less than 2.5 microns in diameter (PM2.5) exposure measurements over 4-6 h repeated over 5 sampling periods between January 2010 and June 2012. We simultaneously obtained continuous recordings of digital ECG using a Holter monitor. We analysed ECG data in the time domain to obtain hourly AC and DC. Linear mixed models were used to assess the associations between hourly PM2.5 exposure and each of hourly AC and DC, controlling for age, smoking status, active smoking, exposure to secondhand smoke, season/time of day when ECG reading was obtained and baseline AC or DC. We also ran lagged exposure response models for each successive hour up to 3 h after onset of exposure.

RESULTS

Mean (SD) shift PM2.5 exposure during welding was 0.47 (0.43) mg/m(3). Significant exposure-response associations were found for AC and DC with increased PM2.5 exposure. In our adjusted models without any lag between exposure and response, a 1 mg/m(3) increase of PM2.5 was associated with a decrease of 1.46 (95% CI 1.00 to 1.92) ms in AC and a decrease of 1.00 (95% CI 0.53 to 1.46) ms in DC. The effect of PM2.5 on AC and DC was maximal immediately postexposure and lasted 1 h following exposure.

CONCLUSIONS

There are short-term effects of metal particulates on AC and DC.

Demographic, health-related, and work-related factors associated with body mass index and body fat percentage among workers at six Connecticut manufacturing companies across different age groups: a cohort study

BACKGROUND

Effective workplace interventions that consider the multifactorial nature of obesity are needed to reduce and prevent obesity among adults. Furthermore, the factors associated with obesity may differ for workers across age groups. Therefore, the objective of this study was to identify demographic, health-related, and work-related factors associated with baseline and changes in body mass index (BMI) and body fat percentage (BFP) and among Connecticut manufacturing workers acrossage groups.

METHODS

BMI and BFPof 758 workers from six Connecticut manufacturing companies were objectively measuredat two time points approximately 36 months apart. Demographic, health-related, and work-related factors wereassessed via questionnaire. All variables were included in linear regression models to identify factors associated with baseline and changes in BMI and BFP for workers in 3 age groups: <45 years (35 %), 45-55 years (37 %), >55 years (28 %).

RESULTS

There were differences in baseline and changes in BMI and BFP among manufacturing workers across age groups. Being interested in changing weight was significantly (p < 0.01) associated with higher baseline BMI and BFP across all age categories. Other factors associated with higher baseline BMI and BFP differed by age group and included: male gender (BMI p = 0.04), female gender (BFP p < 0.01), not having a college education (BMI p = 0.01, BFP p = 0.04), having childcare responsibilities (BMI p = 0.04), and working less overtime (p = 0.02) among workers in the <45 year age category, male gender (BMI p = 0.02), female gender (BFP p < 0.01) and reporting higher stress in general (BMI p = 0.04) among workers in the 45-55 year age category, and female gender (BFP p < 0.01) and job tenure (BFP p = 0.03) among workers in the >55 year age category. Few factors were associated with change in BMI or BFP across any age category.

CONCLUSIONS

Among manufacturing workers, we identified associations between individual, health-related, and work-related factors and baseline BMIand BFP that differed by age. Such results support the use of strategies tailored to the challenges faced by workers in specific age groups rather than adopting a one size fits all approach. Effective interventions should consider a full range of individual, health-related, and work-related factors. More work must be done to identify factors or strategies associated with changes in obesity over time.

Traditional and environmentally preferable cleaning product exposure and health symptoms in custodians

BACKGROUND

We investigated the associations between traditional and environmentally preferable cleaning product exposure and dermal, respiratory, and musculoskeletal symptoms in a population of custodians.

METHODS

We analyzed associations between symptoms and exposure to traditional and environmentally preferable cleaning product exposure among 329 custodians.

RESULTS

We observed increased odds of dermal (P < 0.01), upper (P = 0.01) and lower respiratory (P = 0.01), and upper extremity (P < 0.01), back (P < 0.01), and lower extremity (P = 0.01) musculoskeletal symptoms associated with increased typical traditional cleaning product exposure. We observed significant trends for increased odds of dermal (P = 0.03) and back (P = 0.04) and lower (P = 0.02) extremity musculoskeletal symptoms associated with increased typical environmentally preferable cleaning product exposure.

CONCLUSIONS

Fewer positive associations and reduced odds of health symptoms associated with environmentally preferable cleaning product exposure suggest that these products may represent a safer alternative to traditional cleaning products.

Characterization of Urinary Phthalate Metabolites Among Custodians

Phthalates, a ubiquitous class of chemicals found in consumer, personal care, and cleaning products, have been linked to adverse health effects. Our goal was to characterize urinary phthalate metabolite concentrations and to identify work and nonwork sources among custodians using traditional cleaning chemicals and 'green' or environmentally preferable products (EPP). Sixty-eight custodians provided four urine samples on a workday (first void, before shift, end of shift, and before bedtime) and trained observers recorded cleaning tasks and types of products used (traditional, EPP, or disinfectant) hourly over the work shifts. Questionnaires were used to assess personal care product use. Four different phthalate metabolites [monoethyl phthalate (MEP), monomethyl phthalate (MMP), mono (2-ethylhexyl) phthalate (MEHP), and monobenzyl phthalate (MBzP)] were quantified using liquid chromatography mass spectrometry. Geometric means (GM) and 95% confidence intervals (95% CI) were calculated for creatinine-adjusted urinary phthalate concentrations. Mixed effects univariate and multivariate modeling, using a random intercept for each individual, was performed to identify predictors of phthalate metabolites including demographics, workplace factors, and personal care product use. Creatinine-adjusted urinary concentrations [GM (95% CI)] of MEP, MMP, MEHP, and MBzP were 107 (91.0-126), 2.69 (2.18-3.30), 6.93 (6.00-7.99), 8.79 (7.84-9.86) µg g(-1), respectively. An increasing trend in phthalate concentrations from before to after shift was not observed. Creatinine-adjusted urinary MEP was significantly associated with frequency of traditional cleaning chemical intensity in the multivariate model after adjusting for potential confounding by demographics, workplace factors, and personal care product use. While numerous demographics, workplace factors, and personal care products were statistically significant univariate predictors of MMP, MEHP, and MBzP, few associations persisted in multivariate models. In summary, among this population of custodians, we identified both occupational and nonoccupational predictors of phthalate exposures. Identification of phthalates as ingredients in cleaning chemicals and consumer products would allow workers and consumers to avoid phthalate exposure.

Heart rate variability and DNA methylation levels are altered after short-term metal fume exposure among occupational welders: a repeated-measures panel study

Background

In occupational settings, boilermakers are exposed to high levels of metallic fine particulate matter (PM_2.5) generated during the welding process. The effect of welding PM_2.5 on heart rate variability (HRV) has been described, but the relationship between PM_2.5, DNA methylation, and HRV is not known.

Methods

In this repeated-measures panel study, we recorded resting HRV and measured DNA methylation levels in transposable elements Alu and long interspersed nuclear element-1 (LINE-1) in peripheral blood leukocytes under ambient conditions (pre-shift) and right after a welding task (post-shift) among 66 welders. We also monitored personal PM_2.5 level in the ambient environment and during the welding procedure.

Results

The concentration of welding PM_2.5 was significantly higher than background levels in the union hall (0.43 mg/m³ vs. 0.11 mg/m³, p < 0.0001). The natural log of transformed power in the high frequency range (ln HF) had a significantly negative association with PM_2.5 exposure (β = -0.76, p = 0.035). pNN10 and pNN20 also had a negative association with PM_2.5 exposure (β = -0.16%, p = 0.006 and β = -0.13%, p = 0.030, respectively). PM_2.5 was positively associated with LINE-1 methylation [β = 0.79%, 5-methylcytosince (%mC), p = 0.013]; adjusted for covariates. LINE-1 methylation did not show an independent association with HRV.

Conclusions

Acute decline of HRV was observed following exposure to welding PM_2.5 and evidence for an epigenetic response of transposable elements to short-term exposure to high-level metal-rich particulates was reported.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2458-14-1279) contains supplementary material, which is available to authorized users.

Inverse association between toenail arsenic and body mass index in a population of welders

Recent data show that arsenic may play a role in obesity-related diseases. However, urinary arsenic studies report an inverse association between arsenic level and body mass index (BMI). We explored whether toenail arsenic, a long-term exposure measure, was associated with BMI in 74 welders with known arsenic exposure. BMI showed significant inverse associations with toenail arsenic (p=0.01), which persisted in models adjusted for demographics, diet and work history. It is unclear whether low arsenic biomarker concentrations in high BMI subjects truly reflect lower exposures, or instead reflect internal or metabolic changes that alter arsenic metabolism and tissue deposition.

Toenail metal concentration as a biomarker of occupational welding fume exposure

In populations exposed to heavy metals, there are few biomarkers that capture intermediate exposure windows. We sought to determine the correlation between toenail metal concentrations and prior 12-month work activity in welders with variable, metal-rich, welding fume exposures. Forty-eight participants, recruited through a local union, provided 69 sets of toenail clippings. Union-supplied and worker-verified personal work histories were used to quantify hours welded and respirator use. Toenail samples were digested and analyzed for lead (Pb), manganese (Mn), cadmium (Cd), nickel (Ni), and arsenic (As) using ICP-MS. Spearman correlation coefficients were used to examine the correlation between toenail metal concentrations. Using mixed models to account for multiple participation times, we divided hours welded into three-month intervals and examined how weld hours correlated with log-transformed toenail Pb, Mn, Cd, Ni, and As concentrations. Highest concentrations were found for Ni, followed by Mn, Pb and As, and Cd. All the metals were significantly correlated with one another (rho range = 0.28-0.51), with the exception of Ni and As (rho = 0.20, p = 0.17). Using mixed models adjusted for age, respirator use, smoking status, and BMI, we found that Mn was associated with weld hours 7-9 months prior to clipping (p = 0.003), Pb was associated with weld hours 10-12 months prior to clipping (p = 0.03) and over the entire year (p = 0.04). Cd was associated with weld hours 10-12 months prior to clipping (p = 0.05), and also with the previous year's total hours welded (p = 0.02). The association between Ni and weld hours 7-9 months prior to clipping approached significance (p = 0.06). Toenail metal concentrations were not associated with the long-term exposure metric, years as a welder. Results suggest Mn, Pb, and Cd may have particular windows of relevant exposure that reflect work activity. In a population with variable exposure, toenails may serve as useful biomarkers for occupational metal fume exposures to Mn, Pb, and Cd during distinct periods over the year prior to sample collection.

Traffic-related exposures and biomarkers of systemic inflammation, endothelial activation and oxidative stress: a panel study in the US trucking industry

BACKGROUND

Experimental evidence suggests that inhaled particles from vehicle exhaust have systemic effects on inflammation, endothelial activation and oxidative stress. In the present study we assess the relationships of short-term exposures with inflammatory endothelial activation and oxidative stress biomarker levels in a population of trucking industry workers.

METHODS

Blood and urine samples were collected pre and post-shift, at the beginning and end of a workweek from 67 male non-smoking US trucking industry workers. Concurrent measurements of microenvironment concentrations of elemental and organic carbon (EC & OC), and fine particulate matter (PM2.5) combined with time activity patterns allowed for calculation of individual exposures. Associations between daily and first and last-day average levels of exposures and repeated measures of intercellular and vascular cell adhesion molecule-1 (ICAM-1 & VCAM-1), interleukin 6 (IL-6) and C-reactive protein (CRP) blood levels and urinary 8-Hydroxy-2'-Deoxyguanosine (8-OHdG) were assessed using linear mixed effects models for repeated measures.

RESULTS

There was a statistically significant association between first and last-day average PM2.5 and 8-OHdG (21% increase, 95% CI: 2, 42%) and first and last-day average OC and IL-6 levels (18% increase 95% CI: 1, 37%) per IQR in exposure. There were no significant findings associated with EC or associations suggesting acute cross-shift effects.

CONCLUSION

Our findings suggest associations between weekly average exposures of PM2.5 on markers of oxidative stress and OC on IL-6 levels.

Secondhand tobacco smoke exposure and heart rate variability and inflammation among non-smoking construction workers: a repeated measures study

BACKGROUND

Although it has been well recognized that exposure to secondhand tobacco smoke (SHS) is associated with cardiovascular mortality, the mechanisms and time course by which SHS exposure may lead to cardiovascular effects are still being explored.

METHODS

Non-smoking workers were recruited from a local union and monitored inside a union hall while exposed to SHS over approximately 6 hours. Participants were fitted with a continuous electrocardiographic monitor upon enrollment which was removed at the end of a 24-hr monitoring period. A repeated measures study design was used where resting ECGs and blood samples were taken from individuals before SHS exposure (baseline), immediately following SHS exposure (post) and the morning following SHS exposure (next-morning).Inflammatory markers, including high sensitivity C-reactive protein (CRP) and white blood cell count (WBC) were analyzed. Heart rate variability (HRV) was analyzed from the ECG recordings in time (SDNN, rMSSD) and frequency (LF, HF) domain parameters over 5-minute periods. SHS exposure was quantified using a personal fine particulate matter (PM2.5) monitor.Linear mixed effects regression models were used to examine within-person changes in inflammatory and HRV parameters across the 3 time periods. Exposure-response relationships with PM2.5 were examined using mixed effects models. All models were adjusted for age, BMI and circadian variation.

RESULTS

A total of 32 male non-smokers were monitored between June 2010 and June 2012. The mean PM2.5 from SHS exposure was 132 μg/m3. Immediately following SHS exposure, a 100 μg/m3 increase in PM2.5 was associated with declines in HRV (7.8% [standard error (SE) =3%] SDNN, 8.0% (SE = 3.9%) rMSSD, 17.2% (SE = 6.3%) LF, 29.0% (SE = 10.1%) HF) and increases in WBC count 0.42 (SE = 0.14) k/μl. Eighteen hours following SHS exposure, a 100 μg/m3 increase in PM2.5 was associated with 24.2% higher CRP levels.

CONCLUSIONS

Our study suggest that short-term SHS exposure is associated with significantly lower HRV and higher levels of inflammatory markers. Exposure-associated declines in HRV were observed immediately following exposure while higher levels of CRP were not observed until 18 hours following exposure. Cardiovascular autonomic and inflammation responses may contribute to the pathophysiologic pathways that link SHS exposure with adverse cardiovascular outcomes.

Traffic-related air pollution exposures and changes in heart rate variability in Mexico City: a panel study

BACKGROUND

While air pollution exposures have been linked to cardiovascular outcomes, the contribution from acute gas and particle traffic-related pollutants remains unclear. Using a panel study design with repeated measures, we examined associations between personal exposures to traffic-related air pollutants in Mexico City and changes in heart rate variability (HRV) in a population of researchers aged 22 to 56 years.

METHODS

Participants were monitored for approximately 9.5 hours for eight days while operating a mobile laboratory van designed to characterize traffic pollutants while driving in traffic and "chasing" diesel buses. We examined the association between HRV parameters (standard deviation of normal-to-normal intervals (SDNN), power in high frequency (HF) and low frequency (LF), and the LF/HF ratio) and the 5-minute maximum (or average in the case of PM(2.5)) and 30-, 60-, and 90-minute moving averages of air pollutants (PM(2.5), O(3), CO, CO(2), NO(2), NO(x), and formaldehyde) using single- and two-pollutant linear mixed-effects models.

RESULTS

Short-term exposure to traffic-related emissions was associated with statistically significant acute changes in HRV. Gaseous pollutants - particularly ozone - were associated with reductions in time and frequency domain components (α = 0.05), while significant positive associations were observed between PM(2.5) and SDNN, HF, and LF. For ozone and formaldehyde, negative associations typically increased in magnitude and significance with increasing averaging periods. The associations for CO, CO(2), NO(2), and NO(x) were similar with statistically significant associations observed for SDNN, but not HF or LF. In contrast, PM(2.5) increased these HRV parameters.

CONCLUSIONS

Results revealed an association between traffic-related PM exposures and acute changes in HRV in a middle-aged population when PM exposures were relatively low (14 μg/m(3)) and demonstrate heterogeneity in the effects of different pollutants, with declines in HRV - especially HF - with ozone and formaldehyde exposures, and increases in HRV with PM(2.5) exposure. Given that exposure to traffic-related emissions is associated with increased risk of cardiovascular morbidity and mortality, understanding the mechanisms by which traffic-related emissions can cause cardiovascular disease has significant public health relevance.

Personal breathing zone exposures among hot-mix asphalt paving workers; preliminary analysis for trends and analysis of work practices that resulted in the highest exposure concentrations

An exposure assessment of hot-mix asphalt (HMA) paving workers was conducted to determine which of four exposure scenarios impacted worker exposure and dose. Goals of this report are to present the personal-breathing zone (PBZ) data, discuss the impact of substituting the releasing/cleaning agent, and discuss work practices that resulted in the highest exposure concentration for each analyte. One-hundred-seven PBZ samples were collected from HMA paving workers on days when diesel oil was used as a releasing/cleaning agent. An additional 36 PBZ samples were collected on days when B-100 (100% biodiesel, containing no petroleum-derived products) was used as a substitute releasing/cleaning agent. Twenty-four PBZ samples were collected from a reference group of concrete workers, who also worked in outdoor construction but had no exposure to asphalt emissions. Background and field blank samples were also collected daily. Total particulates and the benzene soluble fraction were determined gravimetrically. Total organic matter was determined using gas chromatography (GC) with flame ionization detection and provided qualitative information about other exposure sources contributing to worker exposure besides asphalt emissions. Thirty-three individual polycyclic aromatic compounds (PACs) were determined using GC with time-of-flight mass spectrometry; results were presented as either the concentration of an individual PAC or a summation of the individual PACs containing either 2- to 3-rings or 4- to 6-rings. Samples were also screened for PACs containing 4- to 6-rings using fluorescence spectroscopy. Arithmetic means, medians, and box plots of the PBZ data were used to evaluate trends in the data. Box plots illustrating the diesel oil results were more variable than the B-100. Also, the highest diesel oil results were much higher in concentration than the highest B-100 results. An analysis of the highest exposure results and field notes revealed a probable association between these exposures and the use of diesel oil, use of a diesel-powered screed, elevated HMA paving application temperatures, lubricating and working on broken-down equipment, and operation of a broom machine.

Using urinary biomarkers of polycyclic aromatic compound exposure to guide exposure-reduction strategies among asphalt paving workers

INTRODUCTION

Paving workers are exposed to polycyclic aromatic compounds (PACs) while working with hot-mix asphalt (HMA). Further characterization of the source and route of these exposures is necessary to guide exposure-reduction strategies.

METHODS

Personal air (n=144), hand-wash (n=144), and urine (n=480) samples were collected from 12 paving workers over 3 workdays during 4 workweeks. Urine samples were collected at preshift, postshift, and bedtime and analyzed for 10 hydroxylated PACs (1-OH-pyrene; 1-, 2-, 3-, 4-OH-phenanthrene; 1-, 2-OH-naphthalene; 2-, 3-, 9-OH-fluorene) by an immunochemical quantification of PACs (I-PACs). The air and hand-wash samples were analyzed for the parent compounds corresponding to the urinary analytes. Using a crossover study design, each of the 4 weeks represented a different exposure scenario: a baseline week (normal conditions), a dermal protection week (protective clothing), a powered air-purifying respirator (PAPR) week, and a biodiesel substitution week (100% biodiesel provided to replace the diesel oil normally used by workers to clean tools and equipment). The urinary analytes were analyzed using linear mixed-effects models.

RESULTS

Postshift and bedtime concentrations were significantly higher than preshift concentrations for most urinary biomarkers. Compared with baseline, urinary analytes were reduced during the dermal protection (29% for 1-OH-pyrene, 15% for I-PACs), the PAPR (24% for 1-OH-pyrene, 15% for I-PACs), and the biodiesel substitution (15% for 1-OH-pyrene) weeks. The effect of PACs in air was different by exposure scenario (biodiesel substitution>dermal protection>PAPR and baseline) and was still a significant predictor of most urinary analytes during the week of PAPR use, suggesting that PACs in air were dermally absorbed. The application temperature of HMA was positively associated with urinary measures, such that an increase from the lowest application temperature (121°C) to the highest (154°C) was associated with a 72% increase in ΣOH-fluorene and 1-OH-pyrene and an 82% increase in ΣOH-phenanthrene. Though PACs in hand-wash samples were not predictors of urinary analytes, the effects observed during the PAPR scenario and the week of increased dermal protection provide evidence of dermal absorption.

CONCLUSIONS

Our results provide evidence that PACs in air are dermally absorbed. Reducing the application temperature of asphalt mix appears to be a promising strategy for reducing PAC exposure among paving workers. Additional reductions may be achieved by requiring increased dermal coverage of workers and by substituting biodiesel for diesel oil as a cleaning agent.

Predictors of dermal exposures to polycyclic aromatic compounds among hot-mix asphalt paving workers

OBJECTIVES

The primary objective of this study was to identify the source and work practices that affect dermal exposure to polycyclic aromatic compounds (PACs) among hot-mix asphalt (HMA) paving workers.

METHODS

Four workers were recruited from each of three asphalt paving crews (12 workers) and were monitored for three consecutive days over 4 weeks for a total of 12 sampling days per worker (144 worker days). Two sampling weeks were conducted under standard conditions for dermal exposures. The third week included the substitution of biodiesel for diesel oil used to clean tools and equipment and the fourth week included dermal protection through the use of gloves, hat and neck cloth, clean pants, and long-sleeved shirts. Dermal exposure to PACs was quantified using two methods: a passive organic dermal (POD) sampler specifically developed for this study and a sunflower oil hand wash technique. Linear mixed-effects models were used to evaluate predictors of PAC exposures.

RESULTS

Dermal exposures measured under all conditions via POD and hand wash were low with most samples for each analyte being below the limit of the detection with the exception of phenanthrene and pyrene. The geometric mean (GM) concentrations of phenanthrene were 0.69 ng cm(-2) on the polypropylene layer of the POD sampler and 1.37 ng cm(-2) in the hand wash sample. The GM concentrations of pyrene were 0.30 ng cm(-2) on the polypropylene layer of the POD sampler and 0.29 ng cm(-2) in the hand wash sample. Both the biodiesel substitution and dermal protection scenarios were effective in reducing dermal exposures. Based on the results of multivariate linear mixed-effects models, increasing frequency of glove use was associated with significant (P < 0.0001) reductions for hand wash and POD phenanthrene and pyrene concentrations; percent reductions ranged from 40 to 90%. Similar reductions in hand wash concentrations of phenanthrene (P = 0.01) and pyrene (P = 0.003) were observed when biodiesel was substituted for diesel oil as a cleaning agent, although reductions were not significant for the POD sampler data. Although task was not a predictor of dermal exposure, job site characteristics such as HMA application temperature, asphalt grade, and asphalt application rate (tons per hour) were found to significantly affect exposure. Predictive models suggest that the combined effect of substituting biodiesel for diesel oil as a cleaning agent, frequent glove use, and reducing the HMA application temperature from 149°C (300°F) to 127°C (260°F) may reduce dermal exposures by 76-86%, varying by analyte and assessment method.

CONCLUSIONS

Promising strategies for reducing dermal exposure to PACs among asphalt paving workers include requiring the use of dermal coverage (e.g. wearing gloves and/or long sleeves), substituting biodiesel for diesel oil as a cleaning agent, and decreasing the HMA application temperature.

Neuropsychological effects of low-level manganese exposure in welders

While the neuropsychological effects of high manganese (Mn) exposure in occupational settings are well known, the effects of lower levels of exposure are less understood. In this study, we investigated the neuropsychological effects of lower level occupational Mn exposure in 46 male welders (mean age=37.4, S.D.=11.7 years). Each welders' cumulative Mn exposure indices (Mn-CEI) for the past 12 months and total work history Mn exposure were constructed based on air Mn measurements and work histories. The association between these exposure indices and performance on cognitive, motor control, and psychological tests was examined. In addition, among a subset of welders (n=24) who completed the tests both before and after a work shift, we examined the association between cross-shift Mn exposure assessed from personal monitoring and acute changes in test scores. Mn exposures in this study (median=12.9 μg/m³) were much lower, as compared to those observed in other similar studies. Increasing total Mn-CEI was significantly associated with slower reaction time on the continuous performance test (CPT; p<0.01), as well as worse mood for several scales on the Profile of Mood States (POMS; confused, tired, and a composite of tired and energetic, all p ≤ 0.03). Increasing Mn-CEI over the previous 12 months was significantly associated with worse mood on the sad, tense, and confused POMS scales (all p ≤ 0.03) and the association with worse CPT performance approached significance (p=0.10). Higher Mn exposure over the course of a workday was associated with worse performance on the CPT test across the day (p=0.06) as well as declines in fine motor control over the work-shift (p=0.04), adjusting for age and time between the 2 tests. Our study suggests that even at relatively low Mn exposure levels neuropsychological effects may manifest particularly with respect to attention, mood, and fine motor control.

Circadian variation of heart rate variability among welders

OBJECTIVE

To compare the circadian variation of hourly heart rate variability (HRV) on work and non-workdays among boilermaker construction workers.

METHOD

A panel study of 18 males monitored by 24-h ambulatory ECG over 44 observation-days on paired work and non-workdays was conducted. ECGs were analysed and the SD of normal-to-normal beats index (SDNN(i)) was calculated from 5-min data and summarised hourly. SDNN(i)s over work and non-workdays were compared using linear mixed-effects models to account for repeated measures and harmonic regression to account for circadian variation.

RESULTS

Both work and non-work hourly HRV exhibited circadian variation with an increase in the evening and a decrease in the afternoon. SDNN(i) was lower on workdays as compared with non-workdays with the largest, statistically significant differences observed between 10:00 and 16:00, during active working. Lower SDNN(i), albeit smaller yet statistically significant differences, was also observed in the evening hours following work (17:00-21:00) and early morning (4:00). In regression models using all time periods, an average workday SDNN(i) was 8.1 ms (95% CI -9.8 to -6.3) lower than non-workday SDNN(i). The circadian pattern of HRV exhibited two peaks which differed on work and non-workdays.

CONCLUSION

While workday and non-workday HRV followed a circadian pattern, decreased HRV and variation of the circadian pattern were observed on workdays. Declines and changes in the circadian pattern of HRV is a concern among this exposed population.

Assessment of occupational exposure to manganese and other metals in welding fumes by portable X-ray fluorescence spectrometer

Elemental analysis of welding fume samples can be done using several laboratory-based techniques. However, portable measurement techniques could offer several advantages. In this study, we sought to determine whether the portable X-ray fluorescence spectrometer (XRF) is suitable for analysis of five metals (manganese, iron, zinc, copper, and chromium) on 37-mm polytetrafluoroethylene filters. Using this filter fitted on a cyclone in line with a personal pump, gravimetric samples were collected from a group of boilermakers exposed to welding fumes. We assessed the assumption of uniform deposition of these metals on the filters, and the relationships between measurement results of each metal obtained from traditional laboratory-based XRF and the portable XRF. For all five metals of interest, repeated measurements with the portable XRF at the same filter area showed good consistency (reliability ratios are equal or close to 1.0 for almost all metals). The portable XRF readings taken from three different areas of each filter were not significantly different (p-values = 0.77 to 0.98). This suggested that the metal rich PM(2.5) deposits uniformly on the samples collected using this gravimetric method. For comparison of the two XRFs, the results from the portable XRF were well correlated and highly predictive of those from the laboratory XRF. The Spearman correlation coefficients were from 0.325 for chromium, to 0.995 for manganese and 0.998 for iron. The mean differences as a percent of the mean laboratory XRF readings were also small (<5%) for manganese, iron, and copper. The differences were greater for zinc and chromium, which were present at very low amounts in our samples and below the limits of detection of the portable XRF for many of the samples. These five metals were moderately to strongly correlated with the total fine particle fraction on filters (Spearman rho = 0.41 for zinc to 0.97 for iron). Such strong correlations and comparable results suggested that the portable XRF could be used as an effective and reliable tool for exposure assessment in many studies.

Circulating adhesion molecules after short-term exposure to particulate matter among welders

BACKGROUND

Studies from several countries indicate that welders experience increased risk of mortality and morbidity from ischaemic heart disease. Although the underlying mechanisms are unclear, vascular responses to particulate matter contained in welding fumes may play a role. To investigate this, we studied the acute effects of welding fume exposure on the endothelial component of vascular function, as measured by circulating adhesion molecules involved in leukocyte adhesion (sICAM-1 and sVCAM-1) and coagulation (vWF).

METHODS

A panel of 26 male welders was studied repeatedly across a 6 h work-shift on a high exposure welding day and/or a low exposure non-welding day. Personal PM(2.5) exposure was measured throughout the work-shift. Blood samples were collected in the morning (baseline) prior to the exposure period, immediately after the exposure period, and the following morning. To account for the repeated measurements, we used linear mixed models to evaluate the effects of welding (binary) and PM(2.5) (continuous) exposure on each blood marker, adjusting for baseline blood marker concentration, smoking, age and time of day.

RESULTS

Welding and PM(2.5) exposure were significantly associated with a decrease in sVCAM-1 in the afternoon and the following morning and an increase in vWF in the afternoon.

CONCLUSIONS

The data suggest that welding and short-term occupational exposure to PM(2.5) may acutely affect the endothelial component of vascular function.

Vascular function, inflammation, and variations in cardiac autonomic responses to particulate matter among welders

Patients with health conditions associated with impaired vascular function and inflammation may be more susceptible to the adverse health effects of fine particulate (particulate matter with a mass median aerodynamic diameter of </=2.5 mum (PM(2.5))) exposure. In 2006, the authors conducted a panel study to investigate directly whether vascular function and inflammation (assessed by C-reactive protein) modify PM(2.5)-associated reductions in heart rate variability among 23 young male workers (mean age, 40 years) from Massachusetts. Concurrent 24-hour ambulatory electrocardiogram and personal PM(2.5) exposure information was collected over a total of 36 person-days, including either or both welding and nonwelding days. Linear mixed models were used to examine the 5-minute standard deviation of normal-to-normal intervals (SDNN) in relation to the moving PM(2.5) averages in the preceding 1-4 hours. C-reactive protein levels and 3 measures of vascular function (augmentation index, mean arterial pressure, and pulse pressure) were determined at baseline. The authors observed an inverse association between the 1-hour PM(2.5) and 5-minute SDNN. Greater SDNN declines were observed among those with C-reactive protein (P(interaction) < 0.001) and augmentation index (P = 0.06) values at or above the 75th percentile and pulse pressure values below the 75th percentile (P < 0.001). Systemic inflammation and poorer vascular function appear to aggravate particle-related declines in heart rate variability among workers.

Acute changes in vascular function among welders exposed to metal-rich particulate matter

BACKGROUND

Although welding fume exposure is associated with adverse cardiovascular outcomes, the mechanisms remain unclear. To investigate the role of vascular function, we assessed levels of the augmentation index (a correlate of arterial stiffness) after short-term exposure to welding-derived fine particulate matter (PM2.5).

METHODS

In a panel study, we monitored 26 male welders over 24 hours on a welding day (n = 25), a non-welding day (n = 15), or both (n = 14). Augmentation index (expressed as a percent) was obtained in the morning before exposure (baseline) and after exposure in the afternoon and the following morning. Personal PM2.5 exposure was measured over 6 hours of welding or an equivalent non-welding period. We used linear mixed models adjusting for baseline augmentation index, smoking, age, and time to evaluate the effects of welding (binary) and PM2.5 (continuous) on augmentation index levels. We also assessed modification by welding exposure the day before monitoring (binary).

RESULTS

Welding was associated with a 2.8% increase in afternoon augmentation index (95% confidence interval = -1.4 to 7.0) and a 2.4% decrease (-6.9 to 2.2) in next-morning augmentation index. Additional exposure the day prior to monitoring was associated with a greater afternoon increase (5.1%; 0.8 to 9.5). Using PM2.5 concentration, a positive association was observed in the afternoon and an inverse association the next morning; results differed by previous day's welding status after excluding outliers.

CONCLUSIONS

Subsequent to welding fume exposure, there is an increase in afternoon augmentation index and a decrease in next-morning augmentation index, with greater changes after consecutive days of exposure. These results suggest that exposure to the PM2.5 component of welding fume elicits acute adverse vascular responses.

PM2.5 metal exposures and nocturnal heart rate variability: a panel study of boilermaker construction workers

BACKGROUND

To better understand the mechanism(s) of particulate matter (PM) associated cardiovascular effects, research priorities include identifying the responsible PM characteristics. Evidence suggests that metals play a role in the cardiotoxicity of fine PM (PM2.5) and in exposure-related decreases in heart rate variability (HRV). We examined the association between daytime exposure to the metal content of PM2.5 and night HRV in a panel study of boilermaker construction workers exposed to metal-rich welding fumes.

METHODS

Twenty-six male workers were monitored by ambulatory electrocardiogram (ECG) on a workday while exposed to welding fume and a non-workday (baseline). From the ECG, rMSSD (square root of the mean squared differences of successive intervals) was summarized over the night (0:00-7:00). Workday, gravimetric PM2.5 samples were analyzed by x-ray fluorescence to determine metal content. We used linear mixed effects models to assess the associations between night rMSSD and PM2.5 metal exposures both with and without adjustment for total PM2.5. Matched ECG measurements from the non-workday were used to control for individual cardiac risk factors and models were also adjusted for smoking status. To address collinearity between PM2.5 and metal content, we used a two-step approach that treated the residuals from linear regression models of each metal on PM2.5 as surrogates for the differential effects of metal exposures in models for night rMSSD.

RESULTS

The median PM2.5 exposure was 650 microg/m3; median metal exposures for iron, manganese, aluminum, copper, zinc, chromium, lead, and nickel ranged from 226 microg/m3 to non-detectable. We found inverse linear associations in exposure-response models with increased metal exposures associated with decreased night rMSSD. A statistically significant association for manganese was observed, with a decline of 0.130 msec (95% CI: -0.162, -0.098) in night rMSSD for every 1 microg/m3 increase in manganese. However, even after adjusting for individual metals, increases in total PM2.5 exposures were associated with declines in night rMSSD.

CONCLUSION

These results support the cardiotoxicity of PM2.5 metal exposures, specifically manganese. However the metal component alone did not account for the observed declines in night HRV. Therefore, results suggest the importance of other PM elemental components.