Diesel Engine Exhaust Exposure in Relation to Lung Cancer in Long-Haul Truck Drivers: An Eight-Step Concept Analysis.

BACKGROUND: Long-haul truck drivers (LHTDs) face a number of occupational hazards. One such hazard is exposure to diesel engine exhaust (DEE). However, this concept has yet to be analyzed. To address this gap, a concept analysis was conducted to explore the effects of DEE in relation to lung cancer. METHODS: Walker and Avant's eight-step concept analysis method was utilized: concept selection, analysis purpose, concept uses, defining attributes, model case, borderline case, antecedents and consequences, and empirical referents. PubMed, Scopus, and CINAHL databases were searched for relevant literature. FINDINGS: Diesel engine exhaust was identified as a mixture of gases and particulates that are considered carcinogenic. Defining attributes of DEE for truckers include respiratory effects such as decreased peak flow and increased airway resistance leading to symptoms such as a phlegm-producing cough, eye and throat irritation, exacerbation of asthma symptoms, and allergic responses. The identified level of DEE exposure associated with these attributes is 75 µg EC/m3 for 1 to 2 hours daily or a long-term exposure of 10 µg EC/m3. The conceptual definition of DEE in truckers was illustrated by the attributes, antecedents, consequences, model case, and empirical referents. CONCLUSION: Lung cancer was identified as a significant consequence of occupational DEE exposure for LHTDs. This analysis highlights the need for future research to develop interventions that will safeguard truckers from the adverse health effects of DEE exposure.

An Agenda for Advancing Research and Prevention at the Nexus of Work Organization, Occupational Stress, and Mental Health and Well-Being.

Work characteristics and worker well-being are inextricably connected. In particular, the characteristics of work organization shape and perpetuate occupational stress, which contributes to worker mental health and well-being outcomes. Consequently, the importance of understanding and addressing connections between work organization, occupational stress, and mental health and well-being-the focus of this Special Issue-increasingly demand attention from those affected by these issues. Thus, focusing on these issues in the long-haul truck driver (LHTD) sector as an illustrative example, the purpose of this commentary is as follows: (1) to outline current research approaches and the extant knowledge base regarding the connections between work organization, occupational stress, and mental health; (2) to provide an overview of current intervention strategies and public policy solutions associated with the current knowledge base to protect and promote worker mental health and well-being; and (3) to propose a two-pronged agenda for advancing research and prevention for workers during the 21st century. It is anticipated that this commentary, and this Special Issue more broadly, will both echo numerous other calls for building knowledge and engaging in this area and motivate further research within complementary current and novel research frameworks.

A mixed-methods approach to examining safety climate among truck drivers.

The purpose of the current study was to use a mixed-methods approach to understanding safety climate and the strategies to improve safety climate among truck drivers. Using both survey (N = 7246) and interview (N = 18) responses provided by truck drivers regarding key safety climate items, the current study identified a number of positive and negative policies, procedures and practices that truck drivers perceived as the determinants of whether their organizations are committed to the promotion of safety at work. Item response theory (IRT) analyses were conducted to identify discrimination parameters indicating which safety climate items were most sensitive to the safety climate level. Discriminative items were identified at both the organization and group levels which can be used to evaluate safety climate and differentiate a high versus low safety climate across groups and organizations in the trucking industry. Based on our results, we also offer safety researchers and practitioners some recommendations on what and/or how to intervene with and promote organizational safety climate in the trucking industry.

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.

Individual employee's perceptions of " Group-level Safety Climate" (supervisor referenced) versus " Organization-level Safety Climate" (top management referenced): Associations with safety outcomes for lone workers.

Research has shown that safety climate is among the strongest predictors of safety behavior and safety outcomes in a variety of settings. Previous studies have established that safety climate is a multi-faceted construct referencing multiple levels of management within a company, most generally: the organization level (employee perceptions of top management's commitment to and prioritization of safety) and group level (employee perceptions of direct supervisor's commitment to and prioritization of safety). Yet, no research to date has examined the potential interaction between employees' organization-level safety climate (OSC) and group-level safety climate (GSC) perceptions. Furthermore, prior research has mainly focused on traditional work environments in which supervisors and workers interact in the same location throughout the day. Little research has been done to examine safety climate with regard to lone workers. The present study aims to address these gaps by examining the relationships between truck drivers' (as an example of lone workers) perceptions of OSC and GSC, both potential linear and non-linear relationships, and how these predict important safety outcomes. Participants were 8095 truck drivers from eight trucking companies in the United States with an average response rate of 44.8%. Results showed that employees' OSC and GSC perceptions are highly correlated (r= 0.78), but notable gaps between the two were observed for some truck drivers. Uniquely, both OSC and GSC scores were found to have curvilinear relationships with safe driving behavior, and both scores were equally predictive of safe driving behavior. Results also showed the two levels of climate significantly interacted with one another to predict safety behavior such that if either the OSC or GSC scores were low, the other's contribution to safety behavior became stronger. These findings suggest that OSC and GSC may function in a compensatory manner and promote safe driving behavior even when either OSC or GSC scores are low. The results of this study provide critical insight into the supplementary interaction between perceptions of OSC and GSC. Recommendations for future research, as well as practical recommendations for organizational intervention, are discussed.

Gene expression network analyses in response to air pollution exposures in the trucking industry.

BACKGROUND: Exposure to air pollution, including traffic-related pollutants, has been associated with a variety of adverse health outcomes, including increased cardiopulmonary morbidity and mortality, and increased lung cancer risk. METHODS: To better understand the cellular responses induced by air pollution exposures, we performed genome-wide gene expression microarray analysis using whole blood RNA sampled at three time-points across the work weeks of 63 non-smoking employees at 10 trucking terminals in the northeastern US. We defined genes and gene networks that were differentially activated in response to PM2.5 (particulate matter ≤ 2.5 microns in diameter) and elemental carbon (EC) and organic carbon (OC). RESULTS: Multiple transcripts were strongly associated (padj < 0.001) with pollutant levels (48, 260, and 49 transcripts for EC, OC, and PM2.5, respectively), including 63 that were statistically significantly correlated with at least two out of the three exposures. These genes included many that have been implicated in ischemic heart disease, chronic obstructive pulmonary disease (COPD), lung cancer, and other pollution-related illnesses. Through the combination of Gene Set Enrichment Analysis and network analysis (using GeneMANIA), we identified a core set of 25 interrelated genes that were common to all three exposure measures and were differentially expressed in two previous studies assessing gene expression attributable to air pollution. Many of these are members of fundamental cancer-related pathways, including those related to DNA and metal binding, and regulation of apoptosis and also but include genes implicated in chronic heart and lung diseases. CONCLUSIONS: These data provide a molecular link between the associations of air pollution exposures with health effects.

Occupational vehicle-related particulate exposure and inflammatory markers in trucking industry workers.

BACKGROUND: Previous studies have suggested an association between particulate air pollution and cardiovascular disease, but the mechanism is still unclear. OBJECTIVE: We examined the association between workplace exposure to vehicle-related particles and cardiovascular disease related systemic inflammatory markers, C-reactive protein (hs-CRP), soluble intercellular adhesion molecule-1 (sICAM-1), and interleukin-6 (IL-6) in 137 trucking terminal workers (non-drivers) in the U.S. trucking industry. METHODS: We visited two large trucking terminals in 2009 and measured vehicle-related elemental carbon (EC), organic carbon (OC), and particulate matter with aerodynamic diameter ≤2.5µm (PM2.5), for 5 days consecutively at the main work areas. Each participant provided a blood sample and completed a health questionnaire during the sampling period. Individual workplace exposure level was calculated by 12-h time weighted moving averages based on work shift. The association between each blood marker and exposure to each pollutant during 0-12, 12-24, 24-36, and 36-48h before the blood draw was examined by multivariable regression analyses. RESULTS: In general, OC and EC had a positive association with sICAM-1, especially for exposure periods 12-24 (lag12-24) and 24-36 (lag24-36)h prior to blood draw [ß=54.9 (95%CI: 12.3-97.5) for lag12-24 and ß=46.5 (95%CI: 21.2-71.8) for lag12-24; change in sICAM-1 (in ng/mL) corresponding to an IQR increase in OC]. A similar pattern was found for EC and PM2.5. We did not find an association between measured pollutants up to 48h before blood draw and hs-CRP or IL-6. CONCLUSION: In this group of healthy workers, short-term exposure to vehicle-related air pollutants may be associated with sICAM-1. Our findings may be dependent on the exposure period studied.