Leslie A. MacDonald

Covariation between workplace physical and psychosocial stressors: evidence and implications for occupational health research and prevention

There is increasing interest in distinguishing the effects of physical and psychosocial workplace stressors on the aetiology of work-related musculoskeletal disorders (MSD). Modest associations have been found between psychosocial stressors and MSD, such as intensive load, monotonous work and low job control. Interpretation of these results has been limited by likely covariation between physical and psychosocial stressors. This investigation examined exposure covariation among blue- and white-collar workers employed in a mass production manufacturing environment (N = 410). Physical stressors were assessed from questionnaire and accelerometry. Psychosocial stressors were assessed from questionnaire. Pearson and Spearman correlation coefficients were computed. An exploratory factor analysis procedure identified possible common factors linking specific physical and psychosocial stressors. Moderate to high correlations between some physical and psychosocial stressors showed evidence of covariation both across and within groups. Covariation was strongest among blue-collar production and low-status office workers. Factor analysis results showed considerable shared variance between some physical and psychosocial stressors, such as repetition and job control, suggesting that these disparate stressors manifest from common work organization factors that govern the structure of work. While recognizing the conceptual differences between physical and psychosocial stressors, these results call attention to the strong empirical relationships that can exist between some stressors in the workplace setting. To guard against ambiguous study findings that can occur when exposures are mixed, it is critical that future epidemiologic studies include information about the degree of association between task-level stressors. Future research on work organization determinants of task-level stressors, and their coincident occurrence in jobs with greater specialization, may provide promising new insights into the nature of risk for MSD and effective prevention strategies.

Incorporating work organisation into occupational health research: an invitation for dialogue

The last decade has seen a lively debate emerge about the proper scope of public health research and the value of examining broad social and environmental factors as interacting determinants of morbidity and mortality.1 2 In occupational health and safety, the broader socio-ecological system of most obvious interest is that of the organisations in which workers are employed. However, occupational health researchers have been slow to incorporate broader workplace features into their exposure assessment protocols and epidemiological study designs. The dominant exposure paradigm remains largely confined to the characterisation of risk factors at the job level (fig 1, arrow B). While application of this paradigm has contributed much to our understanding of the association between work and worker health and safety, failure to consider the organisational factors and conditions that are antecedents to job-level hazards could limit our ability to design and implement effective and sustainable hazard controls (affecting arrows A, C, D in fig 1). Examples of this broader perspective already exist within systems safety and macroergonomics models3–7 but we suggest that the importance of the organisational context is relevant for all exposure domains—including chemical hazards. We seek to stimulate dialogue within the occupational health community about the organisational context in which worker injury and illness occurs—and its implications for aetiological research and hazard control. Figure 1 Conceptual pathways that link organisational characteristics with workplace health and safety hazards and worker health outcomes. The box “work organisation” potentially represents multiple levels above the job level. The investigative foci in occupational health and the organisational sciences differ significantly, from job-level to organisational-level.8 While each contributes to our understanding of how working …

Job Stress Among Female Flight Attendants

We evaluated the presence of chronic job stressors among flight attendants (FAs) to examine the relationships between these job stressors and psychological distress and job dissatisfaction. Seventy-three female FAs (90% participation) employed at two commercial airlines completed a detailed questionnaire. Standard questions and scale measures were used to assess job stressors, psychological distress, and job dissatisfaction. The association between job stressors and these outcomes was evaluated using multiple regression analysis. Except for fatigue, distress and job dissatisfaction were moderate to low. Job stressors were found to have a substantive effect on these outcomes, following adjustment for individual factors. Despite moderate-to-low levels of distress and dissatisfaction, targeted efforts to reduce selected job stressors and to enhance social support may be important steps toward improving the well-being and satisfaction of FAs.

Occupation as Socioeconomic Status or Environmental Exposure? A Survey of Practice Among Population-based Cardiovascular Studies in the United States

Decisions about how occupation is used in epidemiologic research can affect conclusions about the importance of socioeconomic and environmental factors in explaining disparities for outcomes such as cardiovascular disease. A review of practices in the collection and use of occupational data was conducted among population-based cardiovascular studies in the United States. Studies were identified for review from the National Heart, Lung, and Blood Institute website and the biomedical database, Computer Retrieval of Information on Scientific Projects, by use of selected criteria. Data collection instruments and study publications were retrieved and reviewed for 30 of 33 studies (91%). Most of the studies (83%) collected at least descriptive occupational data, and more than half (60%) collected data on workplace hazards. The reviewed studies produced 80 publications in which occupational data were used in analyses, most often as an indicator of socioeconomic status. Authors rarely acknowledged known conceptual and empirical links among socioeconomic status, employment stability, and working conditions. Underutilization of data on workplace conditions was found. Existing data could be used more effectively to examine the contribution of work-related social and environmental conditions to the development of modifiable cardiovascular disease through multiple pathways.

Miscarriage among flight attendants.

Background: Cosmic radiation and circadian disruption are potential reproductive hazards for flight attendants. Methods: Flight attendants from 3 US airlines in 3 cities were interviewed for pregnancy histories and lifestyle, medical, and occupational covariates. We assessed cosmic radiation and circadian disruption from company records of 2 million individual flights. Using Cox regression models, we compared respondents (1) by levels of flight exposures and (2) to teachers from the same cities, to evaluate whether these exposures were associated with miscarriage. Results: Of 2654 women interviewed (2273 flight attendants and 381 teachers), 958 pregnancies among 764 women met study criteria. A hypothetical pregnant flight attendant with median first-trimester exposures flew 130 hours in 53 flight segments, crossed 34 time zones, and flew 15 hours during her home-base sleep hours (10 pm–8 am), incurring 0.13 mGy absorbed dose (0.36 mSv effective dose) of cosmic radiation. About 2% of flight attendant pregnancies were likely exposed to a solar particle event, but doses varied widely. Analyses suggested that cosmic radiation exposure of 0.1 mGy or more may be associated with increased risk of miscarriage in weeks 9–13 (odds ratio = 1.7 [95% confidence interval = 0.95–3.2]). Risk of a first-trimester miscarriage with 15 hours or more of flying during home-base sleep hours was increased (1.5 [1.1–2.2]), as was risk with high physical job demands (2.5 [1.5–4.2]). Miscarriage risk was not increased among flight attendants compared with teachers. Conclusions: Miscarriage was associated with flight attendant work during sleep hours and high physical job demands and may be associated with cosmic radiation exposure.

Use of accelerometers as an ergonomic assessment method for arm acceleration a large-scale field trial

Ergonomists need easy-to-use, quantitative job evaluation methods to assess risk factors for upper extremity work-related musculoskeletal disorders in field-based epidemiology studies. One device that may provide an objective measure of exposure to arm acceleration is a wrist-worn accelerometer or activity monitor. A field trial was conducted to evaluate the performance of a single-axis accelerometer using an industrial population (n= 158) known to have diverse upper limb motion characteristics. The second phase of the field trial involved an examination of the relationship between more traditional observation-based ergonomic exposure measures and the monitor output among a group of assembly-line production employees (n= 48) performing work tasks with highly stereotypic upper limb motion patterns. As expected, the linear acceleration data obtained from the activity monitor showed statistically significant differences between three occupational groups known observationally to have different upper limb motion requirements. Among the assembly-line production employees who performed different short-cycle assembly work tasks, statistically significant differences were also observed. Several observation-based ergonomic exposure measures were found to explain differences in the acceleration measure among the production employees who performed different jobs: hand and arm motion speed, use of the hand as a hammer, and, negatively, resisting forearm rotation from the torque of a power tool. The activity monitors were found to be easy to use and non-intrusive, and to be able to distinguish arm acceleration among groups with diverse upper limb motion characteristics as well as between different assembly job tasks where arm monitors were performed repeatedly at a fixed rate.

Clinical guidelines for occupational lifting in pregnancy: evidence summary and provisional recommendations

Empirically based lifting criteria established by the National Institute for Occupational Safety and Health (NIOSH) to reduce the risk of overexertion injuries in the general US working population were evaluated for application to pregnant workers. This report proposes criteria to guide decisions by medical providers about permissible weights for lifting tasks performed at work over the course of an uncomplicated pregnancy. Our evaluation included an extensive review of the literature linking occupational lifting to maternal and fetal health. Although it has been 29 years since the American Medical Associations Council on Scientific Affairs published its report on the Effects of Pregnancy on Work Performance, these guidelines continue to influence clinical decisions and workplace policies. Provisional clinical guidelines derived from the NIOSH lifting criteria that account for recent evidence for maternal and fetal health are presented and aim to improve the standard of care for pregnant workers.

Hand lacerations and job design characteristics in line-paced assembly.

This study investigated risk factors for laceration injuries among workers employed in line-paced manufacturing assembly operations. Most lacerations (76% of 576) occurred on the hands and fingers (grouped as “hand” lacerations). On average, 37% of surveyed workers reported at least one laceration to the hand in the preceding year, resulting in an overall hand laceration rate of 83 per 100 workers per year. An inverse relationship was found between level of job routinization and hand lacerations, with progressively higher rates of hand lacerations occurring among workers assigned to less routine (more variable) work patterns. Fabricated metal parts handling and job variability may be related to increased risk of hand lacerations in line-paced work environments where personal protective equipment is the primary strategy to control exposure to sharp objects.

Ergonomic job design to accommodate and prevent musculoskeletal disabilities.

Work-related musculoskeletal disorders (MSDs) account for a major portion of the cost of work-related injury and illness in the United States. Many of these injuries and illnesses lead to temporary or permanent disability. It is generally accepted that the incidence of MSDs increases when the demands of the job exceed the capabilities of the worker. As the workforce ages and physical capabilities decline, it is anticipated that many more Americans will request disability-related leave resulting from musculoskeletal disorders because they are unable to meet the demands of the job. To prevent these disabilities and to accommodate a wider range of people in the workforce, physical job demands may have to be reduced so that a larger portion of the population will be capable of working. Providing engineering controls or alternative work arrangements allows for accommodation of workers with a wide range of capabilities and can assist in rehabilitation and early return to work following injury.

Associations of work hours with carotid intima–media thickness and ankle–brachial index: the Multi-Ethnic Study of Atherosclerosis (MESA)

Objectives Long working hours may be associated with cardiovascular disease (CVD). The objective was to investigate cross-sectional associations of work hours with carotid intima–media thickness (CIMT) and ankle–brachial index (ABI). Methods Participants were 1694 women and 1868 men from the Multi-Ethnic Study of Atherosclerosis. CIMT and ABI were measured using standard protocols. Information on work hours was obtained from questionnaires. Mean values of CIMT and ABI were examined across five categories of hours worked per week (≤20, 21–39, 40, 41–50 and >50) using analysis of variance/analysis of covariance. p Values for trend were obtained from linear regression models. Results Mean age of participants was 56.9±8.4 years; 52.4% were men. Distinct patterns of association between work hours and the subclinical CVD biomarkers were found for women and men, although this heterogeneity by gender was not statistically significant. Among women only, work hours were positively associated with common (but not internal) CIMT (p=0.073) after full risk factor adjustment. Compared with women working 40 h, those working >50 h were more likely to have an ABI <1 (vs 1–1.4) (OR=1.85, 95% CI 1.01 to 3.38). In men, work hours and ABI were inversely associated (p=0.046). There was some evidence that the association between work hours and ABI was modified by occupational category (interaction p=0.061). Among persons classified as management/professionals, longer work hours was associated with lower ABI (p=0.015). No significant associations were observed among other occupational groups. Conclusions Working longer hours may be associated with subclinical CVD. These associations should be investigated using longitudinal studies.