Peter L Schnall

Publications of Peter L Schnall

• Sedentary work, low physical job demand, and obesity in US workers.

  Authors: BongKyoo Choi, Peter L Schnall, Haiou Yang, Marnie Dobson, Paul Landsbergis, Leslie Israel, Robert Karasek, Dean Baker

  American journal of industrial medicine. 11/2010; 53(11):1088-101.

  Little is known about the role of low physical activity at work (sedentary work or low physical job demand) in the increasing prevalence of obesity of US workers. This cross-sectional and secondaryLittle is known about the role of low physical activity at work (sedentary work or low physical job demand) in the increasing prevalence of obesity of US workers. This cross-sectional and secondary data analysis included 1,001 male and 1,018 female workers (age range: 32-69) from the National Survey of Midlife Development in the United States (MIDUS) II study (2004-2006). Sedentary work and physical job demand were measured by questionnaire items. Total obesity (based on body mass index) and central obesity (based on waist circumference) were defined using WHO criteria. After controlling for covariates (socio-demographic, psychosocial working conditions, health status, and health behaviors), sedentary work, low physical job demand, or their combination increased the risk for total and central obesity in male workers, particularly when they worked longer than 40 hr per week. Sedentary work marginally increased the risk for total and central obesity in female workers. Low physical activity at work is a significant risk factor for total and central obesity in middle-aged US male workers.

• Psychosocial working conditions and active leisure-time physical activity in middle-aged us workers.

  Authors: Bongkyoo Choi, Peter L Schnall, Haiou Yang, Marnie Dobson, Paul Landsbergis, Leslie Israel, Robert Karasek, Dean Baker

  International journal of occupational medicine and environmental health. 10/2010; 23(3):239-53.

  This study was to examine whether psychosocial work characteristics such as job control, psychological job demands, and their combinations are associated with leisure-time physical activity (LTPA) inThis study was to examine whether psychosocial work characteristics such as job control, psychological job demands, and their combinations are associated with leisure-time physical activity (LTPA) in US workers. 2019 workers (age range: 32 to 69) from the National Survey of Midlife Development in the United States (MIDUS) II study (2004-2006) were chosen for this cross-sectional study. Job control and job demands were measured by standard questionnaire items. Active LTPA was defined as "moderate or vigorous" level of physical activity. After controlling for covariates (e.g., age, race, education, income, physical effort at work, obesity, and alcohol consumption), high job control was associated with active LTPA. Active jobs (high control and low demands) and low-strain jobs (high control and high demands), compared to passive jobs (low control and low demands), increased the odds for active LTPA. The associations varied by sex and education level. Job demands alone were not associated with active LTPA. Having on-the-job learning opportunities and decision authority on their tasks may be conducive to active LTPA in middle-aged US workers.

• Elevated blood pressure, decreased heart rate variability and incomplete blood pressure recovery after a 12-hour night shift work.

  Authors: Ta-Chen Su, Lian-Yu Lin, Dean Baker, Peter L Schnall, Ming-Fong Chen, Wen-Chang Hwang, Chen-Fang Chen, Jung-Der Wang

  Journal of occupational health. 01/2008; 50(5):380-6.

  Shift work has been associated with increased risk of cardiovascular disease. This study was designed to determine the hemodynamic effects of 12-hour (12-h) shifts, and changes in blood pressure (BP)Shift work has been associated with increased risk of cardiovascular disease. This study was designed to determine the hemodynamic effects of 12-hour (12-h) shifts, and changes in blood pressure (BP) and heart rate variability (HRV) during 36 h rest time following 12-h shifts. Fifteen male shift workers with a mean age of 32.9 yr were recruited from a semiconductor factory. Ambulatory BP (AmBP) monitoring was performed for a total of 48 h for each participant. Six workers were monitored for 48 h by Holter electrocardiogram on both the day and night shifts. Paired self-comparison was used to estimate the difference between two hourly measurements of 12-h BP, HR, and HRV using the same timetable intra-individually. We also applied mixed models to estimate the effects of 12-h shifts on the delayed recovery of BP and heart rate (HR) in six workers who completed 96-h AmBP monitoring, including a 48-h night shift-rest period and another day shift period. Results showed that 12-h night shift work gave a persistently elevated systolic and diastolic BP (SBP and DBP) and HR, and decreased HRV compared to 12-h day shift work with the corresponding resting time. In addition, there was delayed SBP and DBP recovery on the first 12-h rest time in night shift workers, which was further demonstrated on the second 12-h rest time after adjustment for possible confounders through mixed models. In conclusion, 12-h night shift work may elevate BP and HR and decrease HRV. It is also associated with delayed BP recovery.

• Work conditions and masked (hidden) hypertension—insights into the global epidemic of hypertension

  Authors: Paul A Landsbergis, Peter L Schnall, Karen L. Belkić, Joseph E Schwartz, Baker Dean, Thomas G Pickering

  SJWEH Supplements. 01/2008;

  Hypertension is the leading cause of cardiovascular disease. There is considerable evidence that work conditions play an important role in the etiology of essential hypertension. Ambulatory bloodHypertension is the leading cause of cardiovascular disease. There is considerable evidence that work conditions play an important role in the etiology of essential hypertension. Ambulatory blood pressure during waking hours (work and home) is more strongly associated with subsequent cardiovascular disease than the traditional measurement of casual clinical blood pressure. A person with normal clinical blood pressure but elevated awake ambulatory blood pressure is said to have “masked” (or “occult” or “hidden”) hypertension. Masked hypertension is associated with increased cardiovascular risk, and has been observed in 10–30% of adults with normal clinical blood pressure. It has been hypothesized that exposure to workplace stressors first elevates work, but not clinical, blood pressure; after chronic exposure to stressors, both daytime and clinical pressure become elevated. In this manuscript, an algorithm is provided that targets ambulatory monitoring for high-risk groups and helps detect work-related hypertension. A public health approach incorporating clinical guidelines, workplace surveillance, and improved work conditions is recommended for tackling the epidemic of hypertension.

• Work hours and self-reported hypertension among working people in California.

  Authors: Haiou Yang, Peter L Schnall, Maritza Jauregui, Ta-Chen Su, Dean Baker

  Hypertension. 11/2006; 48(4):744-50.

  Among the risk factors for hypertension, stress, especially work stress, has drawn increasing attention. Another potential work-related risk factor for hypertension identified in the past few yearsAmong the risk factors for hypertension, stress, especially work stress, has drawn increasing attention. Another potential work-related risk factor for hypertension identified in the past few years is work hours. This article presents an analysis of work hours and self-reported hypertension among the working population in the state of California. The data set used for this study comes from the Public Use File of the 2001 California Health Interview Survey. The logistic regression analysis shows a positive association between hours worked per week and likelihood of having self-reported hypertension. Compared with those working between 11 and 39 hours per week, individuals working 40 hours per week were 14% (95% CI: 1.01 to 1.28) more likely to report hypertension, those who worked between 41 and 50 hours per week were 17% (95% CI: 1.04 to 1.33) more likely to report hypertension, and those who worked >or=51 hours per week were 29% (95% CI: 1.10 to 1.52) more likely to report hypertension after controlling for various potentially confounding variables, including demographic and biological risk factors and socioeconomic status. This analysis provides evidence of a positive association between work hours and hypertension in the California working population.

• Is job strain a major source of cardiovascular disease risk?

  Authors: Karen L Belkic, Paul A Landsbergis, Peter L Schnall, Dean Baker

  Scandinavian journal of work, environment & health. 05/2004; 30(2):85-128.

  Empirical studies on job strain and cardiovascular disease (CVD), their internal validity, and the likely direction of biases were examined. The 17 longitudinal studies had the highest validityEmpirical studies on job strain and cardiovascular disease (CVD), their internal validity, and the likely direction of biases were examined. The 17 longitudinal studies had the highest validity ratings. In all but two, biases towards the null dominated. Eight, including several of the largest, showed significant positive results; three had positive, nonsignificant findings. Six of nine case-control studies had significant positive findings; recall bias leading to overestimation appears to be fairly minimal. Four of eight cross-sectional studies had significant positive results. Men showed strong, consistent evidence of an association between exposure to job strain and CVD. The data of the women were more sparse and less consistent, but, as for the men, most of the studies probably underestimated existing effects. Other elements of causal inference, particularly biological plausibility, corroborated that job strain is a major CVD risk factor. Additional intervention studies are needed to examine the impact of ameliorating job strain upon CVD-related outcomes.

• Lower socioeconomic status among men in relation to the association between job strain and blood pressure.

  Authors: Paul A Landsbergis, Peter L Schnall, Thomas G Pickering, Katherine Warren, Joseph E Schwartz

  Scandinavian journal of work, environment & health. 06/2003; 29(3):206-15.

  OBJECTIVES: This study attempted to determine whether the association between job strain (high job demands plus low job control) and blood pressure among men varies by socioeconomic status. METHODS:OBJECTIVES: This study attempted to determine whether the association between job strain (high job demands plus low job control) and blood pressure among men varies by socioeconomic status. METHODS: The cross-sectional associations between job strain and ambulatory blood pressure, by level of education, occupational status, and income, and the interaction between job strain and these measures of socioeconomic status were assessed by multiple linear regression, adjusted for age, race or ethnicity, body mass index, alcohol use, smoking, standing position, and worksite for 283 men, aged 30-60 years, from eight worksites in New York City. RESULTS: A substantial association between job strain and work ambulatory blood pressure was found among men with lower socioeconomic status, ranging from 2.7-11.8 mm Hg systolic to 1.9-6.1 mm Hg diastolic blood pressure, depending upon the measure of socioeconomic status examined. However, in the groups with high socioeconomic status, the association between job strain and ambulatory blood pressure at work was much smaller, the range in blood pressure being 0-5.3 (systolic) and 0.2-2.1 (diastolic) mm Hg. Two of the 10 tests of the interaction between job strain and socioeconomic status had a P-value of <0.05. CONCLUSIONS: These data provide evidence that the relationship between job strain and blood pressure is greater among men with lower socioeconomic status.

• Life-course exposure to job strain and ambulatory blood pressure in men.

  Authors: Paul A Landsbergis, Peter L Schnall, Thomas G Pickering, Katherine Warren, Joseph E Schwartz

  American journal of epidemiology. 06/2003; 157(11):998-1006.

  This 1985-1995 study was designed to assess the association between blood pressure (measured by using an ambulatory monitor) and history of exposure to job strain. Items from the Job ContentThis 1985-1995 study was designed to assess the association between blood pressure (measured by using an ambulatory monitor) and history of exposure to job strain. Items from the Job Content Questionnaire were completed by 213 employed men, aged 30-60 years at entry into the Work Site Blood Pressure Study in New York City, New York, for each previous job they had held. The systolic blood pressure of men employed for >/=25 years who were exposed to job strain for 50% of their work life was 4.8 mmHg (95% confidence interval: -3.7, 13.4) higher at work and 7.9 mmHg (95% confidence interval: 0.8, 15.0) higher at home than that of men with no past exposure, independent of current exposure. Evidence was inconsistent for the hypothesis of rapid induction of/recovery from the effects of job strain on blood pressure, and there was little effect of past job strain on diastolic blood pressure. These findings provide some support for the hypothesis of an effect of cumulative burden of exposure to job strain on systolic blood pressure.

• Validity and reliability of a work history questionnaire derived from the Job Content Questionnaire.

  Authors: Paul A Landsbergis, Peter L Schnall, Thomas G Pickering, Joseph E Schwartz

  Journal of occupational and environmental medicine / American College of Occupational and Environmental Medicine. 12/2002; 44(11):1037-47.

  Job design risk factors for hypertension and heart disease have often been assessed by the Job Content Questionnaire (JCQ). Job characteristics are typically assessed only once, however, which canJob design risk factors for hypertension and heart disease have often been assessed by the Job Content Questionnaire (JCQ). Job characteristics are typically assessed only once, however, which can result in misclassification and bias results toward the null. Newer approaches, which assess job characteristics over a working life, are hampered by the need to ask numerous questions about each job, increasing survey length and potentially reducing response rates. Participants in the Work Site Blood Pressure Study, a prospective study of psychosocial factors and ambulatory blood pressure, completed the JCQ about their current jobs. At later dates, 213 employed men, a subset of the original cohort, retrospectively completed the Work History Questionnaire (WHQ), a short version of the JCQ, for each past job. The WHQ exhibited moderate validity for assessing past job characteristics, a weak association with systolic blood pressure, and expected patterns of change over time. Thus, it may be a valuable tool for measuring the health effects of historical job characteristics, which often change over time.

• Work stressors and cardiovascular disease.

  Authors: Paul A Landsbergis, Peter L Schnall, Karen L. Belkić, Dean Baker, Joseph Schwartz, Thomas G Pickering

  Work (Reading, Mass.). 02/2001; 17(3):191-208.

  Over the past 20 years, an extensive body of research evidence has documented that psychosocial work stressors are risk factors for hypertension and cardiovascular disease. These stressors, whichOver the past 20 years, an extensive body of research evidence has documented that psychosocial work stressors are risk factors for hypertension and cardiovascular disease. These stressors, which appear to be increasing in prevalence, include job strain (the combination of psychological job demands and low job control), imbalance between job efforts and rewards, threat-avoidant vigilant work, and long work hours. This article reviews the evidence linking these stressors with hypertension and CVD, and the physiological and social psychological mechanisms underlying the associations. Also described are methods for measuring work stressors and new, more accurate techniques for measuring blood pressure. Finally, strategies for reducing work stressors and preventing hypertension and CVD are reviewed. These include clinical assessment, worksite health promotion, work organization interventions, legal approaches and work site surveillance.