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.

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.

Dermal exposure and urinary 1-hydroxypyrene among asphalt roofing workers.

The primary objective of this study was to identify significant determinants of dermal exposure to polycyclic aromatic compounds (PACs) among asphalt roofing workers and use urinary 1-hydroxyprene (1-OHP) measurements to evaluate the effect of dermal exposure on total absorbed dose. The study population included 26 asphalt roofing workers who performed three primary tasks: tearing off old roofs (tear-off), putting down new roofs (put-down), and operating the kettle at ground level (kettle). During multiple consecutive work shifts (90 workerdays), dermal patch samples were collected from the underside of each worker's wrists and were analyzed for PACs, pyrene, and benzo(a)pyrene (BAP). During the same work week, urine samples were collected at pre-shift, post-shift, and bedtime each day and were analyzed for 1-OHP (205 urine samples). Linear mixed effects models were used to evaluate the dermal measurements for the purpose of identifying important determinants of exposure, and to evaluate urinary 1-OHP measurements for the purpose of identifying important determinants of total absorbed dose. Dermal exposures to PAC, pyrene, and BAP were found to vary significantly by roofing task (tear-off > put-down > kettle) and by the presence of an old coal tar pitch roof (pitch > no pitch). For each of the three analytes, the adjusted mean dermal exposures associated with tear-off (812 ng PAC/cm2, 14.9 ng pyrene/cm2, 4.5 ng BAP/cm2) were approximately four times higher than exposures associated with operating the kettle (181 ng PAC/cm2, 4.1 ng pyrene/cm2, 1.1 ng BAP/cm2). Exposure to coal tar pitch was associated with a 6-fold increase in PAC exposure (p = 0.0005), an 8-fold increase in pyrene exposure (p < 0.0001), and a 35-fold increase in BAP exposure (p < 0.0001). Similarly, urinary 1-OHP levels were found to be significantly higher on days when an old pitch roof was removed, accounting for a 3.7-fold difference at pre-shift (p = 0.01), a 5.0-fold difference at post-shift (p = 0.004), and a 7.2-fold difference at bedtime (p = 0.002). The pyrene measurements obtained during the work shift were found to be strongly correlated with urinary 1-OHP measurements obtained at the end of that shift (r = 0.8, p < 0.001) as well as at bedtime (r = 0.7, p < 0.001). Ultimately, the results of a distributed lag model indicated that dermal exposure during the preceding 40 hours had a statistically significant effect on urinary 1-OHP. The presence of coal tar pitch was the primary determinant of dermal exposure, particularly for exposure to BAP. However, the task-based differences that were observed while controlling for pitch suggest that exposure to asphalt also contributes to dermal exposures. We found that dermal exposure was a significant determinant of total absorbed dose, suggesting that control strategies aimed at reducing occupational exposure to PACs should include an effort to minimize dermal exposure.