Association of effort–reward imbalance with fingernail cortisol levels in apparel manufacturing workers

In this prospective cross-sectional epidemiological study, we aimed to investigate the relationship between psychosocial job-related stress (effort-reward imbalance [ERI]) and fingernail cortisol levels. In total, 136 daytime employees (109 women and 27 men; age 18-72 [38.9 ± 12.9] years) at a school uniform sewing factory were recruited. Fingernail-based cortisol analysis was performed in September 2017 (Time 1, baseline) and December 2017 (Time 2). The participants completed a short version of the Japanese ERI questionnaire at baseline. Multiple linear regression analyses controlling for potential confounders revealed that the effort score was positively associated with cortisol levels at Time 1 (β=0.252, p=0.004) and Time 2 (β=0.188, p=0.048), whereas no significant associations were observed for reward or ERI ratio. These findings suggest that linking adverse psychological working conditions to stress-related disorders may be biologically plausible. This study also highlights the importance of evaluating specific components of psychosocial stress at work in relation to chronic biological stress markers to enhance understanding of stress-related health risks and inform effective occupational health interventions.