Health effects associated with shift work in 12-hour shift schedule among Iranian petrochemical employees.

INTRODUCTION The main purposes of this study were to investigate shift-work-related health problems in 12-h shift schedule and to identify major factors associated with these problems. MATERIALS AND METHODS This cross-sectional study was conducted at 8 petrochemical plants. The study population consisted of 1203 workers (549 shift and 654 day workers). Data on personal details, the shift schedule and adverse health outcomes were collected with a self-administered questionnaire. RESULTS The results showed that health problems in shift workers were more prevalent than in day workers; however, the differences were significant only in gastrointestinal and musculoskeletal disorders. Logistic regression analysis revealed that in addition to shift work, other variables such as extended work time, type of employment, second job and job unit were associated with health problems. CONCLUSIONS Working shifts is one important variable influencing the health of petrochemical workers. To improve workers' health, interventional program should focus on the shift schedule as well as other significant aspects of working conditions.