Heat stress and its impact on the worker's cortisol concentration: A case study in a metal melding industry

Heat stress is considered as one of the hazardous occupational agents in hot environments. Working under heat stress condition may lead to individuals’ health problems. Several studies have been shown that stress in the working environments can elevate stress hormones such as cortisol. Since heat stress is one of the serious stresses in hot industries including melting, this study was done to investigate the effect of heat stress on the cortisol concentration of workers in one of the melting industries. In this cross-sectional study, 70 workers in two groups of case and control (35 people in case group from foundry unit and 35 people in control group from casting unit without heat stress) were investigated. First, a demographic questionnaire was complete for each subject. Then in order to evaluate the changes in cortisol level, blood samples were taken from the participants during their working hours (9:30 to 10 AM) and the obtained levels were compared with the normal level of cortisol, provided at 7 to 10 AM. In order to assess environmental condition, WBGT (Wet Bulb Globe Temperature) index was measured at three highest including feet, waist and head. Moreover, noise and lighting were measured at the workers work station. Data were analyzed using SPSS software version 16. Regarding WBGT, it was shown that mean WBGT index were 33 C and 16.7 C in case and control groups, respectively. Additionally, cortisol concentration in case group was significantly higher than control group (P<0.001). Results of the present study indicate that physical stresses of working environment can lead to changes in physiology of human body. Thus, variations in hormone level in its consequences in hot environment should be considered in occupational hygine.