Investigation the variation of urine density as an biomarker for dehydration conditions in workers employed in hot workplaces

Background of During physical activity in hot environments, sweating along with evaporation increased, as the most important physiological response, which can lead to dehydration. The aim of this study was to investigate the variation of urine density in dehydration conditions of workers in hot workplaces. In this cross-sectional study, 40 workers in the hot environments were selected as case group and 20 administrative staffs as control group. In order to assess dehydration level in the employees, urinary density was measured at the beginning and end of shifts using hand hold model of Refractometer (density gauge device). In order to evaluation heat stress in workstations, heat stress index was measured using a digital WBGT meter manufactured by Casella. Ultimately, data obtained from this study analyzed using compare means and Cochran tests by SPSS 16 software. In most of the workstations, heat stress index was higher than the national recommended limit; while this index in the control group was lower than the mentioned limit. Based on compare means test, the urine density of the case group at the beginning and end of their shift showed a significant different (p<0.001). In addition, Based on compare means test, the urine density of the case group was higher than the control group at the end of work shift (p <0.01). The level of urine density with regard to the effects of confounding factors could suitably show the levels of dehydration of workers exposed to heat. Therefore, the density of urine can be used as an acceptable biomarker for evaluating the occupational exposure to heat in order to determine the risk of inducing the heat strain.