The Effect of Occupational Noise Exposure on Serum Cortisol Concentration of Night-shift Industrial Workers: A Field Study

Background: In both developed and developing countries, noise is regarded as the most common
occupational hazard in various industries. The present study aimed to examine the effect of sound
pressure level (SPL) on serum cortisol concentration in three different times during the night shift.
Methods: This caseecontrol study was conducted among 75 workers of an industrial and mining firm in
2017. The participants were assigned to one of the three groups (one control and two case groups), with
an equal number of workers (25 participants) in each group. Following the ISO 9612 standard, dosimetry
was adopted to evaluate equivalent SPL using a TES-1345 dosimeter. The influence of SPL on serum
cortisol concentration was measured during the night shift. The serum cortisol concentration was
measured using a radioimmunoassay (RIA) test in the laboratory. Repeated measure analysis of variance
and linear mixed models were used with a ¼ 0.05.
Results: The results indicated a downward trend in the serum cortisol concentration of the three groups
during the night shift. Both SPL and exposure time significantly affected cortisol concentration
(p < 0.0001, p < 0.0001). Conversely, age and body mass index had no significant influence on cortisol
concentration (p ¼ 0.360, p ¼ 0.62).
Conclusion: Based on the obtained results, increasing SPL will lead to enhancement of serum cortisol
concentration. Given that cortisol concentration varies while workers are exposed to different SPLs, this
hormone can be used as a biomarker to study the effect of noise-induced stress.