Effects of Noise Exposure on Serum Cortisol and Some Blood Parameters in Steel Industry Workers

Sound is one of the most important physical factors، which is considered hazardous in industrial environments. Noise had auditory and non-auditory effects such as damaging hearing system، effect on the organ of vision، balance system، electrolytes، neurological and psychological effects، physiological and mental effects. Thus، this study carried out to determine the effects of noise exposure on serum cortisol levels and some blood parameters in steel industry workers.

The number of 50 employees of steel industry as the subject group participated in this cross-sectional study. Demographic information was collected using a questionnaire. In order to review the blood parameters changes such as serum cortisol level، lipid profile and sugar، blood sample was taken from participants before and after the work shifts. Energy averaging (LAeq) was measured by CEL 440 sound level meter and noise equipment analyzed in octave-band frequencies. This study was carried out in field and experimental conditions. In the experimental condition، workers exposed to noise at 85، 95 and 105 dBA for 5 minute in three consecutive days. Finally the results from blood tests were analyzed.

Laboratory findings showed that serum cortisol levels at all of the three sound levels (85، 95 and 105 dB) increased after the noise exposure; however، this change was not statistically significant (P > 0. 05). Lipid TG levels also decreased after noise exposure، but this finding was not significant either (P > 0. 05). HDL and LDL at noise level 85 dBA had descending trend، but compared with pre-exposure time، there was no significant change (P > 0. 05). The fasting blood sugar (FBS) was increased in all the three noise levels، which this change in 95 dBA was statistically significant (P < 0. 001).

The present study showed that exposure to high sound levels led to changes in physiological parameters such as serum cortisol، lipid profile and blood sugar; however، except FBS parameter difference in noise level 95 dBA، other changes in parameters was not statistically significant. Therefore، the noise cannot be considered as a factor affecting the clinical parameters.