Hamzeh Mohammadi, Somayeh Farhang Dehghan, Soheila Khodakarim Ardakani, Farideh Golbabaei,
Volume 12, Issue 3 (9-2022)
Abstract
Introduction: Studies show that in many cases, environmental hazardous agents such as heat, noise, as well as chemical pollutants cause adverse health effects through the mechanism of oxidative stress. This study has examined the effect of exposure to noise and whole-body vibration (WBV) on some parameters of oxidative stress (enzyme superoxide dismutase (SOD), total antioxidant capacity (TAC), and malondialdehyde (MDA)) of workers in a foundry industry.
Material and Methods: The workers were selected based on the calculations related to the sample size and taking into account the inclusion criteria as well as completing the informed consent form. The level of exposure to noise and WBV was measured according to ISO 9612 and ISO 2631, respectively. For each worker, the time-weighted average was calculated. The level of exposure of workers to the studied stressors was divided into three categories: low, medium, and high. The blood samples were taken from all participants between 7-9 am. Then, via ELISA method according to the protocol of the kit manufacturer, the samples were prepared and analyzed. Univariate analysis of variance was performed to determine the “effect size” of each physical stressors on the studied parameters.
Results: The mean levels of MDA, SOD, and TAC among participants were 22.48 (11.19) nmol / ml, 61.28 (10.97) U / ml, and 1.64 (0.90) mM, respectively. Among the exposure variables, noise had the largest effect on MDA level (B = 0.090), which was not statistically significant (P = 0.865). WBV had the largest effect on SOD level (B = -1.469) which was statistically significant (P = 0.016). None of the studied variables had a significant effect on the TAC level; however, among the exposure variables, the greatest effect was related to WBV (B = -0.077; P = 0.133).
Conclusion: The effect of noise on oxidative stress parameters was not statistically significant. The effect of whole-body vibration on oxidative stress parameters except SOD was not statistically significant. Noise and WBV had increasing effect on MDA and decreasing one on SOD and TAC levels.
Seyyed Mohammad Javad Golhosseini, Mohsen Aliabadi, Rostam Golmohammadi, Maryam Farhadian, Mehdi Akbari,
Volume 14, Issue 4 (12-2024)
Abstract
Introduction: Despite the numerous studies on occupational noise-induced hearing loss, there is limited documentation on the vibration effects on the workers’ auditory system. Heavy equipment drivers are exposed to high levels of whole-body vibration (WBV) and noise. Therefore, this study aims to investigate the heavy equipment drivers’ auditory response to WBV exposure and combined exposure to noise and WBV.
Material and Methods: 30 male heavy equipment drivers with an average age of 32.40 ± 4.91 years participated in this study, which was designed based on the repeated measurements model. During 3 defined scenarios of exposure to WBV, combined exposure to noise and WBV, as well as the scenario without exposure, the drivers’ auditory response was measured using distortion product otoacoustic emissions (DPOAE). Statistical analyses were performed by IBM SPSS-25 software.
Results: The range of heavy equipment in-cabin noise was 84-89 dB. Also, the most exposure of drivers to WBV was obtained in the Z axis with an average acceleration of 1.29 m/s2. The DPOAE amplitude of the drivers in all three investigated scenarios showed significant changes (P<0.05); But in comparison between different scenarios, exposure to WBV and combined exposure to noise and WBV had a significant effect on the response of the auditory system of the participants in the study compared to the scenario without exposure (P<0.05). Also, there was a significant difference in the changes of the DPOAE amplitude in different frequencies; Thus, the most changes in the DPOAE amplitude were observed in the frequencies of around 4000 Hz.
Conclusion: The results of this study showed the damaging consequences of exposure to noise and WBV on the auditory response; In addition, the present study provided evidence of synergistic effects of combined exposure to noise and WBV on heavy equipment drivers.
