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Crystalline silica has emerged as a prominent occupational toxicant over extended periods, leading to the development of lung disease and cancer. The objective of this investigation is to establish a benchmark dose (BMD) for crystalline silica micro and nanoparticles based on the dehydrogenase activity of the A549 lung-cell line. The impact of exposure to crystalline silica micro-particles (C–SiO2 MPs) and crystalline silica nanoparticles (C–SiO2 NPs) on A549 epithelial lung cells was examined for durations of 24 and 72 h to evaluate cell viability using the MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay. The determination of dose-response and BMD was carried out through the BMD software v 3.2. The findings reveal a dose-dependent relationship between cell viability and both C–SiO2 MPs and -NPs. The BMDL values for 24 h treatment of C–SiO2 MPs and -NPs were determined to be 2.26 and 0.97 µg/ml, respectively, based on exponential models. Correspondingly, these values were found to be 1.17 and 0.85 µg/ml for the 72 h treatment. This investigation underscores the significance of particle size as a contributing factor in assessing occupational health risks. Moreover, the utilization of BMDL can facilitate the determination of more precise values for occupational exposures by considering various parameters associated with particle presence. [ABSTRACT FROM AUTHOR]

Background and Objective: Individuals constantly hear different sounds that can affect their work and living place. The present study aimed at investigating the effect of traffic noise on cortisol and salivary alpha-amylase biomarkers. Materials and Methods: The subjects were men aged 18 to 35 who performed driving activities for one hour in the laboratory. The tests were performed in two conditions of background noise (35 dBA) and traffic noise with a level of 75 dBA and saliva samples were collected from the subjects before and after driving. Finally, saliva samples were analyzed with cortisol and alpha-amylase kits and by ELISA method. The statistical method used for data analysis was SPSS software (version 24) and data analysis was performed by Wilcoxon statistical test. Results: The results of this study indicated that the concentrations of both biomarkers cortisol and alpha-amylase in background noise conditions after driving were higher than that before the start, although this increase was not significant (p> 0.05). In the presence of traffic noise with a level of 75 dBA, the concentration of both biomarkers after driving was significantly higher than that before driving. (p<0.05) Conclusion: This study demonstrated that exposure to traffic noise can increase the concentration of salivary alpha-amylase and cortisol biomarkers while driving. [ABSTRACT FROM AUTHOR]

Benzo-α-pyrene is one of the most dangerous pollutants during working on asphalt, which is a carcinogenic. This study was aimed to perform health risk assessment of asphalt workers exposure to Benzo-α-pyrene using respiratory air monitoring data. The standard method of NIOSH 5515 (National Institutes of safety and health) was used for sampling and analyzing the Benzo-α-pyrene in the respiratory air. The sampling was done using polytetrafluoroethylene filter (PTFE) and XAD-2 sorbent tube (naphthylisocyanate) and the obtained samples were analyzed by Gas Chromatography with Flame Ionization Detection (GC-FID). The results of the study show that the highest and lowest concentrations belong to the functions of finisher assistance (0.058±0.011 mg m-3) and roller driver (0.042±0.015 mg/m³), respectively. The statistical test showed that the concentration of Benzo-α-pyrene in the respiratory air of different tasks is significantly different from each other (P<0.001). The results of the health risk assessment showed that all tasks are at a high risk level. In addition, comparison of the results of the concentration of Benzo-α-pyrene in the respiratory air and the assessment of health risk indicated that merely monitoring the concentration of the pollutants in the breathing air and comparing it with the allowable limits of exposure are not appropriate and reliable criteria to ensure the absence of disease or health problems. [ABSTRACT FROM AUTHOR]

The way workers perceive noise exposure can play an important role in the adoption of safety behaviors. Therefore, the determination of the relationship among risk awareness, behavior, and exposure can be an extremely important issue in controlling noise exposure. The aim of this study was to investigate the association between risk perception and practice of workers. Workers from 16 printing houses in Tehran province participated in present study. A questionnaire was used for determining the level of risk perception and practice about hearing conservation. The results revealed a significant relationship between risk perception and safety behavior adoption (P < 0.001). A positive and significant correlation was found between these two variables (P < 0.001; rs = 0.912). Also, the results showed that workers with hearing impairment had a better practice. In addition, attention should be paid to preventive principles and encouragement of hearing protection devices usage among employees. [ABSTRACT FROM AUTHOR]

Here are several risk factors in dentistry. Repetitive movements and being in a position for long time due to muscle imbalances and work-related musculoskeletal disorders which can cause problems such as limited mobility, fatigue, job loss or even change job. Muscle imbalance between the stabilizers and mobilizers of the neck and shoulders in dentists leads to increased work-related disorders, superficial muscle fatigue, and deep muscle atrophy, which in turn; leads to many health problems, such as neck pain and disability. To prevent such disorders, a high endurance of the cervical stabilizer muscles is essential for repetitive movements in the distal and shoulder region. In this study the exercise program (including postural exercises, simultaneous training of shoulder-neck, scapular movements and co-contraction) were designed for 48 dentists. The statistical analysis showed that there was a significant decrease in the median frequency slope of the middle deltoid muscle (p = 0.004) and for the group who received the proprioception training along with posture correction exercises and exercise therapy (p = 0.004). Neck pain increased in the control group who received no exercises, after six weeks (p = 0.165). Conclusion: six week corrective exercises with ergonomic intervention balance muscles activity and can be used to decrease musculoskeletal disorders and muscle fatigue in person with Non-Specific Chronic Neck Pain. [ABSTRACT FROM AUTHOR]

AbstractAirborne particulates in iron ore mining are a risk factor for adverse human lung effects. In this study, fine particulates deposited on surfaces of about 1.5 m above the ground and 6 meters from a milling unit of the Gol-e-Gohar iron ore mine were collected through wipe sampling. Dust particles less than 5 µm in diameter were separated with an electronic sieve. Aliquots were prepared from the sieved iron ore dust estimated to be equivalent to respiratory exposure in the iron ore mill in the concentrations of 1, 5, 10, 50, 100, and 250 µg/mL, which were intended to represent equivalent inhaled doses from working one month to a working life (25 years) in the mine. The airborne concentration of respirable particles was about five times the threshold limit value given (TLV®) for iron oxide published by the American Conference of Governmental Industrial Hygienists. The in vitro toxicity range was estimated to be equivalent to an accumulated dose associated with working from one month to a working life in the mine. Treatment of the A549 cells resulted in decreased dehydrogenase activity and cell glutathione content and increased reactive oxygen species (ROS) generation, mitochondrial membrane permeability, and cell apoptosis-necrosis rates. The results of this study revealed the possibility of lung damage at cell doses for respirable airborne iron oxide particles estimated to be equivalent to accumulated lifetime exposures among Gol-e-Gohar miners. Further studies are recommended to investigate the effect of actual contaminants in the workplace on the occurrence of health effects on workers. [ABSTRACT FROM AUTHOR]