Risk assessment of occupational exposure to benzene using numerical simulation in a complex geometry of a reforming unit of petroleum refinery

Numerical simulation application in occupational health studies: a review

Most occupational hazardous agents in workplaces should be evaluated and controlled. Different methods exist for identifying, evaluating and controlling these agents, such as numerical simulation tools. Numerical simulations can help experts to improve occupational health. Due to the importance and abilities of numerical simulations, this study divided occupational hazardous agents into 10 subgroups. These subgroups included air pollution, ventilation, respiratory airways, noise and vibration, lighting, radiation, ergonomics, fire and explosion, risk assessment and personal protective equipment. Recent research studies in each subgroup were then reviewed, and the codes and software used in simulations were determined. The results show that Fluent software and k-ϵ turbulence models are the most used in occupational health studies simulations. Today, different codes and software have been developed for simulation, and we suggest their use in occupational health studies.

Assessment of occupational health and safety risks in a Turkish public hospital using a two-stage hesitant fuzzy linguistic approach

Occupational health and safety (OHS) risk assessment studies have gained importance recently as a result of increasing occupational accidents and occupational diseases. The health sector has a greater risk than many sectors for occupational accidents and occupational diseases. Although the health sector is one of the priority sectors in Turkey, OHS practices have not been fully implemented in this field. For this reason, this study adopts a two-stage approach to assess the OHS risks in the health sector by combining the Fine-Kinney and multi-criteria hesitant fuzzy linguistic term set (HFLTS) methods. The proposed method was applied to the OHS risks in the operating room of a public hospital in Turkey. As a solution to the problem, first, the potential hazards and related risks in the operating room were determined by the experts. In this first stage, 44 hazards were determined from the opinions of experts and records of past incidents. Parameter weights were then determined using the multi-criteria HFLTS method. The multi-criteria HFLTS method was used to evaluate seven hazards to be categorized as substantial-risk or higher according to the Fine-Kinney method, taking into account parameter weights. Sensitivity analysis was then carried out. Finally, actions were taken to mitigate the risks.

Lipidomic analysis reveals disturbances in glycerophospholipid and sphingolipid metabolic pathways in benzene-exposed mice

Benzene, a known occupational and environmental contaminant, has been recognized as the hematotoxin and human carcinogen. Lipids have a variety of important physiological functions and the abnormal lipid metabolism has been reported to be closely related to the occurrence and development of many diseases. In the present study, we aim to utilize LC-MS/MS lipidomic platform to identify novel biomarkers and provide scientific clues for mechanism study of benzene hematotoxicity. Results showed that a total of 294 differential metabolites were obtained from the comparison of benzene-treated group and control group. The glycerophospholipid pathway was altered involving the down-regulation of the levels of phosphatidylcholine and phosphatidylserine. In addition, phosphatidylethanolamine (PE) and 1-Acyl-sn-glycero-3-phosphocholine levels were increased in benzene-treated group. Based on the relationship between PE and autophagy, we then found that effective biomarker of autophagy, Beclin1 and LC3B, were increased remarkably. Furthermore, following benzene treatment, significant decreases in glucosylceramide (GlcCer) and phytosphingosine (PHS) levels in sphingolipid pathway were observed. Simultaneously, the levels of proliferation marker (PCNA and Ki67) and apoptosis regulator (Bax and Caspase-3) showed clear increases in benzene-exposed group. Based on our results, we speculate that disturbances in glycerophospholipid pathway play an important role in the process of benzene-induced hematopoietic toxicity by affecting autophagy, while sphingolipid pathway may also serve as a vital role in benzene-caused toxicity by regulating proliferation and apoptosis. Our study provides basic study information for the future biomarker and mechanism research underlying the development of benzene-induced blood toxicity.

CFD simulation for dispersion of benzene at a petroleum refinery in diverse atmospheric conditions

Atmospheric parameters play a vital role in the dispersion of air pollutants. Benzene is a confirmed human carcinogen. It is also a neurotoxin and an irritant compound. The objective of this study was to examine the CFD simulation by Fluent16 software to simulate and analyze the effect of atmospheric conditions on the dispersion of benzene in eight different scenarios in a petroleum refinery. According to the results of this study, the highest and lowest impacts of atmospheric parameters occurred on spring days and autumn nights, respectively. Wind direction did not have a significant effect on the benzene distribution due to the artificial ceiling of piping installations in the computational domain. However, the wind speed had a critical role in the benzene dispersion. The maximum concentration occurred at 36- to 37-m distance from the inlet boundary for all scenarios except winter nights. On winter nights, this distance increased to 38 m. Benzene concentrations were the highest at their sources of release. They decreased after the artificial ceiling of the pipelines was at 5.5- to 7-m height where the air displacement was not sufficient, and therefore, leading to a gradual reduction in concentration. The accumulation of benzene concentration in the small domain was noticeable compared to the benzene concentration distributed in the total computational domain, and the authors recommended control measures in this domain. This study demonstrated CFD simulation methodology could enable the investigators to predict the benzene concentration dispersion in the atmosphere of a petroleum refinery plant. These findings can be used by occupational health engineers for health risk assessment of refinery personnel involved with maintenance operations and engineering control systems.

Simulation of lead fume emissions in the workplace using computational fluid dynamics in the electronics industry

Computational fluid dynamics (CFD) is a powerful method for predicting the release of pollutants in the workplace and has recently been used as a valuable tool by health authorities. The purpose of this study was to predict the distribution of lead fume in the workplace using computational fluid dynamics in the electronics manufacturing industry. A cross-sectional descriptive and analytical study was conducted in the Neyshabur electronics industry (2019). Individual exposure to lead fume was measured by the OSHA121 method. Simulation and prediction of lead fume emission in the workplace were done using computational fluid dynamics and by the ANSYS16 software. The mean of personal exposure to lead fumes was 0.04 ± 0.01 mg/m3. The software predicted the distribution of lead fumes in the respiratory zone of the worker to be in the range of 0.04 to 0.07 mg/m3, which is very close to the real values. By doubling the suction power of the topical ventilation used, workers' exposure to lead fumes was nearly halved and reached well below the recommended limit. The results showed that CFD is a useful tool for simulating individual contact with pollutants in a geometry. Also, given that the CFD shows the diffusion and distribution of pollutants in all points of a geometry, it is useful to indicate critical locations and conditions.

Public health risk management case concerning the city of Isfahan according to a hypothetical release of HF from a chemical plant

Accidents have happened in the chemical industries all over the world with serious consequences for the adjacent heavily populated areas. In this study, the impact of the probable hypothetical event, releasing considerable amounts of hydrogen fluoride (HF) as a strong irritant into the atmosphere over the city of Isfahan from a strategic chemical plant, was simulated by computational fluid dynamics (CFD). In this model, the meteorological parameters were integrated into time and space, and dispersion of the pollutants was estimated based on a probable accidental release of HF. According to the hypothetical results of the simulation model in this study, HF clouds reached Isfahan in 20 min and exposed 80% of the general public to HF concentration in the range of 0-34 ppm. Then, they dissipated 240 min after the time of the incident. Supposing the uniform population density within the proximity of the city of Isfahan with the population of 1.75 million, 5% of the population (87,500 people) could be exposed for a few minutes to a HF concentration as high as 34 ppm. This concentration is higher than a very hazardous concentration described as the Immediate Danger to Life and Health (30 ppm). This hypothetical risk evaluation of environmental exposure to HF with the potential of health risks was very instrumental for the general public of Isfahan in terms of risk management. Similar studies based on probable accidental scenarios along with the application of a simulation model for computation of dispersed pollutants are recommended for risk evaluation and management of cities in the developing countries with a fast pace of urbanization around the industrial sites.