Journal of chemical health & safety最新文献

We report a reinvestigation of lithium chloride (LiCl) as a catalyst for the ring-opening polymerization (ROP) of l-lactide, using octa(ethylene glycol) dimethyl ether (EG8) as a coordinating agent. Although conducted under inert atmosphere, the presence of trace water does not impair polymerization efficiency, eliminating the need for high-vacuum techniques or aggressive drying protocols. Water initiates the reaction via in situ formation of HO-Li⁺ species, which generate lithium lactate, the actual active species in the system. The Li⁺ coordination environment, modulated by EG8, governs both reactivity and stereocontrol, with prolonged reaction leading to partial epimerization of l-lactide into meso-lactide. The process proceeds with excellent control, as evidenced by narrow dispersities and linear M_n evolution, until interchain condensation occurs. Beyond this, the system enables polymerization from nonrecrystallized l-lactide and activates alcohol-based co-initiators such as 1-pyrenemethanol with quantitative end-group incorporation. This work provides mechanistic insight into LiCl-catalyzed ROP and highlights a safer, function-oriented approach to PLA synthesis under sustainable conditions.

To explore the propagation laws of the domino effect in tank areas, this paper constructs a domino effect analysis model based on the unit accident chain and multifactor synergistic effect. The model not only evaluates the contribution of the unit accident chain to domino effect development but also analyzes the enhanced destructive effect when multiple factors interact. From the perspective of energy accumulation, the heat dose criterion is used to dynamically update the conditional probability tables in the dynamic Bayesian network (DBN), thus more realistically simulating the evolution of the domino effect. It overcomes the limitation of the traditional DBN that can only analyze the domino effect at specific time points and can identify critical vulnerabilities more accurately, providing timely decision support for reducing the impact of accidents. The effectiveness of this method is verified through case studies, confirming its reliability and practicality in analyzing the propagation patterns of the domino effect.

Physical, health, and environmental hazards of chemical substances are classified into hazard classes in the Globally Harmonized System of Classification and Labeling of Chemicals (GHS). Within each hazard class in the GHS classification, the degree of chemical hazard is mostly expressed as a category. The chemical hazard information is in high demand for risk assessment and accident prevention; however, the hazards of most chemical substances are undetermined yet. Investigations on chemical hazards involve a time-consuming step such as in vitro and in vivo studies, whereas more and more novel chemical substances are synthesized on a daily basis. It is essential to accelerate investigations into the identification of chemical hazards. Herein, we use deep learning models to predict the hazard classes and categories of chemical substances in the GHS classification. The chemical structure is expressed as the Simplified Molecular Input Line Entry System (SMILES) notation. A hazard class prediction model is trained on a data set of chemical structures in SMILES that are labeled as to whether they are classified into the hazard class or not. Similarly, a hazard category prediction model is trained on a data set of SMILES labeled with a hazard category within the hazard class. The average accuracy values of hazard class and category prediction models are 89.2 and 70.4%, respectively. Test-time augmentation is employed to gain the ability of robust prediction regardless of the input chemical structure in SMILES. The atoms of a molecule that contribute to the correct prediction are determined by calculating their attribution scores, which provide insight into our prediction models. Our chemical hazard prediction models can be used as a tool for risk assessment and prioritization of physicochemical studies on novel chemical substances.

Natural, technologically enhanced, and industrial radionuclides contribute to occupational ionizing radiation exposure in the oil and gas industry, posing potential risks to workers and the environment. This study evaluates occupational dose levels in Saudi Arabia’s oil and gas sector from 2016 to 2022 using thermoluminescent dosimeters (TLDs). The results show that the annual effective dose (ED) remained below the 20 mSv/year occupational limit set by UNSCEAR, ICRP, and the IAEA, indicating minimal health risk. For the oil industry, the mean ED was 0.57 ± 0.35 mSv (range: 0.05–4.61 mSv), and for the gas industry, it was 0.57 ± 0.26 mSv (range: 0.11–1.62 mSv). The 95% confidence intervals, 0.57 ± 0.011 mSv for oil and 0.57 ± 0.018 mSv for gas, confirm the robustness of these estimates. Notably, this study highlights that TLD-based measurements yield more reliable, job-specific exposure estimates than commonly used computational models. The findings support ongoing regulatory compliance, promote adherence to ALARA principles, and provide a regional benchmark for radiation safety in the oil and gas sector.

Ceramic high efficiency particulate air (HEPA) filter development program began at Lawrence Livermore National Laboratory (LLNL) over 20 years ago. Historical incidents motivated current safety systems at nuclear facilities. A ceramic filter that can survive a fire can provide robust, passive safety protection. Research has been conducted to improve the safety of nuclear facilities and to reduce operational and lifecycle costs, through ceramic filter technology that can survive fire conditions. The research focused on applications in both new facilities as well as meeting operational requirements necessary to retrofit filters into existing DOE facilities. The research has developed multiple filter technologies spanning traditional HEPA filter materials to advanced manufacturing technologies (e.g., electrospinning, additive manufacturing, etc.). This communication will present highlights of selected development efforts for ceramic HEPA filter research, current state-of-the-art for ceramic filters, and future needs including technical, regulatory, and commercial efforts.

The growing demand for energy storage and the rising frequency of lithium ion battery failure events worldwide underscore the urgency of addressing the battery safety challenges. Ensuring the safe and reliable deployment of advanced battery technologies is paramount. Flow batteries present a promising solution for long-duration energy storage, yet their electrolytes pose potential hazards to human health and the environment. The largest scale vanadium–vanadium flow batteries have been reported in China, with a 100 MW/400 MWh system reportedly commissioned in 2022 and a 175 MW/700 MWh battery completed in December 2024. This is equivalent to 150–200 million liters of vanadium electrolyte. This study aims to assess the chemical hazards of the electrolytes in vanadium–vanadium flow battery during failure mode. There is little or no chemical hazard data for the electrolyte mixtures, and the hazard assessment was thus based on chemical reactivity and toxicity data for the individual electrolyte components. Potential failure modes are identified with overcharging (or high cell voltages) in particular presenting potential hazards due to the possible production of toxic gases. Depending on the electrolyte composition, these conditions could result in the evolution of Cl₂, SO₂, H₂S, or PH₃ gases, with immediate associated risks for human health. The two main all-vanadium flow battery chemistries use either sulfuric acid or sulfuric acid/HCl mixtures as the supporting electrolyte, with low concentrations of phosphoric acid often included in the sulfuric acid systems. The sulfuric acid–based cells generate oxygen and hydrogen at the positive and negative half-cell electrodes, respectively, during overcharge. On the other hand, the mixed H₂SO₄/HCl-based chemistries produce chlorine at the positive electrode during overcharge and potentially under normal charging conditions at high states-of-charge if the flow-rate is insufficient. Vanadium electrolytes containing chloride ions therefore present the most significant toxicity hazards in failure mode. The inherently safe design of battery management and control systems, along with electrolyte containment, is an essential measure to ensure safe flow battery operation. The next step involves designing controlled experiments to study overcharging effects on the electrolyte stability and degradation.

Workers who perform arc welding are exposed to fumes generated by the joining of metals. One generated fume is manganese, a metal with heightened toxicological properties. This paper explores welders’ manganese exposures during the four most performed arc welding types: Shielded Metal Arc Welding (SMAW), Gas Tungsten Arc Welding (GTAW), Gas Metal Arc Welding (GMAW), and Flux Cored Arc Welding (FCAW). Exposure data were collected in varying field environmental conditions at Lawrence Livermore National Laboratory (LLNL) in Livermore, California. Conditions ranged from indoor shop areas controlled with local exhaust ventilation (LEV) to outdoor construction areas with variable wind directions and speeds. Exposure samples were taken for both inhalable and respirable fractions of manganese. This sampling effort was conducted in response to the updated 2016 Manganese Threshold Limit Values (TLVs) that were adopted into LLNL’s contract in 2019 to ensure compliance with the new, lower exposure standard. The resulting data collected from the field informed risk level determinations that were calculated using Bayesian Decision Analysis (BDA) to determine potential exceedances to the manganese TLVs. The resulting BDA outcomes indicate potential for manganese overexposure during SMAW, GMAW, and FCAW arc welding processes. LLNL leverages these BDA outcomes to make health and safety risk-based assessment decisions for a wide range of construction, research and development, engineering, and maintenance activities conducted by many of its 9,000+ employee workforce.

Diazonium compounds are synthetically useful in the production of dyes and textiles, however they are highly explosive under dry conditions. Explosion prevention becomes more difficult when new diazonium compounds are synthesized, because while some syntheses include a counterion to increase their stability, this is not always a reliable method to prevent an explosive incident. Due to the uncertainty surrounding the explosiveness of different diazonium compounds, it is important to understand how to safely clean up after an incident and how to determine when it is safe to return a laboratory to typical operational use, particularly when the incident involves a novel compound where a standard does not exist for instrument calibration. Here, an explosive event is discussed involving the synthesis of 4-bromo-benzenediazonium-2-carboxylate. Following the explosive incident and 3-step cleanup, which involved a precautionary neutralization step, samples were collected from the fume hood where the incident occurred. Because the incident involved an unstable, novel compound that is not commercially available and was deemed unsafe to resynthesize for instrument calibration, we assessed the risk of further explosion by analyzing for the stable decomposition products. Mass spectrometry analysis confirmed that the residue in the fume hood contained 5-bromosalicylic acid, a decomposition product of 4-bromo-benzenediazonium-2-carboxylate. Samples were taken from multiple points in the fume hood and analyzed to estimate the spatial distribution of the decomposition product. Based on this analysis, we inferred that the primary decomposition product was far more abundant than residual energetic, indicating the energetic had been consumed or neutralized to a trace quantity where the risk of further explosion was low. The steps presented here─specifically, initial neutralization and then analyzing the spatial distribution of expected decomposition products to assess risk when a novel explosive material is detonated in a confined space─were our approach to assess further risk following an explosion due to a novel diazonium compound without the need for any further handling or resynthesis of the energetic. Here, we present our approach and critically analyze these steps by discussing retrospective lessons learned and alternative analytical approaches.

This study systematically assessed chemical and physical hazards in 28 educational laboratories at the Qazvin University of Medical Sciences using the assessment and classification of hazards in laboratories (ACHiL) framework. The assessment involved walkthrough inspections, interviews, and checklist-based evaluations aligned with the guidelines of the Occupational Safety and Health Administration (OSHA), Globally Harmonized System (GHS) for Classification and Labeling of Chemicals, and National Fire Protection Association (NFPA). Among the 540 chemicals analyzed, 57% were classified as high risk, including substances such as methanol, phenol, nitric acid, and sulfuric acid. The Toxicology, Environmental Health, and Microbiology laboratories showed the highest concentrations of hazardous chemicals. Physical hazards, including electrical risks, ultraviolet radiation, and hot surfaces, were also identified and classified based on WHO and NFPA protocols. The results underscore the urgent need for enhanced chemical safety training, consistent use of personal protective equipment (PPE), improved ventilation systems, and regular inventory updates. This methodology offers a replicable model for laboratory risk assessment and contributes to the advancement of occupational health and safety in academic environments.

Organic peroxides are widely used substances and are hazardous materials. Pressure vessel testing (PVT) is an important method for evaluating rapid thermal decomposition and the hazards of organic peroxides. However, it is difficult to evaluate volatile organic peroxides using PVT. In this paper, the hazardous material characteristic is that temperature and pressure undergo rapid changes during thermal decomposition. The pressure and temperature behaviors of the peroxide thermal decomposition process are investigated using a mini closed pressure vessel test (MCPVT), and the relationship between MCPVT and PVT is explored. The results showed a good linear relationship between the parameter (dP/dt)_Max × (dT/dt)_Max ((dP/dt)_max is the maximum pressure rise rate and (dT/dt)_max is the maximum temperature rise rate) of MCPVT and orifice diameter (D) of PVT. The linear equation is y = 6.576 × 10⁴ × −3.994 × 10⁴ (where y = (dP/dt)_Max × (dT/dt)_Max, x = D). According to the linear equation, the grade classification of rapid thermal decomposition and hazards of organic peroxides is divided into four levels: “none”, “low”, “medium”, and “violent”. In addition, the volatility and thermal decomposition exothermic properties of organic peroxides were studied by thermogravimetric differential thermal analysis (TG-DTA), and it has been found that the peroxides di-t-butyl peroxide (DTBP), cumene hydroperoxide (CHP), dicumyl peroxide (DCP), and t-butyl peroxy acetate (TBPA) are volatile. It is important for fuel additives to have appropriate volatility.