In vitro genotoxicity data of nanomaterials compared to carcinogenic potency of inorganic substances after inhalational exposure

An integrated approach to occupational health risk assessment of manufacturing nanomaterials using Pythagorean Fuzzy AHP and Fuzzy Inference System

Nanomaterials (NMs) have the potential to be hazardous owing to their unique physico-chemical properties. Therefore, the need for Health Risk Assessment (HRA) of NMs is expanding. In this study, a novel HRA was developed by the Pythagorean Fuzzy Health Risk Assessment (PFHRA) approach. Risk is considered to be the outcome of parameters including Occurrence Likelihood (OL), Potential Exposure (PE) and Toxic Effects (TE). In our proposed method, priority weights of sub-factors in Pythagorean Fuzzy-Analytical Hierarchical Process (PF-AHP) were determined by pairwise comparison based on expert judgment. After determining parameter scores, both RM and risk class (i.e., negligible, minor, major and critical) were reported as Fuzzy Inference System (FIS) output. Ultimately, a risk management strategy is presented for NMs manufacturing workplaces. This proposed method provides experts with more flexibility to express their opinions. The PFHRA approach was applied for two scenarios. The production scenario for SiNPs can create minor (5%) and major (95%) occupational health risks; the production scenario for ZnONPs can create minor (100%) concerns. However, the production SiNPs and ZnONPs utilizing the CB Nanotool technique had a major and minor risk class, respectively. The results of the present study confirmed the reliability and applicability of this approach.

Atmospheric elemental carbon pollution and its regional health disparities in China

Previous studies have reported that atmospheric elemental carbon (EC) may pose potentially elevated toxicity when compared to total ambient fine particulate matter (PM2.5). However, most research on EC has been conducted in the US and Europe, whereas China experiences significantly higher EC pollution levels. Investigating the health impact of EC exposure in China presents considerable challenges due to the absence of a monitoring network to document long-term EC levels. Despite extensive studies on total PM2.5 in China over the past decade and a significant decrease in its concentration, changes in EC levels and the associated mortality burden remain largely unknown. In our study, we employed a combination of satellite remote sensing, available ground observations, machine learning techniques, and atmospheric big data to predict ground EC concentrations across China for the period 2005-2018, achieving a spatial resolution of 10 km. Our findings reveal that the national average annual mean EC concentration has remained relatively stable since 2005, even as total PM2.5 levels have substantially decreased. Furthermore, we calculated the all-cause non-accidental deaths attributed to long-term EC exposure in China using baseline mortality data and pooled mortality risk from a cohort study. This analysis unveiled significant regional disparities in the mortality burden resulting from long-term EC exposure in China. These variations can be attributed to varying levels of effectiveness in EC regulations across different regions. Specifically, our study highlights that these regulations have been effective in mitigating EC-related health risks in first-tier cities. However, in regions characterized by a high concentration of coal-power plants and industrial facilities, additional efforts are necessary to control emissions. This observation underscores the importance of tailoring environmental policies and interventions to address the specific challenges posed by varying emission sources and regional contexts.

The Toxicological Mechanisms of Environmental Soot (Black Carbon) and Carbon Black: Focus on Oxidative Stress and Inflammatory Pathways

The environmental soot and carbon blacks (CBs) cause many diseases in humans, but their underlying mechanisms of toxicity are still poorly understood. Both are formed after the incomplete combustion of hydrocarbons but differ in their constituents and percent carbon contents. For the first time, “Sir Percival Pott” described soot as a carcinogen, which was subsequently confirmed by many others. The existing data suggest three main types of diseases due to soot and CB exposures: cancer, respiratory diseases, and cardiovascular dysfunctions. Experimental models revealed the involvement of oxidative stress, DNA methylation, formation of DNA adducts, and Aryl hydrocarbon receptor activation as the key mechanisms of soot- and CB-induced cancers. Metals including Si, Fe, Mn, Ti, and Co in soot also contribute in the reactive oxygen species (ROS)-mediated DNA damage. Mechanistically, ROS-induced DNA damage is further enhanced by eosinophils and neutrophils via halide (Cl⁻ and Br⁻) dependent DNA adducts formation. The activation of pulmonary dendritic cells, T helper type 2 cells, and mast cells is crucial mediators in the pathology of soot- or CB-induced respiratory disease. Polyunsaturated fatty acids (PUFAs) were also found to modulate T cells functions in respiratory diseases. Particularly, telomerase reverse transcriptase was found to play the critical role in soot- and CB-induced cardiovascular dysfunctions. In this review, we propose integrated mechanisms of soot- and CB-induced toxicity emphasizing the role of inflammatory mediators and oxidative stress. We also suggest use of antioxidants and PUFAs as protective strategies against soot- and CB-induced disorders.

Potential toxicity and safety evaluation of nanomaterials for the respiratory system and lung cancer

Engineered nanomaterials (ENMs) are a diverse group of materials finding increasing use in manufacturing, computing, food, pharmaceuticals, and biomedicine due to their very small size and exceptional properties. Health and safety concerns for ENMs have forced regulatory agencies to consider preventive measures and regulations for workers’ health and safety protection. Respiratory system toxicity from inhalable ENMs is the most important concern to health specialists. In this review, we focus on similarities and differences between conventional microparticles (diameters in mm and μm), which have been previously studied, and nanoparticles (sizes between 1 and 100 nm) in terms of size, composition, and mechanisms of action in biological systems. In past decades, respirable particulate matter (PM), asbestos fibers, crystalline silicate, and various amorphous dusts have been studied, and epidemiological evidence has shown how dangerous they are to human health, especially from exposure in working environments. Scientific evidence has shown that there is a close connection between respirable PM and pulmonary oxidative stress through the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). There is a close connection between oxidative stress in the cell and the elicitation of an inflammatory response via pro-inflammatory gene transcription. Inflammatory processes increase the risk for lung cancer. Studies in vitro and in vivo in the last decade have shown that engineered nanoparticles (ENPs) at various doses can cause ROS generation, oxidative stress, and pro-inflammatory gene expression in the cell. It is assumed that ENPs have the potential to cause acute respiratory diseases and probably lung cancer in humans. The situation regarding chronic exposure at low doses is more complicated. The long-term accumulation of ENPs in the respiratory system cannot be excluded. However, at present, exposure data for the general public regarding ENPs are not available.

Evaluation of in vitro cytoxicity and genotoxicity of size-fractionated air particles sampled during road tunnel construction

In tunnel construction, workers exposed to dust from blasting, gases, diesel exhausts, and oil mist have shown higher risk for pulmonary diseases. A clear mechanism to explain how these pollutants determine diseases is lacking, and alveolar epithelium's capacity to ingest inhaled fine particles is not well characterized. The objective of this study was to assess the genotoxic effect exerted by fine particles collected in seven tunnels using the cytokinesis-block micronuclei test in an in vitro model on type II lung epithelium A549 cells. For each tunnel, five fractions with different aerodynamic diameters of particulate matter were collected with a multistage cascade sampler. The human epithelial cell line A549 was exposed to 0.2 m(3)/mL equivalent of particulate for 24 h before testing. The cytotoxic effects of particulate matter on A549 cells were also evaluated in two different viability tests. In order to evaluate the cells' ability to take up fine particles, imaging with transmission electron microscopy of cells after exposure to particulate matter was performed. Particle endocytosis after 24 h exposure was observed as intracellular aggregates of membrane-bound particles. This morphologic evidence did not correspond to an increase in genotoxicity detected by the micronucleus test.

Preparation and Characterization Challenges to Understanding Environmental and Biological Impacts of Nanoparticles

Increasingly, it is recognized that understanding and predicting nanoparticle behavior is often limited by the degree to which the particles can be reliably produced and adequately characterized. Two examples that demonstrate how sample preparation methods and processing history may significantly impact particle behavior are: 1) an examination of cerium oxide (ceria) particles reported in the literature in relation to the biological responses observed and 2) observations related that influence synthesis and aging of ceria nanoparticles. Examining data from the literature for ceria nanoparticles suggests that thermal history is one factor that has a strong influence on biological impact. Thermal processing may alter many physicochemical properties of the particles, including density, crystal structure, and the presence of surface contamination. However, these properties may not be sufficiently recorded or reported to determine the ultimate source of an observed impact. A second example shows the types of difficulties that can be encountered in efforts to apply a well-studied synthesis route to producing well-defined particles for biological studies. These examples and others further highlight the importance of characterizing particles thoroughly and recording details of particle processing and history that too often are underreported.