Extracts Of Particulate Matter Research Articles

Monitoring redox stress in human airway epithelial cells exposed to woodsmoke at an air–liquid interface

Wildland fires contribute significantly to the ambient air pollution burden worldwide, causing a range of adverse health effects in exposed populations. The toxicity of woodsmoke, a complex mixture of gases, volatile organic compounds, and particulate matter, is commonly studied in vitro using isolated exposures of conventionally cultured lung cells to either resuspended particulate matter or organic solvent extracts of smoke, leading to incomplete toxicity evaluations. This study aimed to improve our understanding of the effects of woodsmoke inhalation by building an advanced in vitro exposure system that emulates human exposure of the airway epithelium. We report the development and characterization of an innovative system that permits live-cell monitoring of the intracellular redox status of differentiated primary human bronchial epithelial cells cultured at an air–liquid interface (pHBEC-ALI) as they are exposed to unfractionated woodsmoke generated in a tube furnace in real time. pHBEC-ALI exposed to freshly generated woodsmoke showed oxidative changes that were dose-dependent and reversible, and not attributable to carbon monoxide exposure. These findings show the utility of this novel system for studying the molecular initiating events underlying woodsmoke-induced toxicity in a physiologically relevant in vitro model, and its potential to provide biological plausibility for risk assessment and public health measures.

Chemical characterization and speciation of the soluble fraction of Arctic PM10

The chemical composition of the soluble fraction of atmospheric particulate matter (PM) and how these components can combine with each other to form different species affect the chemistry of the aqueous phase dispersed in the atmosphere: raindrops, clouds, fog, and ice particles. The study was focused on the analysis of the soluble fraction of Arctic PM10 samples collected at Ny-Ålesund (Svalbard Islands, Norwegian Arctic) during the year 2012. The concentration values of Na+, K+, NH4+, Ca2+, Mg2+, Mn2+, Cu2+, Zn2+, Fe3+, Al3+, Cl−, NO2−, NO3−, SO42−, PO43−, formate, acetate, malonate, and oxalate in the water-soluble fraction of PM10 were determined by atomic spectroscopy and ion chromatography. Speciation models were applied to define the major species that would occur in aqueous solution as a function of pH (2–10). The model highlights that (i) the main cations such as Na+, K+, Mg2+, and Ca2+ occur in the form of aquoions in the whole investigated pH range; (ii) Cu2+, Zn2+, and, in particular, Fe3+ and Al3+ are mostly present in their hydrolytic forms; and (iii) Al3+, Fe3+, and Cu2+ form solid hydrolytic species that precipitate at pH values slightly higher than neutrality. These latter metals show interesting interactions with oxalate and sulfate ions, too. The speciation models were also calculated considering the seasonal variability of the concentration of the components and at higher concentration levels than those found in water PM extracts, to better simulate concentrations actually found in the atmospheric aqueous phase. The results highlight the role of oxalate as the main organic ligand in solution.Graphical

In vitro toxicity of fine and coarse particulate matter on the skin, ocular and lung microphysiological cell-culture systems

Particulate matter (PM) has been associated with adverse effects on human health, causing allergies, skin and eye irritation and corrosion, respiratory tract irritation, headaches, bronchoconstriction, cardiopulmonary diseases such as asthma, chronic obstructive pulmonary disease (COPD), lung cancer, reproductive problems, premature deaths, and epigenetic changes that lead to a wide variety of cancers, among other health conditions. The air quality in the Medellín - Colombia presents fluctuations that oscillate between the maximum permissible levels established at the national level and by the WHO, which represents a latent risk to people's health. Although important efforts have been made to quantify the different levels of pollution and administrative measures have been established to mitigate air pollution, little research work has been done to establish the relationship between these levels of pollutants and the effects on biological systems. The objective of the present research was to make a morphological and chemical characterization of particulate matter (PM) captured with a commercial air filter and a electrospun nanofiber membrane and evaluate the cytotoxicity of the each PM extracts in monolayer and co-culture models which recreate microphysiological systems of lung, skin and cornea and propose the possible cellular interactions that lead the cytotoxic response of the chemical compounds found in particulate matter in cities. The morphology and elemental chemical characterization were done with scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM – EDS). For the polycyclic aromatic hydrocarbons detection was made with a chromatographic method accoupled to mass spectrometer. Finally, the cytotoxicity was made in monolayers of A549, HEK001, and SIRC cell lines and microphysiological systems consisting of two-cell layer construct to resemble the interaction between fibroblast and epithelial cells that comprises naturally the corneal, skin and lung tissue. We performed three different cocultures models with BALB/3T3 clone A31 as a feeder layer, using porous Transwell® inserts in the in-contact and non-contact way. Monolayer and co-culture models were exposed to coarse and fine PM (1, 2, and 5 mg/mL) and the cell viability was evaluated at 24 h using an MTT assay. The electrospun nanofibers membranes demonstrates higher efficiency to capture PM with different sizes and high concentration of polycyclic aromatic hydrocarbons, heavy metals, and other chemical compounds responsible of many human diseases. Cytotoxic effects of MP were observed in all models at higher concentration; however, models exposed to fine PM exhibited a significant reduction in cell viability compared to those exposed to coarse PM. In addition, multilayer models are more resistant to PM exposure than monolayer models. Furthermore, the study indicated that, depending on the seeding strategy, different results might be observed: the non-contact model showed higher resistance to PM exposure than in-contact for SIRC and HEK001, but A549 monolayers showed the highest viability response. This study demonstrates the usefulness of applying co-culture models to assess environmental pollutant toxicity, in addition to being a potential alternative method to animal testing for risk assessment.

Best Practices to Quantify and Identify Particulate Matter on the Interior Surfaces of Single-Use Systems.

The manufacturing of a wide range of biopharmaceuticals, from antibodies and vaccines to cell-based therapies, increasingly takes place in single-use processing equipment. Manufactured in clean rooms and sealed and sterilized, single-use systems (SUSs) are ready-to-use and easily scalable. Controls in the "clean-build" manufacturing of SUSs reduce the probability of occurrence of particulate matter in SUSs. However, the size, complexity, and limited transparency of SUSs clearly limit the detectability of particulate matter on the interior (fluid-contacting) surfaces of a SUS during a visual inspection, as demonstrated in a recent study. In applications downstream of final filters or in aseptic processing, particulate matter on the surfaces of a SUS could detach and contaminate the final drug product. A realistic assessment of this risk requires reliable test methods that quantify and identify particulate matter present on the interior surfaces of SUSs. Clearly problematic is the common certification of the cleanliness of a SUS via a force-fit adaptation of the pharmacopeial standard USP <788> entitled "Particulate Matter in Injections". USP <788> does not describe a procedure for extraction of particulate matter from the interior surfaces of SUSs. In addition, application of Method 1 Light Obscuration significantly limits the probability of detection for particles in the visible size range (≥ 100 µm). In this article, we describe best practices for extracting, counting, sizing, and chemically identifying particulate matter on the interior surfaces of SUSs. Highly effective procedures for the extraction of particulate matter result from application of the qualification methodology described in a recently published ASTM standard. Filtration of the liquid extract concentrates particulate matter onto the surface of a membrane filter, allowing rapid particle counting and sizing using automated membrane microscopy, along with detailed chemical identification using infrared microscopy and/or automated confocal Raman microscopy.

In vitro toxicity assessment of atmospheric particulate matter on human lung and hepatic cells with agar membrane-based sampling and exposure strategy

ABSTRACT In vitro toxicology research into the health effects of atmospheric particulate matter (PM) depends on the extraction of PM from filters. Previously, we proposed an efficient PM sampling and extraction method based on low-cost agar membrane and performed an exposure study with RAW264.7 macrophages. Here, we extended the application of this strategy, employing lung and hepatic cells, to validate its reliability and reproducibility. One traditional strategy using polytetrafluoroethylene (PTFE) filter was adopted for comparison. Cytotoxicity and proteomics results showed that the PM extracted by two methods induced comparable toxicity to A549 and BEAS-2B cells, while the PM extracted from the agar membranes induced higher toxicity to HepG2 and HL7702 cells than that from the PTFE filters. The differences in the investigations might be associated with the cell's sensitivity to the extracted suspended particles. This work indicated the importance of assessing PM cytotoxicity from the perspective of extraction methods and cell lines.

Size-resolved light-absorbing organic carbon and organic molecular markers in Nanjing, east China: Seasonal variations and sources

Owing to the potential influence of light-absorbing organic carbon (OC), also termed “brown carbon” (BrC), on the planetary radiation budget, many studies have focused on its absorption in single-sized ranges of particulate matter (PM). However, the size distribution and organic tracer-based source apportionment of BrC absorption have not been extensively investigated. In this study, size-resolved PM samples were collected using multi-stage impactors from eastern Nanjing during each season in 2017. The light absorption of methanol-extractable OC at 365 nm (Abs365, Mm−1) was determined using spectrophotometry, and a series of organic molecular markers (OMMs) was measured using a gas chromatography-mass spectrometer. Fine PM with an aerodynamic diameter <2.1 μm (PM2.1) dominated Abs365 (79.8 ± 10.4%) of the total size ranges with maxima and minima in winter and summer, respectively. The distributions of Abs365 shifted to larger PM sizes from winter to spring and summer due to lower primary emissions and increased BrC chromophores in dust. Except for low-volatility (po,*L < 10−10 atm) polycyclic aromatic hydrocarbons (PAHs), the non-polar OMMs, including n-alkanes, PAHs, oxygenated PAHs, and steranes, showed a bimodal distribution pattern. Secondary products of biogenic precursors and biomass burning tracers presented a unimodal distribution peaking at 0.4–0.7 μm, while sugar alcohols and saccharides were enriched in coarse PM. Their seasonal variations in average concentrations reflected intense photochemical reactions in summer, more biomass burning emissions in winter, and stronger microbial activity in spring and summer. Positive matrix factorization was used for the source apportionment of Abs365 in fine and coarse PM samples. Biomass burning contributed an average of 53.9% to the Abs365 of PM2.1 extracts. The Abs365 of coarse PM extracts was associated with various dust-related sources where the aging processes of aerosol organics could occur.

Biological effects of particulate matter samples during the COVID-19 pandemic: a comparison with the pre-lockdown period in Northwest Italy

In 2020, during the COVID-19 pandemic, containment measures were applied inducing potential changes in air pollutant concentrations and thus in air toxicity. This study evaluates the role of restrictions on biological effects of particulate matter (PM) in different Northwest Italy sites: urban background, urban traffic, rural, and incinerator. Daily PM samples collected in 2020 were pooled according to restrictions: January/February (no restrictions), March and April (first lockdown), May/June and July/August/September (low restrictions), October/November/December (second lockdown). The 2019 samples (pre-pandemic period) were pooled as 2020 for comparison. Pools were extracted with organic solvents and extracts were tested to assess cytotoxicity (WST-1 assay) and genotoxicity (comet assay) on BEAS-2B cells, mutagenicity (Ames test) on TA98 and TA100 Salmonella typhimurium strains, and estrogenic activity (gene reporter assay) on MELN cells. Pollutant concentrations were also analyzed (PM10, PM2.5, polycyclic aromatic hydrocarbons). No difference was observed for PM and polycyclic aromatic hydrocarbon concentrations between 2020 and 2019. During lockdown months (2020), PM cytotoxicity/genotoxicity was significantly lower in some sites than during 2019, while considering PM mutagenicity/estrogenic activity some differences were detected but without statistical significance. PM extract effects decreased in some sites during 2020; this may be due to lockdowns that reduced/modified pollutant emissions and may be related also to complex PM origin/formation and to meteorological conditions. In conclusion, the study confirms that PM biological effects cannot be assessed considering only the PM concentration and suggests to include a battery of bioassay for air quality monitoring in order to protect human health from air pollution effects.Graphical

Characterization of elements, PAHs, AhR-activity and pro-inflammatory responses of road tunnel-derived particulate matter in human hepatocyte-like and bronchial epithelial cells

The aims were to characterize the content of elements and polycyclic aromatic hydrocarbons (PAHs) in size-separated particulate matter (PM) sampled in a road tunnel, estimate the contribution of PAHs to the toxic potential, and measure the pro-inflammatory potential of PM samples and extracts with increasing polarity. Several elements/metals previously associated with cytokine responses were found. Based on PAHs levels and published PAHs potency, the calculated mutagenic and carcinogenic activities of size-separated samples were somewhat lower for coarse than fine and ultrafine PM. The AhR-activity of the corresponding PM extracts measured in an AhR-luciferase reporter model (human hepatocytes) were more similar. The highest AhR-activity was found in the neutral (parent and alkylated PAHs) and polar (oxy-PAHs) fractions, while the semi-polar fractions (mono-nitrated-PAHs) had only weak activity. The neutral and polar aromatic fractions from coarse and fine PM were also found to induce higher pro-inflammatory responses and CYP1A1 expression in human bronchial epithelial cells (HBEC3-KT) than the semi-polar fractions. Fine PM induced higher pro-inflammatory responses than coarse PM. AhR-inhibition reduced cytokine responses induced by parent PM and extracts of both size fractions. Contributors to the toxic potentials include PAHs and oxy-PAHs, but substantial contributions from other organic compounds and/or metals are likely.

Chemical and Light-Absorption Properties of Water-Soluble Organic Aerosols in Northern California and Photooxidant Production by Brown Carbon Components.

Atmospheric brown carbon (BrC) can impact the radiative balance of the earth and form photooxidants. However, the light absorption and photochemical properties of BrC from different sources remain poorly understood. To address this gap, dilute water extracts of particulate matter (PM) samples collected at Davis, CA over one year were analyzed using high resolution aerosol mass spectrometry (HR-AMS) and UV-vis spectroscopy. Positive matrix factorization (PMF) on combined AMS and UV-vis data resolved five water-soluble organic aerosol (WSOA) factors with distinct mass spectra and UV-vis spectra: a fresh and an aged water-soluble biomass burning OA (WSBBOAfresh and WSBBOAaged) and three oxygenated OA (WSOOAs). WSBBOAfresh is the most light-absorbing, with a mass absorption coefficient (MAC365nm) of 1.1 m2 g-1, while the WSOOAs are the least (MAC365nm = 0.01-0.1 m2 g-1). These results, together with the high abundance of WSBBOAs (∼52% of the WSOA mass), indicate that biomass burning activities such as residential wood burning and wildfires are an important source of BrC in northern California. The concentrations of aqueous-phase photooxidants, i.e., hydroxyl radical (·OH), singlet molecular oxygen (1O2*), and oxidizing triplet excited states of organic carbon (3C*), were also measured in the PM extracts during illumination. Oxidant production potentials (PPOX) of the five WSOA factors were explored. The photoexcitation of BrC chromophores from BB emissions and in OOAs is a significant source of 1O2* and 3C*. By applying our PPOX values to archived AMS data at dozens of sites, we found that oxygenated organic species play an important role in photooxidant formation in atmospheric waters.

Evaluation of Probes to Measure Oxidizing Organic Triplet Excited States in Aerosol Liquid Water.

Oxidizing triplet excited states of organic matter (3C*) drive numerous reactions in fog/cloud drops and aerosol liquid water (ALW). Quantifying oxidizing triplet concentrations in ALW is difficult because 3C* probe loss can be inhibited by the high levels of dissolved organic matter (DOM) and copper in particle water, leading to an underestimate of triplet concentrations. In addition, illuminated ALW contains high concentrations of singlet molecular oxygen (1O2*), which can interfere with 3C* probes. Our overarching goal is to find a triplet probe that has low inhibition by DOM and Cu(II) and low sensitivity to 1O2*. To this end, we tested 12 potential probes from a variety of compound classes. Some probes are strongly inhibited by DOM, while others react rapidly with 1O2*. One of the probe candidates, (phenylthiol)acetic acid (PTA), seems well suited for ALW conditions, with mild inhibition and fast rate constants with triplets, but it also has weaknesses, including a pH-dependent reactivity. We evaluated the performance of both PTA and syringol (SYR) as triplet probes in aqueous extracts of particulate matter. While PTA is less sensitive to inhibition than SYR, it results in lower triplet concentrations, possibly because it is less reactive with weakly oxidizing triplets.

Effects of particle-bound polycyclic aromatic hydrocarbons and plasticisers from different traffic sources on the human alveolar epithelial cell line A549

Road traffic represents a major source of particulate matter (PM), which is considered the most harmful pollutant for humans. This work aimed to evaluate the toxic effects of polycyclic aromatic hydrocarbons (PAHs) and plasticisers extracted from PM emitted by traffic, including exhaust samples, samples collected in a road tunnel and simultaneously in a nearby urban background atmosphere, and samples from the wear of distinct types of brakes. Different biological endpoints were investigated after exposing human alveolar epithelium A549 cells to the organic extracts: viability, cell cycle alterations and levels of intracellular reactive oxygen species (ROS). The particulate extracts from the wear of low steel brake pads induced greater decreases in cell viability. It was observed that cytotoxicity is more dependent on the individual composition of PAHs than on the global concentration. Exhaust samples from heavy-duty Euro V vehicles induced more toxic effects than Euro VI. Among Euro V vehicles, the exhaust of GTL was the most toxic. The composite weekly sample of the urban background atmosphere showed to be extremely toxic, decreasing cell viability to 2.66%, while the daily road tunnel samples caused a decrease of up to 83.6% at most. In the particulate extracts of the urban background atmosphere, retene and naphthalene were found, which were absent or present at trace levels in the tunnel. Irrespective of the sample, although some changes were observed in the A549 cell cycle after 24 h exposure in all the phases, the differences in the mean values were not great enough to exclude the possibility of random variability. When the results from the three phases (G0/G1, S and G2/M) of the cells exposed to all PM extracts were compared to the control, no statistically significant difference was detected. Regardless of the sample type, no significant increases in cellular ROS levels were observed either.

Tobacco heating system has less impact on bone metabolism than cigarette smoke.

Cigarette smoking promotes osteoclast activity, thus increasing the risk of secondary osteoporosis, leading to osteoporosis-associated fracture and impaired fracture healing. Heated tobacco products (HTP) are considered potential reduced-risk alternatives to cigarettes. However, their impact on bone metabolism remains to be elucidated. We developed an in vitro model that mimics in vivo bone cell interactions to comparatively evaluate the effects of HTPs and cigarette smoke on bone cell functionality and viability. We generated an in vitro coculture system with SCP-1 and THP-1 cells (1:8 ratio) cultured on a decellularized Saos-2 matrix with an optimized coculture medium. We found that, following acute or chronic exposure, particulate matter extract from the aerosol of an HTP, the Tobacco Heating System (THS), was less harmful to the bone coculture system than reference cigarette (1R6F) smoke extract. In the fracture healing model, cultures exposed to the THS extract maintained similar osteoclast activity and calcium deposits as control cultures. Conversely, smoke extract exposure promoted osteoclast activity, resulting in an osteoporotic environment, whose formation could be prevented by bisphosphonate coadministration. Thus, THS is potentially less harmful than cigarette smoke to bone cell differentiation and bone mineralization - both being crucial aspects during the reparative phase of fracture healing.

Quantitative chemical assay of nanogram-level particulate matter using aerosol mass spectrometry: characterization of particles collected from uncrewed atmospheric measurement platforms

Abstract. Aerosol generation techniques have expanded the utility of aerosol mass spectrometry (AMS) for offline chemical analysis of airborne particles and droplets. However, standard aerosolization techniques require relatively large liquid volumes (e.g., several milliliters) and high sample masses that limit their utility. Here we report the development and characterization of a micronebulization AMS (MN-AMS) technique that requires as low as 10 µL of sample and can provide the quantification of the nanogram level of organic and inorganic substances via the usage of an isotopically labeled internal standard (34SO42-). Using standard solutions, the detection limits for this technique were determined at 0.19, 0.75, and 2.2 ng for sulfate, nitrate, and organics, respectively. The analytical recoveries for these species are 104 %, 87 %, and 94 %, respectively. This MN-AMS technique was applied successfully to analyze filter and impactor samples collected using miniature particulate matter (PM) samplers deployable on uncrewed atmospheric measurement platforms, such as uncrewed aerial systems (UASs) and tethered balloon systems (TBSs). Chemical composition of PM samples collected from a UAS field campaign conducted at the Department of Energy's (DOE) Southern Great Plains (SGP) observatory was characterized. The offline MN-AMS data compared well with the in situ PM composition measured by a co-located aerosol chemical speciation monitor (ACSM). In addition, the MN-AMS and ion chromatography (IC) agreed well for measurements of sulfate and nitrate concentrations in the PM extracts. This study demonstrates the utility of combining MN-AMS with uncrewed measurement platforms to provide quantitative measurements of ambient PM composition.

Genotoxic effects of particulate matter on larvae of a common and widespread butterfly along an urbanization gradient

Biodiversity is currently declining worldwide. Several threats have been identified such as habitat loss and climate change. It is unknown if and how air pollution can work in addition or in synergy to these threats, contributing to the decline of current species and/or local extinction. Few studies have investigated the effects of particulate matter (PM), the main component of air pollution, on insects, and no studies have investigated its genotoxic effects through Micronucleus assay. Butterflies play an important role in the environment, as herbivores during larval stages, and as pollinators as adults. The aim of this study was to evaluate the genotoxic effects of PM10 from different sites along a gradient of population urbanization, on a common cabbage butterfly species (Pieris brassicae). PM10 was collected from April to September in an urban (Turin, Italy), a suburban (Druento, Italy) and a mountain site (Ceresole Reale, Italy) with different urbanization levels. P. brassicae larvae (n = 218) were reared in the laboratory under controlled conditions (26 °C, L:D 15:9) on cabbage plants (average 9.2 days), and they were exposed to PM10 organic extracts (20 and 40 m3/mL) or dimethyl sulfoxide (controls) through vaporization. After exposure, larvae were dissected and cells were used for the Micronucleus (MN) assay. Results showed that all PM extracts induced significant DNA damage in exposed larvae compared to controls, and that increasing the PM dose (from 20 to 40 m3/mL) increased genotoxic effects. However, we did not detect any significant differences between sites with different urbanization levels. In conclusion, PM at different concentrations induced genotoxic effects on larvae of a common butterfly species. More alarmingly, PM could work in addition to and/or in synergy with other compounds (e.g. pesticides) and, especially on species already threatened by other factors (e.g. fragmentation), thus affecting the vitality of populations, leading to local extinctions.

Feature extraction and prediction of fine particulate matter (PM2.5) chemical constituents using four machine learning models

The concentrations of fine particulate matter (PM2.5) constituents, which are very important and essential information for the identification of air pollution sources, were predicted at three sites (Seoul, Ulsan, Baengnyeong) in South Korea between 2016 and 2018 using four machine learning (ML) models: generative adversarial imputation network (GAIN), fully connected deep neural network (FCDNN), random forest (RF), and k-nearest neighbor (kNN). 3 PM2.5 constituent groups, namely 8 ions, 2 carbons, and 15 trace elements, were targeted for prediction. The latest hyperparameter optimization techniques were used to learn air pollution characteristics from ambient PM2.5-related information, such as time, meteorology, and air pollutant concentrations. We compared the feature extraction abilities of the four models. The prediction accuracy identified by the coefficient of determination (R2) between prediction and observation was highest in GAIN, followed by FCDNN and RF or kNN. On availability of data on the time, air pollutant concentrations, and/or meteorology, simultaneously missed 20 % data of all PM2.5 constituent groups were predicted, with R2 = 0.897, 0.861, 0.785, and 0.801 by the GAIN, FCDNN, RF, and kNN, respectively. As missing ratios (20 %, 40 %, 60 %, 80 %) of input data increased, prediction accuracy decreased in the four models and was predominantly more noticeable in GAIN and kNN. As the available period of data increased, prediction accuracy increased in GAIN and FCDNN. Trace elements were predicted with the lowest R2 in all models among the target constituent groups. Study sites with more emission sources showed lower prediction accuracy, resulting in the highest R2 in Baengnyeong island and the lowest in Ulsan. According to the current findings, ML models can be used to evaluate various air pollution issues for which data is missing.

Cabbage butterfly as bioindicator species to investigate the genotoxic effects of PM10.

Atmospheric pollution poses a serious threat to environment and human health, and particulate matter (PM) is one of the major contributors. Biological effects induced by PM are investigated through in vitro assays using cells and by in vivo tests with laboratory model animals. However, also the estimation of adverse effects of pollutants, including airborne ones, on wild animals, such as insects, is an essential component of environmental risk assessment. Among insects, butterflies are sensitive to environmental changes and are important wild pollinators, so they might be suitable as environmental bioindicator species. The aim of this study was to evaluate the suitability of a wild cabbage butterfly species (Pieris brassicae) as a bioindicator organism to assess the genotoxic effects of PM10 collected in different sites. PM10 was collected from April to September in urban, suburban, and rural sites. P. brassicae larvae were reared in laboratory under controlled conditions on cabbage plants and exposed to PM10 organic extracts or dimethyl sulfoxide (controls) through vaporization. After exposure, larvae were dissected, and cells were used for comet assay. All PM extracts induced significant DNA damage in exposed larvae compared to controls and the extract collected in the most polluted site caused the highest genotoxic effect. In conclusion, the study suggested that butterflies, such as P. brassicae, could be applied as sensitive and promising bioindicators to investigate air quality and PM genotoxicity. Indeed, the use of these organisms allows the detection of genotoxic effects induced by PM sampled also in low-polluted areas.

Estimation and Health Risk Assessment of Respirable Silica in the Ambient Particulate Matter of Dhaka City

A simple, rapid, and efficient spectrophotometric method was developed for the quantification of respirable crystalline silica (SiO2) in atmospheric particulate matter (PM). The PM samples were collected for 24 hours from two different locations at the University of Dhaka (Mukarram Hussain Khundker Building-MHK and Teacher Student Centre-TSC) using a low-volume air sampler from September to December 2021. The extraction of PM loaded filters followed by filtration resulted in a clear solution. Using UV-visible spectroscopy, the concentration of silica in the filtrate was evaluated by treating the filtrate with molybdate-3 reagent and an amino acid suspension. The average PM-bound silica concentrations at MHK and TSC were 7.72 and 33.86 μgm-3 respectively. Compared to MHK, the silica content in the ambient atmosphere of TSC was four times higher, owing to extensive metro-rail construction work at TSC. The contribution of silica to PM was 3.47% (Site 1) and 5.15% (Site 2). The Hazard Quotient (HQ) was used to characterize the non-cancer risk posed by respirable silica. TSC recorded a high value of 12.87 for the hazard quotient of respirable silica compared to 2.57 for MHK indicating that the exposed inhabitants may have adverse noncancer health impacts. Carcinogenic risk assessment of silica showed that 1 in 341 individuals at MHK and 1 in 78 individuals at TSC could get cancer in their lifetime. This is the first study that demonstrated the high level of PM-bound respirable silica severely degraded air quality as well as potential human health in Dhaka. Dhaka Univ. J. Sci. 70(2): 35-41, 2022 (July)

Polyunsaturated fatty acids, vitamin E and lycopene alleviate ambient particulate matter organic extracts-induced oxidative stress in canine lung cells via the Nrf2/HO-1 pathway.

Exposure to environmental particulate matter (PM) causes lung damage in humans, but it is not sufficiently studied in companion animals. In this work, we found that organic extracts (OE) of PM induced oxidative stress and were more cytotoxic than water-soluble extracts (WE) of PM in canine (Canis familiaris) pulmonary alveolar type II epithelial (PAE) cells. Subsequently, we evaluated the alleviating effects of polyunsaturated fatty acid mixtures (eicosapentaenoic and docosahexaenoic acids), vitamin E, and lycopene on OE-exposed PAE cells. The results indicated that the three nutrients attenuated OE-induced oxidative stress. Compared with OE-exposed PAE cells, cells pretreated with the three nutrients exhibited a 1.7 ~ 2.2-fold reduction in reactive oxygen species, 15.58% ~ 19.96% increase in cell viability, 26.19% ~ 29.32% reduction in lactate dehydrogenase release and 33.87% ~ 40.10% reduction in intracellular malondialdehyde. Meanwhile, the activities of superoxide dismutase, catalase, and glutathione peroxidase increased by 35.22% ~ 47.70%, 45.36% ~ 64.13%, and 48.56% ~ 68.18%. Besides, microscopic observation revealed that nutrients improved cell morphology, as evidenced by reduced cell shrinkage and increased apposition. Finally, the mechanisms of OE toxicity and antioxidant nutrients were explored respectively. The results revealed that OE triggered cytotoxicity by directly disrupting antioxidant enzyme activity through activation of ROS, while nutrients inhibited OE-induced cellular oxidative stress via upregulation of the Nrf2/HO-1 signaling pathway. The present study may provide significant insights into the prevention of PM-induced lung diseases by antioxidant supplementation in animals.

Determination of trace concentrations of simple phenols in ambient PM samples.

Phenols are hazardous, but yet ubiquitous in the environment, including in atmospheric aerosols due to combustion emissions. There, phenols are subjected to secondary transformations, producing even more toxic nitrophenolic air pollutants. However, primary simple phenols, i.e. those containing only hydroxyl, methyl and methoxy substituents are not easy to detect. Trace concentrations, semi-volatile character and poorly ionizable functional groups prevent us from their determination by the most common analytical techniques, such as gas and liquid chromatography with mass spectrometric detection (GC/LC-MS). Here, we present a new derivatization method for MS/MS detection with positive ion electrospray ionization (+ESI-MS/MS) of simple phenols in atmospheric particulate matter (PM) extracts. The method is sensitive, selective, and robust, and requires no sample concentration step, which is critical due to the volatile character of the target analytes. After derivatization with dansyl chloride, phenol, catechol, cresols and guaiacol were detected in urban PM samples from Ljubljana, Slovenia. This method finally enables to study the abundance of primary phenols in atmospheric PM from different sources, which will improve understanding of secondary aerosol (trans)formation pathways and allow for more targeted mitigation strategies in respect to airborne phenolic pollutants.

Determination of whole mixture-based potency factors for cancer risk assessment of complex environmental mixtures by in vitro testing of standard reference materials.

Whole mixture-based testing using in vitro new approach methodologies (NAMs) has been suggested to facilitate the hazard and risk assessment of complex environmental mixtures. Previous studies have shown that phosphorylation of DNA damage signaling proteins checkpoint kinase 1 (pChk1) and histone 2AX (γH2AX) are sensitive markers that can be used for estimating carcinogenicity potencies in vitro. Here, and with the aim to better validate the applicability, in vitro-based Mixture Potency Factors (MPFs) of Standard Reference Materials (SRMs) from environmental polycyclic aromatic hydrocarbon (PAH)-containing mixtures were determined and compared to published mutagenicity and tumorigenicity data. Also, genotoxicity was assessed by a flow cytometry-based micronucleus (MN) assay which showed that only benzo[a]pyrene (B[a]P) and coal tar SRM (SRM1597a) caused dose-dependent increases of MN formation, while extracts of diesel particulate matter (SRM1650b), diesel particulate extract (SRM1975), and urban dust (SRM1649b) did not. However, a dose-dependent activation of DNA damage signaling was observed for all PAHs and SRMs. The results demonstrated that all SRMs were more potent than B[a]P, at B[a]P-equivalent concentrations, to induce pChk1 and γH2AX, and that western blot was more sensitive than the In-Cell Western assay in detecting their activation in response to these complex mixtures. Relative MPFs, based on dose-response modelling of pChk1 and γH2AX, ranged 113 - 5270 for the SRMs, indicating several orders of magnitude higher genotoxic potential than B[a]P. Moreover, these MPFs were in good agreement with potency values based on published data from Salmonella mutagenicity and in vivo carcinogenicity studies. In conclusion, these comparisons further validate the feasibility of applying in vitro NAMs, such as whole-mixture based MPFs, in cancer risk assessment of complex mixtures.