Aromatic Hydrocarbons Research Articles

A new yeast-based bioreporter for simple, sensitive, and cost-effective detection of dioxin-like compounds

Dioxin-like compounds (DLCs) are environmental xenobiotics that can activate the aryl hydrocarbon receptors (AhR), thereby imposing a significant threat to human health through biomagnifications processes. In this study, a dioxin-activated nano-luminescent Saccharomyces cerevisiae bioreporter, called DnaSc, was developed for simple and rapid detection of DLCs and AhR agonists. The bioreporter used nano-luciferase (NLuc) as a signal generator to emit bioluminescent signals in response to DLCs without cell lysis. Through optimizing AhR nuclear translocator (ARNT) expression and engineering the AhR, the yeast-based bioassay exhibited a detection limit of 10 fM for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) within 6h, making it the most sensitive whole-cell biosensor reported to date. Furthermore, the detection capacity of the dioxin-activated nano-luminescent S. cerevisiae bioreporter (DnaSc) bioassay for DLCs and AhR agonists was characterized. In summary, the yeast-based bioreporter developed in this study provided a simple, sensitive, and cost-effective method for DLCs detection.

Combination screen in multi-cell type tumor spheroids reveals interaction between aryl hydrocarbon receptor antagonists and E1 ubiquitin-activating enzyme inhibitor: Aryl-hydrocarbon receptor antagonist drug combinations

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that regulates genes of drug transporters and metabolic enzymes to detoxify small molecule xenobiotics. It has a complex role in cancer biology, influencing both the progression and suppression of tumors by modulating malignant properties of tumor cells and anti-tumor immunity, depending on the specific tumor type and developmental stage. This has led to the discovery and development of selective AhR modulators, including BAY 2416964 which is currently in clinical trials. To identify small molecule anticancer agents that might be combined with AhR antagonists for cancer therapy, a high-throughput combination screen was performed using multi-cell type tumor spheroids grown from malignant cells, endothelial cells, and mesenchymal stem cells. The AhR selective antagonists BAY 2416964, GNF351, and CH-223191 were tested individually and in combination with twenty-five small molecule anticancer agents. As single agents, BAY 2416964 and CH-223191 showed minimal activity, whereas GNF351 reduced the viability of some spheroid models at concentrations greater than 1 µM. The activity of most combinations aligned well with the single agent without apparent contributions from the AhR antagonist. All three AhR antagonists sensitized tumor spheroids to TAK-243, an E1 ubiquitin-activating enzyme inhibitor. These combinations were active in spheroids containing bladder, breast, ovary, kidney, pancreas, colon, and lung tumor cell lines. The AhR antagonists also potentiated pevonedistat, a selective inhibitor of the NEDD8-activating enzyme E1 regulatory subunit, in several tumor spheroid models. In contrast, the AhR antagonists did not enhance the cytotoxicity of the proteasome inhibitor bortezomib.

Nicotine promotes pathogenic bacterial growth and biofilm formation in peri-implant.

Introduction. Peri-implantitis is a plaque-associated disease that leads to implant loss and arises from bacterial biofilms on the surface of the implant. Smoking is a risk factor for peri-implantitis and impedes treatment effectiveness. Additionally, aryl hydrocarbon receptor (AHR), IL-6, and IL-22 levels are related to peri-implantitis.Aim. We aimed to investigate the effects of nicotine on inflammatory response, bacterial growth and biofilm formation.Hypothesis/Gap Statement. We hypothesized that nicotine promoted pathogenic bacterial growth and biofilm formation, thereby aggravating inflammation.Methodology. The expression of AHR, IL-6 and IL-22 was measured in peri-implant sulci fluid using quantitative PCR and Western blot analyses. The cementum was incubated with bacterial suspension including Porphyromonas gingivalis, Streptococcus sanguinis and Fusobacterium nucleatum and treated with 100, 200, 250 and 300 µg ml-1 nicotine, and then, the absorbance and number of colony-forming units were detected. Biofilm formation was evaluated using the tissue culture plate method and safranin O staining. Carbohydrates and proteins were measured by the phenol-sulfuric acid method and the bicinchoninic acid method, respectively.Results. The results indicated that smoking increased the levels of AHR, IL-6 and IL-22. Functionally, nicotine promoted the growth of P. gingivalis, S. sanguinis and F. nucleatum. Additionally, it promoted the biofilm formation of these bacteria and increased the contents of carbohydrates and proteins.Conclusion. Nicotine promoted bacterial growth and biofilm build-up, suggesting that smoking may aggravate the progression of peri-implantitis.

AHR activation relieves deoxynivalenol-induced disruption of porcine intestinal epithelial barrier functions

Mycotoxins are ubiquitous natural pollutants that pose a serious threat to public health. Deoxynivalenol (DON) as one of the most prominent mycotoxins has a noticeable adverse effect on intestinal barrier function, which depends on the intestinal barrier integrity. However, the potential mechanisms and effective therapeutic strategies remain unclear. Aryl hydrocarbon receptor (AHR) has been implicated in the modulation of intestinal barrier function and inflammation. The study aims to investigate the unique role of AHR in mediating DON-induced intestinal epithelial barrier function. In the current study, we revealed that DON triggered mitochondrial structural damage and functional impairment, leading to oxidative stress and apoptosis in porcine jejunal epithelial cells (IPEC-J2). DON altered the integrity of IPEC-J2 cells by disrupting the distribution and function of tight junction proteins. Additionally, DON activated TNF-α/NF-κB/MLCK signaling pathway, thereby eliciting inflammatory response. Notably, DON inhibited AHR nuclear translocation and attenuated xenobiotic response element promoter activity and its target genes. However, overexpression of AHR mitigated DON-induced disruption of intestinal epithelial barrier functions by suppressing TNF-α/NF-κB/MLCK pathway in IPEC-J2 cells. Our findings indicate that AHR regulates intestinal epithelial barrier function and therefore is a novel therapeutic molecule for intestinal disorders.

200℃ ТЕМПЕРАТУРАДА АУЫР МҰНАЙДЫ БУМЕН ТЕРМИЯЛЫҚ ӨҢДЕУДІҢ ТИІМДІЛІГІН АРТТЫРУ ҮШІН БЕТТІК БЕЛСЕНДІ ЗАТТАРДЫ ҚОЛДАНУ

In the presented work influence of surfactants on of the oil transformation regularities in hydrothermal conditions was studied. The oil with density 0,9727 g/cm3 was chosen as objects of research. It has been established that the introduction of surfactants reduces the content of resinous asphaltenes as a result of peptizing action on asphaltene aggregates. As a result, more carbon-heteroatom bonds in asphaltenes are involved in the processes of destructive hydrogenation. According to the results of SARA - and chromato-mass-spectral analysis, a change of mass fractions of each fraction is observed. When using the surfactant "SA-3" the content of saturated hydrocarbons is 20% higher than in the original sample, while in the oil sample with the surfactant "SBG" the content is almost unchanged. The content of aromatic hydrocarbons increased significantly with the addition of "SBG" by 19%, and with the addition of "SA-3" by 10%, which is due to the newly formed low molecular weight saturated and aromatic hydrocarbons. Asphaltene content also changed significantly, the sample with the addition of "SA-3" showed a decrease of 12% and with the addition of "Biolub green" a decrease of 9% relative to the original oil. The dynamic viscosity at 20℃ of the original oil is 3000 mPa∙s at a shear rate of 1.3 s-1. When using non-ionic surfactants of GK "Mirrico" of "Biolub green" type after the experiments, the viscosity decreases by 22%, and when adding "SA-3" surfactants by 30%. The use of surfactants in the development of heavy oil fields by steam-heat methods will increase the oil recovery factor.

Foreign experience in determining the group hydrocarbon composition of petroleum feedstock and petroleum products

Determination of the group hydrocarbon composition (saturated and aromatic hydrocarbons, resins, asphaltenes) of petroleum dispersed systems is predominantly carried out using chromatographic analysis methods: liquid adsorption chromatography, high-performance liquid chromatography, thin-layer chromatography with flame ionization detection. The specificity of standard methods developed for the analysis of petroleum feedstock and petroleum products using a particular method often results in the incompatibility of results both in terms of the nomenclature of the identified hydrocarbon groups and the determined concentration values. This review provides a comparative assessment of chromatographic methods for analyzing the group hydrocarbon composition of petroleum feedstock and petroleum products, their features, advantages, and disadvantages. The main options for modifying standard methods aimed at achieving correlation between the results obtained by different analysis methods are described.

Aroma-active compounds in Russian sturgeon (Acipenser gueldenstaedtii) raised in recirculating aquaculture systems

The rearing system affects the nutritional and sensorial qualities of the Russian sturgeon (Acipenser gueldenstaedtii), a niche yet commercially valuable aquaculture species for caviar production. In the present work, we aimed to comprehensively characterize the odorant composition of fillets from Russian sturgeon raised in a recirculating aquaculture system (RAS) and discuss potential sources and formation pathways. A total of 114 odorants were detected through the application of combined sensory-instrumental analyses, of which 88 were successfully identified and 20 substances were found to be among the most potent odor constituents. The most dominant odorants were assigned to several specific substance classes, including aldehydes, alcohols, terpenes, ketones, organic acids, lactones, heterocycles, aromatic hydrocarbons, and sulfur-containing aldehydes. The compounds (E)-hex-2-enal, (Z)-hept-4-enal, cuminaldehyde, non-3-yn-1-ol, 3-carene, 2-methylisoborneol, geosmin, oct-1-en-3-one, nonan-3-one, (Z)-1,5-octadien-3-one, octane-2,3-dione, nonan-2-one, hexanoic acid, γ-crotonolactone, γ-octalactone, 2-acetyl-thiazoline, methional, and (2E,4Z,7Z)-trideca-2,4,7-trienal had high flavor dilution factors and are described for the first time as potent odor-active compounds associated with the Russian sturgeon. Overall, oct-1-en-3-one, (Z)-1,5-octadien-3-one, octane-2,3-dione, nonan-2-one, 2-methylisoborneol, and hexanoic acid had the highest flavor dilution factors. This study offers a basis for future development in the sturgeon RAS industry from the perspective of flavor characterization by providing deep insights into the fundamental composition and origins of the complex world of aquaculture fish aroma.

Benzo[a]pyrene: A carcinogen, its sources, adverse effects, and preventive measures

A polycyclic aromatic hydrocarbon called benzo[a]pyrene (B[a]P) is produced during incomplete burning of fuels. The most common way humans consume B[a]P is through food products, particularly grilled or smoked foods. B[a]P is also frequently detected in the sediments, soil, surface water, and air. Once bioactivated, it produces a highly reactive epoxide monomer that can create adducts by chemically reacting with biological molecules, such as DNA. B[a]P is implicated in various cancers due to its interaction with the aromatic hydrocarbon receptor (AhR). Apart from its detrimental impacts on development and reproduction, this substance also suppresses the immune system. Microbes, however, are critical to cleaning up the B[a]P-contaminated environment. This review focuses on forming B[a]P in different compartments of the environment and human surroundings, and the mechanisms responsible for its harmful effects and carcinogenic risk. This review also discusses the strategies for the deterioration of B[a]P.

Spatial interaction and risk zoning of compound pollutants in farmland soils: Insights from heavy metals and polycyclic aromatic hydrocarbons in Hezhang County, China

The accurate identification and assessment of comprehensive risks associated with compound pollution in agricultural ecosystems remain significant challenges due to the complexity of pollution sources, soil heterogeneity, and spatial variability. In this study, bivariate local indicators of spatial association (LISA) were applied to analyze the spatial interaction between heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) in farmland soils in Hezhang County. The results revealed distinct clusters with elevated concentrations of both HMs and PAHs, predominantly in areas affected by long-standing lead-zinc mining and smelting activities. Positive matrix factorization (PMF) was utilized to identify mining and smelting activities, and associated coal consumption as common sources of both pollutants, contributing 53 % and 28 %, respectively. Ecological health risk assessment results indicated that the combined pollution in this area has led to particularly severe ecological and cancer risks, with the pollution coefficient (Pc) exceeding 3.0, and risk values for both adults and children surpassing the threshold of 10−4. Through the integration of advanced bivariate LISA mapping and thorough risk assessment, this study precisely delineated ecological risk zones (33.1 %) and more refined health risk zones (40.1 %) associated with combined pollution. The southwest of Hezhang was identified as a critical hotspot for combined pollution risks, primarily due to intensive mining and smelting activities in the region. Overall, this study underscores the utility of bivariate LISA as a robust approach for delineating spatial clustering patterns caused by combined pollutants. It provides crucial insights for identifying regions with heightened human health and ecological risks in rural settings.

Impact of Skin Decontamination Wipe Solutions on the Percutaneous Absorption of Polycyclic Aromatic Hydrocarbons

Firefighter occupational exposures were categorized as a class 1 (known) carcinogen by the International Agency for Research on Cancer in 2022. As a result, firefighters have become heavily focused on identifying effective and easy to implement decontamination strategies to reduce their chemical exposures. Skin decontamination using wipes post-exposure is one decontamination strategy that every firefighter has available to them. However, firefighters have expressed concerns over the ingredients in the wipe solution increasing dermal absorption. The goal of this study was to determine if the ingredients in skin decontamination wipe solution had any enhancement effect on the dermal absorption of phenanthrene. To determine any enhancement effects, the additive solution of four skin decontamination wipe products was applied to porcine skin 15 min after chemical dosing. The absorption of phenanthrene was tested in vitro using a flow-through diffusion cell system over eight hours. The wipe solution effects on dermal absorption were determined by measuring multiple absorption characteristics including cumulative absorption (µg/cm2), absorption efficiency (% dose absorbed), lag time (minutes), flux (µg/cm2/h), diffusivity (cm2/h), and permeability (cm/h). No penetration enhancement effects were observed in any of the skin decontamination wipe solutions tested; rather, all wipe solutions decreased the absorption of phenanthrene. Slight differences in cumulative absorption among two pairings of skin decontamination wipe solutions, wipes 1 and 3 vs. wipes 2 and 4, were observed, indicating that some ingredients may impact dermal absorption. These findings show that firefighters should continue using skin decontamination wipes to reduce their dermal exposures to fireground contaminants with little concern of increasing the absorption of phenanthrene.

The Impact of Green Infrastructure on the Quality of Stormwater and Environmental Risk

Increasing urbanization and the associated sealing of areas and the use of storm sewer systems for drainage not only increase the risk of flooding but also reduce water quality in streams into which stormwater is discharged. Green infrastructure (GI) measures are applied with the aim of managing this stormwater sustainably and reducing the associated risks. To this end, a quantitative–qualitative approach was developed to simulate GI—namely, rain gardens, bioretention cells, and vegetative bioswales—at the urban catchment scale. The findings highlight the potential of applying GI measures to managing stormwater more effectively in urban environments and mitigating its negative pollution-related impacts. For the housing estate analyzed, a simulated implementation of GI resulted in a reduction in pollution, measured as total nitrogen (N; 9–52%), nitrate-N (5–30%), total phosphorus (11–59%), chemical oxygen demand (8–46%), total suspended solids (13–73%), copper (12–64%), zinc (Zn; 16–87%), polycyclic aromatic hydrocarbons (16–91%), and the hydrocarbon oil index (HOI; 15–85%). Reducing the concentrations of pollutants minimizes the risk to human health determined via the HOI from a low-risk level to zero risk and reduces the ecological risk in terms of Zn pollution from a significant risk to a low risk of adverse effects. The modeling conducted clearly shows that the GI solutions implemented facilitated a quantitative reduction and a qualitative improvement in stormwater, which is crucial from an environmental perspective and ensures a sustainable approach to stormwater management. Lowering the levels of stormwater pollution through the implementation of GI will consequently lower the environmental burden of pollutants in urban areas.

Oxidation of Polycyclic Aromatic Hydrocarbons (PAHs) Triggered by a Photochemical Synergistic Effect between High- and Low-Molecular-Weight PAHs.

Photooxidation of polycyclic aromatic hydrocarbons (PAHs), which are widely observed in atmospheric particulate matter (PM), largely determines their atmospheric fate. In the environment, PAHs are highly complex in chemical composition, and a great variety of PAHs tend to co-occur. Despite extensive investigation on the photochemical behavior of individual PAH molecules, the photochemical interaction among these coexisting PAHs is still not well understood. Here, we show that during photooxidation, there is a strong photochemical synergistic effect among PAHs extracted from soot particles. We find that neither small PAHs with low molecular weights of 200-350 Da and 4-8 aromatic rings (named PAHsmall) nor large PAHs with high molecular weights of 350-600 Da and 8-14 aromatic rings (named PAHlarge) undergo photooxidation under red-light irradiation (λ = 648 nm), even though PAHlarge can absorb light with this wavelength. Interestingly, when PAHlarge is mixed with PAHsmall, substantial photooxidation is observed for both PAHlarge and PAHsmall. Comparisons of in situ infrared (IR), high-resolution mass spectrometry, and electron paramagnetic resonance analysis indicate that the presence of PAHsmall inhibits the light quenching effect arising from the π-π stacking of PAHlarge. This leads to the formation of singlet oxygen (1O2), which initiates the photooxidation. Our findings reveal a new mechanism for the photooxidation of PAHs and suggest that complex atmospheric PAHs exhibit distinct photoreactivity from simple systems.

An overview on analytical methods and the occurrence of organic pollutants in cigarette litter

Cigarette litter, such as cigarette ash, cigarette butts, and cigarette butt leachates, can contain organic pollutants similar to those in cigarette smoke, but studies on these waste types are still relatively limited. This review article compiles information from studies published over the past four decades on organic pollutants in cigarette ash, cigarette butts, and leachates from cigarette butts, to provide insights into quantitatively analytical methods and the presence of these toxicants in cigarette litter. The main organic pollutants found in cigarette litter include: volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), polycyclic aromatic hydrocarbons (PAHs), nicotine, and aromatic amines. Gas chromatography or liquid chromatography coupled with mass spectrometry detection have been the most frequently used methods to characterize organic pollutants in cigarette litter. Toxic substances in improperly disposed cigarette waste can pollute the environment through evaporation into the air or leakage through leachates into the water environment, seepage into soil, accumulate in sediment, and cause negative effects on organisms. Further studies on analytical method development, pollution monitoring, and risk assessment related to organic pollutants in cigarette waste are needed.

Current Pharmaceutical Approach to Investigate the Impact of Polycyclic Aromatic Hydrocarbons in Cigarette Smoke on Human Health

Current Pharmaceutical Approach to Investigate the Impact of Polycyclic Aromatic Hydrocarbons in Cigarette Smoke on Human Health

Determination of Polycyclic Aromatic Hydrocarbons (PAHs) in Clarias gariepinus and Tilapia zillii Smoked using Charcoal and Gas Smoking Kilns in Benue State

Determination of Polycyclic Aromatic Hydrocarbons (PAHs) in Clarias gariepinus and Tilapia zillii Smoked using Charcoal and Gas Smoking Kilns in Benue State

Ineffectiveness of 6,2',4'-trimethoxyflavone in mitigating cerebral ischemia/reperfusion injury after post-reperfusion administration in rats.

Pharmacological inhibition of aryl hydrocarbon receptor (AhR) activation after ischemia alleviates cerebral ischemia/reperfusion (IR) injury. To investigate whether AhR antagonist administration after reperfusion was also effective in attenuating cerebral IR injury. A total of 24 Sprague-Dawley rats were divided into the sham-operated group (no IR), control group (IR), and 6,2',4'-trimethoxyflavone (TMF) group (IR + TMF administration), with 10 rats assigned to each group. Cerebral IR injury was induced by 60 min of middle cerebral artery occlusion followed by reperfusion. TMF (5 mg/kg) was used as the AhR antagonist and was administered intraperitoneally immediately after reperfusion. Cerebral IR injury was observed using magnetic resonance imaging (MRI) and neurobehavioral assessments at baseline, immediately after ischemia, and at 3 days after ischemia. On MRI, the TMF group showed no significant differences in relative apparent diffusion coefficient (ADC), T2, and fractional anisotropy (FA) values; midline shift value; and infarct volume. In terms of neurobehavioral function, factors such as grip strength, contralateral forelimb use, time to touch, and time to remove adhesive tape from the forepaw, were also not significantly different between the control and TMF groups. This study demonstrated that AhR treatment after reperfusion had no noticeable effect on reducing cerebral IR injury in rats.

Solubility Study of a Ladder-Like Polyphenylsilsesquioxane for Membrane Application

In this work, the solubility of a high-molecular-weight homopolymer, a ladder polyphenylsilsesquioxane, was studied in different classes of solvents, including alcohols, aprotic solvents, ketones, alkanes, and aromatic hydrocarbons. The Hansen parameters and the parameter of long-range interaction between the polymer and the solvent were analyzed. The insolubility of L-PPSQ in a wide range of solvents allows for expecting that the properties of a membrane on its basis would be stable during operation in these media. At the same time, aprotic solvents are well suited for the preparation of membranes based on L-PPSQ by the solution phase inversion method.

Occurrences of Deposited Polycyclic Aromatic Hydrocarbons in Wax of Plant Leaves Using Laser Scanning Microscopy and Gas Chromatography–Mass Spectrometry

The knowledge of the deposition fate of ambient polycyclic aromatic hydrocarbons (PAHs) on plant leaves is limited. To fill in this knowledge gap, this study strives to observe the intermolecular complex between the polycyclic aromatic hydrocarbons and epicuticular wax of plant leaves using laser scanning microscopy. Epicuticular wax refers to a type of organic mixture that covers the outermost layer of leaves. The leaves of 20 tree species were collected in Beijing in July 2023. The concentrations of 31 PAHs were quantified by gas chromatography–mass spectrometry. Furthermore, the intermolecular complexes of polycyclic aromatic hydrocarbons and epicuticular wax were found with a fluorescence spectrofluorometer and laser scanning microscopy. The levels of total PAHs across 20 tree species ranged from 12.4 ng g−1 to 68.4 ng g−1. Differences in the amounts of total PAHs across tree leaves were observed, which may be ascribed to the differences in leaf surface across tree types. The higher concentration of low-molecular-weight PAHs was found in leaves compared to high-molecular-weight PAHs. The fluorescence spectrofluorometer identified the formation of a new intermolecular complex with fluorescence emission at an excitation wavelength of 340 nm between PAHs and epicuticular wax relative to PAHs. We used laser scanning microscopy with a 405 nm laser for excitation to observe the new intermolecular complex of PAHs and epicuticular wax on the stomata and epicuticular wax of leaves. This study found the intermolecular complex of PAHs on the surface of leaves in situ, which provides important information about the deposition fate of ambient PAHs.

One-Year Impact of Occupational Exposure to Polycyclic Aromatic Hydrocarbons on Sperm Quality

Background: Polycyclic aromatic hydrocarbons (PAHs) have toxic potential, especially as carcinogens, neurotoxins, and endocrine disruptors. The objective of this study is to know the impact of exposure to PAHs on the reproductive health of male workers who operate in solar thermal plants. Methods: Case–control study. A total of 61 men were included: 32 workers exposed to PAH at a solar thermal plant and 29 unexposed people. Seminal quality was studied both at the cellular level (quantity and quality of sperm) and at the biochemical level (magnitudes of oxidative stress in seminal plasma). Results: In exposure to PAHs, a significantly higher seminal leukocyte infiltration was observed, as well as lower activity in seminal plasma of superoxide dismutase (SOD) and a reduced glutathione/oxidised glutathione (GSH/GSSG) ratio. The oxidative stress parameters of seminal plasma did not show a relationship with sperm cellularity, neither in those exposed nor in those not exposed to PAH. Conclusion: One year of exposure to PAH in a solar thermal plant does not have a negative impact on the sperm cellularity of the worker, either quantitatively (sperm count) or qualitatively (motility, vitality, morphology, or cellular DNA fragmentation). However, PAH exposure is associated with lower antioxidant capacity and higher leukocyte infiltration in seminal plasma.

Molecular Interactions Governing the Rat Aryl Hydrocarbon Receptor Activities of Polycyclic Aromatic Compounds and Predictive Model Development

Polycyclic aromatic compounds (PACs) exhibit rat aryl hydrocarbon receptor (rAhR) activities, leading to diverse biological or toxic effects. In this study, the key amino residues and molecular interactions that govern the rAhR activity of PACs were investigated using in silico strategies. The homology model of rAhR was first docked with 90 PACs to yield complexes, and the results of the molecular dynamics simulations of 16 typical complexes showed that the binding energies of the complexes range from −7.37 to −26.39 kcal/mol. The major contribution to the molecular interaction comes from van der Waals forces, and Pro295 and Arg316 become the key residues involved in most complexes. Two QSAR models were further developed to predict the rAhR activity of PACs (in terms of log IEQ for PACs without halogen substitutions and log%-TCDD-max for halogenated PACs). Both models have good predictive ability, robustness, and extrapolation ability. Molecular polarizability, electronegativity, size, and nucleophilicity are identified as the important factors affecting the rAhR activity of PACs. The developed models could be employed to predict the rAhR activity of other reactive PACs. This work provides insight into the mechanisms and interactions of the rAhR activity of PACs and assists in the assessment of their fate and risk in organisms.