Organ-specific distribution of 7-chlorinated benz[a]anthracene and regulation of selected cytochrome P450 genes in rats

Chlorinated Anthracenes Induced Pulmonary Immunotoxicity in 3D Coculture Spheroids Simulating the Lung Microenvironment

Chlorinated anthracenes (Cl-Ants), persistent organic pollutants, are widely detected in the environment, posing potential lung toxicity risks due to frequent respiratory exposure. However, direct evidence and a comprehensive understanding of their toxicity mechanisms are lacking. Building on our prior findings of Cl-Ants' immunotoxic risks, this study developed a three-dimensional coculture spheroid model mimicking the lung's immune microenvironment. The objective is to explore the pulmonary immunotoxicity and comprehend its mechanisms, taking into account the heightened immune reactivity and frequent lung exposure of Cl-Ants. The results demonstrated that Cl-Ants exposure led to reduced spheroid size, increased macrophage migration outward, lowered cell viability, elevated 8-OHdG levels, disturbed anti-infection balance, and altered cytokine production. Specifically, the chlorine substituent number correlates with the extent of disruption of spheroid indicators caused by Cl-Ants, with stronger immunotoxic effects observed in dichlorinated Ant compared to those in monochlorinated Ant. Furthermore, we identified critical regulatory genes associated with cell viability (ALDOC and ALDOA), bacterial response (TLR5 and MAP2K6), and GM-CSF production (CEBPB). Overall, this study offers initial in vitro evidence of low-dose Cl-PAHs' pulmonary immunotoxicity, advancing the understanding of Cl-Ants' structure-related toxicity and improving external toxicity assessment methods for environmental pollutants, which holds significance for future monitoring and evaluation.

Parent and halogenated polycyclic aromatic hydrocarbons exposure in aluminum smelter workers: Serum levels, accumulation trends, and association with health indicators

Polycyclic aromatic hydrocarbons (PAHs) and their halogenated derivatives (HPAHs) can be unintentionally formed and released during industrial thermal processes. However, information on internal exposure and health risks of PAHs and HPAHs for thermal industry workers is very limited. In this study, serum samples from 220 aluminum smelter workers in East China were analyzed, and the relationship between the levels of these pollutants and various health indicators was also assessed. The workers had markedly higher serum concentrations of PAHs and HPAHs than the controls. The serum concentrations of ∑13PAHs and ∑9HPAHs increased with increasing age and occupational exposure duration in male workers. A positive correlation was observed between the ∑13PAH and ∑9HPAH serum concentrations, and the concentration of ∑13PAHs was approximately 50 times higher than that of ∑9HPAHs. For benzo[a]pyrene equivalent (BaPeq)-based risk assessment, the contribution of PAHs and HPAHs to the risk was 80 % and 20 % in the workers. PAHs and HPAHs showed a positive association with pulmonary hypofunction, hypertension and abnormal electrocardiogram. This study indicates occupational exposure to these toxic pollutants remains a significant issue and provides evidence that elevated serum levels of ∑13PAHs and ∑9HPAHs may be associated with an increased risk of lung and cardiovascular diseases.

Presence of Halogenated Polycyclic Aromatic Hydrocarbons in Milk Powder and the Consequence to Human Health

Recent reports of the presence of halogenated derivatives of polycyclic aromatic hydrocarbons (PAHs) in human foods of animal origin, such as chlorinated (ClPAHs) and brominated (BrPAHs) PAHs, suggest that their contamination in dairy products may also pose a human health risk. This study used GC/Orbitrap-MS to analyze 75 congeners of halogenated PAHs and parent PAHs in milk and creaming powder samples commonly found in grocery stores in Sri Lanka and Japan. Our investigation revealed a total of 31 halogenated PAHs (HPAHs) in the samples. The concentrations of total parent PAHs in the samples from Sri Lanka and Japan ranged from not detected (n.d.)−0.13 and <0.001−16 ng/g dry weight (d.w.). Total ClPAHs and BrPAHs in the samples ranged from 0.01−3.35 and 1.20−5.15 ng/g (d.w.) for Sri Lanka, and 0.04−2.54 and n.d.−2.03 ng/g d.w. for Japan, respectively. The ClPAHs were dominated by chlorinated-pyrene, -fluoranthene, and -benzo[a]pyrene congeners, whereas the BrPAHs were dominated by brominated-naphthalene and -pyrene congeners. The toxic assessment estimated based on the intake of toxic equivalency quotients (TEQs) for target compounds in milk powders revealed that HPAHs might contribute additively to the PAHs-associated health risk to humans, indicating that more research is needed.

Parent and Halogenated Polycyclic Aromatic Hydrocarbons in the Serum of Coal-Fired Power Plant Workers: Levels, Sex Differences, Accumulation Trends, and Risks

Workers in coal-fired power plants are at a high risk of exposure to polycyclic aromatic hydrocarbons (PAHs) and their halogenated derivatives (HPAHs), yet no studies have investigated such exposure of HPAHs. In this study, 12 PAHs and 8 chlorinated PAHs, but no brominated PAHs, were detected in >80% of serum samples from workers of a coal-fired power plant in eastern China. Serum HPAH concentrations were higher in plant workers (16-273 ng/g lipid) than in people without occupational exposure (12-51 ng/g lipid), and serum PAH and HPAH concentrations both in male and female workers were positively correlated with the occupational exposure duration, with an estimated doubling time of 11-17 years. Correlations were found between concentrations of ∑₈HPAHs and ∑₁₂PAHs but not between 7-chlorobenz[a]anthracene (7-ClBaA) and 1-chloropyrene (1-ClPyr) and their respective parent PAHs. In males, total concentrations of PAHs and HPAHs were positively correlated with pulmonary hypofunction and hypertension but not with abnormal electrocardiogram. The benzo[a]pyrene equivalents ratio of ∑₈HPAHs/∑₁₂PAHs was 0.3 ± 0.1. Among the HPAHs in the serum, 9-chlorophenanthrene, 7-ClBaA, and 1-ClPyr showed high health risks. This study is the first report on HPAH exposure in coal-fired power plant workers and provides new evidence on the health risks of PAHs and HPAHs in humans.

Ultrasensitive determination of 39 parent and emerging halogenated polycyclic aromatic hydrocarbons in human serum

Halogenated polycyclic aromatic hydrocarbons (HPAHs) have attracted extensive attention because of their high toxicity and bioaccumulation. However, there has been no report on the content of HPAHs in human tissues and the corresponding analytical method. In this study, a method for the simultaneous determination of 16 polycyclic aromatic hydrocarbons (PAHs) and 23 HPAHs in human serum was developed and validated. Simple and stable removal of interfering substances in complex serum and the detection of ultra-trace HPAHs are the key difficulties. After 0.5 mL serum was treated with formic acid and 10% isopropanol, samples were prepared by solid phase extraction (SPE) and analyzed by gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS). The recoveries of the method were 65-103%, with low detection limits of 0.001-0.019 ng mL^-1. For HPAHs, the precision was in the range of 0.2-10% according to relative standard deviation (RSD). Subsequently, the developed method was validated for serum samples obtained in hospitals, and 8 PAHs and 12 HPAHs were detected. The concentration of ∑HPAHs was 23 ± 12 ng g^-1 lipid in females and 21 ± 10 ng g^-1 lipid in males, in which phenanthrene and anthracene halogenated derivatives were the main components. The level of HPAHs was correlated with PAHs, which was 23-119 times higher than that of HPAHs. The detected HPAHs contain highly toxic and persistent components, representing an ongoing human health risk, which should receive more attention.

Transcriptomics and metabolomics analyses provide insights into the difference in toxicity of benzo[a]pyrene and 6-chlorobenzo[a]pyrene to human hepatic cells

The toxicological information of chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs), as derivatives of PAHs, is still relatively lacking. In this study, a combination of transcriptomics and metabolomics approach was adopted to explore the changes in toxicity to human L02 hepatocytes after chlorination of benzo[a]pyrene (B[a]P) at 6 position. In general, 6-Cl-B[a]P produced a stronger toxicity to human hepatic cells than did parent B[a]P. When exposure concentrations were 5 and 50 nM, 6-Cl-B[a]P caused a weaker transcriptomic perturbation relative to B[a]P, whereas a stronger metabolomic perturbation, a stronger oxidative stress and a stronger inhibition effect on cell viability were caused by 6-Cl-B[a]P than did parent B[a]P. Pathway enrichment analysis indicated that 6-Cl-B[a]P produced a more widely perturbation to metabolic pathways than did B[a]P. Although they both significantly impaired the function of mitochondrial electron transport chain (ETC), the exact mechanism is different. B[a]P suppressed the expression of 20 genes regulating mitochondrial ETC mainly via AhR activation. However, 6-Cl-B[a]P produced a stronger inhibition on the activities of complexes I and V than did B[a]P. Meanwhile, 6-Cl-B[a]P also exhibited a stronger inhibition effect on mitochondrial β oxidation of fatty acid. Furthermore, 6-Cl-B[a]P and B[a]P both significantly disturbed the nucleotide metabolism, glycerophospholipid metabolism and amino acid metabolism in L02 cells.

Environmental profile, distributions and potential sources of halogenated polycyclic aromatic hydrocarbons

Halogenated polycyclic aromatic hydrocarbons (HPAHs) are high lipophilic and degradation-resistant, which have been detected in the air, water, sediment and biota. HPAHs tend to have strong adverse effects on animals and humans. Although we have realized HPAHs are emerging contaminants which needs to be paid attention, there is still a lack of their individual commercial standards. This makes it difficult for understanding HPAHs comprehensively. This review is devoted to collect all the results have reported, and give a systemic look of their global distributions, influence factors and sources. Compared with air, studies on other environmental matrices (water and sediment) are more limited. The researches on organisms are fewest. Comparing the studied congeners, there are more studies on ClPAHs than BrPAHs. Human activities contribute mostly to their occurrence. Further, we then also introduce the toxicity and analytical methods to better understand HPAHs. The future research directions are also provided. Through this review, we can conclude there is an urgent need to develop analysis methods and ecologic risk assessment for better exploring HPAHs. Effective methods should be done to control HPAHs. Therefore, this review can provide a good basis for researchers to understand and control global pollution.

Accumulation of halogenated polycyclic aromatic hydrocarbons by different tuna species, determined by high-resolution gas chromatography Orbitrap mass spectrometry

Halogenated polycyclic aromatic hydrocarbon (HPAH) concentrations in tissues from three tuna species Thunnus albacares (yellowfin tuna), Katsuwonus pelamis (skipjack tuna), and Auxis thazard (frigate tuna) were determined by high-resolution gas chromatography Orbitrap mass spectrometry. The tuna samples were collected from the Indian Ocean. The instrument conditions gave high mass accuracy at 0.9 m/z isolation width of the mass filter and a mass error of <±1.0 ppm for many HPAHs. A total of 29 of the 30 targets chlorinated PAHs (ClPAHs) and 20 of the 21 targets brominated PAHs (BrPAHs) were detected in the tuna muscle samples. The mean total ClPAH, BrPAH and PAH concentrations for tuna were 127.2, 156.6 and 682.8 ng/g lipid weight, respectively. The mean total ClPAH and BrPAH concentrations (ng/g lipid weight) in the tuna were considerably lower than that of PAH concentrations. The mean total ClPAH, BrPAH and PAH concentrations in T. albacares respectively were 185.8, 249.2 and 784.1 ng/g lipid weight, irrespective of the body sizes. The mean total ClPAH, BrPAH and PAH concentrations in K. pelamis respectively were 45.1, 24.8 and 555.6 ng/g lipid weight. The mean total ClPAH, BrPAH and PAH concentrations in A. thazard respectively were 34.09, 4.73 and 433.24 ng/g lipid weight. The total ClPAH concentrations and body weights significantly positively correlated for T. albacares. The mean total ClPAH concentration in white muscles was significantly higher (p < 0.05) for large than for small T. albacares. This suggests ClPAHs could bioaccumulate in T. albacares, possibly because they are poorly metabolized. The chlorinated phenanthrene and pyrene concentrations indicated tuna accumulate these compounds increasingly effectively as the tuna grow. This was the first time large numbers of HPAHs were found in biological samples. HPAHs may adversely affect the health of humans consuming tuna.

Local and seasonal variations in concentrations of chlorinated polycyclic aromatic hydrocarbons associated with particles in a Japanese megacity

Concentrations of particle-bound polycyclic aromatic hydrocarbons (PAHs) and chlorinated PAHs (ClPAHs) were measured in different seasons at five sampling stations in Nagoya, a Japanese megacity. The annual mean total ClPAH and total PAH concentrations were 43.3-92.6pg/m(3) and 5200-8570pg/m(3), respectively. The concentrations of total ClPAHs were significantly variable than those of total PAHs, and both total concentrations through the seasons did not significantly correlate at any of the stations. Principal component analysis was used to characterize the ClPAH sources, resulted that ClPAHs were found to be associated with the sources of high-molecular-weight PAHs in the warmer seasons and of low-molecular-weight PAHs in the colder seasons. These findings suggest that principal sources of particle-bound ClPAHs are present in the local area, and change in the seasons. Toxic equivalent (TEQ) concentrations were estimated to assess the risks associated with exposure to ClPAHs in air. The TEQ concentrations in the samples were 0.05-0.32pg-TEQ/m(3). The TEQ concentrations in summer were approximately half the TEQ concentrations in the other seasons at all of the stations.

Mammalian models of chemically induced primary malignancies exploitable for imaging-based preclinical theragnostic research

Compared with transplanted tumor models or genetically engineered cancer models, chemically induced primary malignancies in experimental animals can mimic the clinical cancer progress from the early stage on. Cancer caused by chemical carcinogens generally develops through three phases namely initiation, promotion and progression. Based on different mechanisms, chemical carcinogens can be divided into genotoxic and non-genotoxic ones, or complete and incomplete ones, usually with an organ-specific property. Chemical carcinogens can be classified upon their origins such as environmental pollutants, cooked meat derived carcinogens, N-nitroso compounds, food additives, antineoplastic agents, naturally occurring substances and synthetic carcinogens, etc. Carcinogen-induced models of primary cancers can be used to evaluate the diagnostic/therapeutic effects of candidate drugs, investigate the biological influential factors, explore preventive measures for carcinogenicity, and better understand molecular mechanisms involved in tumor initiation, promotion and progression. Among commonly adopted cancer models, chemically induced primary malignancies in mammals have several advantages including the easy procedures, fruitful tumor generation and high analogy to clinical human primary cancers. However, in addition to the time-consuming process, the major drawback of chemical carcinogenesis for translational research is the difficulty in noninvasive tumor burden assessment in small animals. Like human cancers, tumors occur unpredictably also among animals in terms of timing, location and the number of lesions. Thanks to the availability of magnetic resonance imaging (MRI) with various advantages such as ionizing-free scanning, superb soft tissue contrast, multi-parametric information, and utility of diverse contrast agents, now a workable solution to this bottleneck problem is to apply MRI for noninvasive detection, diagnosis and therapeutic monitoring on those otherwise uncontrollable animal models with primary cancers. Moreover, it is foreseeable that the combined use of chemically induced primary cancer models and molecular imaging techniques may help to develop new anticancer diagnostics and therapeutics.

Complementary nontargeted and targeted mass spectrometry techniques to determine bioaccumulation of halogenated contaminants in freshwater species

Assessing the toxicological significance of complex environmental mixtures is challenging due to the large number of unidentified contaminants. Nontargeted analytical techniques may serve to identify bioaccumulative contaminants within complex contaminant mixtures without the use of analytical standards. This study exposed three freshwater organisms (Lumbriculus variegatus, Hexagenia spp., and Pimephales promelas) to a highly contaminated soil collected from a recycling plant fire site. Biota extracts were analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and mass defect filtering to identify bioaccumulative halogenated contaminants. Specific bioaccumulative isomers were identified by comprehensive two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry (GCxGC-HRToF). Targeted analysis of mixed brominated/chlorinated dibenzo-p-dioxins and dibenzofurans (PXDD/PXDFs, X = Br and Cl) was performed by atmospheric pressure gas chromatography tandem mass spectrometry (APGC-MS/MS). Relative sediment and biota instrument responses were used to estimate biota-sediment accumulation factors (BSAFs). Bioaccumulating contaminants varied among species and included polychlorinated naphthalenes (PCNs), polychlorinated dibenzofurans (PCDFs), chlorinated and mixed brominated/chlorinated anthracenes/phenanthrenes, and pyrenes/fluoranthenes (Cl-PAHs and X-PAHs, X = Br and Cl), as well as PXDD/PXDFs. Bioaccumulation potential among isomers also varied. This study demonstrates how complementary high-resolution mass spectrometry techniques identify persistent and bioaccumulative contaminants (and specific isomers) of environmental concern.

Imepitoin as novel treatment option for canine idiopathic epilepsy: pharmacokinetics, distribution, and metabolism in dogs

Imepitoin is a novel anti-epileptic licensed in the European Union for the treatment of canine idiopathic epilepsy. The aim of this study was to characterize the pharmacokinetics of imepitoin in dogs and to evaluate the interaction with drug metabolizing enzymes. Upon administration of imepitoin tablets at a dose of 30 mg/kg to beagle dogs, high plasma levels were observed within 30 min following oral dosing, with maximal plasma concentrations of 14.9–17.2 μg/mL reached after 2–3 h. In a crossover study, co-administration of imepitoin tablets with food reduced the total AUC by 30%, but it did not result in significant changes in T_max and C_max, indicating lack of clinical relevance. No clinically relevant effects of sex and no accumulation or metabolic tolerance were observed upon twice daily dosing. Following single dose administration of 10–100 mg/kg, dose linearity was found. Administering [¹⁴C] imepitoin, high enteral absorption of 92% and primary fecal excretion were identified. Plasma protein binding was only 55%. At therapeutic plasma concentrations, imepitoin did not inhibit microsomal cytochrome P450 family liver enzymes in vitro. In rats, no relevant induction of liver enzymes was found. Therefore, protein binding or metabolism-derived drug–drug interactions are unlikely. Based on these data, imepitoin can be dosed twice daily, but the timing of tablet administration in relation to feeding should be kept consistent.