Parent Polycyclic Aromatic Hydrocarbons Research Articles

Effective isolation and comprehensive quantification of EPA16 PAHs, EU15+1 PAHs, 17 halogenated PAHs, and 18 oxygenated PAHs in soybean oil

Halogenated and oxygenated polycyclic aromatic hydrocarbons (XPAHs and OPAHs) have attracted increasing attention due to their considerable or higher toxicity than the corresponding parent PAHs. However, only a few kinds of PAH derivatives were monitored in vegetable oils due to the difficulties in analysis. This study aimed to establish analytical methods for 24 PAHs, 17 XPAHs and 18 OPAHs in soybean oil. The modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) pretreatment followed by GC-MS/MS or UPLC-MS/MS analysis was applied in this study. The results showed that the modified QuEChERS pretreatment could successfully extract 56 PAHs and derivatives in soybean oil, which saved organic solvent to a great extent. Simultaneous determination of EPA16 PAHs, EU15+1 PAHs, 17 XPAHs, and 12 OPAHs in soybean oil was achieved by GC-MS/MS analysis, which had recoveries of 61.33-111.61% and relative standard deviations (RSDs) of 1.35-19.89%. UPLC-MS/MS analysis obtained recoveries from 51.61% to 109.45% and RSDs from 1.31% to 15.05% for 14 OPAHs. As a supplement to GC-MS/MS, UPLC-MS/MS exhibited high sensitivity to ortho-OPAHs and benzo[a]pyrene–quinone isomers. Through GC-MS/MS and UPLC-MS/MS analyses, the concentrations of two XPAHs and ten OPAHs in soybean oils were firstly reported. In short, this study offered guidance for comprehensive analyses of PAHs, XPAHs, and OPAHs in vegetable oils.

Pollution Characteristics and Health Risks of Polycyclic Aromatic Compounds (PACs) in Soils of a Coking Plant.

Coke production is an important source of environmental polycyclic aromatic compounds (PACs), including parent polycyclic aromatic hydrocarbons (PAHs) and their derivatives. The focus near coking plants has primarily been on parent-PAH contamination, with less attention given to highly toxic derivatives. In this study, soil samples were collected from both within and outside of a coking plant. The concentrations of parent-PAHs and their derivatives, including methylated-PAHs, oxygenated-PAHs, and nitrated-PAHs, were examined. Spatial interpolation was employed to determine their spatial distribution patterns. Methods for identifying potential sources and conducting incremental lifetime cancer risk analysis were used. This could achieve a comprehensive understanding of the status of PAC pollution and the associated health risks caused by coke production. The concentrations of total PACs inside the plant ranged from 7.4 to 115.8 mg/kg, higher than those outside (in the range of 0.2 to 65.7 mg/kg). The spatial distribution of parent-PAH concentration and their derivatives consistently decreased with increasing distance from the plant. A significant positive correlation (p < 0.05) among parent-PAHs and their derivatives was observed, indicating relatively consistent sources. Based on diagnostic ratios, the potential emission sources of soil PACs could be attributed to coal combustion and vehicle emissions, while principal component analysis-multiple linear regression further indicated that primary emissions and secondary formation jointly influenced the PAC content, accounting for 60.4% and 39.6%, respectively. The exposure risk of soil PACs was dominated by 16 priority control PAHs; the non-priority PAHs' contribution to the exposure risk was only 6.4%.

Development and Field Application of a Diffusive Gradients in Thin-Films Passive Sampler for Monitoring Three Polycyclic Aromatic Hydrocarbon Derivatives and One Polycyclic Aromatic Hydrocarbon in Waters

Polycyclic aromatic hydrocarbon (PAH) derivatives are widely present in the environment, and some are more hazardous than their parent PAHs. However, compared to PAHs, PAH derivatives are less studied due to challenges in monitoring as a result of their low concentrations in environmental matrixes. Here, we developed a new passive sampler based on diffusive gradients in thin films (DGT) to monitor PAH derivatives and PAHs in waters. In the laboratory study, the XAD18-DGT device exhibited high adsorption rates and was demonstrated to be suitable for deployment in environmental waters on the timescale of months. The diffusion coefficients, D, were 5.30 × 10−6 cm2 s−1, 4.51 × 10−6 cm2 s−1, 4.03 × 10−6 cm2 s−1 and 3.34 × 10−6 cm2 s−1 for 9-fluorenone (9-FL), 1-chloroanthraquinone (1-CLAQ), 9-nitroanthracene (9-NA) and phenanthrene (Phe), respectively, at 25 °C. The DGT device’s performance was independent of pH, ionic strength, deployment time and storage time, indicating it can be widely used in natural waters. In the field study, the target pollutant concentrations measured by the DGT are in good accordance with those determined via grab sampling. Then, the DGT devices were utilized to quantify PAH derivatives and PAHs in several rivers in Hefei, China. This work demonstrates the feasibility of using the DGT technique to detect trace PAH derivatives and PAHs in waters.

Air-soil cycling of oxygenated, nitrated and parent polycyclic aromatic hydrocarbons in source and receptor areas

Polycyclic aromatic hydrocarbons (PAHs) and their oxygenated and nitrated derivatives, OPAHs and NPAHs, are semivolatile air pollutants which are distributed and cycling regionally. Subsequent to atmospheric deposition to and accumulation in soils they may re-volatilise, a secondary source which is understudied.We studied the direction of air-soil mass exchange fluxes of 12 OPAHs, 17 NPAHs, 25 PAHs and one alkylated PAH in two rural environments being influenced by the pollutant concentrations in soil and air, by season, and by land cover. The OPAHs and NPAHs in samples of topsoil, of ambient air particulate and gas phases and in the gas-phase equilibrated with soil were analysed by GC-APCI-MS/MS. The pollutants soil burdens show a pronounced seasonality, a winter maximum for NPAHs and PAHs and a summer maximum for OPAHs. One order of magnitude more OPAH and parent PAH are found stored in forest soil than in nearby grassland soil. Among a number of 3–4 ring PAHs, the OPAHs benzanthrone and 6H-benzo(c,d)pyren-6-one, and the NPAHs 1- and 2-nitronaphthalene, 9-nitrophenanthrene and 7-nitrobenz(a)anthracene are found to re-volatilise from soils at a rural background site in central Europe in summer. At a receptor site in northern Europe, net deposition of polycyclic aromatic compounds (PACs) prevails and re-volatilisation occurs only sporadic.Re-volatilisation of a number of PACs, including strong mutagens, from soils in summer and even in winter indicates that long-range atmospheric transport of primary PAC emissions from central Europe to receptor areas might be enhanced by secondary emissions from soils.

Indoor air levels of polycyclic aromatic compounds (PAC) in public buildings with creosote impregnated constructions – A pilot case study using passive samplers

Creosote has been used in Sweden as a wood preservative in buildings since the 19th century. These buildings can function as workplaces, homes, and cultural buildings to which the public has access. Creosote contains polycyclic aromatic hydrocarbons (PAH) which are well known carcinogens. To understand exposure and risks in an indoor environment, it is important to determine air levels of parent PAHs as well as the more toxic nitrated and oxygenated PAH derivatives (NPAH, OPAH).This study aims to investigate indoor air levels of polycyclic aromatic compounds (PACs) e.g., PAH, NPAH, OPAH and dibenzothiophenes in buildings containing creosote sources and whether these levels pose a health risk.Four cultural buildings were studied, all located within a radius of 130 m. Two were known to have creosote sources, and two had not. Polyurethane foam passive air samplers (PUF-PAS) were used to indicate possible point sources. PUF-PAS measurements were performed for one month in each building winter and summer. Simultaneously, PAC outdoor level measurements were performed.Buildings with creosote impregnated constructions had notably higher indoor air levels of PAC (31–1200 ng m−3) compared to the two buildings without creosote sources (14–45 ng m−3). The PAH cancer potency (sum of benzo[a]pyrene equivalents (BaPeq)) was more than one order of magnitude higher in the buildings containing creosote impregnated wood compared to reference buildings. The highest value was 5.1 BaPeq ng m−3 which was significantly higher than the outdoor winter measurement (1.3 BaPeq ng m−3). Fluoranthene and phenanthrene, with significant distribution in gas phase, but also several particulate NPAHs contributed significantly to the total cancer risk. Thus, creosote containing buildings can still contaminate the indoor air with PACs despite being over a hundred years old. The PUF-PAS was shown to be a good tool providing quantitative/semiquantitative measures of PACs exposure in indoor microenvironments.

Hazardous implications of halogenated polycyclic aromatic hydrocarbons in feedstuff: Congener specificity and toxic levels in feed ingredients and feeds

Studies have shown that halogenated polycyclic aromatic hydrocarbons (HPAHs), including chlorinated (ClPAHs) and brominated PAHs (BrPAHs), could be hazardous pollutants due to their pervasive occurrence in the environment. However, their accumulation properties and toxic potentials in animal feedstuffs remain unclear. This study investigated 75 congeners of parent PAHs, ClPAHs, and BrPAHs in animal-based feed ingredients and fish and swine feeds in Japan using a GC/Orbitrap MS system. The total parent PAHs ranged from below the method detection limit (<MDL) to 2700 ng/g lipid weight (l.w.), with the highest concentration found in fish oil. The total ClPAHs and BrPAHs were in the ranges of <MDL to 104.55 and 0.21–54.38 ng/g l.w., respectively, with their highest concentrations detected in fish meal. The maximum detection frequencies for parent PAHs, ClPAHs, and BrPAHs were detected for fluorene (75 %), trichloropyrene (86 %), and 2-bromonaphthalene (97 %), respectively. The highest ClPAH concentrations were dominated by dichloropyrene (61.92 ng/g l.w., fish meal). The BrPAHs were mostly contributed by 1-bromonaphthalene (33.94 ng/g l.w., animal fat) and 2-bromonaphthalene (22.37 ng/g l.w., fish meal). The toxic assessment estimated for target compounds in various feed ingredients and feed based on the toxic equivalency quotients (TEQs) revealed that HPAHs could additively contribute (up to 100 %) to PAH-like toxic effects. Despite their high detection frequencies and concentrations, several ClPAHs and BrPAHs had no relative toxic potency values. Thus, the TEQs were underestimated, indicating that urgent in-depth research is required to obtain toxicological data for predominant HPAHs.

Method Development for Quantitative Analysis of Polycyclic Aromatic Hydrocarbons, Nitrogen Heterocycles and Sulfur Heterocycles in Crude Oils Using Quadrupole Time-of-Flight Mass Spectrometry

An oil spill is a catastrophic event that results in various toxic polycyclic aromatic hydrocarbons (PAHs) entering the environment. Polycyclic aromatic nitrogen heterocycles (PANHs) are more toxic to the environment than their parent PAHs. The high cost and paucity of available PANH standards, the lower abundance of PANHs relative to PAHs, and the difficult separation due to co-elution with PAHs have all contributed to the scarcity of related published literature on the determination of these compounds. To overcome these challenges, a new quantitative method has been successfully developed and validated for the inclusion of 113 polycyclic aromatic carbon (PAC) compounds in a single injection. The 113 compounds consist of PAHs, nitrogen heterocycles, sulfur heterocycles, and alkylated equivalents. Distinct separation of the PANHs and their alkylated counterparts (APANHs) from PAHs was achieved using a gas chromatography quadrupole time-of-flight (GC-QToF) mass spectrometer. The instrument resolved compounds by the high-resolution extraction of monoisotopic masses, allowing response correction factors (RCFs) to be determined from available PANH standards and to calculate concentrations from PAH calibration standards. The developed method was applicable to crude oil samples, generating concentrations of PANHs and relevant information on compound stability for use in oil spill forensics investigation. Development of this practical PAC method provides a powerful tool for screening toxic contaminants, assessing environmental impact, and monitoring recovery following an oil spill.

Reactions of deoxyribonucleotide bases with sulfooxymethyl or halomethyl polycyclic aromatic hydrocarbons induce unwinding of DNA supercoils

Torsional stress in double-stranded DNA enables and regulates facets of chromosomal metabolism, replication, and transcription and requires regulatory enzymatic systems including topoisomerases and histone methyltransferases. As such, this machinery may be subject to deleterious effects from reactive mutagens, including ones from carcinogenic polycyclic aromatic hydrocarbon (PAH) adduct formation with DNA. Supercoiled plasmid DNA was investigated for its torsional responses to adducts formed in vitro from PAH benzylic carbocation reactive intermediates created spontaneously by release of leaving groups. PAH sulfate esters were found to (1) unwind DNA in a concentration dependent manner, and (2) provide maximum unwinding in a pattern consistent with known carcinogenicities of the parent PAHs, that is, 6-methylbenzo[a]pyrene > 7,12-methylbenz[a]anthracene > 3-methylcholanthrene > 9-methylanthracene > 7-methylbenz[a]anthracene > 1-methylpyrene. Supercoil unwinding was demonstrated to be dependent on the presence of sulfate or chloride leaving groups such that reactive carbocations were generated in situ by hydrolysis. In silico modeling of intercalative complex topology showed PAH benzylic carbocation reactive functional groups in alignment with target nucleophiles on guanine bases in a 5’-dCdG-3’ pocket in agreement with known formation of nucleotide adducts. Inhibitory or modulatory effects on PAH-induced supercoil unwinding were seen with ascorbic acid and an experimental antineoplastic agent Antineoplaston A10 in agreement with their known anticarcinogenic properties. In summary, the reactive PAH intermediates studied here undoubtedly participate in well-known mutational mechanisms such as frameshifts and apurinic site generation. However, they are also capable of random disruption of chromosomal supercoiling in a manner consistent with the known carcinogenicities of the parent compounds, and this mechanism may represent an additional detrimental motif worthy of further study for a more complete understanding of chemical carcinogenicity.

The occurrence and sources of PAHs, oxygenated PAHs (OPAHs), and nitrated PAHs (NPAHs) in soil and vegetation from the Antarctic, Arctic, and Tibetan Plateau

Although the fate of PAHs in the three polar regions (Antarctic, Arctic, and Tibetan Plateau) has been investigated, the occurrence and contamination profiles of PAH derivatives such as oxygenated PAHs (OPAHs) and nitrated PAHs (NPAHs) remain unclear. Some of them are more toxic and can be transformed from PAHs in environment. This study explored and compared the concentrations composition profiles and potential sources of PAHs, OPAHs, and NPAHs in soil and vegetation samples from the three polar regions. The total PAH, OPAH, and NPAH concentrations were 3.55–519, n.d.–101, and n.d.–1.10 ng/g dry weight (dw), respectively. The compounds were dominated by three-ring PAHs, and the most abundant individual PAH and OPAH were phenanthrene (PHE) and 9-fluorenone (9-FO), respectively. The sources of PAHs and their derivatives were qualitatively analyzed by the diagnostic ratios and quantified using the positive matrix factorization (PMF) model. The ratios of PAH derivatives to parent PAHs (9-FO/fluorene and 9,10-anthraquinone/anthracene) were significantly higher in the Antarctic samples than in the Arctic and TP samples, implying a higher occurrence of secondary OPAH and NPAH formation in the Antarctic region. To our knowledge, this is the first comparative study that simultaneously investigated the contamination profiles of PAHs and their derivatives in the three polar regions. The findings of this study provide a scientific basis for the development of risk assessment and pollution control strategies in these fragile regions.

The occurrence, sources, and health risks of substituted polycyclic aromatic hydrocarbons (SPAHs) cannot be ignored

Similar to parent polycyclic aromatic hydrocarbons (PPAHs), substituted PAHs (SPAHs) are prevalent in the environment and harmful to humans. However, they have not received much attention. This study investigated the occurrence, distribution, and sources of 10 PPAHs and 15 SPAHs in soil, water, and indoor and outdoor PM2.5 and dust in high-exposure areas (EAH) near industrial parks and low-exposure areas (EAL) far from industrial parks. PAH pollution in all media was more severe in the EAH than in the EAL. All SPAHs were detected in this study, with alkylated and oxygenated PAHs being predominant. Additionally, 3-OH-BaP and 1-OH-Pyr were detected in all dust samples in this study, and 6-N-Chr, a compound with carcinogenicity 10 times higher than that of BaP, was detected at high levels in all tap water samples. According to the indoor-outdoor ratio, PAHs in indoor PM2.5 in the EAH mainly originated from indoor pollution sources; however, those in the EAL were simultaneously affected by indoor-outdoor air exchange and indoor sources. Most target PAHs tended to deposit from air to dust, and this tendency was significantly negatively associated with the octanol-air partitioning coefficient of PAHs. SPAHs in the environment are primarily derived from the petroleum industry and the mixed combustion of gasoline, biomass, and coal. The toxicity equivalence factors of SPAHs were predicted using QSAR models to assess their lifetime carcinogenic risk (ILCR). The ILCRtotal from PAHs for adults in the EAH was >10−4. Though the levels of 6-N-Chr and 1-Me-Pyr in the environment were markedly lower than those of PPAHs, their ILCRs from PM2.5 inhalation and dermal contact with water exceeded 10−6. This study is significant for recognizing and controlling the health risks associated with SPAHs in humans.

Gas–particle partitioning and dry deposition of atmospheric parent, alkylated, nitrated and hydroxyl polycyclic aromatic hydrocarbons over the Bohai sea and northern Yellow sea in autumn

To elucidate the gas–particle partitioning characteristics and dry deposition contributions of polycyclic aromatic hydrocarbons (PAHs) in the marine environment, 23 integrated air samples were collected during a research cruise in the northern Yellow Sea (NYS) and Bohai Sea (BS) in mid-autumn 2020. The atmospheric concentrations of 23 parent PAHs (PPAHs), 18 alkylated PAHs (APAHs), five nitrated PAHs (NPAHs), and seven hydroxyl PAHs (OPAHs) in gaseous and particulate phases were measured simultaneously. The total concentrations of 53 PAHs varied from 8.77 to 348 ng/m3. The 2-ring and 3-ring PPAHs and APAHs had lower particle-bound fractions than those of the NPAHs and OPAHs. For the gas–particle partitioning of the PAHs, the gas–particle partitioning coefficients (Kp) estimated using an octanol–air partition coefficient (KOA)–based model and KOA/soot–air partition coefficient (KSA) dual model (KOA–KSA dual model) were lower than the Kp measured in the field. Underestimation of the Kp commonly occurred with these models, but the KOA–KSA dual model was more suitable than the KOA–based model for gas–particle partitioning of the 53 atmospheric PAHs in the BS and NYS. The estimated atmospheric dry deposition fluxes of the 53 PAHs ranged from 631 to 14,345 ng/m2/day. The BS receives a PAHs load of up to 117 tons/year. The study provides background information on the occurrence and environmental fate of PAHs and could be vitally important for environmental safety management for the Northwest Pacific Ocean.

Concurrent assessment of diffusive and advective PAH movement strongly affected by temporal and spatial changes

Chemical movement influences exposure, remediation and interventions. Understanding chemical movement in addition to chemical concentrations at contaminated sites is critical to informed decision making. Using seepage meters and passive sampling devices we assessed both diffusive and advective flux of bioavailable polycyclic aromatic hydrocarbons (PAHs) at three time points, across two seasons, at a former creosote site in St. Helens, Oregon, United States. To our knowledge, this is the first time both diffusive and advective fluxes have been measured simultaneously at a contaminated site. Concentrations of 39 parent PAHs were determined by gas chromatography triple quadrupole mass spectrometry. Across both seasons and all sites, diffusive flux of PAHs was up to three orders of magnitude larger than advective flux. Release of PAHs from sediments and water were identified, likely from legacy contamination, as well as deposition from the air into the site from contemporary and other sources. The majority of PAH movement was comprised of three and four ring PAHs. Chemical movement on the site was found to be spatially and temporally variable. Volatilization decreased and atmospheric deposition increased from summer to fall. At the locations with higher levels of contamination, sum PAH release from sediments decreased by more than two orders of magnitude from summer to late fall. These data reflect the spatial heterogeneity and temporal variability of this site and demonstrate the importance of seasonality in assessing chemical movement at contaminated sites. Results from this study can inform future legacy site assessments to optimize remediation strategies and assess remediation effectiveness.

Emissions of nitrated and oxygenated polycyclic aromatic hydrocarbons bound to coarse particles from solid fuel combustion

Parent polycyclic aromatic hydrocarbons (PAHs) emitted by residential sector have been well studied, however, data on PAHs derivatives such as nitrated PAHs (nPAHs) and oxygenated PAHs (oPAHs) are scarce. In this study, emission factors (EFs) of PM10-bound nPAHs and oPAHs from the combustion of eight different solid fuels in three different stoves in rural homes were measured in field, and a total of twelve fuel-stove combinations were included. Results showed that the field-based EFs for different fuel-stove combinations varied over three orders of magnitude, which ranged from 3.3 to 514 μg/kg and from 0.1 to 214 mg/kg for nPAHs and oPAHs, respectively. Biomass burning had 2.2 and 14.8 times higher EFs values of nPAHs and oPAHs compared with coal burning. The size distribution pattern of PAHs derivatives confirmed that they prefer to bind to fine particles. The composition profiles of nPAHs and oPAHs varied largely in different coals, while slightly in different biomasses. Furthermore, the nPAHs and oPAHs composition profiles varied largely from emission source to the nearby atmosphere, implying that the composition of PAHs derivative changed during small-scale transport process. Results from this study can fill in the data gap in PAHs derivative emissions from residential solid fuel combustion and help to evaluate the environmental and health impacts of residential solid fuel combustion.

Metagenomic insights into the microbial cooperative networks of a benz(a)anthracene-7,12-dione degrading community from a creosote-contaminated soil

Genotoxicity of PAH-contaminated soils can eventually increase after bioremediation due to the formation and accumulation of polar transformation products, mainly oxygenated PAHs (oxy-PAHs). Biodegradation of oxy-PAHs has been described in soils, but information on the microorganisms and mechanisms involved is still scarce. Benz(a)anthracene-7,12-dione (BaAQ), a transformation product from benz(a)anthracene frequently detected in soils, presents higher genotoxic potential than its parent PAH. Here, using sand-in-liquid microcosms we identified a specialized BaAQ-degrading subpopulation in a PAH-contaminated soil. A BaAQ-degrading microbial consortium was obtained by enrichment in sand-in-liquid cultures with BaAQ as sole carbon source, and its metagenomic analysis identified members of Sphingobium, Stenotrophomonas, Pusillimonas, Olivibacter, Pseudomonas, Achromobacter, and Hyphomicrobiales as major components. The integration of data from metabolomic and metagenomic functional gene analyses of the consortium revealed that the BaAQ metabolic pathway was initiated by Baeyer-Villiger monooxygenases (BVMOs). The presence of plasmid pANTQ-1 in the metagenomic sequences, identified in a previous multi-omic characterization of a 9,10-anthraquinone-degrading isolate recovered from the same soil, suggested the occurrence of a horizontal gene transfer event. Further metagenomic analysis of the BaAQ-degrading consortium also provided insights into the potential roles and interactions within the consortium members. Several potential auxotrophies were detected, indicating that relevant nutritional interdependencies and syntrophic associations were taking place within the community members, not only to provide suitable carbon and energy sources, but also to supply essential nutrients and cofactors. Our work confirms the essential role that BVMO may play as a detoxification mechanism to mitigate the risk posed by oxy-PAH formation during bioremediation of contaminated soils.

Polycyclic aromatic hydrocarbons (PAHs) in coal preparation plant products: A contributor to environmental pollution

Coal and coal gangue are petrogenic sources of polycyclic aromatic hydrocarbons (PAHs), which cause adverse impacts on the environment. Raw coal, cleaned coal, slime, slack gangue, and lump gangue from the Pingshuo No. 1 Coal Preparation Plant, China, were analyzed to determine the concentrations and compositions of 16 priority parent PAHs (16PAHs) and their alkylated derivatives (aPAHs). The ∑16PAH and ∑aPAH concentrations in the samples ranged from 18.7 to 139.2 mg/kg and 22.2 to 262.3 mg/kg, respectively, and ranked as follows: cleaned coal > raw coal > slime > lump gangue > slack gangue. Coal gangues had a higher proportion and lower degree of alkylation of 4–6-ring PAHs than coals. A summary analysis of references related to coal and coal gangue diagnostic ratios showed that their ratios could not be used to differentiate them from other PAH sources, indicating that the release of particulate coal and coal gangue would increase the uncertainty of environmental PAH identification results. The diagnostic ratios of coal gangue were relatively concentrated, and comparing the ratio distribution could reveal the coal gangue source PAHs. The toxicity risk of slack gangue was higher than that of lump gangue based on the benzo[a]pyrene-equivalent concentration; hence, more attention should be given to its escape to the environment.

Breathing in danger: Unveiling the link between human exposure to outdoor PM2.5-bound polycyclic aromatic hydrocarbons and lung cancer risk in an urban residential area of China

Numerous studies have extensively examined the risk of lung cancer associated with polycyclic aromatic hydrocarbons (PAHs), with particular emphasis on the 16 priority PAHs. However, this may underestimate the actual risk. This study seeks to enhance the current risk assessment framework by integrating four additional parent PAHs such as Dibenzo[a,h]pyrene, Dibenzo[a,l]pyrene, Dibenzo[a,e]pyrene, 7H-benzo[c]fluorene with potentially high risk of causing cancer. By considering their physicochemical properties, metabolism, and bioavailability, the study also examines the relationship between low molecular weight (LMW) - and high molecular weight (HMW)-PAH doses and the risk of developing cancer in the human lungs. The study was conducted in Ningbo, China and identified five PAH sources: natural gas combustion (NGC), vehicular exhaust (VE), coal combustion (CC), biomass burning (BB), and volatilization of unburnt fuel (VUF). This study emphasizes the elevated risk associated with highly carcinogenic PAHs, as they consistently exceed acceptable limits for lung cancer risk throughout the year. Based on the study's estimation, approximately 324 out of every one million individuals exposed to PAHs face an increased cancer risk over their lifetime. This research emphasizes the importance of identifying source specific lung cancer risk in residential areas to protect the exposed population. Moreover, while there is a moderate connection between LMW-PAH doses and lung cancer risk, a strong relationship is observed with HMW-PAHs.

Nitro substituent caused negative impact on occurrence and development of atherosclerotic plaque by PM2.5-bound polycyclic aromatic compounds

PM2.5 exposure is a significant risk factor for the occurrence and development of atherosclerosis. Polycyclic aromatic hydrocarbons (PAHs) play prominent roles in PM2.5-related toxicity. However, the nitrated derivatives of PAHs, nitrated polycyclic aromatic hydrocarbons (NPAHs), have strong oxidizing properties due to the nitro substituents. Thus, the in vivo and in vitro experiments exposure to benzo[a]pyrene (BaP) and 6-nitro benzo[a]pyrene (NBaP) were conducted to evaluate the effect of nitro substituent on the atherosclerosis due to (or attributable to) PAHs. The results showed that NBaP exposure induced the inhibition of human umbilical vein endothelial cells (HUVECs) viability and cell morphology damage via more severe oxidative stress than BaP exposure. Furthermore, exposure to PM2.5-bound NBaP caused dyslipidemia in the Apolipoprotein E-deficient (ApoE−/−) mice, including the increment of total cholesterol, triglycerides, low-density lipoprotein cholesterol, and malondialdehyde levels, and the decrement of high-density lipoprotein cholesterol levels, superoxide dismutase and glutathione peroxidase levels in serum and aorta. Furthermore, histology showed atherosclerotic plaque in the aorta of ApoE−/− mice. However, there were no significant differences of the physiological and pathological changes between BaP and control groups. Thus, NPAHs induced endothelial dysfunction and dyslipidemia via severe oxidative stress, and further accelerated the occurrence and development of atherosclerosis compared with the parent PAHs. Our findings provide the first evidence that nitro substituent caused much severer negative health impact of polycyclic aromatic compounds, which highlight the significance of NPAHs in health risk estimation of polycyclic aromatic compounds.

Gender-specific associations between mixture of polycyclic aromatic hydrocarbons and telomere length.

Evidence shows the relationships of individual environmental PAHs by their urinary metabolites with relative telomere length (RTL), which may be affected by biological gender differences. Since plasma parent PAHs are not metabolized, it may reflect human exposure to PAHs more realistically in daily life. Thus, exploring joint associations between plasma parent PAHs and RTL is urgent, which may identify the major contributor to its adverse effect. In this study,2577 participants were obtained from the Henan Rural Cohort. The level of PAHs in blood samples was detected by gas chromatography coupled with tandem mass spectrometry. RTL in blood samples was detected by quantitative polymerase chain reaction. Generalized linear models or quantile g-computation were performed to evaluate the associations between the individual or a mixture of PAHs and RTL. Results from generalized linear models showed that each unit increment in BghiP value corresponded to a 0.098 (95%CI: 0.067, 0.129) increment in RTL for men; each unit increment in BaP, BghiP and Flu value corresponded to a 0.041 (95%CI: 0.014, 0.068), 0.081 (95%CI: 0.055, 0.107) and 0.016 (95%CI: 0.005, 0.027) increment in RTL for women. Results from quantile-g computation revealed that each one-quantile increment in the mixture of 10 PAHs corresponded to a 0.057 (95%CI: 0.021, 0.094) and 0.047 (95%CI: 0.003, 0.091) increment in RTL valuesof women and men, but these associations were mainly ascribed to three PAHs for women (BaP, Flu and BghiP) and men (BaP, BghiP and Pyr), respectively. Similar results were found in smoking men and cooking women without smoking. Our study foundthat exposure to 10 PAHs mixture was positively associated with RTL across gender, mainly attributed to Flu, BaP and BghiP, implicating that gender-specific associations may be ascribed to tobacco and cooking smoke pollution. The findings provided clues for effective measures to control PAHs pollutants-related aging disease.Clinical trial registration The Henan Rural Cohort Study has been registered at the Chinese Clinical Trial Register (Registration number: ChiCTR-OOC-15006699). Date of registration: 06 July 2015. http://www.chictr.org.cn/showproj.aspx?proj=11375 .

Characterization of scrubber water discharges from ships using comprehensive suspect screening strategies based on GC-APCI-HRMS

An extended suspect screening approach for the comprehensive chemical characterization of scrubber discharge waters from exhaust gas cleaning systems (EGCSs), used to reduce atmospheric shipping emissions of sulphur oxides, was developed. The suspect screening was based on gas chromatography coupled with high-resolution mass spectrometry (GC-HRMS) and focused on the identification of polycyclic aromatic hydrocarbons (PAHs) and their alkylated derivatives (alkyl-PAHs), which are among the most frequent and potentially toxic organic contaminants detected in these matrices. Although alkyl-PAHs can be even more abundant than parent compounds, information regarding their occurrence in scrubber waters is scarce. For compound identification, an in-house compound database was built, with 26 suspect groups, including 25 parent PAHs and 23 alkyl-PAH homologues. With this approach, 7 PAHs and 12 clusters of alkyl-PAHs were tentatively identified, whose occurrence was finally confirmed by target analysis using GC coupled with tandem mass spectrometry (GC-MS/MS). Finally, a retrospective analysis was performed to identify other relevant (poly)cyclic aromatic compounds (PACs) of potential concern in scrubber waters. According to it, 18 suspect groups were tentatively identified, including biphenyls, dibenzofurans, dibenzothiophenes and oxygenated PAHs derivatives. All these compounds could be used as relevant markers of scrubber water contamination in heavy traffic marine areas and be considered as potential stressors when evaluating scrubber water toxicity.

A Systematic Review of Polycyclic Aromatic Hydrocarbon Derivatives: Occurrences, Levels, Biotransformation, Exposure Biomarkers, and Toxicity.

Polycyclic aromatic hydrocarbon (PAH) derivatives constitute a significant class of emerging contaminants that have been ubiquitously detected in diverse environmental matrixes, with some even exhibiting higher toxicities than their corresponding parent PAHs. To date, compared with parent PAHs, fewer systematic summaries and reanalyses are available for PAH derivatives with great environmental concerns. This review summarizes the current knowledge on the chemical species, levels, biotransformation patterns, chemical analytical methods, internal exposure routes with representative biomarkers, and toxicity of PAH derivatives, primarily focusing on nitrated PAHs (NPAHs), oxygenated PAHs (OPAHs), halogenated PAHs (XPAHs), and alkylated PAHs (APAHs). A collection of 188 compounds from four categories, 44 NPAHs, 36 OPAHs, 56 APAHs, and 52 XPAHs, has been compiled from 114 studies that documented the environmental presence of PAH derivatives. These compounds exhibited weighted average air concentrations that varied from a lower limit of 0.019 pg/m3 to a higher threshold of 4060 pg/m3. Different analytical methods utilizing comprehensive two-dimensional gas chromatography coupled with high-resolution time-of-flight mass spectrometry (GC × GC-TOF-MS), gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF-MS), comprehensive two-dimensional gas chromatography coupled to quadrupole mass spectrometry (GC × GC-QQQ-MS), and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), that adopted untargeted strategies for the identification of PAH derivatives are also reviewed here. Additionally, an in-depth analysis of biotransformation patterns for each category is provided, including the likelihood of specific biotransformation reaction types. For the toxicity, we primarily summarized key metabolic activation pathways, which could result in the formation of reactive metabolites capable of covalently bonding with DNA and tissue proteins, and potential health outcomes such as carcinogenicity and genotoxicity, oxidative stress, inflammation and immunotoxicity, and developmental toxicity that might be mediated by the aryl hydrocarbon receptor (AhR). Finally, we pinpoint research challenges and emphasize the need for further studies on identifying PAH derivatives, tracking external exposure levels, evaluating internal exposure levels and associated toxicity, clarifying exposure routes, and considering mixture exposure effects. This review aims to provide a broad understanding of PAH derivatives' identification, environmental occurrence, human exposure, biotransformation, and toxicity, offering a valuable reference for guiding future research in this underexplored area.