Carcinogenic Polycyclic Aromatic Hydrocarbons Research Articles

Corelease of Genotoxic Polycyclic Aromatic Hydrocarbons and Nanoparticles from a Commercial Aircraft Jet Engine - Dependence on Fuel and Thrust.

Jet engines are important contributors to global CO2 emissions and release enormous numbers of ultrafine particles into different layers of the atmosphere. As a result, aviation emissions are affecting atmospheric chemistry and promote contrail and cloud formation with impacts on earth's radiative balance and climate. Furthermore, the corelease of nanoparticles together with carcinogenic polycyclic aromatic hydrocarbons (PAHs) affects air quality at airports. We studied exhausts of a widely used turbofan engine (CFM56-7B26) operated at five static thrust levels (idle, 7, 30, 65, and 85%) with conventional Jet A-1 fuel and a biofuel blend composed of hydro-processed esters and fatty acids (HEFA). The particles released, the chemical composition of condensable material, and the genotoxic potential of these exhausts were studied. At ground operation, particle number emissions of 3.5 and 0.5 × 1014 particles/kg fuel were observed with highest genotoxic potentials of 41300 and 8800 ng toxicity equivalents (TEQ)/kg fuel at idle and 7% thrust, respectively. Blending jet fuel with HEFA lowered PAH and particle emissions by 7-34% and 65-67% at idle and 7% thrust, respectively, indicating that the use of paraffin-rich biofuels is an effective measure to reduce the exposure of airport personnel to nanoparticles coated with genotoxic PAHs (Trojan horse effect).

Functionally coherent transcriptional responses of Jatropha curcas and Pseudomonas fragi for rhizosphere mediated degradation of pyrene

Pyrene is an extremely hazardous, carcinogenic polycyclic aromatic hydrocarbon (PAH). The plant–microbe interaction between Pseudomonas fragi DBC and Jatropha curcas was employed for biodegradation of pyrene and their transcriptional responses were compared. The genome of P. fragi DBC had genes for PAH degrading enzymes i.e. dioxygenases and dehydrogenases, along with root colonization (trpD, trpG, trpE and trpF), chemotaxis (flhF and flgD), stress adaptation (gshA, nuoHBEKNMG), and detoxification (algU and yfc). The transcriptional expression of catA and yfc that respectively code for catabolic enzyme (catechol-1, 2-dioxygnase) and glutathione-s-transferase for detoxification functions were quantitatively measured by qPCR. The catA was expressed in presence of artificial root exudate with or without pyrene, and glucose confirming the non-selective approach of bacteria, as desired. Pyrene induced 100-fold increase of yfc expression than catA, while there was no expression of yfc in absence of pyrene. The transcriptome of plant roots, in presence of pyrene, with or without P. fragi DBC inoculation was analysed. The P. fragi DBC could upregulate the genes for plant growth, induced the systemic acquired resistance and also ameliorated the stress response in Jatropha roots.

Polycyclic aromatic hydrocarbons (PAHs) in the surficial sediments of the Abadan freshwater resources − Northwest of the Persian Gulf

This research focused on investigating the contamination levels, sources, and potential ecological and human health risks associated with 16 polycyclic aromatic hydrocarbons (PAHs) present in surficial sediments of the Abadan freshwater resources in the northwest of the Persian Gulf. The concentrations of ∑16PAHs varied between 67.8 and 57,748 ng/g with an average of 8222 ng/g. Approximately 30 % of the ∑16PAHs were attributed to seven carcinogenic PAHs. The predominant components of the PAHs found in the sediments were the 3- and 4-ring PAHs, which accounted for approximately 63 % of the total PAHs present in the surficial sediments. The diagnostic ratios and principal component analysis (PCA) indicate that the PAHs detected in the sediments originated from various sources, including traffic emissions, coal, and biomass combustion, petroleum leakage, and wastewater. According to our ecological risk assessment, substantial harm to the biota was observed in the Arvand River. An assessment of cancer risk indicated that both adults and children in Abadan area are exposed to a considerable cancer risk due to the presence of PAHs. In conclusion, ongoing monitoring of PAH pollution and implement measures to protect freshwater ecosystems near the Persian Gulf are essential.

Mass transfer research on solid-liquid separation of extracted coal tar residue based on diffusion model

A large amount of coal tar residue (CTR) produced in the process of coal coking and tar processing is recognized as hazardous industrial waste with a high carbon content and strong carcinogenic polycyclic aromatic hydrocarbons. Through solvent extraction, CTR can be separated into economically valuable tar and fixed carbon, and waste recycling can be realized. In this paper, a mathematical model of CTR solid-liquid extraction is established based on a diffusion model and experiments, and the mass transfer law, mass transfer equation, and influence of different conditions of solid-liquid separation of CTR from toluene extraction are studied. First, the empirical formula is used to derive the change in the mass transfer coefficient kf outside the particles during extraction, and the kf gradually decreases as the extraction progresses. The particle swarm optimization is used to obtain the best effective diffusion coefficient Deff, inside the particles, which is 9.65 × 10−14 m2/s. The effective diffusion coefficient, Deff, was determined and corrected based on experimental data. A second-order function was fitted to describe the variation of Deff with temperature. MATLAB software was used to solve the model the concentration change law and extraction law during extraction were obtained. According to the model simulation, the influence of different conditions such as agent residue ratio, stirring speed, particle radius, and temperature on the extraction process is calculated.

Characterisation of flavourous sesame oil obtained from microwaved sesame seed by subcritical propane extraction

This study developed a novel and green method to produce fragrant sesame oil using microwaves and subcritical extraction (SBE). Sesame seeds were microwaved at 540 W for 0–9 min before subcritical propane extraction at 40 °C and 0.5 MPa. SBE caused less deformation to the cellular microstructure of sesame cotyledons while dramatically improving oil yield (96.7–97.1 %) compared to screw processing (SP) (53.1–58.6 %). SBE improved extraction rates for γ-tocopherol (381.1–454.9 μg/g) and sesame lignans (917.9–970.4 mg/100 g) in sesame oil compared to SP (360.1–443.8 μg/g and 872.8–916.8 mg/100 g, respectively). Microwaves generated aroma-active heterocyclics and phenolics faster than hot-air roasting in sesame oil with a better sensory profile. SBE had a higher extraction rate for aroma-active terpenes, alcohols, and esters while reducing the concentrations of carcinogenic PAHs and HCAs in sesame oil. The novel combination process of microwaves and subcritical extraction is promising in producing fragrant sesame oil with superior qualities.

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.

Characterisation of polycyclic aromatic hydrocarbons associated with indoor PM0.1 and PM2.5 in Hanoi and implications for health risks

Polycyclic aromatic hydrocarbons (PAHs) associated with indoor PM pose a high risk to human health because of their toxicity. A total of 160 daily samples of indoor PM2.5 and PM0.1 were collected in Hanoi and analysed for 15 PAHs. In general, the concentrations of carcinogenic PAHs (car-PAHs) accounted for 21% ± 2%, 19.1% ± 2%, and 26% ± 3% of the concentrations of 15 PAHs in PM2.5, PM0.1-2.5, and PM0.1, respectively. Higher percentages of car-PAHs were found in smaller fractions (PM0.1), which can be easily deposited deep in the pulmonary regions of the human respiratory tract. The concentrations of 15 PAHs were higher in winter than in summer. The most abundant PAH species were naphthalene and phenanthrene, accounting for 11%–21% and 19%–23%, respectively. The PAH content in PM0.1 was almost twice as high as those in PM2.5 and PM0.1-2.5. Principal component analysis found that vehicle emissions and the combustion of biomass and coal were the main outdoor sources of PAHs, whereas indoor sources included cooking activities, the combustion of incense, scented candles, and domestic uses in houses. According to the results, 60%–90% of the PM0.1-bound BaP(eq) was deposited in the alveoli region, whereas 63%–75% of the PM2.5-bound BaP(eq) was deposited in head airways (HA), implying that most of the particles deposited in the HA region were PM0.1-2.5. The contributions of dibenz[a,h]anthracene and benzo[a]pyrene were dominant and contributed from 36% to 51% and 31%–50%, respectively, to the carcinogenic potential, whereas benzo[a]pyrene contributed from 30% to 49% to the mutagenic potential for both size fractions. The incremental lifetime cancer risk, simulated by Monte Carlo simulation, was within the limits set by the US EPA, indicating an acceptable risk for the occupants. These results provide an additional scientific basis for protecting human health from exposure to indoor PAHs.

Indoor and Personal PM2.5 Samples Differ in Chemical Composition and Alter Zebrafish Behavior Based on Primary Fuel Source.

Fine particulate matter (PM2.5) exposure has been linked to diverse human health impacts. Little is known about the potential heterogeneous impacts of PM2.5 generated from different indoor fuel sources and how exposure differs between personal and indoor environments. Therefore, we used PM2.5 collected by one stationary sampler in a kitchen and personal samplers (female and male participants), in homes (n = 24) in Kheri, India, that used either biomass or liquified petroleum gas (LPG) as primary fuel sources. PM2.5 samples (pooled by fuel type and monitor placement) were analyzed for oxidative potential and chemical composition, including elements and 125 organic compounds. Zebrafish (Danio rerio) embryos were acutely exposed to varying concentrations of PM2.5 and behavioral analyses were conducted. We found relatively high PM2.5 concentrations (5-15 times above World Health Organization daily exposure guidelines) and varied human health-related chemical composition based on fuel type and monitor placement (up to 15% carcinogenic polycyclic aromatic hydrocarbon composition). Altered biological responses, including changes to mortality, morphology, and behavior, were elicited by exposure to all sample types. These findings reveal that although LPG is generally ranked the least harmful compared to biomass fuels, chemical characteristics and biological impacts were still present, highlighting the need for further research in determining the safety of indoor fuel sources.

Polycyclic aromatic hydrocarbons in the sediments of highly polluted coastal area in the Red Sea: levels, spatial distribution, and risk assessment.

The southern part of the Jeddah coast faces a range of pollution challenges that can impact the water quality and ecosystem in the area. Pollution sources are represented mainly by treated wastewater (TWW), harbor activities, and atmospheric deposition from vehicle exhaustemissions. Polycyclic aromatic hydrocarbons (PAHs) are among the persistent organic pollutants that interfere with all environmental matrices and could cause humane mutagenic and carcinogenic effects. In the present study, 16 priority parent and 21 methylated PAHs (∑37PAHs) were assessed in the sediments of three hot spot coastal sites (Islamic Jeddah port, Al-Arbaeen, and Al-Shabab lagoons) to evaluate the factors affecting their spatial distribution, examine their probable sources and potential adverse effects. The total detected concentrations of ∑37PAHs ranged from 785.9 to 8359.8ng/g dw (average: 2296.3 ± 2017.3ng/g dw). The highest levels of ∑37PAHs were detected near TWW stations. The highest individual PAH congeners observed were phenanthrene, anthracene, and pyrene. PAH molecular diagnostic ratios pointed out different pyrogenic sources. In some specific stations, there was an overlap of petrogenic origin. The sediment samples contained high concentrations of methylated PAHs, with concentrations ranging from 558.42 to 6321.21ng/g dw and an average concentration of 1679.1 ± 1430.7ng/g dw. The sediment quality guidelines indicated that adverse biological effects are likely to occur at least at the two TWW disposal stations and the sediments in these stations are at risk. The values of the mutagenic equivalence quotient (MEQ) and toxic equivalence quotient (TEQ) of carcinogenic PAHs were recorded at 39.88 and 33.17ng/g, respectively.

Molecular-scale investigation on the composition, sources and secondary generation of organic aerosols in polluted central China

Molecular analyses help to better understand the overall picture of characteristics, meteorological effects, sources, and secondary transformations of organic aerosols (OA). A two-year observation campaign was conducted in polluted central China during 2019–2021, and 130 compounds of molecular OA (quantified organic compounds, QOCs) were quantified. The average concentration of QOCs was 1971 ng/m3, showing the highest normalized QOCs in PM2.5 (31 ng/μg) compared to others. Among the QOCs, the polar category contributed 84%, with the dominated abundant fatty acids observed. The enhanced acid ratios of malonic/succinic and octadecanoic/oleic in summer indicated higher aerosol age, significantly promoted by temperature. Three benzenetricarboxylic acids, mostly from secondary formation, also exhibited quite high concentrations in summer. The noticeable presence of carcinogenic polycyclic aromatic hydrocarbons (PAHs) (45% of ∑28PAHs) highlighted severe health risks associated with human exposure, particularly in winter (56 ng/m3, approximately 7 times that in summer). According to the random forest model assessments, meteorological conditions in summer were most conducive to eliminating pollutants, while that in winter contributed 19% of QOC concentration. The Positive Matrix Factorization analysis revealed that anthropogenic secondary organic aerosols (ASOA) and biogenic SOA (BSOA) jointly accounted for 32% of QOCs, followed by biomass burning (20%), coal combustion (17%), vehicle emissions (16%), and cooking (15%). ASOA was positively correlated with O3 (r = 0.58) and aerosol acidity facilitated ASOA production at 40% < relative humidity <80%. On polluted days, BSOA increased as NO2 and PM2.5 increased, contributing to worsened aerosol pollution. In spring and summer, gas-phase oxidation contributed more saturated dicarboxylic acids (52 and 55%), while aqueous-phase conversion predominated in autumn and winter (59 and 66%). This study provides new information on particulate molecular organic compounds as well as the secondary transformation, which is of great significance for formulating the prevention and control measures of aerosol pollution.

Hierarchical metal-dielectric-metal nanostructures as SERS sensors for sensitive detection of polycyclic aromatic hydrocarbons

Due to the wide variety, inaccessible self-degradation, high mutagenicity and carcinogenicity of polycyclic aromatic hydrocarbons (PAHs), it still remains challenging to efficiently identify them, especially in real environment. Herein, we develop a bottom-up self-assembly strategy to construct a sandwich-like hierarchical metal-dielectric-metal system composed of mercaptan-modified Au nanospheres-graphene oxide (GO)-Ag nanowires as surface-enhanced Raman spectroscopy (SERS) sensors for sensitive detection of PAHs. The synergistic integration of metallic layers and the organic mercaptan and GO layer not only provides localized enhanced electromagnetic field region which is induced by the nanogap between the top Au nanospheres and the bottom Ag nanowires, but also effectively traps PAHs in the middle layer through hydrophobic interaction of mercaptan and π-π stacking interaction of GO. By rationally optimizing the SERS substrates, the lowest detection concentrations of pyrene, anthracene, phenanthrene and benzo[a]pyrene could be reached, respectively, at 10−8 M, 10−8 M, 10−8 M and 10−7 M. The hierarchical system shows excellent uniformity, reproducibility and is able to identify various types of PAHs in multi-component mixtures as well as in real water environment. This strategy can provide a general platform to identify hazardous pollutants that are hydrophobic or contain benzene rings, such as pesticides, dyes and polychlorinated biphenyls.

Firefighters' personal exposure to gaseous PAHs during controlled forest fires: A case study with estimation of respiratory health risks and in vitro toxicity

Firefighters are daily exposed to adverse health-hazardous pollutants. Polycyclic aromatic hydrocarbons (PAHs), well known endocrine disruptors with carcinogenic, mutagenic, and teratogenic properties, are among the most relevant pollutants. The characterization of firefighters' occupational exposure to airborne PAHs remains limited; information is scarce for European firefighters. Also, the in vitro assessment of firefighters' respiratory health risks is inexistent. To reply to these scientific gaps, this work characterizes the levels of gaseous PAH in firefighters' personal air during regular working activities at controlled forest fires and at fire stations (control group). Breathable levels were 2.2–26.7 times higher during fire events than in the control group (2.63–32.63 μg/m3versus 1.22 μg/m3, p < 0.001); the available occupational guidelines (100 and 200 μg/m3 defined by the US National Institute for Occupational Safety and Health and the North American Occupational Safety and Health Administration, respectively) were not exceeded. Concentrations of (possible/probable) carcinogenic PAHs were 1.9–15.3 times superior during firefighting (p < 0.001). Increased values of total benzo(a)pyrene equivalents (p = 0.101), dose rates (p < 0.001), and carcinogenic risks (p = 0.063) were estimated in firefighters during controlled fires comparatively with the control group. Firefighters' breathable gaseous phase collected during fire events contributed to induce a significant viability decrease (<70 %; p < 0.05) in A549 and Calu-3 cell lines. The principal component analysis (PCA) allowed the differentiation between firefighters participating in controlled fire events from the control group. PCA analysis demonstrated the potential of PAHs to distinguish different sources of firefighters´ occupational exposure and of combining estimated health risk parameters with in vitro toxicities determined with human-breathable air collected during real-life scenarios. Overall, the participation in controlled fire events contributes to the respiratory health burden of firefighting forces. However, more studies are needed to corroborate these preliminary findings, explore the respiratory toxicological mechanisms, and support the implementation of preventive actions and mitigation strategies to pursue firefighters' health.

Levels of polycyclic aromatic hydrocarbon in the soil around typical automobile repair workshops in Nigeria

Background: This study determined the levels of polycyclic aromatic hydrocarbons (PAHs) in the soil around typical automobile repair workshops in Nigeria. Risk assessment associated with human contact with the soil was carried out using hazard quotient (HQ) and incremental life cancer risk (ILCR) from human unconscious ingestion and dermal contact with the soil. Methods: Soil samples were obtained at different automobile workshops in Ado-Ekiti, Western Nigeria. The PAHS in the samples were extracted using dichloromethane and extracts were cleaned up using silica-alumina gel open column chromatography. Analysis of PAHs in the soil was done using a gas chromatograph coupled to a mass selective detector operated on electron ionization mode. Results: The results showed the mean PAHs concentration at the sampling locations ranged from 5.58 – 6.4 μg/g and the mean ∑ carcinogenic PAHs was 58.4 μg/g, equivalent to 59.39 % of total PAHs observed. The mean Toxicity equivalence (TEQs) ranged from 0.02 - 6.680 μg/g. Benzo (a) pyrene and dibenzo(a,h)anthracene have the highest toxicity equivalent. The total ILCRs from accidental ingestion and dermal contact in adults were 1 ×10^(-3) and 9.8 ×10^(-5) , for adults and children respectively; both are higher than the permissible limit stipulated by the World Health Organization.The HQs obtained are several folds higher than 1. This implies high carcinogenic and non-carcinogenic risks for children and adults. Conclusions: The study revealed the levels of PAHs and also revealed the risks associated with human contact with the soil around automobile repair workshops.

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.

Assessment of High-temperature Refined Charcoal to Improve the Safety of Grilled Meat Through the Reduction of Carcinogenic PAHs

This study presents mitigation strategies for reducing carcinogenic polycyclic aromatic hydrocarbon (PAH) contamination levels in grilled meat using high-temperature refined charcoal (HTC) prepared by Iwate kiln, also known as high-quality charcoal. Four different types of HTC were investigated for their properties in conjunction with their potential to reduce PAHs in grilled meat, including high-temperature Eucalyptus charcoal (HTEC), Leucaena charcoal (HTLC), Acacia charcoal (HTAC), and bamboo charcoal (HTBC). The results showed that all HTCs had higher fixed carbon, higher heating value, and lower volatile compounds (83.07–87.81%, 7,306–7,765 Kcal/g, and 6.98–11.97%, respectively) than commercial low-temperature refined charcoal (LTC) (65.33%, 6,728 Kcal/g, and 22.22%, respectively). The current high fixed carbon content and heating value responded to the rising maximum temperature of charcoal up to 500–600°C, providing heat source stabilization to control the radiant energy exposure of charcoal during grilling, thereby shortening grilling time. The PAH16 value of the LTC-grilled sample (144.41 μg/kg) was significantly higher than that of the HTEC, HTLC, and HTAC-grilled samples (98.21, 80.75, and 79.56 μg/kg, respectively). However, PAH16 levels in the sample grilled with HTBC were unexpectedly high (265.75 μg/kg), and cooking loss was not significantly different between samples grilled with all charcoals. Overall, the findings indicated that using HTC prepared from Eucalyptus, Leucaena, and Acacia woods could reduce PAH contamination in grilled pork by up to 45%. However, more research is needed to determine the best preparation method for high-quality charcoal made from bamboo.

Profile of carcinogenic polycyclic aromatic hydrocarbons in relation with smoking status in COPD patients

Profile of carcinogenic polycyclic aromatic hydrocarbons in relation with smoking status in COPD patients

Predicted no-effect concentration for eight PAHs and their ecological risks in seven major river systems of China

The initial step in the assessment of the ecological risk of pollutants is to determine the predicted no-effect concentration (PNEC). However, ecological risk assessments of eight carcinogenic polycyclic aromatic hydrocarbons (PAHs), including dimethylbenz[a]anthracene (DMBA), methylcholanthrene (MCA), benzo(a)anthracene (BaA), chrysene (CHR), benzo(b)fluoranthene (BbF), benzo(k)fluoranthene (BkF), benzo(a)pyrene (BaP), and dibenzo(a,h)anthracene (DBA), are rarely conducted due to the lack of their PNECs based on test data. In this study, quantitative structure-activity relationship (QSAR) models and interspecies correlation estimation (ICE) models were combined to predict the acute toxicity of these eight target PHAs. A Kolmogorov–Smirnov analysis for species sensitivity distributions (SSDs) of native and all species was conducted. There was no significant difference between the predictions for native Chinese species and the predictions for all species by the QSAR-ICE models. In addition, the feasibility of the QSAR-ICE models was demonstrated by comparing the SSD curves constructed by measured toxicity data of BaP and those predicted by the QSAR-ICE models. The PNECs of the eight PAHs were estimated based on the SSDs and acute to chronic ratio (ACR) method; these data were 0.071 μg/L, 0.033 μg/L, 0.049 μg/L, 0.114 μg/L, 0.019 μg/L, 0.021 μg/L, 0.038 μg/L and 0.054 μg/L for DMBA, DBA, BaP, MCA, BaA, CHR, BbF, BkF, respectively. The higher PNECs of the alkylated PAHs suggested their lower ecological risks. Based on the mixed risk quotient (mRQ) of PAHs through the concentration addition (CA) model, high ecological risk watersheds, such as the Songhua River (mRQ = 1.95), the Liao River (mRQ = 4.59), and the Huai River (mRQ = 1.93), were identified.

Assessment of health risks of PAHs from rural cooking emissions: Neighborhood diffusion and the impact of village settlement characteristics

Solid fuel cooking in rural areas has led to substantial emissions of air pollutants, notably polycyclic aromatic hydrocarbons (PAHs), especially in developing countries such as China. The potential health risks associated with outdoor exposure of residents to PAHs from fugitive cooking exhaust within rural settlements also merit consideration. Consequently, this study employs computational fluid dynamics (CFD) techniques to evaluate the neighborhood diffusion of benzo[a]pyrene (B[a]P), a carcinogenic PAH congener, in a cluster shape rural settlement. Subsequently, the health risks associated with outdoor exposure to neighborhood-diffused PAHs were quantified using the incremental lifetime cancer risk (ILCR) for the susceptible population. The simulations encompass four settlement characteristics, including the angle between approaching wind and streets (θ), street width (SW), slit distance (SD), and building arrangement, to analyze their influence on the neighborhood diffusion of PAHs. The results demonstrate that the highest ILCR resulting from outdoor PAHs exposure within the main activity areas of neighboring buildings exceeds the United States Environmental Protection Agency (USEPA)'s limit of 1×10−6 across all simulated cases. Additionally, settlement characteristics significantly affect the neighborhood diffusion of cooking-generated B[a]P. Smaller θ and staggered arrangement lead to a reduction in the affected area by B[a]P, but result in higher concentrations and ILCR near the source building. Meanwhile, wider street width proves to be an effective strategy for reducing concentrations and ILCR for both neighboring buildings and entire settlement. These findings offer valuable insights for policymakers and urban planners to develop environmentally sustainable rural communities that minimize health risks associated with cooking activities.

Blood Plasma Concentration of Polycyclic Aromatic Hydrocarbons in Under Five Children in Niger Delta, Nigeria

PAHs are known carcinogens associated with immune system suppression, skin irritation, allergic reactions, respiratory problems, mutagenic issues and are generally toxic to humans. In this study, we assessed the presence and proportions of PAHs in the blood plasma of under-five children living in crude oil-polluted environment in Ogoniland, Niger Delta region of Nigeria. Communities resident in close proximity to crude oil exploration sites are constantly faced with environmental, socio-economic and health consequences of crude oil pollution. People can be exposed to PAHs through multiple routes including inhalation, ingestion and dermal contact. Ethical clearance for this study was obtained from the Ethics Committee, University of Port Harcourt. A total of 78 children were recruited from Gokana (male =17, female= 22) and Ideato (Male=15, female=24) using multi-clustered sampling method. Standard procedures were observed in this study. Results obtained were compared with under five children living in non-oil polluted environments within the Niger Delta province. The overall average PAHs was 0.331±0.383 mg/kg for Gokana males and 0.058±0.057mg/kg for Ideato males; overall average PAHs was 0.514±0.373 mg/kg for Gokana females and 0.100±0.049 mg/kg for Ideato female; overall average PAHs was 0.423±0.383 mg/kg Gokana and 0.081±0.057 mg/kg for Ideato. Under-five children in Ogoniland showed positive blood plasma PAHs higher than the comparison group in Ideato. However, carcinogenic PAHs were below levels of concern in the study population. The male gender showed higher positive PAHs than the female gender. Further studies on inflammation, stress factors and overall health status are recommended considering the vulnerability of the study population.

Polycyclic Aromatic Hydrocarbons (PAHs) in Bulgarian Coals: Occurrence, Distribution and Carcinogenicity

The study fills the informative gap on occurrence, distribution, and carcinogenicity of polycyclic aromatic hydrocarbons (PAHs) in Bulgarian coals. It presents quantitative data for content and carcinogenicity of PAHs in different rank raw coals from eight basins with geological age from Late Carboniferous to Late Miocene, Ro=0.17–5.20%. The high amounts of alkylated naphthalene and alkylated phenanthrene determined in the bituminous coals reflect the diagenetic conversion of the plant-derived terpenoids into alkylated PAHs.&#x0D; In this first systematic study of PAHs in Bulgarian raw coals three concentration ranges are established: for Miocene/Eocene age coal – from 1.08 mg/kg to 5.79 mg/kg; for Late Cretaceous/Late Carboniferous age coal – from 77.9 mg/ kg to 137.2 mg/kg; and, for the Late Carboniferous coal – 1.85 mg/kg. The relationship of the total PAHs content vs. raw coal Ro shapes as a “bell” and matches with the published data for the native PAHs from all over the world provenance. The maximal PAHs amount of 137.2 mg/kg at Ro =0.96% for the Late Cretaceous coal lies within the “oil-generation window”, Ro =0.5–1.3% for the kerogen. For all raw coal studied relatively low carcinogenicity is determined based on the well correlated values for B[a]Peq and TEQ parameters.