Carcinogenic Polycyclic Aromatic Hydrocarbons Research Articles

Remediation of carcinogenic PAHs from landfill leachate by Electro-Fenton process – Optimization and modeling

PAHs is the group of emerging micro-pollutants present in most environmental matrices that has the tendency to bioaccumulate and cause carcinogenic effects to human health. The present research involved the quantification and treatment of leachate produced from secured landfill, to eliminate the PAHS. Electro-Fenton process, a class of advanced oxidation process, is adopted to degrade the PAHs using titanium electrodes as both anode and cathode. Artificial intelligence based statistical tool “Central Composite Design” a module of JMP -19 software was used to design the experiments and optimize the critical parameters involved in the research. It was observed that the value of P is significant (P < 0.05) for all the independent variables evidencing the significant correlation between experimental values and predicted values of the software. The value of R2 obtained was 0.96 and 0.97 for COD and PAHs respectively. The maximum removal efficiency of COD and PAH was found to be 84.24% and 90.78% respectively. The optimized conditions obtained from the central composite design were: pH = 5; Fe2+ = 0.1 g/L; H2O2 = 2 g/L; reaction time = 60 min; and electric intensity = 0.2 A. Additionally, optimized experimental conditions were used to study the removal efficiencies of individual 16 PAHs and are also reported. From the close proximity of experimental and predicted results of the software it can be proved that central composite design is efficient enough to be used as a statistical tool in design and analysis for treatment of landfill leachate.

Distribution of 35 Polycyclic Aromatic Hydrocarbons in Pine Needle Samples from Selected Locations in the Republic of Korea.

Polycyclic aromatic hydrocarbons (PAHs), dust, and wax were measured in pine needles, and PAHs were also measured in surface soil. Pearson correlation analysis was performed between the analytical values. The main compounds responsible for the increase in total PAHs were non-carcinogenic phenanthrene and fluoranthene. Therefore, the % content of carcinogenic PAHs decreased with a slope = -0.037 (r = 0.47, p < 0.01), as the total PAH concentration in pine needles increased. Correlations between individual PAHs in pine needles and surface soil were very high when only low-number ring PAHs (2R- and 3R-PAHs) were statistically analyzed and significant when only high-number ring PAHs were statistically analyzed. Low-number ring PAH mainly moves in the gas phase and diffuses into the wax layer, so it was found to be statistically significant with the wax content of pine needles. High-number ring PAHs showed a high correlation with the amount of dust in pine needles because they mainly attached to dust particles and accumulated on the surface of pine needles. The ratios of fluoranthene/pyrene and methylphenanthrene/phenanthrene for predicting the origin of atmospheric PAHs have also been proven valid for pine needles.

Acute toxicity of petroleum asphalt seal coat leachates to Ceriodaphnia dubia is linked to polymer preservatives

Low-VOC waterborne asphalt-emulsion (AE) seal coat is considered more sustainable than solvent-based coal-tar emulsion seal coat because asphalt emulsions contain negligible amounts of carcinogenic PAHs and release fewer harmful volatile organic compounds. Yet, many low-VOC coatings leach water-soluble substances under outdoor conditions. To investigate the chemical composition of seal coat leachates, three AE formulations were cured under natural weathering conditions and exposed to simulated runoff over a 10-day field trial. Runoff was collected and concentrated using ion-exchange solid-phase extraction (SPE) and analyzed using gas chromatography/mass spectrometry (GC–MS). Leached compounds included hydrocarbons, esters, amines, siloxanes, plasticizers, biocides, polyethylene glycol (PEG) ethers, urethanes, and toluene diisocyanate (TDI). Glycol ethers comprised 29–97 % of the measured leachate mass. Two seal coat formulations contained isothiazolinone biocides, methylchloro- and methylisothiazolinone (CMIT/MIT; 0.5 mg/L in runoff), while a third seal coat formulation continuously leached TDI, a reactive polyurethane (PU) precursor (0.7 mg/L in runoff). Biocide-containing leachates showed acute toxicity to the freshwater water flea, Ceriodaphnia dubia after 48 h, while TDI-containing leachate showed no acute toxicity, suggesting that leachate toxicity was due to in-can polymer preservatives. As biocides are implicated in impaired reproductive signaling, these results support the use of alkaline pH to avoid biofouling and reinforce the goal of reducing and/or avoiding the use of biocides altogether, especially for environmentally friendly products.

Biomonitoring polycyclic aromatic hydrocarbon levels in domestic kitchens using commonly grown culinary herbs

AbstractCooking is a significant source of polycyclic aromatic hydrocarbon (PAHs) emissions in indoor environments. A one-month biomonitoring study was carried out in previously selected rural Hungarian kitchens to evaluate cooking-related PAHs concentrations in 4 common kitchen vegetables such as basil, parsley, rocket and chives. The study had two mainobjectives: firstly, to follow PAHs accumulation pattern and to find out if this pattern can be associated with different cooking habits. Also, the usefulness of culinary herbs for indoor bioaccumulation studies was assessed. The 2-ring naphthalene was the dominant PAH in the majority of the samples, its concentrations were in the range of 25.4 µg/kg and 274 µg/kg, of 3-ring PAHs the prevalency of phenanthrene was observed, with highest concentration of 62 µg/kg. PAHs accumulation pattern in tested plants clearly indicated differences in cooking methods and cooking oils used in the selected households. Use of lard and animal fats in general resulted in the high concentrations of higher molecular weight (5- and 6-ring) PAHs, while olive oil usage could be associated with the emission of 2- and 3-ring PAHs. Culinary herbs, however, accumulated carcinogenic PAHs such as benzo[a]anthracene (highest concentration 11.9 µg/kg), benzo[b]fluoranthene (highest concentration 13.8 µg/kg) and chrysene (highest concentration 20.1 µg/kg) which might question their safe use.

Transcriptional and phenotypical alterations associated with a gradual benzo[a]pyrene-induced transition of human bronchial epithelial cells into mesenchymal-like cells

The role of benzo[a]pyrene (BaP), a prominent genotoxic carcinogen and aryl hydrocarbon receptor (AhR) ligand, in tumor progression remains poorly characterized. We investigated the impact of BaP on the process of epithelial-mesenchymal transition (EMT) in normal human bronchial epithelial HBEC-12KT cells. Early morphological changes after 2-week exposure were accompanied with induction of SERPINB2, IL1, CDKN1A/p21 (linked with cell cycle delay) and chemokine CXCL5. After 8-week exposure, induction of cell migration and EMT-related pattern of markers/regulators led to induction of further pro-inflammatory cytokines or non-canonical Wnt pathway ligand WNT5A. This trend of up-regulation of pro-inflammatory genes and non-canonical Wnt pathway constituents was observed also in the BaP-transformed HBEC-12KT-B1 cells. In general, transcriptional effects of BaP differed from those of TGFβ1, a prototypical EMT inducer, or a model non-genotoxic AhR ligand, TCDD. Carcinogenic polycyclic aromatic hydrocarbons could thus induce a unique set of molecular changes linked with EMT and cancer progression.

Personal exposure monitoring to polycyclic aromatic hydrocarbons bound to size-segregated aerosol

Air pollution is a global problem, where impaired air quality significantly damages human health and the environment. Twenty-four hours of personal exposure to size-segregated airborne particulate matter (PM) and associated polycyclic aromatic hydrocarbons (PAHs) were measured in 129 non-smoking residents living in two Czech cities, Ostrava (an industrial area with high levels of air pollution) and Ceske Budejovice (an agricultural area with lower air pollution level) in various seasons between years 2018–2020. Particulate matter (PM) was sampled by cascade impactors based on their aerodynamic diameter (dae, μm) and divided into size fractions: coarse (2.5 < dae), fine (0.25 < dae < 2.5) and ultrafine (<0.25). Size distributions of 20 priority PAHs adsorbed on these PM fractions were analyzed by gas chromatography coupled to tandem mass spectrometry in electron ionization (GC-EI-MS/MS). The total concentration of ∑20PAHs to which residents were exposed ranged from 0.09 ng/m3 to 47.18 ng/m3. A higher level of PAHs was detected in Ostrava (mean: 5.59 ng/m3) than in Ceske Budejovice (mean: 1.96 ng/m3). Statistically significant concentration differences between PAHs in individual seasons were observed in both sampled localities, with higher concentrations measured in winter than in summer. Fine and ultrafine particles predominated in the mass composition of the particulate matter. The ultrafine particle size contained 67–80% of total PAHs. Respiratory health risk was estimated based on inhalation cancer risk (ICR). Cancer risk attributable to personal inhalation exposure ranged from 2.8 × 10−8 to 4.3 × 10−4. In winter, higher cancer risk were found in Ostrava, mainly caused by a high concentration of carcinogenic PAHs bound to ultrafine particles. Overall, the personal monitoring data confirmed a higher air pollution burden in the industrial area and the winter season and highlighted the importance of focusing on ultrafine particles as the main carriers of potentially mutagenic and carcinogenic substances, such as PAHs. In addition, personal monitoring data provided more detailed and accurate information on individual-level exposures, revealing significant differences in exposure concentrations in people living in the same area.

Effect of different smoking times and temperatures on polycyclic aromatic hydrocarbon concentrations in smoked sausages

Smoked pork and chicken sausages were prepared using three different time-temperature combinations; 60 &amp;deg;C for 4 hours, 75 &amp;deg;C for 3 hours, and 90 &amp;deg;C for 2 hours. The amount of polycyclic aromatic hydrocarbons (PAHs) present in these smoked products was estimated using liquid chromatography-mass spectrometry (LC-MS). The PAH compounds were identified using multiple reaction monitoring (MRM) and the retention time of that particular compound. The most potent carcinogenic PAH compound, benzo(a)pyrene (BaP), was not detected in any of the treatments analyzed. The pork and chicken sausages were found to contain the following PAH compounds: Flu, BaA, Chr, BbF, and BkF. Chrysene was found in all samples in the range from 27.38 to 45.08 &amp;micro;g/kg. It was observed that a higher smoking temperature (90 &amp;deg;C) resulted in more PAH compounds in the sausages. Furthermore, the chicken sausages were found to have higher concentrations of PAHs, particularly Chr and BaA, than the pork sausages.

Food shortage driven crop residue burning and health risk

Ending global hunger is one of the greatest challenges humanity faces. The second Sustainable Development Goal (SDG 2), Zero Hunger, seeks to simultaneously address global environmental sustainability and food security challenges. However, ending hunger and food shortage would lead to the increase of agricultural activities and crop yields, which in turn might rise crop residue biomass burning, leading to adverse environmental and health consequences. This study estimated the health risk using modeled airborne benzo[a]pyrene (BaP), a common indicator of carcinogenic polycyclic aromatic hydrocarbons (PAH) released from crop residue biomass burning, and demonstrated the dependence of incremental lifetime lung cancer risk (ILCR) on the prevalence of undernourishment (PoU). Results showed that 10.4% of the global population are exposed to BaP concentration levels exceeding the EU target value (1 ng/m3) due to crop residue burning. The dependence of ILCR on PoU was attributed to increasing post-harvest crop residue biomass burning consequent to growing crop yield motivated by food shortage. Although global mean ILCR from crop residue burning BaP emission was positively correlated with the mean PoU at a correlation coefficient of r = 0.87 (p < 0.0001), positive and negative associations between PoU and ILCR were found among different less-developed countries. Eighty-nine less-developed countries were clustered into five groups, and the response of each group's ILCR to their respective PoU was assessed, which was interpreted by a human development index (HDI) that measured key dimensions of human development. Results also revealed that sustainable agriculture and implementation of air emission control measures play key roles in the association between hunger and ILCR.

Characterization of polycyclic aromatic hydrocarbon from open burning of disposable COVID-19 facemask: Spatial distribution and risk assessment

The use of facemasks as a preventive measure against infection of the COVID-19 virus has some associated environmental impacts, especially in Subs-Saharan African countries where the used facemasks are being disposed of using open burning. Hence this study characterized Polycyclic Aromatic Hydrocarbons (PAHs) emissions from different COVID-19 facemask materials and determined the associated risk of open burning of facemask. Facemasks of different materials were sourced from open dump sites. Each material was combusted in an open reactor and the emissions were collected using A filter-sorbent sampling system. Analysis of PAHs in the sample was carried out using GCMS. The associated health risk was assessed using Incremental Life Cancer Risk (ILCR) and Hazard Quotient (HQ). The result showed the concentration of PAHs emission ranged ∑ PAHs 73.33 –368.16 µg/m3 while carcinogenic PAHs ranged ∑ CarPAHs 26.79–179.74 µg/m3. The result also showed the surgical and N95 facemask emits the highest concentration of PAHs. The modeled annual ground-level PAHs Isopleth reveals the presence of a high concentration of PAHs around the vicinity of the burning site after a year. Proper disposal of these facemask using controlled medical incinerator is highly recommended.

Spatial distribution, source identification, ecological risk assessment, and air–seawater/seawater– Sediment exchange rates of polycyclic aromatic hydrocarbons in Pars special economic energy zone, Iran

Polycyclic aromatic hydrocarbons (PAHs) have been introduced as major pollutants released by the oil, gas, and petrochemical industries. Against this background, the present study examined the coastal air, seawater, and sediments in the Pars Special Economic Energy Zone (PSEEZ), Iran, in terms of pollution caused by such compounds. Considering the industrial facilities and residential areas in this region, the total suspended particulate (TSP), seawater, and sediments were sampled (n = 10) and then analyzed over the course of two seasons via gas chromatography-mass spectrometry (GC–MS). The total concentrations in the TSP, seawater, and sediments were found to be in the range of 346-739ngPAH/gTSP, ND-84.87 µg/L, and ND–306.7 ngg−1(dw), respectively. The positive correlation coefficients between sediment organic matter (OM) and concentrations did not show a significant relationship. Crude oil and its derivatives and biomass-coal combustion were identified as the main sources of pollution. Carcinogenic PAHs (CPAHs) were further detected at much higher concentrations near industrial facilities. Sediment qualityguidelines (SQGs) and risk quotients (RQs) showed that coastal seawater and sediments posed acceptable and moderate ecological risks. According to the fugacity diagrams, the seabed and seawater served as secondary sources of pollution. The total concentration and values obtained in earlier investigations were also comparable. Nonetheless, most maximum points could provide a point-form of the pollutant concentration. Therefore, preventive measures are required to ensure the protection of the environment.

Preliminary study on the enhanced bioremediation of PAH-contaminated soil in Beijing and assessment of remediation effects based on toxicity tests.

In this study, we focused on soil contaminated by polycyclic aromatic hydrocarbons (PAHs) at typical coking-polluted sites in Beijing, conducted research on enhanced PAH bioremediation and methods to evaluate remediation effects based on toxicity testing, and examined changes in pollutant concentrations during ozone preoxidation coupled with biodegradation in test soil samples. The toxicity of mixed PAHs in soil was directly evaluated using the Ames test, and the correlation between mixed PAH mutagenicity and benzo(a)pyrene (BaP) toxicity was investigated in an effort to establish a carcinogenic risk assessment model based on biological toxicity tests to evaluate remediation effects on PAH-contaminated soil. This study provides a theoretical and methodological foundation for evaluating the effect of bioremediation on PAH-contaminated soil at industrially contaminated sites. The results revealed that the removal rate of PAHs after 5min of O3 preoxidation and 4weeks of soil reaction with saponin surfactants and medium was 83.22%. The soil PAH extract obtained after remediation had a positive effect on the TA98 strain at a dose of 2000μg·dish-1, and the carcinogenic risk based on the Ames toxicity test was 8.98 times greater than that calculated by conventional carcinogenic PAH toxicity parameters. The total carcinogenic risk of the remediated soil samples was approximately one order of magnitude less than that of the original soil samples.

Source Apportionment and Health Risk of Some Organic Contaminants in Water and Suspended Particulate Matter from Imo River, Nigeria

The objective of this study was to provide the source identification and assessment of potential health associated with some organic contaminant detected in water and suspended particle matter (SPM) from the Imo River, Nigeria using gas chromatography with a flame ionization detector (GC/FID) after 1:1 ratio solvent mixture (n-hexane and dichloromethane) extraction. The findings on SPM revealed the values; pH (5.42±0.097-5.567±0.057), conductivity (74.58±5.390-87.6±0.9 uS/cm), and total organic carbon (TOC) (3.626±0.366-6.143±0.176), and surface water; pH (6.077±0.049-6.46±0.52), conductivity (49.03±1.430- 58.12±0.553 uS/cm). The total concentrations of both low and high molecular PAHs in SPM recorded at stations1-3 were 4.384 mg/kg, 16.87 mg/kg, and (22.69 mg/kg); surface water 2.329 mg/L, 7.428 mg/L and 6.657 mg/L. The source apportionment of PAHs in SPM and surface water via molecular diagnostic ratios identified both petrogenic source (crude oil, petroleum spillages, and seepages) and pyrogenic sources (combustion of grass, wood, coal, and gas flaring). A further analysis with Principal Component Analysis (PCA) revealed two principal components, with 65.568% for component 1 and 34.432% for component 2 for SPM, and 62.80% for principal components and 37.2% for principal component 2 for surface water. The correlation analysis of PAHs affirmed common sources such as petrogenic and pyrogenic origins. The toxic equivalent factor of total benzo(a)pyrene for 6 ∑PAHs in SPM was recorded as 3.693 mg/kg, 1.605 mg/kg, and 0.453 mg/kg; surface water was recorded as 0.823 mg/L, 1.858 mg/L, and 0.353 mg/L, while the mutagenic equivalency quantities of SPM were recorded as 3.693mg/kg, 1.146 mg/kg, and 0.316 mg/kg; surface water 0.739 mg/L, 0.938, and 0.577 for stations 1-3. The effect of carcinogenic PAHs in SPM was higher in adults than in children, with regards to ILCR analysis. Users of Imo Rivers should be guided on the exposure of SPM and surface water since the toxic, mutagenic, and cancer risk levels of the river are above the permissible limit in some stations.

Concentration of Polycyclic Aromatic Hydrocarbons in Water from Hand-dug Wells in Some Communities in Ekpeyeland, Rivers State, Nigeria

Well water sources from selected communities in Ekpeyeland were assessed for the concentrations of polycyclic aromatic hydrocarbons (PAHs). The assessment was conducted seasonally in six communities. The concentrations of the PAHs were determined using standard methods and procedures and finally quantified by the use of GC-MS chromatography. The result showed the presence of all the 16 USEPA priority PAHs in the examined water samples. Seasonal variations were not significant. The summed values of PAHs from stations and seasons were above the permissible limit required for by WHO. Classification of the different categories of PAHs identified higher molecular weight (HMW) PAHs more in concentration than lower molecular weight (LMW) PAHs in the wells. Source identification proved that both pyrogenic and petrogenic sources were responsible for the presence of PAHs in the well water. However, pyrogenic source was the more prominent source of PAHs in the water. There was high level of carcinogenic PAHs in the water and thus the water portends danger to the users. Therefore, the locals are advised not to consume the water to avoid its effect on the long run.

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.

Hepatoprotective Effects of Flavonoids against Benzo[a]Pyrene-Induced Oxidative Liver Damage along Its Metabolic Pathways.

Benzo[a]pyrene (B[a]P), a highly carcinogenic polycyclic aromatic hydrocarbon primarily formed during incomplete organic matter combustion, undergoes a series of hepatic metabolic reactions once absorbed into the body. B[a]P contributes to liver damage, ranging from molecular DNA damage to the onset and progression of various diseases, including cancer. Specifically, B[a]P induces oxidative stress via reactive oxygen species generation within cells. Consequently, more research has focused on exploring the underlying mechanisms of B[a]P-induced oxidative stress and potential strategies to counter its hepatic toxicity. Flavonoids, natural compounds abundant in plants and renowned for their antioxidant properties, possess the ability to neutralize the adverse effects of free radicals effectively. Although extensive research has investigated the antioxidant effects of flavonoids, limited research has delved into their potential in regulating B[a]P metabolism to alleviate oxidative stress. This review aims to consolidate current knowledge on B[a]P-induced liver oxidative stress and examines the role of flavonoids in mitigating its toxicity.

M6A modification mediates SLC3A2/SLC7A5 translation in 3-methylcholanthrene-induced uroepithelial transformation

3-Methylcholanthracene (3-MC) is one of the most carcinogenic polycyclic aromatic hydrocarbons (PAHs). Long-term exposure to PAHs has been thought of as an important factor in urothelial tumorigenesis. N6-methyladenosine (m6A) exists widely in eukaryotic organisms and regulates the expression level of specific genes by regulating mRNA stability, translation efficiency, and nuclear export efficiency. Currently, the potential molecular mechanisms that regulate m6A modification for 3-MC carcinogenesis remain unclear. Here, we profiled mRNA, m6A, translation and protein level using “-omics” methodologies, including transcriptomes, m6A profile, translatomes, and proteomics in 3-MC-transformed urothelial cells and control cells. The key molecules SLC3A2/SLC7A5 were screened and identified in 3-MC-induced uroepithelial transformation. Moreover, SLC7A5/SLC3A2 promoted uroepithelial cells malignant phenotype in vitro and in vivo. Mechanically, METTL3 and ALKBH5 mediated m6A modification of SLC3A2/SLC7A5 mRNA in 3-MC-induced uroepithelial transformation by upregulating the translation of SLC3A2/SLC7A5. Furthermore, programmable m6A modification of SLC3A2/SLC7A5 mRNA affected the expression of its proteins. Taken together, our results revealed that the m6A modification-mediated SLC3A2/SLC7A5 translation promoted 3-MC-induced uroepithelial transformation, suggesting that targeting m6A modification of SLC3A2/SLC7A5 may be a potential therapeutic strategy for bladder cancer related to PAHs.

Unveiling the Aftermath: Exploring Residue Profiles of Insecticides, Herbicides, and Fungicides in Rice Straw, Soils, and Air Post-Mixed Pesticide-Contaminated Biomass Burning.

This study delved into the impact of open biomass burning on the distribution of pesticide and polycyclic aromatic hydrocarbon (PAH) residues across soil, rice straw, total suspended particulates (TSP), particulate matter with aerodynamic diameter ≤ 10 µm (PM10), and aerosols. A combination of herbicides atrazine (ATZ) and diuron (DIU), fungicide carbendazim (CBD), and insecticide chlorpyriphos (CPF) was applied to biomass before burning. Post-burning, the primary soil pesticide shifted from propyzamide (67.6%) to chlorpyriphos (94.8%). Raw straw biomass retained residues from all pesticide groups, with chlorpyriphos notably dominating (79.7%). Ash residue analysis unveiled significant alterations, with elevated concentrations of chlorpyriphos and terbuthylazine, alongside the emergence of atrazine-desethyl and triadimenol. Pre-burning TSP analysis identified 15 pesticides, with linuron as the primary compound (51.8%). Post-burning, all 21 pesticides were detected, showing significant increases in metobromuron, atrazine-desethyl, and cyanazine concentrations. PM10 composition mirrored TSP but exhibited additional compounds and heightened concentrations, particularly for atrazine, linuron, and cyanazine. Aerosol analysis post-burning indicated a substantial 39.2-fold increase in atrazine concentration, accompanied by the presence of sebuthylazine, formothion, and propyzamide. Carcinogenic PAHs exhibited noteworthy post-burning increases, contributing around 90.1 and 86.9% of all detected PAHs in TSP and PM10, respectively. These insights advance understanding of pesticide dynamics in burning processes, crucial for implementing sustainable agricultural practices and safeguarding environmental and human health.

Significantly Increased Accumulations of PAHs in Scalp Hair During Smoke-haze Period Among Female Adolescents in Chiang Mai, Thailand

Limitations in reporting polycyclic aromatic hydrocarbons (PAHs) accumulated in humans arise from the impact of intense biomass burning and air pollution in upper Southeast Asia. This study analyzed PAHs in human hair samples and explored the associations between ambient PM2.5 and hair PAH concentrations. Follow-up hair collections were conducted on 111 female students, and hair samples with a length of 4 cm were analyzed. Ten different PAHs were identified in the subjects' hair samples. The most substantial pooled estimate of cumulative effects of PM2.5 exposure was observed at lag04 (4-month average). At lag04, every 10 μg/m3 increase in PM2.5 concentration was significantly associated with 0.33, 0.29, 0.35, 0.16, 0.04, 0.64, and 1.66 ng/g hair increases in Acy, Ace, Flu, Ant, Chr, BaP, and total PAHs, respectively (P &lt; 0.05). The findings underscore the significant contribution of ambient PM2.5 exposure to the elevation of PAHs in human hair. Specifically, each centimeter of hair represents a one-month exposure to ambient PM2.5. Moreover, the accumulation of BaP, a carcinogenic PAH, significantly increased at heightened PM2.5 levels, emphasizing the importance of hair analysis in assessing PAH exposure risks and obtaining reliable and comprehensive health risk information. Keywords: Polycyclic aromatic hydrocarbons, Hair analysis, PM2.5

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.