Parent Polycyclic Aromatic Hydrocarbons Research Articles

Evaluation of marine sediment contamination by polycyclic aromatic hydrocarbons along the Karachi coast, Pakistan, 11 years after the Tasman Spirit oil spill

On July 27, 2003, a spill of approximately 31,000 tons of Iranian light crude oil affected the coast of Karachi, Pakistan. Approximately 11 years after the spill, we analyzed polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologues (alkyl-PAHs) as the indicators to evaluate the residual effect of oil spill to the sediment along the Karachi coast. The total concentrations (dry weight) of parent PAHs and alkyl-PAHs ranged from 121.9 to 735.4 and 42.3–1149.9 ng/g, respectively. The estuary and harbor were the two regions with the highest levels of PAHs in the sediment. Conversely, sedimentary PAHs in the oil spill areas and remote coastal areas showed significantly lower levels. Although the results of the source identification indicated the up to 75.2% of the contribution from petroleum and its derivatives, this could only reflect the direct impact of the Karachi city on the presence of PAHs in the coastal sedimentary environment and did not indicated that the oil spill continues to stay 11 years later. Compared with 11 years ago, the sharply reduced PAH content, great changed composition, and the degradation driven trend of diagnostic ratios all indicated a sharp decrease in the influence of PAHs caused by the oil spill. Finally, the ecological risk caused by the PAH residual in the marine sedimentary ecosystem had disappeared along the Karachi coasts, Pakistan.

Formation of Polycyclic Aromatic Hydrocarbon Oxidation Products in α-Pinene Secondary Organic Aerosol Particles Formed through Ozonolysis.

Accurate long-range atmospheric transport (LRAT) modeling of polycyclic aromatic hydrocarbons (PAHs) and PAH oxidation products (PAH-OPs) in secondary organic aerosol (SOA) particles relies on the known chemical composition of the particles. Four PAHs, phenanthrene (PHE), dibenzothiophene (DBT), pyrene (PYR), and benz(a)anthracene (BaA), were studied individually to identify and quantify PAH-OPs produced and incorporated into SOA particles formed by ozonolysis of α-pinene in the presence of PAH vapor. SOA particles were characterized using real-time in situ instrumentation, and collected on quartz fiber filters for offline analysis of PAHs and PAH-OPs. PAH-OPs were measured in all PAH experiments at equal or greater concentrations than the individual PAHs they were produced from. The total mass of PAH and PAH-OPs, relative to the total SOA mass, varied for different experiments on individual parent PAHs: PHE and 6 quantified PHE-OPs (3.0%), DBT and dibenzothiophene sulfone (4.9%), PYR and 3 quantified PYR-OPs (3.1%), and BaA and benz(a)anthracene-7,12-dione (0.26%). Further exposure of PAH-SOA to ozone generally increased the concentration ratio of PAH-OPs to PAH, suggesting longer atmospheric lifetimes for PAH-OPs, relative to PAHs. These data indicate that PAH-OPs are formed during SOA particle formation and growth.

Theoretical study of the formation of dinitro-pyrenes from mononitro-pyrenes initiated by OH radicals

Nitrated polycyclic aromatic hydrocarbons are more mutagenic and carcinogenic than parent PAHs. The formation mechanism of dinitro-pyrenes initiated by OH from mononitro-pyrenes was conducted by quantum chemical calculations. The products are 1,2-, 1,7-, 2,4-, 2,5- and 2,7- dinitropyrenes. Water molecules can decrease the Gibbs activation barriers of water loss step of NO2-OH-nitropyrene. By canonical variational transition state theory with small curvature tunneling correction, the calculated overall rate constants for 1-, 2- and 4-nitropyrene are 8.13 × 10−13 cm3 molecule−1 s−1, 8.90 × 10−13 cm3 molecule−1 s−1 and 1.50 × 10−12 cm3 molecule−1 s−1 at 298 K and 1 atm, respectively.

Simultaneous determination of polycyclic aromatic hydrocarbons and their chlorinated derivatives in grilled foods

Polycyclic aromatic hydrocarbons (PAHs) are unintentionally generated in foods that are cooked, and dietary ingestion of these PAHs is regarded as the dominant route of exposure to PAHs. Some chlorinated PAHs (ClPAHs) are more toxic than their corresponding parent PAHs and can also be generated in food during cooking. Knowledge of the concentrations of ClPAHs in cooked foods has been limited by the lack of an adequate analytical method for measuring ClPAH concentrations in cooked foods. In this study, we developed an analytical method for simultaneous determination of PAHs and ClPAHs in lipid-rich foods. The combination of a potassium hydroxide silica gel column and an activated carbon cartridge enabled us to simultaneously measure PAH and ClPAH concentrations in raw and grilled fish and meats. Twelve kinds of PAHs (e.g., fluorene [Fle], phenanthrene [Phe], fluoranthene [Flu], and pyrene [Pyr]) were detected in grilled foods. The concentrations ranged from below the limit of quantitation (<LOQ) to 310 ng g−1. We also detected 9-monochlorinated Phe (9-ClPhe), 3-monochlorinated Flu (3-ClFlu), 8-monochlorinated Flu (8-ClFlu), and 1-monochlorinated Pyr (1-ClPyr); those concentrations ranged from <LOQ to 0.16 ng g−1. The total concentrations of PAHs were significantly lower in gas-grilled meats than in charcoal-grilled meats. In contrast, the concentrations of ClPAHs were significantly higher in gas-grilled meats than in the charcoal-grilled meats. This pattern could be attributed to the difference of reaction temperatures needed to generate them. Toxic equivalent (TEQ) concentrations, which were calculated based on toxicities relative to benzo[a]pyrene (BaP), were much higher in the grilled foods (0.12–12 ng-BaPeq g−1) for PAHs than for ClPAHs (<LOQ to 0.026 ng-BaPeq g−1).

Sources and gas-particle partitioning of atmospheric parent, oxygenated, and nitrated polycyclic aromatic hydrocarbons in a humid city in southwest China

Polycyclic aromatic hydrocarbons (PAHs) derivatives, such as oxygenated PAHs (OPAHs) and nitrated PAHs (NPAHs), some of which are more toxic and persistent than parent PAHs, have been ubiquitously detected in the environment. Gaseous and particulate PAHs, OPAHs, and NPAHs in the air were measured in an urban environment of Chongqing in southwest China in 2016. Annual average concentrations were 79.9 ± 40.5 ng/m³, 93.7 ± 75.2 ng/m³ and 1.65 ± 1.43 ng/m³ for ∑29 PAHs, ∑10 OPAHs and ∑27 NPAHs, respectively. PAHs had highest level in winter and lowest level in summer while NPAHs and OPAHs showed relatively higher concentrations in summer than spring and autumn, which may be explained by stronger secondary formation of NPAHs and OPAHs in summer. Source apportionment analysis revealed that biomass burning, coal combustion, and petroleum combustion were the main sources for PAHs, while secondary formation, especially in summer, contributed greatly to OPAHs and NPAHs. Gas/particle partition coefficient (logKP) of PAHs, OPAHs and NPAHs, calculated from our observation data, was found to correlate well with the corresponding subcooled liquid vapor pressures (logPLo). The shallower slope of the linear regression between logKP and logPLo for PAHs (−0.61 to −0.52) than OPAHs or NPAHs (−2.14 to −0.73) indicated stronger absorption into the atmospheric particles for PAHs. Three gas/particle partitioning models were evaluated, including the Junger-Pankow adsorption model, the KOA absorption model, and the Dual octanol-air/soot-air model. Compared to the measured values of particle-bound fractions, model predicted values were in reasonable range for PAHs, but were underestimated for NPAHs and OPAHs, suggesting that other important factors such as the influence of RH should be incorporated in gas/particle partitioning models for less hydrophobic compounds, especially in humid areas.

Existence, removal and transformation of parent and nitrated polycyclic aromatic hydrocarbons in two biological wastewater treatment processes

Polycyclic aromatic hydrocarbons (PAHs) and nitrated polycyclic aromatic hydrocarbons (NPAHs) are pollutants commonly present in the environment. Some NPAHs are considered to have more severe toxic effects than their parent PAHs. The existence of 16 PAHs (678.5–3817.8 ng/L in wastewater, 499.9 ng/g-1239.6 ng/g in sludge) and 5 NPAHs (175.8–1392.4 ng/L in wastewater, 483.5 ng/g-2763.1 ng/g in sludge) was determined in a biological wastewater treatment plant (WWTP) in Qingdao, China. Anthracene and naphthalene were the predominant PAHs, and 2-nitrofluorene and 9-nitroanthracene were the predominant NPAHs. Petroleum, liquid fossil fuel combustion and exhaust emissions were the main sources of PAHs and NPAHs in this study. In both the sequencing batch reactor/moving-bed biofilm (SBR/MBBR) and the anaerobic-anoxic-aerobic (A2O) process, low-molecular-weight PAHs were mainly removed through volatilization and biodegradation/biotransformation. Meanwhile, the removal of high-molecular-weight PAHs and NPAHs depended on adsorption and sedimentation. The transformation from PAHs to NPAHs mainly occurred in the aqueous-phase, especially in summer and that was confirmed by mass flow and ratios variation. Overall, the removal capacity of the A2O process for PAHs and NPAHs was better than that of the SBR/MBBR process. Tertiary treatment processes had little effect or even a negative effect on the removal of PAHs and NPAHs.

Biomonitoring of children exposure to urban pollution and environmental tobacco smoke with hair analysis – A pilot study on children living in Paris and Yeu Island, France

The impact of pollution on children's health has been increasingly pointed out in numerous studies which emphasized their increased vulnerability compared to adults. This pilot study investigated the relevance of hair analysis for the assessment of children exposure to pollution and to environmental tobacco smoke (ETS). The methodology based on GC–MS/MS and LC-MS/MS, is the first one to investigate simultaneously parent PAH (n = 15), PAH metabolites (n = 56), nicotine and cotinine in a biological matrix. The method was applied to hair samples collected from 25 children, aged from 2 to 11 years, living in Paris, France, selected as densely populated area with urban pollution including vehicle exhausts, and Yeu Island, a French island in the Atlantic ocean, selected as control area with low population density and no fuel powered vehicles. Nicotine and cotinine were detected in all the samples at concentrations up to 2275 pg/mg and 110 pg/mg respectively, suggesting exposure to ETS in the two areas. 10 parent PAH and 10 metabolites were detected in 100% and in >90% of the samples respectively. Eight of these biomarkers presented a significantly higher concentration in children from Paris than from Yeu Island. The results suggest association between PAH exposure and estimated time of exposure to vehicle exhaust as well as higher exposure to both PAH and ETS in the youngest children. Although these findings need to be confirmed on wider populations, the results obtained in this pilot study strongly support the relevance of hair analysis for the biomonitoring of children exposure to urban pollution and ETS.

Emission factors of particulate matter, CO and CO2 in the pyrolytic processing of typical electronic wastes

A self-designed experimental device was employed to simulate the pyrolytic dismantling process of selected electronic wastes (E-wastes), including printed wiring boards (PWBs) and plastic casings. The generated particulate matter (PM) of different particle sizes, carbon monoxide (CO) and carbon dioxide (CO2) were determined, and the corresponding emission factors (EFs) were estimated. Finer particles with particle sizes of 0.4–2.1 μm accounted for 78.9% and 89.3% of PM emitted by the pyrolytic processing of PWBs and plastic casings, respectively, and the corresponding EFs were 9.68 ± 4.81 and 18.49 ± 7.2 g/kg, respectively. The EFs of CO and CO2 from PWBs and plastic casings were 55.9 ± 26.9 and 1182 ± 439 g/kg, and 133.6 ± 34.6 and 2827 ± 276 g/kg, respectively. Compared with other emission sources, such as coal, biomass, and traffic exhaust, the EFs of E-wastes were relatively higher, especially for PM. There were significant positive correlations (p < 0.05) of the initial contents of carbon and nitrogen in PWBs with the related EFs of PM, CO, and CO2, while the correlations for plastic casings were insignificant. The EFs of CO of PWBs were significantly positively correlated with the corresponding EFs of PM and the parent polycyclic aromatic hydrocarbons (PAHs); however, the same result was not observed for plastic casings.

New values to assess polycyclic aromatic hydrocarbons pollution: Proposed background concentrations in marine sediment cores from the Atlantic Spanish Coast

When dealing with environmental monitoring, background assessment values are needed to identify such concentrations of pollutants that can be assumed as natural. Background Concentration (BC) values are defined for natural compounds as the concentration of a contaminant at a “pristine” or “remote” site based on contemporary or historical data. Previously BC values exist for some polycyclic aromatic hydrocarbons (PAHs), but are under revision and do not exist for individual alkylated PAHs. Moreover, they will differ in different geological locations and should be specified geographically.Based on analytical data obtained from sediment cores from the North Atlantic Coast, this study present BC values for 35 PAHs which will increase the actual database in 10 new values for parent PAHs and, for the first time, for 13 individual alkylated compounds. Granulometric and organic matter studies were performed in the sediments to both classify the studied sediments and to assure that the derived values can be used to evaluate samples with different sedimentary characteristics. The newly presented values have been compared to reference values from different countries.

Retention Behaviour of Alkylated and Non-Alkylated Polycyclic Aromatic Hydrocarbons on Different Types of Stationary Phases in Gas Chromatography

The gas chromatographic retention behaviour of 16 polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs on a new ionic liquid stationary phase, 1,12-di(tripropylphosphonium) dodecane bis(trifluoromethanesulfonyl)imide (SLB®-ILPAH) intended for the separation of PAH mixtures, was compared with the elution pattern on more traditional stationary phases: a non-polar phenyl arylene (DB-5ms) and a semi-polar 50% phenyl dimethyl siloxane (SLB PAHms) column. All columns were tested by injections of working solutions containing 20 parental PAHs from molecular weight of 128 to 278 g/mol and 48 alkylated PAHs from molecular weight of 142 to 280 g/mol on a one dimensional gas chromatography-mass spectrometry (GC-MS) system. The SLB PAHms column allowed separation of most isomers. The SLB®-ILPAH column showed a rather different retention pattern compared to the other two columns and, therefore, provided a potential for use in comprehensive two-dimensional GC (GC×GC). The ionic liquid column and the 50% phenyl column showed good thermal stability with a low bleed profile, even lower than that of the phenyl arylene “low bleed” column.

Early Mechanistic Events Induced by Low Molecular Weight Polycyclic Aromatic Hydrocarbons in Mouse Lung Epithelial Cells: A Role for Eicosanoid Signaling

Low molecular weight polycyclic aromatic hydrocarbons (LMW PAHs; < 206.3 g/mol) are under regulated environmental contaminants (eg, secondhand smoke) that lead to gap junction dysregulation, p38 MAPK activation, and increased mRNA production of inflammatory mediators, such as cytokines and cyclooxygenase (COX2), in lung epithelial cells. However, the early mechanisms involving lipid signaling through the arachidonic acid pathway and subsequent eicosanoid production leading to these downstream events are not known. Common human exposures are to mixtures of LMW PAHs, thus C10 cells (a mouse lung epithelial cell line) were exposed to a representative binary PAH mixture, 1-methylanthracene (1-MeA) and fluoranthene (Flthn), for 30 min-24 h with and without p38 and cytosolic phospholipase A2 (cPLA2) inhibitors. Cytosolic phospholipase A2 inhibition reversed PAH-induced phospho-p38 MAPK activation and gap junction dysregulation at 30 min. A significant biphasic increase in cPLA2 protein was observed at 30 min, 2, and 4 h, as well as COX2 protein at 2 and 8 h. Untargeted metabolomics demonstrated a similar trend with significantly changing metabolites at 30 min and 4 h of exposure relative to 1 h; a "cPLA2-like" subset of metabolites within the biphasic response were predominately phospholipids. Targeted metabolomics showed several eicosanoids (eg, prostaglandin D2 (PGD2), PGE2α) were significantly increased at 4, 8, and 12 h following exposure to the binary PAH mixture and this effect was p38-dependent. Finally, PAH metabolism was not observed until after 8 h. These results indicate an early lipid signaling mechanism of LMW PAH toxicity in lung epithelial cells due to parent PAH compounds.

Emission behaviors of nitro- and oxy-polycyclic aromatic hydrocarbons during pyrolytic disposal of electronic wastes

Emission factors (EFs) of polycyclic aromatic hydrocarbon (PAH) derivatives (12 nitro-PAHs and 4 oxy-PAHs) during the pyrolysis of two types of electronic waste (E-waste) were measured. Compositional profile, particle size distribution, gas-particle partitioning, correlations with precursor species and influences of pyrolytic temperature were investigated. The derivative products were dominated by oxy-PAHs. The averaged EFs of oxy-PAHs were 3.37 ± 4.10 μg/g and 32.6 ± 18.1 μg/g for PWBs and plastic casings, respectively, and those of nitro-PAHs were 85.7 ± 92.4 ng/g and 83.3 ± 69.7 ng/g, respectively. Most EFs of derivative species significantly correlated with their corresponding parent PAHs (p < 0.05), except a few cases, indicating formation of derivatives via related reactions of parent species. Most nitro-PAHs occurred in fine particles with the size < 2.1 μm, and oxy-PAHs were prevailing in fine particles with the size between 0.4 μm and 2.1 μm. Proportions of oxy-PAHs in particulate phase, especially those with higher molecular weight, were noticeably greater than those of the corresponding parent species. Below 480 °C, there was no evident difference in the EFs of PAH derivatives, while the EFs noticeably increased from 520 °C. With the increasing temperature, the majority of oxy-PAHs still occurred on finer particles, while the contribution of coarser particles tended to increase.

Polycyclic aromatic hydrocarbons in two polluted lagoons, eastern coast of the Red Sea: Levels, probable sources, dry deposition fluxes and air-water exchange

The air-water exchange of polycyclic aromatic hydrocarbons (PAHs) is an important process in determining the fate, transport and chemical loadings of these contaminants in the atmosphere and water bodies. Concentration levels of PAHs in air (gaseous and particulate) and surface water were investigated in the environments of two polluted lagoons along the eastern coast of the Red Sea to study air water exchange and dry deposition fluxes. Nine priority parent PAHs and nine methylated PAHs were identified and quantified by GC-MS. The range of total PAHs in surface water was from 120.29 ng L−1 to 524.45 ng L−1 (average: 308.7 ng L−1, n = 19). The PAHs levels in air recorded significant rise form the previous study. The probable sources of dissolved PAHs in water were found predominantly to be of petrogenic origin in one lagoon and of pyrogenic origin in the other lagoon. The dry deposition fluxes for individual congeners ranged between 0.01 ng m−2d−1 to 2.82 μg m−2d−1. After Henry's law constant corrections for temperature and salinity; the air-water exchange fluxes were found in the range of −9.7 × 104 to 8.6 × 106 ngm−2d−1 with an average of 6.8 × 105 ngm−2d−1. Beside the other sources of PAHs in the studied lagoons, high temperature and wastewater dumping might affect the magnitude and direction of air-water exchange fluxes.

Spatiotemporal variation of atmospheric nitrated polycyclic aromatic hydrocarbons in semi-arid and petrochemical industrialized Lanzhou City, Northwest China.

Polyurethane foam-based passive air sampler (PUF-PAS) and passive dry deposition sampler (PAS-DD) were adopted, for thefirst timeever in China, to investigate the atmospheric levels and spatial-temporal distributions of air burdens and dry deposition fluxes of 12 nitrated polycyclic aromatic hydrocarbons (NPAHs) during winter and summer seasons in a multiple site field campaign in a petrochemical industrialized capital city in Northwest China. The results showed that the highest air concentration and dry deposition fluxes of ∑12NPAHs occurred at a heavy traffic site among 18 sampling sites in both winter and summer season. The lowest air concentration and dry deposition fluxes were observed at the background site. The mean concentrations of ∑12NPAHs in the ambient air were 8.6 ± 8.1ngm-3 in winter and 15 ± 11ngm-3 in summer. The mean dry deposition fluxes of ∑12NPAHs were 1.8 × 103 ± 1.9 × 103ng(m2day)-1 in winter and 1.4 × 103 ± 1.3 × 103ng(m2day)-1 in summer, respectively. The total concentration of 12 NPAHs was mainly dominated by 1-nitro-naphthalene (1N-NAP) and 2-nitro-naphthalene(2N-NAP) in air, accounting for 32% in winter and 45% in summer of ∑12NPAHs. 7-Nitro-benzo [a] anthracene (7N-BaA) made the largest contribution to dry deposition fluxes of ∑12NPAHs, accounting for 28% in winter and 24% in summer. The ratios of ∑12NPAHs/∑15pPAHs (parent polycyclic aromatic hydrocarbons) were calculated to identify potential sources of NPAHs across the city. The results revealed that the main atmospheric air concentration and dry deposition fluxes of 12 NPAHs could be attributed to the primary emissions in winter and the secondary reaction formation in summer. The sources of primary emissions could be traced back to petrochemical, steel mills, as well as aluminum industries in winter and vehicle exhaust in summer. Higher ∑12NPAH/∑15pPAH concentration ratios in summer indicated that the oxidation of pPAHs contributed to the secondary formation of NPAHs via atmospheric chemical reactions in this petrochemical industrialized mountain-valley city.

Exposure to polycyclic aromatic hydrocarbons in women living in the Chinese cities of BaoDing and Dalian revealed by hair analysis

Polycyclic aromatic hydrocarbons (PAH) are produced from incomplete combustion of organic matter and released as environmental contaminants from activities such as transports, wood combustion, coal-fired power plants. In numerous urban areas worldwide, the levels of PAH exposure are considered critical regarding public health issues. The possibility to detect PAH and PAH metabolites biologically incorporated in human hair was demonstrated and proposed as biomarkers of exposure. Nevertheless, the possibility to distinguish different levels of exposure between different populations is still needed to validate the relevance of hair analysis in epidemiological studies. In this work, hair samples were collected from 204 women from two cities in China based on one year Air Quality Index history from governmental data (Baoding as polluted city and Dalian less polluted city). 8 out of the 15 parent PAH and 7 out of the 56 metabolites analyzed in this study were detected in all the samples. The highest concentrations in hair were observed for phenanthrene (4.2 to 889 pg/mg) > fluoranthene (1.05 to 204 pg/mg) > pyrene (3.2 to 124 pg/mg) for parent PAH, and for 9-OH-fluorene (0.04 to 1.78 pg/mg) > 2-OH-naphthalene (0.68 to 811 pg/mg) > 1-OH-anthracene (0.24 to 10.9 pg/mg) for metabolites. 14 parent PAH and 15 metabolites presented a significantly higher concentration in the hair samples collected from Baoding, as compared to Dalian. The median concentration of parent PAH was from 1.5 to 2.8 times higher in the hair of the subjects from Baoding than in subjects from Dalian and that of PAH metabolites was from 1 to 2.3 times higher. The study of inter-chemical associations revealed similarities and differences between the two areas, suggesting common and different sources of exposure depending on PAH respectively. The results confirmed the relevance of hair analysis to identify qualitative and quantitative differences in PAH exposure between populations from different areas. This study is the first one to investigate both parent PAH and their metabolites in a biological matrix.

Simultaneous Determination of 32 Polycyclic Aromatic Hydrocarbon Derivatives and Parent PAHs Using Gas Chromatography-Mass Spectrometry: Application in Groundwater Screening.

A simple, practical and precise method for the simultaneous analysis of 32 different polycyclic aromatic hydrocarbon (PAHs) including 16 parent PAHs, 8 oxygenated-PAHs (oxy-PAHs), 4 chloro-PAHs, and 4 nitrogen-containing heterocyclic PACs (N-PACs), in groundwater was established via gas chromatography-mass spectrometry (GC-MS) combined with liquid-liquid extraction (LLE). The obtained detection method possesses instrument detection limits (at a signal to noise of 3:1) in the range of 0.05-10ng/mL and method detection limits in the range of 1.7-13.2ng/L. The average recoveries of the 32 analytes were in the range of 54.3%-127.0% with relative standard deviations (RSDs) < 20%, and the recoveries of 16 PAH derivatives ranged from 54.3 to 115.1% with RSDs < 17.9%. The method has been successfully applied to the screening of 64 groundwater samples from eastern China. The results revealed that 30 types of targets including 16 PAHs and 14 PAH derivatives were detected and that the groundwater in most areas is slightly polluted, while the pollution of Jiangsu Province and Shandong Province was more serious.

Effect of biodiesel on PAH, OPAH, and NPAH emissions from a direct injection diesel engine.

Polycyclic aromatic hydrocarbon (PAH), oxy- and nitro-derivate PAH (OPAH and NPAH) emissions from a direct injection diesel engine fueled with conventional fossil diesel (D), waste cooking oil biodiesel (B100), and their two blends (B20 and B50) were compared. The results show that B100 can reduce low molecular weight PAHs such as naphthalene, acenaphthylene, and fluorene as much as 90% compared with diesel. However, the emissions of high molecular weight PAHs including benzo[b]fluoranthene, benzo[k]fluoranthene, and benzo[a]pyrene decrease slightly when using B100. The emission levels for PAHs and OPAHs present comparable, while NPAH emission levels are five to ten times lower than those of PAHs and OPAHs. Compared with diesel, PAH and NPAH emissions significantly decrease. On the contrary, an increase trend of OPAH emission has been observed with adding biodiesel. For the specific parent PAHs and its oxygenated and nitrated derivatives, the fractions of parent PAHs gradually decrease with increasing biodiesel content in the blends, while the corresponding oxygenated and nitrated derivative fractions observably increase, especially for the high molecular weight compounds. Considering the increase of OPAH and NPAH fractions in total particle-phase PAHs when using biodiesel, in-depth biodiesel cytotoxicity assessment should be conducted.

Influences of Light Intensity and β-Carotene on Polycyclic Aromatic Hydrocarbons and Aldehydes in Vegetable Oil: A Case Study Using Palm Oil

This study investigated the effects of three light intensities on four types of palm oils during consecutive storage for 12 months at 4 °C. The concentrations of 4-hydroxy-2- trans-hexenal (4-HHE), 4-hydroxy-2- trans-nonenal (4-HNE), polycyclic aromatic hydrocarbon (PAH)4, and PAH8 in the oils significantly increased with the increasing light intensity after storage. The red palm oil had the lowest rate of increase of 4-HNE, while 5° palm oil had the highest rate of increase of the PAH, OPAH, 4-HNE, and peroxide values during storage. For the same type of oil, OPAHs increased significantly under a light intensity of 6000 lx (lx) after storage. The increasing concentrations of 9FO, ATQ, and BaPO in the oils stored at 6000 lx showed a positive relation to their corresponding parent PAHs, indicating that PAH oxidation occurred at 6000 lx. The results suggest that light intensity and β-carotene may control PAHs, OPAHs, and 4-hydroxy-trans- alkenals for vegetable oil storage, transportation, and retail.

Polycyclic Aromatic Compounds Identified in Thirdhand Smoke Contaminated House Dust

Thirdhand smoke (THS) is the residue of tobacco smoke that remains in house dust and on surfaces, and can be re-emitted into air and further react in the indoor environment to create additional compounds. THS-contaminated house dust poses a special risk to children due to their hand-to-mouth behaviors, as well as their vulnerable stage of development. Chemicals already characterized in THS-contaminated house dust include nicotine, tobacco-specific nitrosamines, and polycyclic aromatic hydrocarbons (PAHs). Here we report on the concentrations of a suite of non-traditionally measured polycyclic aromatic compounds (PACs), including oxygenated-PAHs and methyl-PAHs, which may be more toxic than parent PAHs. House dust samples were collected using the HVS3 cyclone vacuum from homes of smokers (n&amp;#61;30) and nonsmokers (n&amp;#61;9) in San Diego, CA, USA, and characterized for a variety of PACs by GCxGC/ToF-MS. Multiple PACs were elevated in dust samples from smokers&amp;#8217; as compared to nonsmokers&amp;#8217; homes. Of particular note was the detection of 1,2,naphthoquinone (1,2NQ), which was the most highly abundant oxy-PAH, and was elevated in smokers&amp;#8217; homes relative to nonsmokers&amp;#8217; (median 7822 ng/m2 vs. 4111 ng/m2), though this difference was not significant. 1,2NQ levels were significantly correlated with nicotine measured in the same samples (rho &amp;#61; 0.0374, p&amp;#61;0.027), suggesting that this compound may be associated with THS. 1,2 NQ is directly mutagenic and has not been reported before in house dust to our knowledge, though it has been reported in tobacco smoke, PM2.5 air pollution and diesel exhaust. Results indicate that measurement of traditional 16 EPA PAHs may underestimate toxic compounds in house dust, and that thirdhand smoke in house dust may be a source of elevated levels of certain toxic PACs. The compound 1,2 NQ and other PACs in house dust may pose a risk to children and policies should be strengthened to prevent THS exposure in homes.

The aryl hydrocarbon receptor (AhR) activity and DNA-damaging effects of chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs)

An increasing number of studies have indicated that environmental contamination with chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) has been underestimated. However, insufficient available toxicological information on Cl-PAHs makes evaluating their risks to health challenging. Two in vitro bioassays were used in the present study to characterize the aryl hydrocarbon receptor (AhR) activity and DNA-damaging effects of 22 low-molecular-weight PAHs and their Cl-PAHs by using the EROD assay in rat hepatoma (H4IIE) cells and the SOS/umu test (S. typhimurium TA1535/pSK1002). Compared with their parent PAHs, most of the Cl-PAHs enhanced AhR-mediated activity in the EROD assay. 1,3,6,8-Tetrachloro-pyrene (1,3,6,8-Tetracl-Py) induced the greatest potency of EROD activity (83.1%-TCDD-max) and its single point ReP was 6.64 × 10−6. Compared with their parent PAHs, several Cl-PAHs showed significant DNA-damaging effects in the SOS/umu test with the addition of S9, and the toxic equivalency of benzo[a]pyrene (TEQBaP) was calculated for them. 9-Chloroanthracene (9-Ant) and 5,6-Dichloroacenaphthene (5,6-Dicl-Ace) had relatively high TEQBaP (0.62 and 0.54, respectively). However, only 1,3,6,8-Tetracl-Py elicited strong DNA-damaging effects in the absence of S9. The degree of chlorination, the position of chlorine substitutions, and the structure of parent PAHs influenced the potency of low-molecular-weight PAHs with regard to their AhR activity and DNA-damaging effects. More concern should be raised for these environmentally relevant pollutants.