Polycyclic aromatic hydrocarbons identified in soot extracts from domestic coal-burning stoves of Henan Province, China

Tracking the history of polycyclic aromatic compounds in London through a River Thames sediment core and ultrahigh resolution mass spectrometry

Polycyclic aromatic compounds (PACs), including polycyclic aromatic hydrocarbons (PAHs) and heteroatom-containing analogues, constitute an important environmental contaminant class. For decades, limited numbers of priority PAHs have been routinely targeted in pollution investigations, however, there is growing awareness for the potential occurrence of thousands of PACs in the environment. In this study, untargeted Fourier transform ion cyclotron resonance mass spectrometry was used for the molecular characterisation of PACs in a sediment core from Chiswick Ait, in the River Thames, London, UK. Using complex mixture analysis approaches, including aromaticity index calculations, the number of molecular PAC components was determined for eight core depths, extending back to the 1930s. A maximum of 1676 molecular compositions representing PACs was detected at the depth corresponding to the 1950s, and a decline in PAC numbers was observed up the core. A case linking the PACs to London's coal consumption history is presented, alongside other possible sources, with some data features indicating pyrogenic origins. The overall core profile trend in PAC components, including compounds with oxygen, sulfur, nitrogen, and chlorine atoms, is shown to broadly correspond to the 16 priority PAH concentration profile trend previously determined for this core. These findings have implications for other industry-impacted environments.

Benzo[b]naphtho[d]thiophenes and naphthylbenzo[b]thiophenes: Their aryl hydrocarbon receptor-mediated activities and environmental presence

Polycyclic aromatic sulfur heterocyclic compounds (PASHs) belong among ubiquitous environmental pollutants; however, their toxic effects remain poorly understood. Here, we studied the aryl hydrocarbon receptor (AhR)-mediated activity of dibenzothiophene, benzo[b]naphtho[d]thiophenes, and naphthylbenzo[b]thiophenes, as well as their presence in two types of environmental matrices: river sediments collected from both rural and urban areas, and in airborne particulate matter (PM_2.5) sampled in cities with different levels and sources of pollution. Benzo[b]naphtho[2,1-d]thiophene, benzo[b]naphtho[2,3-d]thiophene, 2,2-naphthylbenzo[b]thiophene, and 2,1-naphthylbenzo[b]thiophene were newly identified as efficient AhR agonists in both rat and human AhR-based reporter gene assays, with 2,2-naphthylbenzo[b]thiophene being the most potent compound identified in both species. Benzo[b]naphtho[1,2-d]thiophene and 3,2-naphthylbenzo[b]thiophene elicited AhR-mediated activity only in the rat liver cell model, while dibenzothiophene and 3,1-naphthylbenzo[b]thiophene were inactive in either cell type. Independently of their ability to activate the AhR, benzo[b]naphtho[1,2-d]thiophene, 2,1-naphthylbenzo[b]thiophene, 3,1-naphthylbenzo[b]thiophene, and 3,2-naphthylbenzo[b]thiophene inhibited gap junctional intercellular communication in a model of rat liver epithelial cells. Benzo[b]naphtho[d]thiophenes were dominant PASHs present in both PM_2.5 and sediment samples, with benzo[b]naphtho[2,1-d]thiophene being the most abundant one, followed by benzo[b]naphtho[2,3-d]thiophene. The levels of naphthylbenzo[b]thiophenes were mostly low or below detection limit. Benzo[b]naphtho[2,1-d]thiophene and benzo[b]naphtho[2,3-d]thiophene were identified as the most significant contributors to the AhR-mediated activity in the environmental samples evaluated in this study. Both induced nuclear translocation of the AhR, and they induced CYP1A1 expression in a time-dependent manner, suggesting that their AhR-mediated activity may depend on the rate of their intracellular metabolism. In conclusion, some PASHs could be significant contributors to the overall AhR-mediated toxicity of complex environmental samples suggesting that more attention should be paid to the potential health impacts of this group of environmental pollutants.

FT-ICR mass spectrometry for molecular characterization of water-insoluble organic compounds in winter atmospheric fine particulate matters

Water-insoluble organic compounds (WIOCs) are an important fraction of atmospheric fine particulate matters (PM_2.5), which could affect the climate system and threaten human health potentially. In this study, molecular characterization of WIOCs in PM_2.5 were investigated by 15 T Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with atmospheric pressure photoionization (APPI) source in positive ion mode. A total of 2573 and 1875 molecular formulas were identified in WIOCs extracted by dichloromethane, which were collected in hazy and normal days, respectively. The identified molecular formulas were further classified into four major subgroups, including CH, CHN, CHO and CHNO compounds. CHO compounds predominated in WIOCs, accounting for more than 60% in both samples. CHNO compounds (26.6%) and CH compounds (16.1%) were the second highest subgroups in WIOCs from the hazy days and normal days, respectively. The relative abundance and number of nitro-substituted aromatic compounds were significantly higher in hazy days than in normal days. The molecular composition of WIOCs was more complex in hazy days while more aromatic compounds were identified in normal days.

Nontarget Screening of Polycyclic Aromatic Compounds in Atmospheric Particulate Matter Using Ultrahigh Resolution Mass Spectrometry and Comprehensive Two-Dimensional Gas Chromatography

Polycyclic aromatic hydrocarbons (PAHs) are mutagenic and carcinogenic. 16 PAHs as priority pollutants listed by the US Environmental Protection Agency were usually monitored. Therefore, multiple potentially toxic polycyclic aromatic compounds (PACs) are not monitored. In this study, atmospheric particulate matter samples from Beijing were analyzed using atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and comprehensive two-dimensional gas chromatography-time-of-flight (GC × GC-TOF) mass spectrometry. The FT-ICR data detected high molecular weight PAHs, alkylated PAHs (APAHs) and heteroatom PAHs. The GC × GC-TOF data tentatively identified 386 PACs in five categories of identification confidence. Twenty-one spectra in the unknown class were manually resolved. Eighty-two PACs with high identification confidence were proposed for further research. The identities of five PAHs and five APAHs that are currently not regulated were confirmed using available standards and quantified in some samples. Some of these PACs, such as dibenzo[a,e]pyrene (C₂₂H₁₄) and 1-methylpyrene (C₁₇H₁₂), should be of concern because of their contamination levels and the high toxicities of themselves and/or their derivatives. This study highlights the possibility of expanding the traditional lists of PAHs to improve pollution control and risk assessment accuracy.

Variation in black carbon concentration and aerosol optical properties in Beijing: Role of emission control and meteorological transport variability

Black carbon (BC), which is a by-product with incomplete combustion of carbonaceous materials, can be used as an indicator of combustion emissions and is an important climate forcer. In this study, a spatial-temporal synthesis of BC aerosols and the affecting factors was conducted in urban Beijing. As observed, BC showed a spatial pattern with high concentration in south and low in north. BC concentration evidently decreased by approximately 61% between 2005 and 2017. From 2015 to 2017, the mass ratio of BC/PM_2.5 dropped by 28%, which suggested a more efficient effect of control measures to BC than PM_2.5. The BC/CO ratio dropped by 22%, which indicated the decreasing emission from fossil fuel sources. With regard to BC loading, the spectral dependence of absorption aerosol exhibited significant seasonal variations. High absorption Ångström exponent (α) was observed during heating season, which reflected the increasing contribution of brown carbon (BrC) to light absorption. Backward trajectory analysis showed that the levels of BC and PM_2.5 were high in Cluster-South and Cluster-West. BrC absorption was high in Cluster-West, Cluster-Northwest and Cluster-Northeast, due to the biomass and coal burning for domestic heating and aging processes on a regional scale. The effects of emission control and transport variability on pollutant variation were estimated on the basis of the cluster analysis. Results indicated that the effect of emission reduction was the major reason for the decrease of BC from 2015 to 2017, which resulted in a 34% reduction of BC concentration. Meanwhile, transport variability caused a 15% reduction.

Excitation-Emission Matrix Spectroscopy for Analysis of Chemical Composition of Combustion Generated Particulate Matter

Analysis of particulate matter (PM) is important for the assessment of human exposures to potentially harmful agents, notably combustion-generated PM. Specifically, polycyclic aromatic hydrocarbons (PAHs) found in ultrafine PM have been linked to cardiovascular diseases and carcinogenic and mutagenic effects. In this study, we quantify the presence and concentrations of PAHs with lower molecular weight (LMW, 126 < MW < 202) and higher molecular weight (HMW, 226 < MW < 302), i.e., smaller and larger than Pyrene, in combustion-generated PM using excitation-emission matrix (EEM) fluorescence spectroscopy. Laboratory combustion PM samples were generated in a laminar diffusion inverted gravity flame reactor (IGFR) operated on ethylene and ethane. Fuel dilution by Ar in 0% to 90% range controlled the flame temperature. The colder flames result in lower PM yields however, the PM PAH content increases significantly. Temperature thresholds for PM transition from low to high organic carbon content were characterized based on the maximum flame temperature (T_max,c ∼ 1791 to 1857 K) and the highest soot luminosity region temperature (T*_c ∼ 1600 to 1650K). Principal component regression (PCR) analysis of the EEM spectra of IGFR samples correlates to GCMS data with R² = 0.988 for LMW and 0.998 for HMW PAHs. PCR-EEM analysis trained on the IGFR samples was applied to PM samples from woodsmoke and diesel exhaust, the model accurately predicts HMW PAH concentrations with R² = 0.976 and overestimates LMW PAHs.

Identification of 7-9 ring polycyclic aromatic hydrocarbons in coals and petrol coke using High performance liquid chromatography - Diode array detection coupled to Atmospheric pressure laser ionization - Mass spectrometry (HPLC-DAD-APLI-MS)

Polycyclic aromatic hydrocarbons containing at least 24 carbon atoms (≥C₂₄-PAH) are often associated with pyrogenic processes such as combustion of fuel, wood or coal, and occur in the environment in diesel particulate matter, black carbon and coal tar. Some of the ≥C₂₄-PAH, particularly the group of dibenzopyrenes (five isomers, six aromatic rings) are known to show high mutagenic and carcinogenic activita. Gas chromatography - mass spectrometry is a well-established method for the analysis of lower molecular weight PAH but is not optimally suited for the analysis of ≥C₂₄-PAH due to their low vapor pressures. Also, hundreds of ≥C₂₄-PAH isomers are possible but only a few compounds are commercially available as reference standards. Therefore, in this study, a combination of multidimensional liquid chromatography, UV-Vis diode array detection, PAH selective and highly sensitive atmospheric pressure laser ionization - mass spectrometry is used to detect and unequivocally identify PAH. For identification of PAH in two bituminous coals and one petrol coke sample, unique and compound specific UV-Vis spectra were acquired. It was possible to identify ten compounds (naphtho[1,2,3,4-ghi]perylene, dibenzo[b,ghi]perylene, dibenzo[e,ghi]perylene, dibenzo[cd,lm]perylene, benzo[a]coronene, phenanthrol[5,4,3,2-abcde]perylene, benzo[ghi]naphtho[8,1,2-bcd]perylene, benzo[pqr]naphtho[8,1,2-bcd]perylene, naphtho[8,1,2-abc]coronene and tribenzo[e,ghi,k]perylene) by comparison of acquired spectra with spectra from literature. Additionally, it was possible to detect similar distribution patterns in different samples and signals related to alkylated naphthopyrenes, naphthofluoranthenes or dibenzopyrenes. Subsequent effect-directed analysis of a bituminous coal sample using the microEROD (ethoxyresorufin-O-deethylase) bioassay showed high suitability and revealed lower EROD induction for the ≥C₂₄-PAH (TEQ range 0.67-10.07 ng/g) than for the allover < C₂₄-PAH containing fraction (TEQ 84.00 ng/g). Nevertheless, the toxicity of ≥C₂₄-PAH has a significant impact compared with <C₂₄-PAH and must be considered for risk assessment. The LC-DAD-APLI-MS method, presented in this study, is a powerful tool for the unequivocal identification of these ≥ C₂₄-PAH.

Resonance-stabilized hydrocarbon-radical chain reactions may explain soot inception and growth

Mystery surrounds the transition from gas-phase hydrocarbon precursors to terrestrial soot and interstellar dust, which are carbonaceous particles formed under similar conditions. Although polycyclic aromatic hydrocarbons (PAHs) are known precursors to high-temperature carbonaceous-particle formation, the molecular pathways that initiate particle formation are unknown. We present experimental and theoretical evidence for rapid molecular clustering–reaction pathways involving radicals with extended conjugation. These radicals react with other hydrocarbon species to form covalently bound complexes that promote further growth and clustering by regenerating resonance-stabilized radicals through low-barrier hydrogen-abstraction and hydrogen-ejection reactions. Such radical–chain reaction pathways may lead to covalently bound clusters of PAHs and other hydrocarbons that would otherwise be too small to condense at high temperatures, thus providing the key mechanistic steps for rapid particle formation and surface growth by hydrocarbon chemisorption.

Modular Design of Fluorescent Dibenzo- and Naphtho-Fluoranthenes: Structural Rearrangements and Electronic Properties

A library of 12 dibenzo- and naphtho-fluoranthene polycyclic aromatic hydrocarbons (PAHs) with MW = 302 (C₂₄H₁₄) was synthesized via a Pd-catalyzed fluoranthene ring-closing reaction. By understanding the various modes by which the palladium migrates during the transformation, structural rearrangements were bypassed, obtaining pure PAHs in high yields. Spectroscopic and electrochemical characterization demonstrated the profound diversity in the electronic structures between isomers. Highlighting the significant differences in emission of visible light, this library of PAHs will enable their standardization for toxicological assessment and potential use as optoelectronic materials.

Molecular Marker Study of Particulate Organic Matter in Southern Ontario Air

To study the origins of airborne particulate organic matter in southern Ontario, molecular marker concentrations were studied at Hamilton, Simcoe, and York Gateway Tunnel, representing industrial, rural, and heavy traffic sites, respectively. Airborne particulate matter smaller than 10 μm in aerodynamic diameter was collected on quartz filters, and the collected samples were analyzed for total carbons, 5-6 ring PAHs, hopanes, n-alkanes (C₂₀ to C₃₄), and oxygenated aromatic compounds. Results showed that PAH concentrations at all three sites were highly correlated, indicating vehicular emissions as the major source. Meanwhile, in the scatter plots of α,β-hopane and trisnorhopane, concentrations displayed different trends for Hamilton and Simcoe. The slopes of the linear regressions for Hamilton and the tunnel were statistically the same, while the slope for Simcoe was significantly different from those. Comparison with literature values revealed that the trend observed at Simcoe was explained by the influence from coal combustion. We also found that the majority of oxygenated aromatic compounds at both sites were in the similar level, possibly implying secondary products contained in the southern Ontario air. Regardless of some discrepancies, absolute principal component analysis applied to the datasets could reproduce those findings.

Source-oriented risk assessment of inhalation exposure to ambient polycyclic aromatic hydrocarbons and contributions of non-priority isomers in urban Nanjing, a megacity located in Yangtze River Delta, China

Sixteen U.S. EPA priority polycyclic aromatic hydrocarbons (PAHs) and eleven non-priority isomers including some dibenzopyrenes were analyzed to evaluate health risk attributable to inhalation exposure to ambient PAHs and contributions of the non-priority PAHs in a megacity Nanjing, east China. The annual average mass concentration of the total 16 EPA priority PAHs in air was 51.1 ± 29.8 ng/m³, comprising up to 93% of the mass concentration of all 27 PAHs, however, the estimated Incremental Lifetime Cancer Risk (ILCR) due to inhalation exposure would be underestimated by 63% on average if only accounting the 16 EPA priority PAHs. The risk would be underestimated by 13% if only particulate PAHs were considered, though gaseous PAHs made up to about 70% of the total mass concentration. During the last fifteen years, ambient Benzo[a]pyrene decreased significantly in the city which was consistent with the declining trend of PAHs emissions. Source contributions to the estimated ILCR were much different from the contributions for the total mass concentration, calling for the introduce of important source-oriented risk assessments. Emissions from gasoline vehicles contributed to 12% of the total mass concentration of 27 PAHs analyzed, but regarding relative contributions to the overall health risk, gasoline vehicle emissions contributed 45% of the calculated ILCR. Dibenzopyrenes were a group of non-priority isomers largely contributing to the calculated ILCR, and vehicle emissions were probably important sources of these high molecular weight isomers. Ambient dibenzo[a,l]pyrene positively correlated with the priority PAH Benzo[g,h,i]perylene. The study indicates that inclusion of non-priority PAHs could be valuable for both PAH source apportionment and health risk assessment.

Association of Genetic Variants of CYP2C19 and CYP2D6 with Esophageal Squamous Cell Carcinoma Risk in Northern India, Kashmir

Genetic polymorphism in xenobiotic metabolizing enzymes (XMEs) is associated with various malignancies. However, the association of esophageal cancer with XMEs is mixed. The current study was aimed to explore the association of genetic polymorphisms of cytochrome (CYP) 2C19 and CYP2D6 genotypes with esophageal squamous cell carcinoma (ESCC) risk in Kashmir, India. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing methods were used for genotyping of 492 ESCC cases and equal number of individually matched controls. Conditional logistic regression models were used to assess odds ratios (ORs) and 95% confidence intervals. Increased ESCC risk was observed in subjects with variant genotypes of CYP2C19 (OR = 3.3) or CYP2D6 (OR = 2.1) and risk was higher (OR = 4.6) in subjects who harbored both the genotypes. Almost same but higher risk turned when subjects were smokers and carried a variant genotype of CYP2C19 (OR = 4.4) or CYP2D6 (OR = 4.7). Risk was appreciably increased in subjects who had family history of any cancer and also harbored a variant genotype of either CYP2C19 (OR = 15.5) or CYP2D6 (OR = 9.7). Subjects harboring a variant genotype of CYP2D6 showed an added risk when they used biomass as fuel (OR = 4.6). In conclusion, variant genotypes of CYP2C19 and CYP2D6 are associated with an increased risk of ESCC.

Characteristics of PAHs from deep-frying and frying cooking fumes

Cooking fumes are an important indoor source of polycyclic aromatic hydrocarbons (PAHs). Because indoor pollution has a more substantial impact on human health than outdoor pollution, PAHs from cooking fumes have drawn considerable attention. In this study, 16 PAHs emitted through deep-frying and frying methods using rapeseed, soybean, peanut, and olive oil were examined under a laboratory fume hood. Controlled experiments were conducted to collect gas- and particulate-phase PAHs emitted from the cooking oil fumes, and PAH concentrations were quantified via high-performance liquid chromatography (HPLC). The results show that deep-frying methods generate more PAHs and benzo[a]pyrene (B[a]P) (1.3 and 10.9 times, respectively) because they consume greater volumes of edible oil and involve higher oil temperatures relative to those of frying methods. In addition, the total B[a]Peq concentration of deep-frying is 2.2-fold larger than that of frying. Regarding the four types of edible oils studied, rapeseed oil produced more PAH emission than the other three oil varieties. For all of the cooking tests, three- and four-ringed PAHs were the main PAH components regardless of the food and oil used. Concerning the PAH partition between gas and particulate phase, the gaseous compounds accounted for 59-96 % of the total. Meanwhile, the particulate fraction was richer of high molecular weight PAHs (five-six rings). Deep-frying and frying were confirmed as important sources of PAH pollution in internal environments. The results of this study provide additional insights into the polluting features of PAHs produced via cooking activities in indoor environments.

Family history of cancer and the risk of squamous cell carcinoma of oesophagus: a case-control study in Kashmir, India

Background:

Only a few studies have examined the association between family history of cancer (FHC) and the risk of oesophageal squamous cell carcinoma (ESCC) in high incidence areas of ESCC. We conducted a case–control study to evaluate the relationship between FHC and ESCC risk in Kashmir, India, with analysis of detailed epidemiological data and information on multiple gene polymorphisms.

Methods:

We collected detailed information on FHC and a number of socio-demographic and lifestyle factors, and also obtained blood samples for genetic analysis from 703 histopathologically confirmed ESCC cases and 1664 individually matched controls. Conditional logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs).

Results:

Participants who had FHC showed a strong association with ESCC risk, and the risk was stronger when first-degree relatives (FDRs) had FHC (OR=6.8; 95% CI=4.6–9.9). Having a sibling with a cancer showed the strongest association (OR=10.8; 95% CI=6.0–19.3), but having a child with a cancer was not associated with ESCC risk. A history of any cancer in the spouse was also associated with ESCC risk (OR=4.1; 95% CI=1.6–10.2). Those with two or more relatives with FHC were at a higher risk of ESCC. After restricting FHC to familial ESCC only, the above associations were strengthened, except when spouses were affected with ESCC (OR=2.5; 95% CI=0.7–8.9). When we examined the associations between several single-nucleotide polymorphisms and ESCC in those with and without FHC, the associations of variant genotypes in cytochrome P450 (CYP) 2C19 and CYP2D6 and the wild genotype of CYP2E1 with ESCC were much stronger in those with FHC. The FHC had an additive interaction with several risk factors of ESCC in this population.

Conclusion:

Our results showed that FHC was strongly associated with ESCC risk in Kashmir. It seems both genetic factors and shared environment are involved in this association.

Time to Say Goodbye to the 16 EPA PAHs? Toward an Up-to-Date Use of PACs for Environmental Purposes

The 16 EPA PAHs have played an exceptionally large role above all in environmental and analytical sciences in the last 40 years, but now there are good reasons to question their utility in many circumstances even though their use is so established and comfortable. Here we review the reasons why the list has been so successful and why sometimes it is seen as less relevant. Three groups of polycyclic aromatic compounds (PAC) are missing: larger and highly relevant PAHs, alkylated PACs, and compounds containing heteroatoms. Attempts to improve the situation for certain matrixes are known and here: (1) an updated list of PAHs (including the 16 EPA PAHs) for the evaluation of the toxicity in the environment (40 EnvPAHs); (2) a list of 23 NSO-heterocyclic compounds and 6 heterocyclic metabolites; and (3) lists of 10 oxy-PAHs and 10 nitro-PAHs are proposed for practical use in the future. A discussion in the scientific community about these lists is invited. Although the state of knowledge has improved dramatically since the introduction of the 16 EPA PAHs in the 1970s, this summary also shows that more research is needed about the toxicity, occurrence in the environment and chemical analysis, particularly of alkylated PAHs, higher molecular weight PAHs and substituted PACs such as amino-PAHs, cyano-PAHs, etc.. We also suggest that a long overdue discussion of an update of regulatory environmental PAH analysis is initiated.

Polycyclic aromatic hydrocarbons (PAHs) in ambient aerosols from Beijing: characterization of low volatile PAHs by positive-ion atmospheric pressure photoionization (APPI) coupled with Fourier transform ion cyclotron resonance

Aromatic fractions derived from aerosol samples were characterized by gas chromatography and mass spectrometry (GC-MS), high temperature simulated distillation (SIMDIS), and positive-ion atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), respectively. It was found that about 27 wt % compounds in aromatic fractions could not be eluted from a GC column and some large molecule PAHs were neglected in GC-MS analysis. APPI FT-ICR MS was proven to be a powerful approach for characterizing the molecular composition of aromatics, especially for the large molecular species. An aromatic sample from Beijing urban aerosol was successfully characterized by APPI FT-ICR MS. Results showed that most abundant aromatic compounds in PM2.5 (particles with aerodynamic diameter ≤ 2.5 μm) were highly condensed hydrocarbons with 4-8 aromatic rings and their homologues with very short alkyl chains. Furthermore, heteroatom-containing hydrocarbons were found as the significant components of the aromatic fractions: O1, O2, N1, and S1 class species with 10-28 DBEs (double bond equivalents) and 14-38 carbon numbers were identified by APPI FT-ICR MS. The heteroatom PAHs had similar DBEs and carbon number distribution as regular PAHs.

Can Coronene and/or Benzo(a)pyrene/Coronene ratio act as unique markers for vehicle emission?

Coronene is a high molecular weight polycyclic aromatic hydrocarbon with seven aromatic rings. It, more specifically a lower ratio of Benzo[a]pyrene to Coronone (BaP/COR), is suggested as a marker for vehicle emission. In the present study, emissions of Coronene were measured from residential combustions of wood, crop straw, and pellets. The detection of COR in non-vehicle emission sources, and comparable BaP/COR ratios between the solid fuel combustion and vehicle emissions indicated that the generality of COR or the BaP/COR ratio as markers for the vehicle emission would be questionable, especially for the area where solid fuel combustion dominated the PAHs emission.

Variation in PAH-related DNA adduct levels among non-smokers: the role of multiple genetic polymorphisms and nucleotide excision repair phenotype

Polycyclic aromatic hydrocarbons (PAHs) likely play a role in many cancers even in never-smokers. We tried to find a model to explain the relationship between variation in PAH-related DNA adduct levels among people with similar exposures, multiple genetic polymorphisms in genes related to metabolic and repair pathways, and nucleotide excision repair (NER) capacity. In 111 randomly selected female never-smokers from the Golestan Cohort Study in Iran, we evaluated 21 SNPs in 14 genes related to xenobiotic metabolism and 12 SNPs in eight DNA repair genes. NER capacity was evaluated by a modified comet assay, and aromatic DNA adduct levels were measured in blood by32P-postlabeling. Multivariable regression models were compared by Akaike's information criterion (AIC). Aromatic DNA adduct levels ranged between 1.7 and 18.6 per 10(8) nucleotides (mean: 5.8 ± 3.1). DNA adduct level was significantly lower in homozygotes for NAT2 slow alleles and ERCC5 non-risk-allele genotype, and was higher in the MPO homozygote risk-allele genotype. The sum of risk alleles in these genes significantly correlated with the log-adduct level (r = 0.4, p < 0.001). Compared with the environmental model, adding Phase I SNPs and NER capacity provided the best fit, and could explain 17% more of the variation in adduct levels. NER capacity was affected by polymorphisms in the MTHFR and ERCC1 genes. Female non-smokers in this population had PAH-related DNA adduct levels three to four times higher than smokers and occupationally-exposed groups in previous studies, with large inter-individual variation which could best be explained by a combination of Phase I genes and NER capacity.

Polycyclic aromatic hydrocarbons and esophageal squamous cell carcinoma

Esophageal cancer (EC) is the 8th most common cancer and the 6th most frequent cause of cancer mortality worldwide. Esophageal squamous cell carcinoma (ESCC) is the most common type of EC. Exposure to polycyclic aromatic hydrocarbons (PAHs) has been suggested as a risk factor for developing ESCC. In this paper we will review different aspects of the relationship between PAH exposure and ESCC. PAHs are a group of compounds that are formed by incomplete combustion of organic matter. Studies in humans have shown an association between PAH exposure and development of ESCC in many populations. The results of a recent case-control study in a high risk population in northeastern Iran showed a dramatic dose-response relationship between PAH content in non-tumor esophageal tissue (the target tissue for esophageal carcinogenesis) and ESCC case status, consistent with a causal role for PAH exposure in the pathogenesis of ESCC.  Identifying the main sources of exposure to PAHs may be the first and most important step in designing appropriate PAH-reduction interventions for controlling ESCC, especially in high risk areas. Coal smoke and drinking mate have been suggested as important modifiable sources of PAH exposure in China and Brazil, respectively. But the primary source of exposure to PAHs in other high risk areas for ESCC, such as northeastern Iran, has not yet been identified. Thus, environmental studies to determining important sources of PAH exposure should be considered as a high priority in future research projects in these areas.

A multi-day environmental study of polycyclic aromatic hydrocarbon exposure in a high-risk region for esophageal cancer in China

Linzhou, China has one of the highest rates of esophageal squamous cell carcinoma in the world. Exposure to carcinogenic polycyclic aromatic hydrocarbons (PAHs), such as benzo[a]pyrene (BaP), may have a role in this increased risk. To better understand PAH sources, we measured PAHs in the air and food of 20 non-smokers over multiple days and compared the concentrations with a urinary PAH biomarker, 1-hydroxypyrene glucuronide (1-OHPG). Sampling occurred over 4 consecutive days. Kitchen air samples (days 2-3) and duplicate diet samples (days 1-4) were analyzed for 14 or more unique PAHs, including BaP. Daily urine samples (days 1-3) were analyzed for 1-OHPG. Mixed-effects models were used to evaluate the associations between air or food PAH concentrations and urine 1-OHPG concentrations. The median kitchen air BaP concentration was 10.2 ng/m(3) (interquartile range (IQR): 5.1-20.2 ng/m(3)). The median daily food BaP concentration and intake were 0.08 ng/g (IQR=0.04-0.16 ng/g) and 86 ng/day (IQR=41-142 ng/day), respectively. The median 1-OHPG concentration was 3.36 pmol/ml (IQR=2.09-6.98 pmol/ml). In mixed-effects models, 1-OHPG concentration increased with same-day concentration of food BaP (P=0.07). Although PAH concentrations in air were not associated with 1-OHPG concentrations, the high concentrations of PAHs in both air and food suggest that they are both important routes of exposure to PAHs in this population. Further evaluation of the role of PAH exposure from air and food in the elevated rates of esophageal cancer in this region is warranted.

Determination of benzo[a]pyrene and dibenzopyrenes in a Chinese coal fly ash certified reference material

Air pollution from coal combustion is of great concern in China because coal is the country's principal source of energy and it has been estimated that coal combustion is one of the main sources of polycyclic aromatic hydrocarbon (PAH) emissions in the nation. This study reports the concentrations of 15 PAHs including benzo[a]pyrene, dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,i]pyrene and dibenzo[a,h]pyrene in a coal fly ash certified reference material (CRM) from China. To the best of our knowledge, dibenzo[a,l]pyrene, dibenzo[a,i]pyrene and dibenzo[a,h]pyrene concentrations in coal fly ash particles have not previously been reported. Benzo[a]pyrene is the only one of the studied hydrocarbons whose concentration in the coal fly ash CRM had previously been certified. The concentration of this species measured in this present work was twice the certified value. This is probably because of the exhaustive accelerated solvent extraction method employed. Consecutive extractions indicated an extraction recovery in excess of 95% for benzo[a]pyrene. For the other determined PAHs, repeat extractions indicated recoveries above 90%.

Quantifying the total and bioavailable polycyclic aromatic hydrocarbons and dioxins in biochars

Biochar soil amendment is advocated to mitigate climate change and improve soil fertility. A concern though, is that during biochar preparation PAHs and dioxins are likely formed. These contaminants can possibly be present in the biochar matrix and even bioavailable to exposed organisms. Here we quantify total and bioavailable PAHs and dioxins in a suite of over 50 biochars produced via slow pyrolysis between 250 and 900 °C, using various methods and biomass from tropical, boreal, and temperate areas. These slow pyrolysis biochars, which can be produced locally on farms with minimum resources, are also compared to biochar produced using the industrial methods of fast pyrolysis and gasification. Total concentrations were measured with a Soxhlet extraction and bioavailable concentrations were measured with polyoxymethylene passive samplers. Total PAH concentrations ranged from 0.07 μg g(-1) to 3.27 μg g(-1) for the slow pyrolysis biochars and were dependent on biomass source, pyrolysis temperature, and time. With increasing pyrolysis time and temperature, PAH concentrations generally decreased. These total concentrations were below existing environmental quality standards for concentrations of PAHs in soils. Total PAH concentrations in the fast pyrolysis and gasification biochar were 0.3 μg g(-1) and 45 μg g(-1), respectively, with maximum levels exceeding some quality standards. Concentrations of bioavailable PAHs in slow pyrolysis biochars ranged from 0.17 ng L(-1) to 10.0 ng L(-1)which is lower than concentrations reported for relatively clean urban sediments. The gasification produced biochar sample had the highest bioavailable concentration (162 ± 71 ng L(-1)). Total dioxin concentrations were low (up to 92 pg g(-1)) and bioavailable concentrations were below the analytical limit of detection. No clear pattern of how strongly PAHs were bound to different biochars was found based on the biochars' physicochemical properties.

Exposure to Polycyclic Aromatic Hydrocarbons Among Never Smokers in Golestan Province, Iran, an Area of High Incidence of Esophageal Cancer - a Cross-Sectional Study with Repeated Measurement of Urinary 1-OHPG in Two Seasons

Studies have suggested a possible role of polycyclic aromatic hydrocarbons (PAHs) in the etiology of esophageal cancer in Golestan Province, Iran, where incidence of this cancer is very high. In order to investigate the patterns of non-smoking related exposure to PAHs in Golestan, we conducted a cross-sectional study collecting questionnaire data, genotyping polymorphisms related to PAH metabolism, and measuring levels of 1-hydroxypyrene glucuronide (1-OHPG), a PAH metabolite, in urine samples collected in two seasons from the same group of 111 randomly selected never-smoking women. Beta-coefficients for correlations between 1-OHPG as dependent variable and other variables were calculated using linear regression models. The creatinine-adjusted 1-OHPG levels in both winter and summer samples were approximately 110 μmol/molCr (P for seasonal difference = 0.40). In winter, red meat intake (β = 0.208; P = 0.03), processed meat intake (β = 0.218; P = 0.02), and GSTT1-02 polymorphism ("null" genotype: β = 0.228; P = 0.02) showed associations with 1-OHPG levels, while CYP1B1-07 polymorphism (GG versus AA + GA genotypes: β = -0.256; P = 0.008) showed an inverse association. In summer, making bread at home (> weekly versus never: β = 0.203; P = 0.04), second-hand smoke (exposure to ≥3 cigarettes versus no exposure: β = 0.254; P = 0.01), and GSTM1-02 "null" genotype (β = 0.198; P = 0.04) showed associations with 1-OHPG levels, but GSTP1-02 polymorphism (CT + TT versus CC: β = -0.218; P = 0.03) showed an inverse association. This study confirms high exposure of the general population in Golestan to PAHs and suggests that certain foods, cooking methods, and genetic polymorphisms increase exposure to PAHs.

Carcinogenic potencies of polycyclic aromatic hydrocarbons for back-door neighbors of restaurants with cooking emissions

In the present study, 21 polycyclic aromatic hydrocarbon (PAH) congeners were measured in the exhaust stack of 3 types of restaurants: 9 Chinese, 7 Western, and 4 barbeque (BBQ). The total PAH concentration of BBQ restaurants (58.81 ± 23.89 μg m(-3)) was significantly higher than that of Chinese (20.99 ± 13.67 μg m(-3)) and Western (21.47 ± 11.44 μg m(-3)) restaurants. The total benzo[a]pyrene potency equivalent (B[a]P(eq)) concentrations, however, were highest in Chinese restaurants (1.82 ± 2.24 μg m(-3)), followed by Western (0.86 ± 1.43 μg m(-3), p<0.01) and BBQ-type restaurants (0.59 ± 0.55 μg m(-3), p<0.01). We further developed a probabilistic risk model to assess the incremental lifetime cancer risk (ILCR) for people exposed to carcinogenic PAHs. Because the exhaust stack directly affected the back-door neighbors of these restaurants, we were concerned with the real exposure of groups near the exhaust stack outlets of these restaurants. The ILCRs for total exposure of the neighbors (inhalation+dermal contact+ingestion) were 2.6-31.3, 1.5-14.8, and 1.3-12.2 × 10(-6) in Chinese, Western, and BBQ restaurants, respectively. We suggest that the maximum acceptable exposure time to the exhaust stack outlet area for Chinese, Western, and BBQ restaurants ranges between 5-19, 17-42, and 18-56 h month(-1), respectively, based on an ILCR of less than 10(-6).

Esophageal squamous cell carcinoma - precursor lesions and early diagnosis

Squamous cell carcinoma of the esophagus (SCCE) carries a poor prognosis due to late diagnosis. Early detection is highly desirable, since surgical and endoscopic resection offers the only possible cure for esophageal cancer. Population screening should be undertaken in high risk areas, and in low or moderate risk areas for people with risk factors (alcoholics, smokers, mate drinkers, history of head and neck cancer, achalasia and lye stricture of the esophagus). Esophageal balloon cytology is an easy and inexpensive sampling technique, but the current methods are insufficient for primary screening due to sampling errors. Conventional endoscopy with biopsy remains the standard procedure for the identification of pre-malignant and early malignant changes in esophageal mucosa and endoscopic detection. It may be enhanced by several techniques such as dye and optic chromoendoscopy, magnifying endoscopy, and optical-based spectroscopic and imaging modalities. Since more than 80% of SCCE deaths occur in developing countries, where expensive techniques such as narrow band imaging (NBI) and autofluorescence imaging are unavailable, the most cost-effective tool for targeting biopsies may be Lugol dye chromoendoscopy, since it is easy, accurate, inexpensive and available worldwide. In ideal conditions, or in developed countries, is it reasonable to think that optimal detection will require a combination of techniques, such as the combination of Lugol’s chromoendoscopy and NBI to identify esophageal areas that require further characterization by a high resolution technique. The efficacy and cost-effectiveness will determine whether these modalities will become part of standard endoscopy practice.

Polycyclic aromatic hydrocarbons with molecular weight 302 in PM 2.5 at two industrial sites in South China

Daytime and nighttime PM(2.5) samples were collected between August 5 and 16, 2009 and between January 24 and February 4, 2010 in an industrial complex site (site A) and an electronic waste recycling site (site B) to determine the seasonal and diurnal variations of 19 individual polycyclic aromatic hydrocarbons (PAHs) with molecular weight 302 (MW302) including four highly carcinogenic dibenzopyrene (DBP) isomers dibenzo[a,l]pyrene (DBalP), dibenzo[a,e]pyrene (DBaeP), dibenzo[a,i]pyrene (DBaiP), and dibenzo[a,h]pyrene (DBahP). This is the first report on DBP isomers in air particles from South China. The total concentration of PAH MW302 isomers ranged from 1.65 to 3.60 ng m(-3) in summer and 3.82 to 9.81 ng m(-3) in winter. The strongest peaks in the chromatograms of the MW302 isomers were naphtha[2,1-a]pyrene (N21aP), dibenzo[j,l]fluoranthene (DBjlF), naphtha[1,2-b]fluoranthene (N12bF), naphtha[1,2-k]fluoranthene (N12kF) and dibenzo[a,e]fluoranthene (DBaeF), constituting 52.0 to 55.4% of the total MW302 isomers. All the MW302 isomers showed notable seasonal variations. Most of the MW302 isomers in site B showed distinctive diurnal variations with higher concentrations occurring in the night. Taking into account both concentration and potency equivalence factors (PEFs), the strongest carcinogen in the analyzed samples was DBaiP, and the ratios of sum carcinogenic potency of four highly carcinogenic DBP isomers to benzo[a]pyrene (BaP) was about 0.94 in winter to 1.89 in summer, indicating the importance of DBP isomers for the risk assessment. Health risk assessment indicated that on average, 1 in 100 000 residents in the two industrial sites may have an increased risk of cancer due to PAH exposure.

Analysis of carcinogenic polycyclic aromatic hydrocarbons in complex environmental mixtures by LC-APPI-MS/MS

Here we developed a highly sensitive, fast and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the detection and analysis of 16 different polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs that have been identified as carcinogens and classified according to their biological potency. Comparison to standard analysis procedures based on gas chromatography-mass spectrometry (GC-MS) instrumentation demonstrated an improved easiness of sample preparation and sensitivity of detection achieved with the new LC-MS/MS method employing an atmospheric pressure photoionization (APPI) source attached to an API 4000 mass spectrometer (LC-APPI-MS/MS). The favorable outcome could be confirmed by analyzing complex mixtures such as certain Standard Reference Materials (SRMs) obtained from the National Institute of Standards & Technology (NIST), i.e., SRM 1975 and SRM 2975, and several diesel exhaust soots provided by the German automobile industry. Certified concentrations of individual analytes provided by NIST not only could be confirmed, but additional extremely potent carcinogens such as several isomeric hexacyclic dibenzopyrenes (DBPs), 5-methylchrysene (5-MC), and others have been detected in these crude samples in a concentration range down to below 1 ng g(-1) raw material.

The effect of housing characteristics and occupant activities on the respiratory health of women and children in Lao PDR

The paper presents the results of a study conducted into the relationship between dwelling characteristics and occupant activities with the respiratory health of resident women and children in Lao People's Democratic Republic (PDR). Lao is one of the least developed countries in south-east Asia with poor life expectancies and mortality rates. The study, commissioned by the World Health Organisation, included questionnaires delivered to residents of 356 dwellings in nine Districts in Lao PDR over a five month period (December 2005-April 2006), with the aim of identifying the association between respiratory health and indoor air pollution, in particular exposures related to indoor biomass burning. Adjusted odds ratios were calculated for each health outcome separately using binary logistic regression. After adjusting for age, a wide range of symptoms of respiratory illness in women and children aged 1-4 years were positively associated with a range of indoor exposures related to indoor cooking, including exposure to a fire and location of the cooking place. Among women, "dust always inside the house" and smoking were also identified as strong risk factors for respiratory illness. Other strong risk factors for children, after adjusting for age and gender, included dust and drying clothes inside. This analysis confirms the role of indoor air pollution in the burden of disease among women and children in Lao PDR.

Association between indoor air pollution measurements and respiratory health in women and children in Lao PDR

This article presents the results of a study on the association between measured air pollutants and the respiratory health of resident women and children in Lao PDR, one of the least developed countries in Southeast Asia. The study, commissioned by the World Health Organisation, included PM(10), CO and NO(2) measurements made inside 181 dwellings in nine districts within two provinces in Lao PDR over a 5-month period (12/05-04/06), and respiratory health information (via questionnaires and peak expiratory flow rate (PEFR) measurements) for all residents in the same dwellings. Adjusted odds ratios were calculated separately for each health outcome using binary logistic regression. There was a strong and consistent positive association between NO(2) and CO for almost all questionnaire-based health outcomes for both women and children. Women in dwellings with higher measured NO(2) had more than triple of the odds of almost all of the health outcomes, and higher concentrations of NO(2) and CO were significantly associated with lower PEFR. This study supports a growing literature confirming the role of indoor air pollution in the burden of respiratory disease in developing countries. The results will directly support changes in health and housing policy in Lao PDR.

PRACTICAL IMPLICATIONS

This is the first study that investigated indoor air quality and its impact within residential dwellings in Lao PDR, which is one of the poorest and least developed countries in south-east Asia, with a life-expectancy of 56 years in 2008. While there have been other studies published on indoor air quality in other developing countries, the situation in Laos is different because the majority of houses in Laos used wood stoves, and therefore, emissions from wood burning are the dominant sources of indoor air pollution. In other countries, and studies, while emission from wood burning was investigated, wood was rarely the main or the only fuel used, as the houses used in addition (or solely) dung, kerosene or coal. The study quantified, for the first time, concentrations in houses two provinces in Laos PDR and shed light on the impact of human activities and urban design on pollutant concentrations and respiratory health. This study contributes to the accumulation of evidence to provide more reliable estimates of risk and a more informed basis for decision-making by concerned governments and communities.

Navajo coal combustion and respiratory health near Shiprock, New Mexico

Indoor air pollution has been identified as a major risk factor for acute and chronic respiratory diseases throughout the world. In the sovereign Navajo Nation, an American Indian reservation located in the Four Corners area of the USA, people burn coal in their homes for heat. To explore whether/how indoor coal combustion might contribute to poor respiratory health of residents, this study examined respiratory health data, identified household risk factors such as fuel and stove type and use, analyzed samples of locally used coal, and measured and characterized fine particulate airborne matter inside selected homes. In twenty-five percent of homes surveyed coal was burned in stoves not designed for that fuel, and indoor air quality was frequently found to be of a level to raise concerns. The average winter 24-hour PM_2.5 concentration in 20 homes was 36.0 μg/m³. This is the first time that PM_2.5 has been quantified and characterized inside Navajo reservation residents' homes.

Seasonal variation, sources and gas/particle partitioning of polycyclic aromatic hydrocarbons in Guangzhou, China

Air samples were collected weekly at an urban site and a suburban site in Guangzhou City, China, from April 2005 to March 2006, to measure the concentrations of polycyclic aromatic hydrocarbons (PAHs) in the ambient air and study their seasonal variations, gas/particle partitioning, origins and sources. The concentrations of summation Sigma16-PAHs (particle+gas) were 129.9+/-73.1 ng m(-)(3) at the urban site and 120.4+/-48.5 ng m(-)(3) at the suburban site, respectively. It was found that there was no significant difference in PAH concentrations between the urban and suburban sites. Seasonal variations of PAH concentrations at the two sampling sites were similar, with higher levels in the winter that gradually decreased to the lowest levels in the summer. The average concentrations of summation Sigma16-PAHs in the winter samples were approximately three times higher than those of the summer samples because in the summer local emissions dominated, and in the winter the contribution from outside sources or transported PAHs is increased. The plot of logK(p) versus logP(L)(0) for the data sets of summer and winter season samples had significantly different slopes at both sampling sites. The slopes for the winter samples were steeper than those for the summer samples. It was also observed that gas/particle partitioning of PAHs showed different characteristics depending on air parcel trajectories. Steeper slopes were obtained for an air parcel that traveled across the continent to the sampling site from the northern or northeastern sector, whereas shallower slopes were obtained for air masses that traveled across the sea from the southern or eastern sector. Diagnostic ratio analytical results imply that the origins of PAHs were mainly from petroleum combustion and coal/biomass burning. The anthracene/phenanthrene and benzo[a]anthracene/chrysene ratios in the winter were significantly lower than those in the summer, which indicate that there might be long-range transported PAH input to Guangzhou in the winter.

A source study of atmospheric polycyclic aromatic hydrocarbons in Shenzhen, South China

Air pollution has become a serious problem in the Pearl River Delta, South China, particularly in winter due to the local micrometeorology. In this study, atmospheric polycyclic aromatic hydrocarbons (PAHs) were monitored weekly in Shenzhen during the winter of 2006. Results indicated that the detected PAHs were mainly of vapor phase compounds with phenanthrene dominant. The average vapor phase and particle phase PAHs concentration in Shenzhen was 101.3 and 26.7 ng m( - 3), respectively. Meteorological conditions showed great effect on PAH concentrations. The higher PAHs concentrations observed during haze episode might result from the accumulation of pollutants under decreased boundary layer, slower wind speed, and long-term dryness conditions. The sources of PAHs in the air were estimated by principal component analysis in combination with diagnostic ratios. Vehicle exhaust was the major PAHs source in Shenzhen, accounting for 50.0% of the total PAHs emissions, whereas coal combustion and solid waste incineration contributed to 29.4% and 20.6% of the total PAHs concentration, respectively. The results clearly indicated that the increasing solid waste incinerators have become a new important PAHs source in this region.

Measurements of black and organic carbon emission factors for household coal combustion in China: implication for emission reduction

Household coal combustion is considered as the greatest emission source for black carbon (BC) and an important source for organic carbon (OC) in China. However, measurements on BC and OC emission factors (EF(BC) and EF(OC)) are still scarce, which result in large uncertainties in emission estimates. In this study, a detailed data set of EF(BC) and EF(OC) for household coal burning was presented on the basis of 38 coal/stove combination experiments. These experiments included 13 coals with a wide coverage of geological maturity which were tested in honeycomb-coal-briquette and raw-coal-chunk forms in three typical coal stoves. Averaged values of EF(BC) are 0.004 and 0.007 g/kg for anthracite in briquette and chunk forms and 0.09 and 3.05 g/kg for bituminous coal, respectively; EF(OC) are 0.06 and 0.10 g/kg for anthracite and 3.74 and 5.50 g/kg for bituminous coal in both forms, respectively. Coal maturity was found to be the most important influencing factor relative to coal's burning forms and the stove's burning efficiency, and when medium-volatile bituminous coals (MVB) are excluded from use, averaged EF(BC) and EF(OC) for bituminous coal decrease by 50% and 30%, respectively. According to these EFs, China's BC and OC emissions from the household sector in 2000 were 94 and 244 gigagrams (Gg), respectively. Compared with previous BC emission estimates for this sector (e.g., 465 Gg by Ohara et al., Atmos. Chem. Phys. 2007, 7, 4419-4444), a dramatic decrease was observed and was mainly attributed to the update of EFs. As suggested by this study, if MVB is prohibited as household fuel together with further promotion of briquettes, BC and OC emissions in this sector will be reduced by 80% and 34%, respectively, and then carbonaceous emissions can be controlled to a large extent in China.

Airborne particulates and polycyclic aromatic hydrocarbons (PAHs) in ambient air in Donghe, northern China

Five sets of size-fractionated particles were collected in a northern China village in various seasons in order to measure respirable airborne particulates (PM10) and particulate phase polycyclic aromatic hydrocarbons (PAHs) in ambient air. The time-weighted annual mean concentration and standard deviation of PM10 were 358 +/- 107 microg/m3, higher than both the national standard (100 microg/m3) and the levels observed in several contaminated northern Chinese cities. In addition to high levels of PAHs (391 +/- 487 ng/m3), the fraction of higher molecular weight PAHs was higher than most reported in the literature, and the time-weighted annual mean benzo(a)pyrene equivalent concentration was 44.2 +/- 51.4 ng/m3, more than four times the national standard of 10 ng/m3 and 44 times the WHO guideline of 1 ng/m3. Apparently, residents in Donghe suffer from exposure to high levels of both PM10 and particulate phase PAHs. The particle size distribution was centered in the range of Dp < or = 3.3 microm in winter and shifted to the ranges of Dp < or = 2.1 microm and 5.8 microm < Dp < 10 microm in spring and summer respectively. Approximately 90.0% of PAHs were associated with airborne particulates with Dp < or = 2.1 microm.

Non-discriminating flash pyrolysis and thermochemolysis of heavily contaminated sediments from the Hamilton Harbor (Canada)

Analytical pyrolysis of sediments contaminated with pollutants of medium to high molecular weights (up to approximately 500 Da) is very challenging when using conventional pyrolysis systems due to discrimination of high molecular weight analytes. In the framework of this contribution, non-discriminating pyrolysis and thermochemolysis using rapid heating in a Silcosteel capillary were applied to study organic pollutants in heavily contaminated sediments taken from the Hamilton Harbor. The novel pyrolysis approach, requiring very small amounts of sample, turned out to be very useful as a rapid screening method, e.g. for risk assessment studies, proving superior to commonly used solvent extraction. Main pollutants in the sediments under study included aromatic hydrocarbons, chiefly originating from coal tar and petroleum. Polycyclic aromatic hydrocarbons (PAHs) beyond six-rings, including coronene and truxene, could be detected. Sequential tetramethyl ammonium hydroxide-induced thermochemolysis performed at 500 and 750 degrees C enabled the differentiation between organic pollutants sorbed onto the sediment matrix on the one hand, and structural moieties of the condensed polymeric humic sediment matrix along with bound residues on the other hand. Thermochemolysis at 500 degrees C removed sorbates quantitatively, leaving only bare polymeric humic matrix. Significant PAH source indicators provided evidence that the lipidic fraction sorbed onto the sediments originated from PAHs formed chiefly in coal combustion processes. The polymeric humic organic matter network of the less polluted sediment was mainly of petrogenic origin, whereas black carbon, kerogen, etc. contributed to the organic carbon of the heavily polluted sediment. Thermochemolysis at 500 degrees C was also used to study fatty acid profiles of the sediments. The fatty acid methyl ester patterns obtained for the two sites under study differed significantly, with strong indications that microbial attenuation of the pollutants at the heavily polluted site 2 was strongly suppressed.

Atmospheric polycyclic aromatic hydrocarbons in north China: a winter-time study

The contamination and outflow of atmospheric polycyclic aromatic hydrocarbons (PAHs) in the Chinese Northern Plain, a region with a total area of 300 000 km2 and a high PAH emission density, were investigated. Polyurethane foam (PUF) and PM10 samples were collected at 46 sites located in urban, rural (towns or villages), and control (remote mountain) areas in the winter from November 2005 to February 2006. The observed concentrations of atmospheric PAHs were generally higher than those reported for developed countries and southern Chinese cities. It was found that there was no significant difference in air PAH concentrations between the urban and the rural areas (514 +/- 563 ng/m3 and 610 +/- 645 ng/ m3, respectively), while the PAH concentrations at the control sites (57.1 +/- 12.6 ng/m3) were 1 order of magnitude lower than those at the other sites. The primary reason for the similarity in PAH concentrations between urban and rural areas was the fact that the predominant sources of biomass and domestic coal combustion were widely spread over the study area. The partition constants (K(PM10)) of PAHs were significantly correlated to the corresponding values of subcooled liquid-vapor pressure (pL0). However, the regression slopes of log K(PM10) versus log pL0 were much steeper than -1, indicating adsorption dominated over absorption. Three distinct patterns of outflow from the study area were identified by forward trajectory and cluster analysis.

Genotoxicity of organic extracts of house dust from Shanxi, China

Indoor combustion of solid fuel such as coal may generate respirable particles containing polycyclic aromatic hydrocarbons (PAH) that may adhere to settled dust. Dust might therefore present a major source of PAH exposure in humans. This study evaluated the in vitro and in vivo genotoxicity of PAH mixtures extracted from house dust samples. Four dust samples (E1-4) were collected from houses in Shanxi, China, where coal is heavily used for heating and cooking. For comparison, a coal sample was also collected from one of the houses and included in the analyses. The samples were extracted with methylene chloride:acetone (95:5 v/v), dried, and redissolved in appropriate solvents for assessment in genotoxicity assays. Samples were evaluated for their ability to induce point mutations in bacteria and DNA adducts in vivo. DNA adduct levels were analyzed by nuclease P1-enhanced 32P-postlabeling. PAH were quantified using gas chromatography/mass spectrometry. Based on chemical analysis, sample E1 had the highest concentration by sampling area of benzo[a]pyrene (BaP) (181 microg/m2) and total PAH (10100 microg/m2). However, based on the microbial genotoxicity assay, sample E3, with the highest carcinogenic PAH/total PAH ratio (26%), produced the greatest number of revertants. In mice, administration of the extract of coal induced more adducts (9.81 adducts per 10(9) nucleotides) than dust extracts. The results of this study confirm the presence of genotoxic chemicals in residential dust. Inhalation of respirable particles containing similar mixtures of PAH represents a cancer risk for humans.

Investigation of the solvent extracts of humic organic matter (HOM) isolated from the Ravenna Lagoon to study environmental pollution and microbial communities

Solvent extracts of HOM isolated from highly polluted sediments from the Ravenna Lagoon were studied. Diagnostic indicators included polycyclic aromatic hydrocarbons (PAHs) and nonylphenols as hazardous organic pollutants to characterize anthropogenic pollution, as well as fatty acids (FA, analysed as methyl esters, FAME) to characterize microbial communities responsible for natural attenuation processes. The distribution of PAHs including cyclopentafused surrogates pointed to a significant pyrogenic origin, characteristic for methane combustion. The PAH distribution was characterized by high concentrations of highly carcinogenic analytes with molecular weights of 276Da (benzo[ghi]perylene prevailing) and 300Da (coronene prevailing). The PAH pattern as obtained by solvent extraction was very different from that obtained from pyrolysis/thermochemolysis of the HOM polymeric matrix. The FA pattern indicated strong bacterial input, with a significant contribution from methanotrophic bacteria as revealed by monounsaturated members with n:1omega8 and n:1omega5 double bonds in the alkyl chain. Terrestrial inputs as revealed by FAME analysis beyond C(20) with pronounced even-over-odd discrimination were of minor significance. This was confirmed by the pattern of nC(24)-nC(30) alcohols in strong even-over-odd prevalence occurring in relatively low concentrations. The hopane hydrocarbon distribution reflected a distinctive impact from industrial processes utilizing heavy fractions of petroleum as feedstock. Hopanols along with the 17beta(H),21beta(H)-bishomohopanoic acid pointed to hopane producers, including methanotrophic and sulfate-reducing bacteria. Nonylphenols, which could not be detected in the pyrograms of solvent-extracted HOM matrix, had a total concentration of about 70microg g(-1) referred to the HOM in the solvent extract. In addition to common phytosterols including beta-sitosterol, coprostanol could be detected in the solvent extracts pointing to human fecal matter contamination. Concentration of resin acids turned out to be very low, thus no harmful environmental effects are to be expected from these compounds.

Diffuse PAH contamination of surface soils: environmental occurrence, bioavailability, and microbial degradation

The purpose of this review is to recognize the scientific and environmental importance of diffuse pollution with polycyclic aromatic hydrocarbons (PAHs). Diffuse PAH pollution of surface soil is characterized by large area extents, low PAH concentrations, and the lack of point sources. Urban and pristine topsoils receive a continuous input of pyrogenic PAHs, which induces a microbial potential for PAH degradation. The significance of this potential in relation to black carbon particles, PAH bioaccessibility, microbial PAH degradation, and the fate of diffuse PAHs in soil is discussed. Finally, the state-of-the-art methods for future investigations of the microbial degradation of diffuse PAH pollution are reviewed.

Solid-phase extraction with C30 bonded silica for analysis of polycyclic aromatic hydrocarbons in airborne particulate matters by gas chromatography–mass spectrometry

A solid-phase extraction (SPE) method using triacontyl bonded silica (C30) as sorbent was developed for the determination of 16 US Environmental Protection Agency polycyclic aromatic hydrocarbons (PAHs) in airborne particulate matters quantitatively by gas chromatography-mass spectrometry (GC-MS). Optimization experiments were conducted using spiked standard aqueous solution of PAHs and real airborne particulates samples aiming to obtain highest SPE recoveries and extraction efficiency. Factors were studied in SPE procedures including the concentration of organic modifier, flow rate of sample loading and elution solvents. The ultrasonication time and solvents were also investigated. Recoveries were in the range of 68-107% for standard PAHs aqueous solution and 61-116% for real spiked sample. Limits of detection (LODs) and limits of quantification (LOQs) with standard solution were in the range of 0.0070-0.21 microgL(-1) and 0.022-0.67 microgL(-1), respectively. The optimized method was successfully applied to the determination of 16 PAHs in real airborne particulate matters.

Development of a house dust standard reference material for the determination of organic contaminants

National-level health survey studies, such as the National Human Exposure Assessment Survey field program, have targeted the determination of organic contaminants in house dust in an effort to characterize human exposure in the domestic environment. As the effort to further understand human health effects in relation to organic contaminants associated with indoor dust accelerates, the need for an indoor dust Standard Reference Material (SRM) that is characterized for organic contaminants has become critical. To meet this need, a new organic contaminant house dust SRM has been developed. SRM 2585 Organic Contaminants in House Dust is intended for use in evaluating analytical methods for the determination of selected polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCB) congeners, chlorinated pesticides, and polybrominated diphenyl ether (PBDE) congeners in house dust and similar matrices. The material may also be useful for evaluation and comparison of methods or instruments used for sampling in the indoor environment. Moreover, because of the material's extensive characterization (140 organic contaminant concentrations), the material may be useful in toxicity studies related to indoor air (in vitro or in vivo). The determination of the concentrations of PAHs (including alkyl-PAHs and PAHs with molecular mass 300 and 302), PCBs, and chlorinated pesticides is reported here, and these results are compared to values reported in the literature for house dust.

What Do We Know about C28H14 and C30H14 Benzenoid Hydrocarbons and Their Evolution to Related Polymer Strips?

While critically reviewing the current status of what is known about C28H14 and C30H14 benzenoid isomers, which are ubiquitous pyrolytic constituents, some new insights will be presented. Representative isomers belonging to these benzenoid hydrocarbons are at the crossroads to homologous series that extend to infinite polymer strips that have been the object of numerous molecular modeling studies. The goal of these studies is to understand their potential electronic properties for material science applications. Along the way, some prior numerical results are supplemented.