Mutagenicity of C24H14 PAH in human cells expressing CYP1A1

Lung cancer associated with combustion particles and fine particulate matter (PM2.5) - The roles of polycyclic aromatic hydrocarbons (PAHs) and the aryl hydrocarbon receptor (AhR)

Air pollution is the leading cause of lung cancer after tobacco smoking, contributing to 20% of all lung cancer deaths. Increased risk associated with living near trafficked roads, occupational exposure to diesel exhaust, indoor coal combustion and cigarette smoking, suggest that combustion components in ambient fine particulate matter (PM2.5), such as polycyclic aromatic hydrocarbons (PAHs), may be central drivers of lung cancer. Activation of the aryl hydrocarbon receptor (AhR) induces expression of xenobiotic-metabolizing enzymes (XMEs) and increase PAH metabolism, formation of reactive metabolites, oxidative stress, DNA damage and mutagenesis. Lung cancer tissues from smokers and workers exposed to high combustion PM levels contain mutagenic signatures derived from PAHs. However, recent findings suggest that ambient air PM2.5 exposure primarily induces lung cancer development through tumor promotion of cells harboring naturally acquired oncogenic mutations, thus lacking typical PAH-induced mutations. On this background, we discuss the role of AhR and PAHs in lung cancer development caused by air pollution focusing on the tumor promoting properties including metabolism, immune system, cell proliferation and survival, tumor microenvironment, cell-to-cell communication, tumor growth and metastasis. We suggest that the dichotomy in lung cancer patterns observed between smoking and outdoor air PM2.5 represent the two ends of a dose-response continuum of combustion PM exposure, where tumor promotion in the peripheral lung appears to be the driving factor at the relatively low-dose exposures from ambient air PM2.5, whereas genotoxicity in the central airways becomes increasingly more important at the higher combustion PM levels encountered through smoking and occupational exposure.

Application of fused-grid-based CYP-Template systems for genotoxic substances to understand the metabolisms

Understanding of metabolic processes is a key factor to evaluate biological effects of carcinogen and mutagens. Applicability of fused-grid Template* systems of CYP enzymes (Drug Metab Pharmacokinet 2019, 2020, 2021, and 2022) was tested for three phenomena. (1) Possible causal relationships between CYP-mediated metabolisms of β-naphthoflavone and 3-methylcholanthrene and the high inducibility of CYP enzymes were examined. Selective involvement of non-constitutive CYP1A1, but not constitutive CYP1A2, was suggested on the oxidative metabolisms of efficient inducers, β-naphthoflavone and 3-methylcholanthrene. These results supported the view of the causal link of their high inducibility with their inefficient metabolisms due to the lack of CYP1A1 in livers at early periods after the administration of both inducers. (2) Clear differences exist between human and rodent CYP1A1 enzymes on their catalyses with heterocyclic amines, dioxins and polyaromatic hydrocarbons (PAHs). Reciprocal comparison of simulation results with experimental data suggested the rodent specific site and distinct sitting-preferences of ligands on Template for human and rodent CYP1A1 enzymes. (3) Enhancement of metabolic activation and co-mutagenicity have been known as phenomena associated with Salmonella mutagenesis assay. Both the phenomena were examined on CYP-Templates in ways of simultaneous bi-molecule bindings of distinct ligands as trigger and pro-metabolized molecules. α-Naphthoflavone and norharman served consistently as trigger-molecules to support the oxidations of PAHs and arylamines sitting simultaneously as pro-metabolized molecules on Templates of CYP1A1, CYP1A2 and CYP3A4. These CYP-Template simulation systems with deciphering capabilities are promising tools to understand the mechanism basis of metabolic activations and to support confident judgements in safety assessments.

Characterization of elements, PAHs, AhR-activity and pro-inflammatory responses of road tunnel-derived particulate matter in human hepatocyte-like and bronchial epithelial cells

The aims were to characterize the content of elements and polycyclic aromatic hydrocarbons (PAHs) in size-separated particulate matter (PM) sampled in a road tunnel, estimate the contribution of PAHs to the toxic potential, and measure the pro-inflammatory potential of PM samples and extracts with increasing polarity. Several elements/metals previously associated with cytokine responses were found. Based on PAHs levels and published PAHs potency, the calculated mutagenic and carcinogenic activities of size-separated samples were somewhat lower for coarse than fine and ultrafine PM. The AhR-activity of the corresponding PM extracts measured in an AhR-luciferase reporter model (human hepatocytes) were more similar. The highest AhR-activity was found in the neutral (parent and alkylated PAHs) and polar (oxy-PAHs) fractions, while the semi-polar fractions (mono-nitrated-PAHs) had only weak activity. The neutral and polar aromatic fractions from coarse and fine PM were also found to induce higher pro-inflammatory responses and CYP1A1 expression in human bronchial epithelial cells (HBEC3-KT) than the semi-polar fractions. Fine PM induced higher pro-inflammatory responses than coarse PM. AhR-inhibition reduced cytokine responses induced by parent PM and extracts of both size fractions. Contributors to the toxic potentials include PAHs and oxy-PAHs, but substantial contributions from other organic compounds and/or metals are likely.

Health Risk Assessment on Exposure to PM2.5-bound PAHs from an Urban-industrial Area in Rayong City, Thailand

BACKGROUND: A city's industrial area's air quality has become a major priority. PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) are one of the most common pollutants in urban-industrial area, and can be linked to health problems. AIM: This study aims to 1) investigate PM2.5 and PAHs emitted from roadside area (RS) and industrial estate (IE) in Rayong city 2) assess the inhalation of PM2.5 and PAHs on the human health of the age group. METHODS: PM2.5-bound PAHs were investigated and thier carcinogenic risk was evalued in this study. PM2.5 samples were collected on quartz filters contained in a mini-volume air sampler and analyzed for PAHs by GC-MS. RESULTS: The average PM2.5 concentrations at RS and IE were 43.3±26.8 and 40.4±21.7 µg/m3, while the values of total PAHs in both sites were 1.68±1.53 and 1.34±1.22 ng/m3, respectively. However, it was found that the PM2.5 and PAHs values were not significantly different (p>0.05). The results revealed that the individual lifetime cancer risk (Ric) of PM2.5 values for children and adults at both sites indicated acceptable cancer risk (10-6 to10-4). According to the incremental lifetime cancer risk (ILCR) values of PAHs for different age groups, exposure to PAHs in PM2.5 through the inhalation pathway was a negligible (<10-6). CONCLUSION: As a result, the PM2.5 concentrations have substantial implications for Rayong city’s environmental management and protection, relating to car emissions and coal combustion.

Polycyclic aromatic hydrocarbons in PM1, PM2.5 and PM10 atmospheric particles: identification, sources, temporal and spatial variations

This study reports temporal and spatial variations of 16 different species of particulate polycyclic aromatic hydrocarbons (particle-bonded PAHs) in the indoor and outdoor environments of three sampling sites in Bandar Mahshahr city, Iran. A low-volume air sampler was employed to collect size-segregated particulate matter during winter (October to December 2015), and summer (July to September 2016). The results showed that the annual concentrations of indoor and outdoor PM10 and PM2.5 were much higher than the related World Health Organization guidelines. The concentration of total particle-bonded PAHs (TPAHs) was higher in winter than in summer and a significant difference between the two sampling seasons was observed. The indoor and outdoor carcinogenic PAHs to TPAHs concentrations ratios in the sampling sites in summer and winter were as follow: for PM10 40.15-42.51%, PM2.5 41.30-42.97%, and PM1 43.07-44.36%, respectively; furthermore, the smaller the particle size, the higher the percentage of carcinogenic PAHs. 2 ring PAHs had a very small contribution to the total PAHs (about 1%), whereas PAHs with 3-to-4 rings had much larger contributions, ranging from 71.65% to 75.17%. The results demonstrated that as PM size decreased, the proportion of 5-to-6-ring PAHs to the total PAHs increased. Since 5-to-6- ring PAHs are considered to be more toxic, hence more attention should be paid to fine particles. The diagnostic ratios of indoor and outdoor of three sampling sites in both seasons suggested that petrogenic sources, as well as combustion of petroleum and other fossil fuels were the main PAHs sources.

Human Family 1-4 cytochrome P450 enzymes involved in the metabolic activation of xenobiotic and physiological chemicals: an update

This is an overview of the metabolic activation of drugs, natural products, physiological compounds, and general chemicals by the catalytic activity of cytochrome P450 enzymes belonging to Families 1-4. The data were collected from > 5152 references. The total number of data entries of reactions catalyzed by P450s Families 1-4 was 7696 of which 1121 (~ 15%) were defined as bioactivation reactions of different degrees. The data were divided into groups of General Chemicals, Drugs, Natural Products, and Physiological Compounds, presented in tabular form. The metabolism and bioactivation of selected examples of each group are discussed. In most of the cases, the metabolites are directly toxic chemicals reacting with cell macromolecules, but in some cases the metabolites formed are not direct toxicants but participate as substrates in succeeding metabolic reactions (e.g., conjugation reactions), the products of which are final toxicants. We identified a high level of activation for three groups of compounds (General Chemicals, Drugs, and Natural Products) yielding activated metabolites and the generally low participation of Physiological Compounds in bioactivation reactions. In the group of General Chemicals, P450 enzymes 1A1, 1A2, and 1B1 dominate in the formation of activated metabolites. Drugs are mostly activated by the enzyme P450 3A4, and Natural Products by P450s 1A2, 2E1, and 3A4. Physiological Compounds showed no clearly dominant enzyme, but the highest numbers of activations are attributed to P450 1A, 1B1, and 3A enzymes. The results thus show, perhaps not surprisingly, that Physiological Compounds are infrequent substrates in bioactivation reactions catalyzed by P450 enzyme Families 1-4, with the exception of estrogens and arachidonic acid. The results thus provide information on the enzymes that activate specific groups of chemicals to toxic metabolites.

Human health and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in sediment of Woji creek in the Niger Delta region of Nigeria

Human health risk was determined by assessing risk due to dermal contact with the sediment and Benzo [a] pyrene -equivalent concentrations (BaP-TEQ- carcinogenic equivalents and BaP-MEQ- mutagenic equivalents). Ecological risk of PAHs in the sediment was determined by comparing PAHs concentrations to effect range low (ERL) and effect range median (ERM); to estimate the risk associated with the combined effects of PAHs, mean ERM quotient (mERMq) was calculated. Results revealed that hazard index (HI) due to dermal contact of the sediment for adults are 596 and 73.84 for children. Similarly, cancer risk for adults was all >10^-1 and was within 10^-3 ≤ 10^-1 for children, for every compound; the sum of cancer risk for adults and children were 8.26 and 1.022 respectively.

Environmental six-ring polycyclic aromatic hydrocarbons are potent inducers of the AhR-dependent signaling in human cells

The toxicities of many environmental polycyclic aromatic hydrocarbons (PAHs), in particular those of high-molecular-weight PAHs (with MW higher than 300), remain poorly characterized. The objective of this study was to evaluate the ability of selected environmentally relevant PAHs with MW 302 (MW302 PAHs) to activate the aryl hydrocarbon receptor (AhR), since this represents a major toxic mode of action of PAHs. A large number of the evaluated compounds exhibited strong AhR-mediated activities, in particular in human models. The studied MW302 PAHs also significantly contributed to the overall calculated AhR activities of complex environmental mixtures, including both defined standard reference materials and collected diesel exhaust particles. The high AhR-mediated activities of representative MW302 PAHs, e.g. naphtho[1,2-k]fluoranthene, corresponded with the modulation of expression of relevant AhR target genes in a human lung cell model, or with the AhR-dependent suppression of cell cycle progression/proliferation in estrogen-sensitive cells. This was in a marked contrast with the limited genotoxicity of the same compound(s). Given the substantial levels of the AhR-activating MW302 PAHs in combustion particles, it seems important to continue to investigate the toxic modes of action of this large group of PAHs associated with airborne particulate matter.

Ambient PM2.5 and PM10 bound PAHs in Islamabad, Pakistan: Concentration, source and health risk assessment

Polycyclic aromatic hydrocarbons (PAHs) in ambient particulate matter contribute considerably to human health risk. Simultaneous sampling of ambient PM_2.5/PM₁₀ was done to analyze the Ʃ16PAH across the four seasons of 2017 in Islamabad, Pakistan. The average Ʃ16PAH concentrations in PM_2.5 and PM₁₀ were 25.69 and 40.69 ng m^-3_, respectively. For both PM_2.5 and PM₁₀, the highest PAHs concentration was in winter (45.14, 67.10 ng m^-3), while the lowest was in summer (16.40, 28.18 ng m^-3). Source appointment indicated that vehicular exhaust, i.e., diesel, gasoline and alternatively fuel liquid natural gas (LNG), and compressed natural gas (CNG) combustion was the primary PAHs contributor, whereas biomass burning and fuel combustion (coal, biomass, wood, CNG) from stationary sources were another important sources. Health risk assessment showed that the lifetime cancer risk (LCR) values of PAHs were higher than the acceptable level in all four seasons. LCR values were the highest in winter (9.23 × 10^-4 for PAHs in PM_2.5 and 13.98 × 10^-4 for PAHs in PM₁₀) which were 9 and 13 times higher than tolerable cancer risk level respectively, and they were 2-3 times higher than the acceptable values in other seasons.

Concentration levels and carcinogenic and mutagenic risks of PM2.5-bound polycyclic aromatic hydrocarbons in an urban-industrial area in South Africa

Concerns over the health effects of exposure to particulate matter of aerodynamic diameter of less than 2.5 μm (PM_2.5) led the South African Government to establish the national standard for PM_2.5 in the year 2012. However, there is currently no exposure limit for polycyclic aromatic hydrocarbons (PAHs) and PM_2.5-bound PAHs. The understanding of the concentration levels and potential health risks of exposure to PM_2.5-bound PAHs is important in ensuring a suitable risk assessment and risk management plans. This study, therefore, determined the concentration levels and carcinogenic and mutagenic health risks of PM_2.5-bound PAHs. A hundred and forty-four PM_2.5 samples were collected over 4 months during the winter and summer seasons of 2016 in an industrial area. The concentrations of 16 PAHs were analysed by gas chromatography-mass spectrometry, and their carcinogenic and mutagenic risks were determined using the Human Health Risk Assessment model. The mean winter (38.20 ± 8.4 μg/m³) and summer (22.3 ± 4.1 μg/m³) concentrations of PM_2.5 levels were lower than the stipulated 40 μg/m³ daily limit. The daily inhalation and ingestion exposure to PAHs for all age groups were higher than the daily exposure through the dermal contact. Children and adults are more likely to inhale and ingest PAHs in PM_2.5 than infants. The excess cancer risk and excess mutagenic risk values were below the priority risk level (10^-4). There is a potential risk of 1-8 per million persons developing cancer from exposure to benzo[a]anthracene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, and dibenz[a,h]anthracene over a lifetime of 70 years.

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.

PAHs contamination levels in the breast milk of Ghanaian women from an e-waste recycling site and a residential area

Breast milk samples from 128 primipararae and multiparae Ghanaian women were screened for Polycyclic Aromatic Hydrocarbons (PAHs) from 2014 and 2016. These were breast milk from women residing or working around an electronic waste recycling site and a reference area (a residential area). This research is aimed at assessing PAHs levels in human milk samples from some Ghanaian mothers, prediction of the sources of these PAHs and the probable carcinogenic and mutagenic risks to infants. PAHs in the breast milk were analyzed using a gas chromatography coupled with a mass spectrometer (GC-MS/MS). A total of 18 PAH congeners were identified in the human milk samples with a total range between <LOD and 15,936.57 ng/g lipid wt and an overall mean of 1105.63 ng/g lipid wt. In general, the mean concentrations of low molecular weight PAHs were appreciably greater than the high molecular weight PAHs in the breast milk samples. Naphthalene recorded the highest mean concentrations of 1026.52 ng/g lipid wt and 78.73 ng/g lipid wt for both e-waste and residential areas, respectively. Naphthalene contributed 77.4% of the total PAHs in the milk samples. Most of the high molecular weight PAHs were below the limit of detection in milk samples from Kwabenya (a residential area) but were detected in the milk samples from Agbogbloshie (e-waste recycling site). The diagnostic ratio tests in this study suggest that most of the PAHs in the milk samples are originating from pyrogenic sources. Risk assessment for carcinogenicity and mutagenicity on infants based on this study were 1.1 × 10^-5 and 1.9 × 10^-5, respectively.

Effect of air pollutants and toxic emissions from various mileage of motorcycles and aerosol related carcinogenicity and mutagenicity assessment

This research investigates the mileage and the health risk assessment of aerosol carcinogenicity and mutagenicity emitted by ten in-use motorcycles. The total p-PAHs emission factor of ten in-use motorcycles are 676.3 μg km^-1 with average of 67.6 ± 13.6 μg km^-1. Naphthalene (Nap) shows the largest emission factors, followed by phenanthrene (PA) and fluoranthen (FL). The mileage present high correlation coefficient (Rsp = 0.681) with CO. CO is associated with cumulative mileage leading to bad combustion efficiency, which caused low to high relationship for total p-PAHs (Rsp = 0.388), PM_2.5 (Rsp = 0.680) and NOx (Rsp = 0.799). Both PM_2.5 and total p-PAHs are generally generated via incomplete combustion and the results expressed the moderate to high correlation (Rsp = 0.578, 0.898) with NOx. Taking into consideration of high-mileage motorcycles (30,001-50,000 km), the toxic equivalent of carcinogenicity and mutagenicity exhaust are about 4.67, 1.99 and 3.89, 2.0 times higher than low (10,001-20,000 km) and middle (20,001-30,000 km) cumulative mileages, respectively. Therefore, in the conclusion of our study in compared with that of other research directed the fact that lower carcinogenicity and mutagenicity emission factor were found at lower cumulative mileages motorcycles however, the impact increases with the high cumulative mileage motorcycles.

Burden of disease for workers attributable to exposure through inhalation of PPAHs in RSPM from cooking fumes

Polycyclic aromatic hydrocarbons (PAHs), some of which are classified as possible carcinogens (WHO), have been detected in cooking fumes in considerable amounts. Distribution of 24 PAHs on varying particle sizes was analyzed in cooking emission. Analysis of cooking fumes from vegetarian and non-vegetarian food was carried out separately in the kitchen of a hostel mess in IIT Kanpur during November 2012 and February 2013. Respirable suspended particulate matter (RSPM) and particle-bound polycyclic aromatic hydrocarbons (PPAHs) showed a similar sequence regarding concentration observed in vegetarian and non-vegetarian food. PAHs with carcinogenic potential was detected and quantified mostly in the fine particles. Total PAH concentrations in the fine and ultrafine ranges together accounted for > 90% of the total carcinogenic PAHs, highlighting them as primary carriers of PAHs rather than coarser particles. Benzo [a] pyrene (B [a]P) levels contribute > 70% to total carcinogenic potential and > 60%, to mutagenic potential, respectively. The total toxicity impact on the workers due to the PAHs emitted from cooking fumes was 3.374 × 10^-10 DALYs, with B [a] P contributing the most (> 70%) despite its low concentration. Exposure to cooking fumes especially for people involved in this activity on a daily basis (chefs, hostel mess workers, among others) raises health concerns. An extensive examination of impacts due to exposure to emissions in both particle and gas phase on a long-term basis is required.

Exposure to polycyclic aromatic hydrocarbons in atmospheric PM1.0 of urban environments: Carcinogenic and mutagenic respiratory health risk by age groups

We investigated the carcinogenic and mutagenic respiratory health risks related to the exposure to atmospheric PAHs in an urban area. Our study focused in the association of these pollutants and their possible effect in human health, principally respiratory and circulatory diseases. Also, we determined a relationship between the inhalation risk of PAHs and meteorological conditions. We validated the hypothesis that in winter PAHs with high molecular weight associated to submicron particles (PM₁) may increase exposure risk, especially for respiratory diseases, bronchitis and pneumonia diseases. Moreover, in our study we verified the relationship between diseases and several carcinogenic PAHs (Ind, BbkF, DahA, BaP, and BghiP). These individual PAHs contributed the most to the potential risk of exposure for inhalation of PM_1.0. Even at lower ambient concentrations of BaP and DahA in comparison with individual concentrations of other PAHs associated to PM_1.0. Mainly, research suggests to include carcinogenic and mutagenic PAHs in future studies of environmental health risk due to their capacity to associate to PM₁₀. Such carcinogenic and mutagenic PAHs are likely to provide the majority of the human exposure, since they originate from dense traffic urban areas were humans congregate.

Genotoxic Effects of Benzo[a]pyrene and Dibenzo[a,l]pyrene in a Human Lung Cell Line

Several studies have shown that polycyclic aromatic hydrocarbons (PAHs) produce genotoxic effects in assays performed in vivo and in vitro. This study was undertaken to investigate the ability of benzo[ a]pyrene (BP) and dibenzo[ a,l]pyrene (DBP) to induce DNA damage in a human lung fibroblast cell line (MRC-5), using sister-chromatid exchanges test (SCEs), the comet assay, and evaluating point mutations in codon 12 of the K- ras protooncogene by polymerase chain reaction–single-strand conformation polymorphisms (PCR-SSCPs) and restriction fragment length polymorphisms (RFLP)-enriched PCR methods. Sister-chromatid exchanges frequencies were significantly increased in cells exposed to benzo[ a]pyrene and dibenzo[ a,l]pyrene in relation to controls ( p < .001). Using the standard alkaline comet assay, significant differences between groups were found for the variable comet moment (CM) when cells were exposed to BP ( p < .001) and DBP ( p < .001). Nevertheless, PCR-SSCP and RFLP-enriched PCR methods did not show any association between treatments with BP and DBP and K- ras point mutations. The data presented in this study indicated that BP and DBP induced both DNA strand breaks and sister-chromatid exchanges but not significant point mutations at codon 12 of K- ras gene in the MRC-5 cell line.

Size distribution and sources of 37 toxic species of particulate polycyclic aromatic hydrocarbons during summer and winter in Baoshan suburban area of Shanghai, China

The objectives of this study were to assess the size-segregated distribution and sources of 37 different species of particulate polycyclic aromatic hydrocarbons (PAHs) in a suburban area of Shanghai metropolitan City, China. The ambient particulate sampling was carried out on the rooftop of a five-stories building in Baoshan campus of Shanghai University. An Andersen high-volume air sampler was employed to collect ambient size-segregated particulate matter during summer of August to September and winter of November to December 2015. The high toxic PAHs were determined by a gas chromatography mass spectrometry. The concentrations of total PAHs in suspended particulate matter (SPM) and PM1.1 (suspended particulate matter below 1.1μm in diameter) in the suburban area of Shanghai were 4.58-14.5ng/m(3) and 1.82-8.56ng/m(3), respectively in summer, and 43.6-160ng/m(3) and 23.2-121ng/m(3), separately in winter. 1,8-Naphthalic anhydride (1,8-NA) showed the highest concentration among 37 different species of PAHs in the suburban area of Shanghai. The concentrations of high molecular PAHs (e.g. 5-6 ring PAHs) followed a nearly unimodal size distribution with the highest peaks in PM1.1. The diagnostic ration qualitatively indicated that PAHs in SPM of Shanghai were mainly derived from motor-vehicle or petroleum combustion in summer and from coal and biomass combustion in winter. According to the calculated toxicity equivalency factors based on the methods of Nisbet and Lagoy and the potency equivalency factors (PEF) recommended by U.S. EPA, the highest contributors in the total carcinogenicity of the PAHs in SPM and PM1.1 were dibenzo[a,h]pyrene (46.2% and 45.0% in summer), benzo[a]pyrene (44.4% and 43.8% in winter) and benz[j]aceanthrylene (80.2% and 83.1% in summer and 83.1% and 84.0% in winter), respectively. Therefore, benzo[a]pyrene seemed to be a lower contributor than other carcinogenic PAHs.

Polycyclic aromatic hydrocarbons in three commercially available fish species from the Bonny and Cross River estuaries in the Niger Delta, Nigeria

The concentrations and compositional patterns of the USEPA 16 polycyclic aromatic hydrocarbons were investigated in three commercially available fish species, Chrysichthys nigrodigitatus, Cynoglossus senegalensis and Polydactylus quadratifilis, from the Bonny and Cross River systems in the eastern Niger Delta of Nigeria. The objective of the study was to provide useful information on the levels and sources of polycyclic aromatic hydrocarbons (PAHs) and the associated risks with their consumption. The 16 PAHs in the fish samples were extracted by ultrasonication with hexane/dichloromethane, and the concentrations of PAHs in the extracts were quantified by gas chromatography-mass spectrometry. The measured concentrations of the Ʃ16 PAHs in Chrysichthys nigrodigitatus, Polydactylus quadratifilis and Cynoglossus senegalensis ranged from 106 to 491, from 43.1 to 1734 and from 96.4 to 937 μg kg(-1) in the Bonny River system and from 20.0 to 975, from 24.7 to 506 and from 24.9 to 387 μg kg(-1) in the Cross River system, respectively. The compositional patterns of the PAHs showed that the three- and four-ringed PAHs were the major contributors to the PAH burden in these fish species. The diagnostic ratios indicate that the PAHs in these fish samples originated mainly from combustion processes. The health risk assessment, as determined from the benzo[a]pyrene potency equivalent factor, margin of exposure and incremental lifetime cancer risk, indicates that PAHs in the majority of these fish species can induce potential carcinogenic effects.

Characterization of polycyclic aromatic hydrocarbons in fugitive PM10 emissions from an integrated iron and steel plant

Fugitive emissions of PM10 (particles <10μm in diameter) and associated polycyclic aromatic hydrocarbons (PAHs) were monitored in the vicinity of coking unit, sintering unit, blast furnace and steel manufacturing unit in an integrated iron and steel plant situated in India. Concentrations of PM10, PM10-bound total PAHs, benzo (a) pyrene, carcinogenic PAHs and combustion PAHs were found to be highest around the sintering unit. Concentrations of 3-ring and 4-ring PAHs were recorded to be highest in the coking unit whereas 5-and 6-ring PAHs were found to be highest in other units. The following indicatory PAHs were identified: indeno (1,2,3-cd) pyrene, dibenzo (a,h) anthracene, benzo (k) fluoranthene in blast furnace unit; indeno (1,2,3-cd) pyrene, dibenzo (a,h) anthracene, chrysene in sintering unit; Anthracene, fluoranthene, chrysene in coking unit and acenaphthene, fluoranthene, fluorene in steel making unit. Total-BaP-TEQ (Total BaP toxic equivalent quotient) and BaP-MEQ (Total BaP mutagenic equivalent quotient) concentration levels ranged from 2.4 to 231.7ng/m(3) and 1.9 to 175.8ng/m(3), respectively. BaP and DbA (dibenzo (a,h) anthracene) contribution to total-BaP-TEQ was found to be the highest.

Studies on size distribution and health risk of 37 species of polycyclic aromatic hydrocarbons associated with fine particulate matter collected in the atmosphere of a suburban area of Shanghai city, China

Polycyclic aromatic hydrocarbons (PAHs) in suspended particulate matter (SPM) contribute significantly to health risk. Our objectives were to assess the size distribution and sources of 26 PAHs and 11 polycyclic aromatic compounds (PACs) in SPM in the suburban area, Shanghai city, China. Air sampling was carried out on the rooftop of a five-stories building in the campus of Shanghai University. An Andersen high-volume air sampler was employed to collect ambient size-segregated particles from August to September 2015. The toxic particulate PAHs were determined by the gas chromatography mass spectrometry. The concentrations of total PAHs (TPAHs) in SPM and PM1.1 (suspended particulate matter below 1.1 μm) were in the ranges of 4.58-14.5 ng m(-3) and 1.82-8.56 ng m(-3), respectively. 1,8-naphthalic anhydride showed the highest concentrations among 37 species of PAHs and PACs ranging 7.76-47.9 ng m(-3) and 1.50-17.6 ng m(-3) in SPM and PM1.1, respectively. The concentrations of high molecular weight 5-6 ring PAHs followed a nearly unimodal size distribution with the highest peak in PM1.1, while other lower molecular weight PAHs were not dependent on particle sizes. The toxicity analysis indicated that the carcinogenic potency of particulate PAHs primarily existed in PM1.1. Regarding meteorological parameters and other pollutants, the positive effect of humidity and NO2 over PAHs was confirmed. Diagnostic ration indicated that the particulate PAHs in Shanghai were mainly derived from motor-vehicle or petroleum combustion. The highest benzo[a]pyrene equivalent (BaPeq) in SPM and PM1.1 were 2.15 ng m(-3) and 1.43 ng m(-3) calculated by the toxicity equivalency factor, and 69.31 ng m(-3) and 47.81 ng m(-3) estimated by the potency equivalency factors, respectively. The highest contributors in the total carcinogenicity of the particulate PAHs were dibenzo[a,h]pyrene (46.2% and 45.0%) and benz[j]aceanthrylene (80.2% and 83.1%), respectively while benzo[a]pyrene is lower contributor than other carcinogenic PAHs.

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.

Characterization of PAHs and metals in indoor/outdoor PM10/PM2.5/PM1 in a retirement home and a school dormitory

In the present work, we investigated the characteristics of polycyclic aromatic hydrocarbons (PAHs) and metal(loid)s in indoor/outdoor PM10, PM2.5, and PM1 in a retirement home and a school dormitory in Tehran from May 2012 to May 2013. The results indicated that the annual levels of indoor and outdoor PM10 and PM2.5 were much higher than the guidelines issued by the World Health Organization (WHO). The most abundant detected metal(loid)s in PM were Si, Fe, Zn, Al, and Pb. We found higher percentages of metal(loid)s in smaller size fractions of PM. Additionally, the results showed that the total PAHs (ƩPAHs) bound to PM were predominantly (83-88%) found in PM2.5, which can penetrate deep into the alveolar regions of the lungs. In general, carcinogenic PAHs accounted for 40-47% of the total PAHs concentrations; furthermore, the smaller the particle size, the higher the percentage of carcinogenic PAHs. The percentages of trace metal(loid)s and carcinogenic PAHs in PM2.5 mass were almost twice as high as those in PM10. This can most likely be responsible for the fact that PM2.5 can cause more adverse health effects than PM10 can. The average BaP-equivalent carcinogenic (BaP-TEQ) levels both indoors and outdoors considerably exceeded the maximum permissible risk level of 1 ng/m(3) of BaP. The enrichment factors and diagnostic ratios indicated that combustion-related anthropogenic sources, such as gasoline- and diesel-fueled vehicles as well as natural gas combustion, were the major sources of PAHs and trace metal(loid)s bound to PM.

Quantitative analysis and health risk assessment of polycyclic aromatic hydrocarbons in edible vegetable oils marketed in Shandong of China

This work studies on the quantitative analysis and health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in edible vegetable oils in Shandong, China. The concentrations of 15 PAHs in 242 samples were determined by high performance liquid chromatography coupled with fluorescence detection. The results indicated that the mean concentration of 15 PAHs in oil samples was 54.37 μg kg(-1). Low molecular weight PAH compounds were the predominant contamination. Especially, the carcinogenic benzo(a)pyrene (BaP) was detected at a mean concentration of 1.28 μg kg(-1), which was lower than the limit of European Union and China. A preliminary evaluation of human health risk assessment for PAHs was accomplished using BaP toxic equivalency factors and the incremental lifetime cancer risk (ILCR). The ILCR values for children, adolescents, adults, and seniors were all larger than 1 × 10(-6), indicating a high potential carcinogenic risk on the dietary exposed populations.

Source apportionment of atmospheric PM2.5-bound polycyclic aromatic hydrocarbons by a PMF receptor model. Assessment of potential risk for human health

One year sampling (2011-2012) campaign of airborne PM2.5-bound PAH was performed in Zaragoza, Spain. A source apportionment of total PAH by Positive Matrix Factorization (PMF) was applied in order to quantify potential PAH pollution sources. Four sources were apportioned: coal combustion, vehicular emissions, stationary emissions and unburned/evaporative emissions. Although Directive 2004/107/EC was fulfilled regarding benzo(a)pyrene (BaP), episodes exceeding the limit value of PM2.5 according to Directive 2008/50/EC were found. These episodes of high negative potential for human health were studied, obtaining a different pattern for the exceedances of PM2.5 and the lower assessment threshold of BaP (LATBaP). In both cases, stationary emissions contributed majority to total PAH. Lifetime cancer risk exceeded the unit risk recommended by the World Health Organization for those episodes exceeding the LATBaP and the PM2.5 exceedances for the warm season. For the cold season, the risk was higher for the LATBaP than for the PM2.5 exceedances.

Particulate polycyclic aromatic hydrocarbons (PAH) in the atmosphere of Bizerte city, Tunisia

The particle-phase concentrations of polycyclic aromatic hydrocarbons (PAH) were determined in 13 air samples collected in an urban area of Bizerte (Tunisia) during 2009-2010. Atmospheric particulate samples were extracted by ultrasonic bath and analyzed by high-performance liquid chromatography with fluorescence detection. PAH were found in all the analyzed air samples and the most abundant compounds were pyrene, fluoranthene, benzo[g,h,i]perylene, benzo[b]fluoranthene, chrysene and benzo[a]pyrene. ∑14-PAH concentrations ranging from 9.38 to 44.81 ng m(-3) with mean value of 25.39 ng m(-3). PAH diagnostic ratio source analysis revealed gasoline and diesel vehicular emissions as major sources. The mean total benzo[a]pyrene toxicity equivalent calculated for samples was 3.66 ng m(-3) and the mean contribution of the carcinogenic potency of benzo[a]pyrene was determined to be 55.8 %. Concentrations of particulate PAH in Bizerte city atmosphere were approximately eight times greater than sampled at a nearby rural site.

Risk assessment of inhalation exposure to polycyclic aromatic hydrocarbons in school children

Polycyclic aromatic hydrocarbons (PAHs) associated with the inhalable fraction of particulate matter were determined for 1 year (2009-2010) at a school site located in proximity of industrial and heavy traffic roads in Delhi, India. PM10 (aerodynamic diameter ≤10 μm) levels were ∼11.6 times the World Health Organization standard. Vehicular (59.5%) and coal combustion (40.5%) sources accounted for the high levels of PAHs (range 38.1-217.3 ng m(-3)) with four- and five-ring PAHs having ∼80 % contribution. Total PAHs were dominated by carcinogenic species (∼75%) and B[a]P equivalent concentrations indicated highest exposure risks during winter. Extremely high daily inhalation exposure of PAHs was observed during winter (439.43 ng day(-1)) followed by monsoon (232.59 ng day(-1)) and summer (171.08 ng day(-1)). Daily inhalation exposure of PAHs to school children during a day exhibited the trend school hours > commuting to school > resting period in all the seasons. Vehicular source contributions to daily PAH levels were significantly correlated (r = 0.94, p < 0.001) with the daily inhalation exposure level of school children. A conservative estimate of ∼11 excess cancer cases in children during childhood due to inhalation exposure of PAHs has been made for Delhi.

Effect of smoke generation sources and smoke curing duration on the levels of polycyclic aromatic hydrocarbon (PAH) in different suites of fish

The research studied the impact of smoke generation sources on PAH contamination in four different smoke-cured fish (mackerel, sardine, tuna and Cigar minnows). The smoke sources used included acacia, sugarcane bagasse and mangrove. PAHs in the smoke-cured fish were analysed using Varian GC/MS (3800-GC) system. The mean total PAH concentrations in the smoked fish (n=108) ranged from 250.59-1376.09 μg/kg in tuna, cigar minnows, sardine and mackerel smoke-cured with sugarcane bagasse, mangrove and acacia for between 2 and 8h. The mean BaP levels for most fish cured with smoke from acacia and mangrove for between 2 and 8h were all above the European Commission set limit of 5.0 μg/kg. Positive correlations (at P=0.01, 2-tailed) were observed between PAH levels in smoked fish and lignin contents of wood type used for the smoke generation, the fat content and the smoke-curing duration. Risk assessment conducted using benzo[a]pyrene carcinogenic and mutagenic toxicity equivalency factors (TEF and MEF respectively) showed high risk associated with consuming fish smoke-cured with hard woods (acacia and mangroves). Sugarcane bagasse was found to be relatively the best and safest smoke-generating source for smoke-curing of fish among the three wood types when using the traditional kiln.

Cytogenetic biomarkers for the assessment of the influence of pollution on natural fish populations

Cytogenetic analysis methods were used to study the developing embryos of the following four Coregonidae species: Coregonus peled (Gmelin), Coregonus lavaretus (Gmelin), Coregonus nasus (Pallas) and Coregonus muksun (Pallas). Spawners of these species were selected from rivers and lakes of the Tyumen region (Russia) with different levels of pollution. The variability of the chromosomal aberration rate was analyzed during a monitoring period of more than 20 years. The level of chromosomal mutability in the embryonic cells of these fishes was found to have steadily increased during the observation period (1989-2011). The higher frequency of chromosomal mutations at different stages of embryogenesis in broad whitefish, C. nasus (Pallas), was noted in comparison with other species. The possible use of chromosomal mutation frequency as an indicator (biomarker) to characterize the state of a population is discussed.

Contributions of human enzymes in carcinogen metabolism

Considerable support exists for the roles of metabolism in modulating the carcinogenic properties of chemicals. In particular, many of these compounds are pro-carcinogens that require activation to electrophilic forms to exert genotoxic effects. We systematically analyzed the existing literature on the metabolism of carcinogens by human enzymes, which has been developed largely in the past 25 years. The metabolism and especially bioactivation of carcinogens are dominated by cytochrome P450 enzymes (66% of bioactivations). Within this group, six P450s--1A1, 1A2, 1B1, 2A6, 2E1, and 3A4--accounted for 77% of the P450 activation reactions. The roles of these P450s can be compared with those estimated for drug metabolism and should be considered in issues involving enzyme induction, chemoprevention, molecular epidemiology, interindividual variations, and risk assessment.

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).

Cancer chemoprevention by dietary chlorophylls: a 12,000-animal dose-dose matrix biomarker and tumor study

Recent pilot studies found natural chlorophyll (Chl) to inhibit carcinogen uptake and tumorigenesis in rodent and fish models, and to alter uptake and biodistribution of trace (14)C-aflatoxin B1 in human volunteers. The present study extends these promising findings, using a dose-dose matrix design to examine Chl-mediated effects on dibenzo(def,p)chrysene (DBC)-induced DNA adduct formation, tumor incidence, tumor multiplicity, and changes in gene regulation in the trout. The dose-dose matrix design employed an initial 12,360 rainbow trout, which were treated with 0-4000ppm dietary Chl along with 0-225ppm DBC for up to 4weeks. Dietary DBC was found to induce dose-responsive changes in gene expression that were abolished by Chl co-treatment, whereas Chl alone had no effect on the same genes. Chl co-treatment provided a dose-responsive reduction in total DBC-DNA adducts without altering relative adduct intensities along the chromatographic profile. In animals receiving DBC alone, liver tumor incidence (as logit) and tumor multiplicity were linear in DBC dose (as log) up to their maximum-effect dose, and declined thereafter. Chl co-treatment substantially inhibited incidence and multiplicity at DBC doses up to their maximum-effect dose. These results show that Chl concentrations encountered in Chl-rich green vegetables can provide substantial cancer chemoprotection, and suggest that they do so by reducing carcinogen bioavailability. However, at DBC doses above the optima, Chl co-treatments failed to inhibit tumor incidence and significantly enhanced multiplicity. This finding questions the human relevance of chemoprevention studies carried out at high carcinogen doses that are not proven to lie within a linear, or at least monotonic, endpoint dose-response range.

Concentration and photochemistry of PAHs, NPAHs, and OPAHs and toxicity of PM2.5 during the Beijing Olympic Games

Atmospheric particulate matter with diameter <2.5 um (PM(2.5)) was collected at Peking University (PKU) in Beijing, China before, during, and after the 2008 Olympics and analyzed for black carbon (BC), organic carbon (OC), lower molecular weight (MW < 300) and MW302 Polycyclic Aromatic Hydrocarbons (PAHs), nitrated PAHs (NPAHs) and oxygenated PAHs (OPAHs). In addition, the direct and indirect acting mutagenicity of the PM(2.5) and the potential for DNA damage to human lung cells were also measured. Significant reductions in BC (45%), OC (31%), MW< 300 PAH (26-73%), MW 302 PAH (22-77%), NPAH (15-68%), and OPAH (25-53%) concentrations were measured during the source control and Olympic periods. However, the mutagenicity of the PM(2.5) was significantly reduced only during the Olympic period. The PAH, NPAH, and OPAH composition of the PM(2.5) was similar throughout the study, suggesting similar sources during the different periods. During the source control period, the parent PAH concentrations were correlated with NO, CO, and SO(2) concentrations, indicating that these PAHs were associated with both local and regional emissions. However, the NPAH and OPAH concentrations were only correlated with the NO concentrations, indicating that the NPAH and OPAH were primarily associated with local emissions. The relatively high 2-nitrofluoranthene/1-nitropyrene ratio (25-46) and 2-nitrofluoranthene/2-nitropyrene ratio (3.4-4.8), suggested a predominance of photochemical formation of NPAHs through OH-radical-initiated reactions in the atmosphere. On average, the ∑NPAH and ∑OPAH concentrations were 8% of the parent PAH concentrations, while the direct-acting mutagenicity (due to the NPAH and OPAH) was 200% higher than the indirect-acting mutagenicity (due to the PAH). This suggests that NPAH and OPAH make up a significant portion of the overall mutagenicity of PM(2.5) in Beijing.

Determination of polycyclic aromatic hydrocarbons with molecular weight 302 in water samples by solid-phase nano-extraction and laser excited time-resolved Shpol'skii spectroscopy

Monitoring of high-molecular weight polycyclic aromatic hydrocarbons (HMW-PAH) via simple and cost effective methods still remains a challenge. In this article, we combine solid-phase nano-extraction (SPNE) and 4.2 K laser-excited time resolved Shpol'skii spectroscopy (LETRSS) into a valuable alternative for the water analysis of dibenzo[a,l]pyrene, dibenzo[a,h]pyrene, dibenzo[a,i]pyrene and naphtho[2,3-a]pyrene. In comparison to the original SPNE procedure, the present method improves PAH recoveries and reduces extraction time from 30 to 20 min per sample. Quantitative release of HMW-PAH into the Shpol'skii matrix (n-octane) is best accomplished with a mixture of 48 μL of methanol and 2 μL of 1-pentanethiol. Their migration into the 50 μL layer of n-octane provides highly resolved spectra with distinct fluorescence lifetimes for unambiguous isomer determination. Complete analysis takes less than 30 min per sample and consumes only 100 micro-liters of organic solvents. 500 μL of water are sufficient to obtain limits of detection ranging from 16 ng L(-1) (dibenzo[a,l]pyrene) to 55 ng L(-1) (dibenzo[a,i]pyrene), relative standard deviations better than 3% and analytical recoveries above 90%. Although a straightforward comparison to chromatographic methods is not possible because of the lack of analytical figures of merit on HMW-PAH, the excellent precision of measurements, limits of detection and overall recoveries makes SPNE-LETRSS an attractive approach to water analysis of HMW-PAH.

Assessment of benzo(a)pyrene-equivalent carcinogenicity and mutagenicity of residential indoor versus outdoor polycyclic aromatic hydrocarbons exposing young children in New York City

The application of benzo(a)pyrene (BaP)-toxic equivalent factor to polycyclic aromatic hydrocarbons (PAH) concentrations can provide a more accurate risk assessment from environmental exposure to PAH. We hypothesized that BaP-equivalent toxicity determined following residential air monitoring among young urban children may vary by season. Residential indoor and outdoor air levels of PAH measured over two-weeks in a cohort of 5-6 year old children (n = 260) in New York City were normalized to the cancer and mutagen potency equivalent factor of BaP (BaP = 1). Data are presented as carcinogenic equivalents (BaP-TEQ) and mutagenic equivalents (BaP-MEQ) for the sum of 8 PAH (Sigma(8)PAH; MW >or= 228) and individual PAH and compared across heating versus nonheating seasons. Results show that heating compared to nonheating season was associated significantly with higher (BaP-TEQ)(Sigma8PAH) and (BaP-MEQ)(Sigma8PAH) both indoors and outdoors (p < 0.001). Outdoor (BaP-TEQ)(Sigma8)(PAH) and (BaP-MEQ)(Sigma8PAH) were significantly higher than the corresponding indoor measures during the heating season (p < 0.01). These findings suggest that at levels encountered in New York City air, especially during the heating season, residential exposure to PAH may pose an increased risk of cancer and mutation.

Deployment of coal briquettes and improved stoves: possibly an option for both environment and climate

The use of coal briquettes and improved stoves by Chinese households has been encouraged by the government as a means of reducing air pollution and health impacts. In this study we have shown that these two improvements also relate to climate change. Our experimental measurements indicate that if all coal were burned as briquettes in improved stoves, particulate matter (PM), organic carbon (OC), and black carbon (BC) could be annually reduced by 63 +/- 12%, 61 +/- 10%, and 98 +/- 1.7%, respectively. Also, the ratio of BC to OC (BC/OC) could be reduced by about 97%, from 0.49 to 0.016, which would make the primary emissions of household coal combustion more optically scattering. Therefore, it is suggested that the government consider the possibility of: (i) phasing out direct burning of bituminous raw-coal-chunks in households; (ii) phasing out simple stoves in households; and, (iii) financially supporting the research, production, and popularization of improved stoves and efficient coal briquettes. These actions may have considerable environmental benefits by reducing emissions and mitigating some of the impacts of household coal burning on the climate. International cooperation is required both technologically and financially to accelerate the emission reduction in the world.

DNA adducts formation and induction of apoptosis in rat liver epithelial 'stem-like' cells exposed to carcinogenic polycyclic aromatic hydrocarbons

The bipotent liver progenitor cells, so called oval cells, may participate at the early stages of hepatocarcinogenesis induced by chemical carcinogens. Unlike in mature parenchymal cells, little is known about formation of DNA adducts and other genotoxic events in oval cells. In the present study, we employed spontaneously immortalized rat liver WB-F344 cell line, which is an established in vitro model of oval cells, in order to study genotoxic effects of selected carcinogenic polycyclic aromatic hydrocarbons (PAHs). With exception of dibenzo[a,l]pyrene, and partly also benzo[g]chrysene and benz[a]anthracene, all other PAHs under the study induced high levels of CYP1A1 and CYP1B1 mRNA. In contrast, we observed distinct genotoxic and cytotoxic potencies of PAHs. Dibenzo[a,l]pyrene, and to a lesser extent also benzo[a]pyrene, benzo[g]chrysene and dibenzo[a,e]pyrene, formed high levels of DNA adducts. This was accompanied with accumulation of Ser-15 phosphorylated form of p53 protein and induction of apoptosis. Contrary to that, benz[a]anthracene, chrysene, benzo[b]fluoranthene and dibenzo[a,h]anthracene induced only low amounts of DNA adducts formation and minimal apoptosis, without exerting significant effects on p53 phosphorylation. Finally, we studied effects of 2,4,3',5'-tetramethoxystilbene and fluoranthene, inhibitors of CYP1B1 activity, which plays a central role in metabolic activation of dibenzo[a,l]pyrene. In a dose-dependent manner, both compounds inhibited apoptosis induced by dibenzo[a,l]pyrene, suggesting that it interferes with the metabolic activation of the latter one. The present data show that in model cell line sharing phenotypic properties with oval cells, PAHs can be efficiently metabolized to form ultimate genotoxic metabolites. Liver progenitor cells could be thus susceptible to this type of genotoxic insult, which makes WB-F344 cell line a useful tool for studies of genotoxic effects of organic contaminants in liver cells. Our results also suggest that, unlike in mature hepatocytes, CYP1B1 might be a primary enzyme responsible for formation of DNA adducts in liver progenitor cells.

Prediction of PAH mutagenicity in human cells by QSAR classification

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants of high environmental concern. The experimental data of a mutagenicity test on human B-lymphoblastoid cells (alternative to the Ames bacterial test) for a set of 70 oxo-, nitro- and unsubstituted PAHs, detected in particulate matter (PM), were modelled by Quantitative Structure-Activity Relationships (QSAR) classification methods (k-NN, k-Nearest Neighbour, and CART, Classification and Regression Tree) based on different theoretical molecular descriptors selected by Genetic Algorithms. The best models were validated for predictivity both externally and internally. For external validation, Self Organizing Maps (SOM) were applied to split the original data set. The best models, developed on the training set alone, show good predictive performance also on the prediction set chemicals (sensitivity 69.2-87.1%, specificity 62.5-87.5%). The classification of PAHs according to their mutagenicity, based only on a few theoretical molecular descriptors, allows a preliminary assessment of the human health risk, and the prioritisation of these compounds.

Radical−Molecule Reactions for Aromatic Growth: A Case Study for Cyclopentadienyl and Acenaphthylene

Polycyclic aromatic hydrocarbon growth from acenaphthylene and cyclopentadienyl was investigated by using the B3LYP/6-31G(d,p) and BH&HLYP/6-31G(d,p) levels of theory as well as transition state theory. The reaction pathways of cyclopentadienyl bearing hydrocarbons are different from those without these moieties and cannot be adequately accounted for by the existing acetylene addition and aryl-aryl addition mechanisms. The reaction mechanisms identified in this paper lead to the formation of fluoranthene, aceanthrylene, and acephenanthrylene. Rate constants of the radical-molecule addition and subsequent intramolecular addition steps predict that the 1,2 double bond in acenaphthylene is much more reactive than the 3,4 and 4,5 double bonds. Fluoranthene is the most abundant product produced at high temperatures and the yield of acephenanthrylene is bigger than that of aceanthrylene. The computational results are discussed in light of pyrolysis experiments on CPD-indene and CPD-acenaphthylene mixtures conducted by Prof. Mulholland's research group reported in a previous work.

Formation of Naphthalene, Indene, and Benzene from Cyclopentadiene Pyrolysis: A DFT Study

Four new reaction pathways for polycyclic aromatic hydrocarbon growth from cyclopentadiene pyrolysis are proposed and investigated using the B3LYP/6-31G(d,p) level of theory. These pathways allow for the production of indene, naphthalene, and benzene through intramolecular addition, C-H beta-scission, and C-C beta-scission reaction mechanisms, respectively. Results show that the intramolecular addition channel is favored at low temperatures, and the C-H beta-scission channel and the newly identified C-C beta-scission pathway become significant when the temperature increases. These results are in qualitative agreement with the experimental results previously obtained by this research group indicating that the main product at low temperature is indene, while benzene and naphthalene production dominate at the high-temperature end.