Major Polycyclic Aromatic Hydrocarbons Research Articles

Measured and predicted affinities of binding and relative potencies to activate the AhR of PAHs and their alkylated analogues

Polycyclic aromatic hydrocarbons (PAHs) and their alkylated forms are important components of crude oil. Both groups of PAHs have been reported to cause dioxin-like responses, mediated by aryl hydrocarbon receptor (AhR). Thus, characterization of binding affinity to the AhR of unsubstituted or alkylated PAHs is important to understand the toxicological consequences of oil contamination on ecosystems. We investigated the potencies of major PAHs of crude oil, e.g., chrysene, phenanthrene and dibenzothiophene, and their alkylated forms (n=17) to upregulate expression of AhR-mediated processes by use of the H4IIE-luc transactivation bioassay. In addition, molecular descriptors of different AhR activation potencies among PAHs were investigated by use of computational molecular docking models. Based on responses of the H4IIE-luc in vitro assay, it was shown that potencies of PAHs were determined by alkylation in addition to the number and conformation of rings. Potencies of AhR-mediated processes were generally greater when a chrysene group was substituted, especially in 1-methyl-chrysene. Significant negative correlations were observed between the in vitro dioxin-like potency measured in H4IIE-luc cells and the binding distance estimated from the in silico modeling. The difference in relative potency for AhR activation observed among PAHs and their alkylated forms could be explained by differences among binding distances in the ligand binding domain of the AhR caused by alkylation. The docking model developed in the present study may have utility in predicting risks of environmental contaminants of which toxicities are mediated by AhR binding.

Reducing polycyclic aromatic hydrocarbons content in coal tar pitch by potassium permanganate oxidation and solvent extraction

This study was conducted to assess the feasibility of using potassium permanganate (KMnO4) as an oxidant to reduce 7 carcinogenic polycyclic aromatic hydrocarbons (PAHs) content in two coal tar pitches (CTPs), and to research the oxidation mechanism of KMnO4. It had been observed reduction of major PAHs in CTP after KMnO4 oxidation. The best benzo[a]pyrene equivalency (BaPeq) reduction rate of 82% in n-hexane soluble in a high temperature CTP (HCTP) was achieved with KMnO4 concentration of 0.2M treated for 5h. Specifically, a higher phenanthrene reduction rate (90%) was obtained by using the Soxhlet extraction with n-hexane as solvent on the KMnO4 oxidized HCTP. The single PAH removal rate roughly increases with increasing rings number of PAH, following the order of phenanthrene<fluoranthene<pyrene<benzo[a]pyrene<benzo(b)fluoranthene<indeno[1,2,3-ed]pyrene<benzo[g,h,i]perylene under the same conditions. By using gel penetration chromatography (GPC) and gas chromatography–mass spectrometry (GC–MS), electrophilic substitution reaction was speculated as the oxidation mechanism of CTP by KMnO4.

Exposure to dust-bound PAHs and associated carcinogenic risk in primitive and traditional cooking practices in Pakistan.

The aim of this study was to determine the abundance and distribution of polycyclic aromatic hydrocarbons (PAHs) in dust samples collected from the selected professional cooking workplaces (WCs) and residential household cooking areas (WRs), where traditional and primitive cooking practices are still prevelent. Another aim of this study was to investigate the carcinogenic risk for Pakistani human exposure to dust-bound PAHs via the routes of inhalation, ingestion, and dermal contact. Generally, the concentration of individual congeners of PAHs in surface dust samples of WC sites was higher than those measured in WR sites (p < 0.05). The benzo(a)pyrene (B(a)P), a very high carcinogenic compound, was present in the dust samples from WC sites in the highest mean concentration (630 ng g(-1) dry weight (d.w.)). The BaP mean concentration in WC workplaces was almost eight times higher than the mean value found in WR exposure sites. Moreover, the average concentration of ∑PAHs, combustion origin PAHs (∑COMB) and sum total of 7-carcinogenic PAHs (∑7-carcinogens) were also significantly higher in WC dusts samples than that in WR workplaces. Principal component analysis (PCA) and diagnostic ratios suggested coal/wood combustion as major PAH emission sources in both exposure sites. The average incremental lifetime cancer risk (ILCR) suggested a moderate to potential high cancer risk for adults and children exposed to dust-bound PAHs in both exposure sites, in particular via both dermal and ingestion contact pathways.

In situ X-ray diffraction study of decomposition of polycyclic aromatic hydrocarbons at pressures of 7–15 GPa: Implication to fluids under the Earth's and planetary environments

The behavior of polycyclic aromatic hydrocarbons (PAHs) at high pressures and temperatures has been investigated as a part of study of the deep-seated C–O–H fluids in the Earth and planetary interiors. The theoretical calculations of fluid compositions at the Earth's mantle conditions in the simple C–O–H system indicate that dominant fluid species are CH4 and H2O, with subordinate H2, and heavier hydrocarbons. However, calculations of equations of state for a broader range of hydrocarbons predict an appearance of heavy alkanes and PAHs under high pressures (>6–7GPa). Here, we determined stability of the major PAHs (from naphthalene to coronene) using in situ X-ray diffraction in multianvil apparatus at the SPring-8 synchrotron radiation facility (Japan). It was found, that at 7–9GPa, PAHs become unstable at temperatures above 873–1073K. We suggest that stability of PAHs is limited by benzene ring decomposition. The data for coronene only at 15GPa confirms limited temperature stability of PAHs. The PAH decomposition products consist of amorphous hydrogenated carbon at 7–9GPa at 973–1073K. Coronene decomposition products consist of diamond and trans-polyacetylene at 15.5GPa and 973K. Determined PAH decomposition temperatures (873–1073K) are lower than known Earth's geotherms and subduction slab P–T profiles at pressures of 7–9GPa (220–280km depths). According to these data, PAH inclusions in mantle garnet and diamond should be of secondary origin, precipitating from mantle-derived fluids after or prior to kimberlite magma eruption. Limited temperature stability of PAHs restricts the parameters of their formation in meteorite by high-temperature impact events during early Solar System history.

Comparison of sources of urban ambient particle bound PAHs between non-heating seasons 2009 and 2012 in Belgrade, Serbia

Exposure to increased cconcentrations of polycyclic aromatic hydrocarbons (PAHs) is associated with adverse health problems and specifically with carcinogenic and mutagenic effects. The major PAH sources outdoors are: stationary sources from industry (power plants, incineration, local industry) and domestic sources as the residential heating, burning and pyrolysis of coal, oil, gas, garbage, wood, or other organic substances mobile emissions (diesel and petrol engines), biomass burning and agricultural activities (e.g., open burning of brushwood, straw, stubble). The aim of this study was to assess potential differences in particle-bound PAH levels and source contribution between summer 2009 and 2012 sampling campaigns done at same location in Belgrade urban area. The sampling location is considered representative for a mix of residential, business and industrial areas of New Belgrade, an urban area that has been under rapid development. The average concentrations of PM10 are slightly higher in summer 2012 than in 2009. PM-bound PAH follow the same trend as the PM indicating an increasing strength of PAH sources relative to all PM sources. Appling Positive Matrix Factorization, three potential sources of PAHs in the atmosphere were distinguished: (1) stationary sources, (2) traffic (diesel and gasoline vehicle exhaust) and (3) local open burning sources (OBS). The analysis confirmed higher contribution of traffic and lower of OBS in summer 2012 than in 2009, reflecting higher traffic volumes and absence of or lower local OBS emissions due to burning wood, grass and domestic waste in 2012.

Polycyclic aromatic hydrocarbons (PAHs) in yogurt samples

The concentrations and distributions of major polycyclic aromatic hydrocarbons (PAHs) were determined in 20 kinds of yogurt specimens collected from Italian supermarkets using reversed phase high-performance liquid chromatography equipped with fluorescence detection. The method was validated by determination of recovery percentages, precision (repeatability) and sensitivity (limits of detection) with yogurt samples fortified at 0.25, 0.5 and 1 µg/kg concentration levels. The recovery of 13 PAHs, with the exception of naphthalene and acenaphthene, ranged from 61% to 130% and from 60% to 97% at all the levels for yogurts with low (0.1%) and high (3.9%) fat content, respectively. The method is repeatable with relative standard deviation values <20% for all analytes. The results obtained demonstrate that acenaphthene, fluorantene, phenanthrene, anthracene, fluoranthene and pyrene were found in all samples with a similar distribution, but different content when yogurts with low and high fats were compared.

Ecological and human health hazards of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in road dust of Isfahan metropolis, Iran

This study investigates trace elements and PAHs content in road dust of Isfahan metropolis, central Iran. The mean concentrations of As, Cd, Cu, Ni, Pb, Sb and Zn are 22.15, 2.14, 182.26, 66.63, 393.33, 6.95 and 707.19mgkg−1, respectively. When compared with upper continental crust, the samples generally display elevated trace element concentrations, except for Co and Cr. The decreasing trend of calculated enrichment factors (EFs) is Cd>Pb>Sb>Zn>Cu>As>Ni>Cr>Co. Calculated potential ecological risk reveals that among the analyzed metals, Cd and Pb, have a higher potential ecological risk. Statistically, two identified main sources of trace elements include road traffic emissions and resuspension of soil particles. As, Cd, Cu, Pb, Sb and Zn in Isfahan road dust are strongly influenced by anthropogenic activity, mainly traffic emissions, while Co, Cr and Ni originate from resuspension of soil natural parent particles. The sum of 13 major PAHs (∑13PAHs) mass concentration ranges from 184.64 to 3221.72μgkg−1 with the mean being 1074.58μgkg−1. PAHs sources are identified using PCA analysis. It is demonstrated that the PAHs in Isfahan road dust are mainly derived from traffic emission, coal combustion and petroleum. Toxic equivalent concentrations (TEQs) of PAHs in the road dust ranges between 25.021μgkg−1 and 230.893μgkg−1. High correlation coefficients (r2=0.909 and 0.822, p<0.01) between Benzo[a]pyrene, Benzo[b+k]fluoranthene and toxicity equivalent concentrations of road dust indicate that Benzo[a]pyrene and Benzo[b+k]fluoranthenes are major TEQ contributors. The total incremental life time cancer risk (ILCR) of exposure to PAHs from Isfahan metropolis urban dust is 4.85×10−4 for adult and 5.02×10−4 for children. Estimated results of ILCR indicate that Isfahan residents are potentially exposed to high cancer risk via both dust ingestion and dermal contact.

Concentrations and Sources of Polycyclic Aromatic Hydrocarbons in Water and Sediments from the Huaihe River, China

Surface water and sediments were collected from eleven locations on the middle region of Huaihe River to evaluate the environmental effects of urban and industrial activities. The concentrations of sixteen polycyclic aromatic hydrocarbons (PAHs) in water and sediments were between 1.2–5.1 µg/L and 72–139 ng/g, respectively. High levels of PAHs in water were recorded in comparison to those of other countries, while the concentrations in sediments were low to moderate levels. A weak positive correlation was observed (R2 = 0.49, P = 0.13) between PAHs and total organic carbon in water. However, a significant positive correlation (R2 = 0.79, P = 0.004) was found in sediments, which indicated that total organic carbon was a factor in PAH levels in sediments but not in water. The parent ratios were studied by principal component analysis that showed the PAHs from water were predominantly derived from coal combustion (34%), oil spills (49%), and vehicular emissions (17%), while the major PAH sources to sediments were coal combustion. Using the ecological toxic equivalency factor index, it was concluded that the PAHs levels may provide a potential risk in water but not in sediments.

Mechanistic relationships between hepatic genotoxicity and carcinogenicity in male B6C3F1 mice treated with polycyclic aromatic hydrocarbon mixtures.

The genotoxicity of a complex mixture [neutral fraction (NF)] from a wood preserving waste and reconstituted mixture (RM) mimicking the NF with seven major polycyclic aromatic hydrocarbons (PAHs) and benzo(a)pyrene (BaP) was investigated by determining DNA adducts and tumor incidence in male B6C3F1 mice exposed to three different doses of the chemical mixtures. The peak values of DNA adducts were observed after 24 h, and the highest levels of PAH-DNA adducts were exhibited in mice administered NF + BaP, and the highest tumor incidence and mortality were also observed in this group. DNA adduct levels after 1, 7, or 21 days were significantly correlated with animal mortality and incidence of total tumors including liver, lung, and forestomach. However, only hepatic DNA adducts after 7 days significantly correlated with liver tumor incidence. Most proteins involved in DNA repair including ATM, pATR, Chk1, pChk1, DNA PKcs, XRCC1, FANCD2, Ku80, Mre11, and Brca2 were significantly lower in liver tumor tissue compared to non-tumor tissue. Expressions of proteins involved in apoptosis and cell cycle regulation were also significantly different in tumor versus non-tumor tissues, and it is possible that PAH-induced changes in these gene products are important for tumor development and growth.

Inhibitory effects of polycyclic aromatic hydrocarbons (PAHs) on photosynthetic performance are not related to their aromaticity

Polycyclic aromatic hydrocarbons (PAHs) are very toxic and highly persistent environmental pollutants which accumulate in soil and affect growth of the plants adversely. This study aims to investigate inhibitory effects of 3 major PAH particularly on photosynthetic processes in Arabidopsis thaliana grown in soil treated with PAH. The 3 PAH chosen differ from each other in aromaticity (number of rings) comprising their structure (2 rings: naphthalene, 3 rings: anthracene and 4 rings: pyrene). Several growth parameters and Chlorophyll a fluorescence was monitored in PAH treated plants. BN-PAGe analysis was done in order to get information about change in the protein conformation. PAH treatment led to increased value of Fo which collaborated with increase in the amount of free LHC as seen through BN-Page analysis. Thus PAH were found to inhibit PS II photochemistry and caused distinct change in pigment composition. However the results led us to infer that 3-ring anthracence is more inhibitory as compared to 2-ring naphthalene and 4-ring pyrene. This indicates that aromaticity of PAH is unrelated to their response on photosynthetic processes.

Degradation of polyaromatic hydrocarbons employing biosurfactant-producing Bacillus pumilus KS2

An efficient hydrocarbon-degrading native bacterial strain Bacillus pumilus KS2 (identified by partial 16S rDNA gene sequencing) was isolated from crude oil-contaminated soil collected from oil fields of Lakowa, Sivasagar district of Assam, India. Experiments were conducted under laboratory conditions to determine the efficiency of this biosurfactant-producing strain to degrade polycyclicaromatic hydrocarbons (PAHs). Quantification of the capacity of the biosurfactant to reduce the surface tension (ST) of the culture medium was used as a measure of biosurfactant production. In terms of total petroleum hydrocarbon (TPH) degradation, strain KS2 was able to degrade 80.44 % of the TPH by 4 weeks of incubation. It also demonstrated efficient degradation of PAHs, completely degrading nine of the 16 major PAHs present in the crude oil sample. Strain KS2 also produced biosurfactant which, based on biochemical and FTIR analyses, was glycolipid in nature. To our knowledge, this is the first report showing the potential of a native strain of the North-East region of India for efficient degradation of TPH and PAHs and, consequently, in the remediation of hydrocarbons from contaminated sites.

Sedimentary record of PAHs in the Barigui River and its relation to the socioeconomic development of Curitiba, Brazil

Concentrations of polycyclic aromatic hydrocarbons (PAHs) were determined in a sediment core collected from the Barigui River, in Curitiba, South Brazil. The USEPA's 16 priority PAH concentrations ranged from 39ngg−1 to 2350ngg−1 of dry sediment over a period that corresponds temporally to between ca. 1855 and 2011. The concentrations and patterns of PAH distribution changed over this time period and may be associated with several episodes in the Curitiba's history. Two major PAHs concentration peaks occurred in approximately 1910 and 1970, which might reflect population increases due to immigration programs in the 1890s and the sudden economic development that occurred in Brazil from 1960 to 1980, “The Economic Miracle Period”, respectively. Isomeric ratios revealed that the PAHs had predominantly pyrolytic sources. The population, number of highways and electric energy consumption of Curitiba, as indices of socioeconomic development, were positively correlated with PAH deposition in the sediment core from 1855 to 1970, indicating the influence of socioeconomic development on the environmental load of sedimentary PAHs.

Microarray analysis of gene expression in 3-methylcholanthrene-treated human endothelial cells

Cigarette smoke has many toxic components that can lead to the disruption of various cellular processes. Increase in oxidative stress due to cigarette smoke causes production of reactive oxygen species, which induce vascular disease. 3-methylcholanthrene (3MC) is an environmental contaminant derived from the incomplete combustion of cigarette smoke and is one of the major polycyclic aromatic hydrocarbons. 3MC activates the aryl hydrocarbon receptor and contributes to carcinogenesis and vascular disease. The present study investigated gene expression in 3MC-treated human umbilical vein endothelial cells by microarray gene expression profiling. We found 1,279 and 717 genes with altered gene expression within 24 h of 100 nM and 1 μM 3MC treatment, respectively; these genes were distributed into distinct functional groups. Some of the genes including ICAM1, PTGS2, APOL3, and GPX-1, were related to cardiovascular disease. Our results support the hypothesis that 3MC-stimulated gene expression in endothelial cells may play a role in the development of cardiovascular disease.

Aryl hydrocarbon receptor mediated activities in road dust from a metropolitan area, Hanoi—Vietnam: Contribution of polycyclic aromatic hydrocarbons (PAHs) and human risk assessment

Dioxin-Responsive Chemical-Activated LUciferase gene eXpression assay (DR-CALUX) was applied to assess the total toxic activity of the mixture of PAHs and related compounds as well as dioxin-related compounds in road dust from urban areas of Hanoi, Vietnam. Road dust from Hanoi contained significantly higher DR-CALUX activities (3 to 39, mean 20ng CALUX-TEQ/g dw) than those from a rural site (2 to 13, mean 5ng CALUX-TEQ/g dw). The total concentrations of 24 major PAHs (Σ24PAHs) in urban road dust (0.1 to 5.5, mean 2.5μg/g dw) were also 6 times higher than those in rural road dust (0.08 to 1.5, mean 0.4μg/g dw). Diagnostic ratios of PAHs indicated vehicular engine combustion as the major PAH emission source in both sites. PAHs accounted for 0.8 to 60% (mean 10%) and 2 to 76% (mean 20%) of the measured CALUX-TEQs in road dust for Hanoi the rural site, respectively. Benzo[b]-/benzo[k]fluoranthenes were the major TEQ contributors among PAHs, whereas DRCs contributed <0.1% to CALUX-TEQs for both rural and urban sites. These results suggest TEQ contribution of other aryl hydrocarbon receptor agonists in road dust. Significant PAH concentrations in urban dust indicated high mutagenic and carcinogenic potencies. Estimated results of incremental life time cancer risk (ILCR) indicated that Vietnamese populations, especially those in urban areas such as Hanoi, are potentially exposed to high cancer risk via both dust ingestion and dermal contact. This is the first study on the exposure risk of AhR agonists, including PAHs and DRCs, in urban road dust from a developing country using a combined bio-chemical analytical approach.

Impact of oxidation and biodegradation on the most commonly used polycyclic aromatic hydrocarbon (PAH) diagnostic ratios: Implications for the source identifications

Based on the isomer stability during their formation, PAH diagnostic ratios have been extensively used to determine PAH contamination origin. Nevertheless, it is known that these isomers do not present the same physicochemical properties and that reactions occurring during the transport from an atmospheric source induce changes in the diagnostic ratios. Yet, little is known about reactions occurring in soils contaminated by other sources such as coal tar and coal. Innovative batch experiments of abiotic oxidation and microbial incubations were performed to discriminate independently the influence of these two major processes occurring in soils on the diagnostic ratios of major PAH sources. Three samples were studied, a coking plant soil and two major PAH sources in this soil, namely coal and coal tar. The combustion signature of the coking plant soil showed the major influence of coal tar in the soil sample composition. Some of these ratios were drastically affected by oxidation and biodegradation processes inducing a change in the source signature. The coal tar signature changed to petrogenic source after oxidation with the anthracene/(anthracene+phenanthrene) ratio. According to this ratio, the initial petrogenic signature of the coal changed to a combustion signature after the biodegradation experiment.

Concentration and particle size distribution of polycyclic aromatic hydrocarbons formed by thermal cooking

The concentration and particle size distribution of 19 major polycyclic aromatic hydrocarbons (PAHs) emitted by thermal cooking were investigated. Corn, trout, beef, prawns, and pork were selected for grilling. The PAHs in the oil mist emitted when the food was grilled were collected according to particle size range and analysed by GC/MS. Much higher concentrations of PAHs were detected in the oil mist emitted by grilled pork, trout, and beef samples, which were rich in fat. The main components of the cooking exhaust were 3- and 4-ring PAHs, regardless of food type. The particle size distribution showed that almost all the PAHs were concentrated in particles with diameters of <0.43μm. For pork, the toxic equivalent of benzo[a]pyrene accounted for 50% of the PAHs in particles with diameters of <0.43μm. From these results, we estimated that >90% of the PAHs would reach the alveolar region of the lungs.

Comparative study of polycyclic aromatic hydrocarbons in coral tissues and the ambient sediments from Kenting National Park, Taiwan

Surface sediments and corals (Acropora sp. and Montipora sp.) from the coastline of Kenting were analyzed in 2009 and 2010 for content levels of polycyclic aromatic hydrocarbons (PAHs) using gas chromatography-mass spectrometry. The total PAH concentrations (t-PAH) in corasls (143–1715 ng g−1 dw) were significantly higher than in the ambient sediments (2–59 ng g−1 dw) indicating the bioaccumulation of PAHs in corals. The spatial and seasonal variation in PAH levels suggested that land-loaded contaminants may be the main source of PAHs in the Kenting coral reefs. Based on molecular indices, PAHs were substantially of petroleum origin. The major PAH components were phenanthrene, pyrene and fluorine, but PAH congeners in corals and sediments still have characteristic composition patterns which would be altered by the bio/accumulation mechanisms. Further study is essential to assess and understand the impacts of these chemicals on coral reefs.

Biomonitoring of polycyclic aromatic hydrocarbons in urban and industrial environments of the Western Black Sea Region, Turkey

This research was carried out in the cities of Zonguldak and Eregli, which have been characterized as urban and industrial environments of the Western Black Sea Region, Turkey, in order to assess the contamination of polycyclic aromatic hydrocarbons (PAHs) using mosses as biomonitors. The methodology involved the collection of moss samples (Hypnum cupressiforme), ultrasonic extraction with dichloromethane, cleanup using silica gel and analysis by liquid chromatography with ultraviolet detection. The total PAH concentrations ranged from 78.1 to 1693.5ngg(-1) in Zonguldak and from 15.2 to 275.1ngg(-1) in Eregli. The total PAH concentration in Eregli was about six times lower than that in Zonguldak, revealing the importance of switching from coal to natural gas in residential heating. The diagnostic ratios and the correlation analysis have indicated that coal combustion and traffic emissions were the major PAH sources at both sites. The contour maps were constructed for the determination of spatial distributions of total PAHs, and it was shown for Zonguldak as well as for Eregli that the PAH pollution was much more predominant in highly populated regions. Moving away from the city centres, a gradual decrease in PAH pollution rates was observed.

Compound- and Mixture-Specific Differences in Resistance to Polycyclic Aromatic Hydrocarbons and PCB-126 amongFundulus heteroclitusSubpopulations throughout the Elizabeth River Estuary (Virginia, USA)

Atlantic killifish (Fundulus heteroclitus) inhabiting the Atlantic Wood Industries Superfund Site (Elizabeth River, Portsmouth, VA, USA) are resistant to the acute toxicity and cardiac teratogenesis caused by high levels of polycyclic aromatic hydrocarbons (PAHs) from creosote. The resistance is linked to down regulation of the aryl hydrocarbon receptor (AHR) pathway. We investigated the association between CYP1 activity, as a marker of potential AHR pathway suppression, and contaminant resistance in killifish subpopulations from sites throughout the estuary that varied significantly in PAH contamination level. Adult killifish and sediments were collected from seven sites across approximately 13.7 km in river length within the estuary and from a nearby reference site. Sediment PAH levels were determined using gas chromatography mass spectrometry. Embryos obtained via manual spawning were exposed to individual AHR agonists and PAH mixtures 24 h post fertilization (hpf); CYP1 activity was determined by in ovo ethoxyresorufin-o-deethylase (EROD) at 96 hpf, and cardiac deformity severity was scored at 144 hpf. The total PAH levels measured among the sites varied from approximately 200 to 125,000 ng/g dry sediment. Overall, the resistance to teratogenesis was strongest in the subpopulations from sites in or closest to the major PAH contamination sites, but even embryos from less-contaminated sites within the Elizabeth River demonstrated at least partial resistance to many challenges. Surprisingly, all of the subpopulations tested were highly resistant to PCB-126 (3,3′,4,4′,5-pentachlorobiphenyl). However, the degree of CYP1 activity response varied significantly among subpopulations and did not always correlate strongly with resistance to teratogenesis; some subpopulations resisted the cardiac teratogenesis caused by the challenges at doses that still elicited strong EROD induction. Our results suggest that there is variation in the adaptive phenotype exhibited by laboratory-spawned embryos from killifish subpopulations throughout the estuary. Furthermore, the results show that contaminants have affected killifish subpopulations throughout the estuary, even in sites with lower levels of PAHs.

Emissions of Polycyclic Aromatic Hydrocarbons, Polychlorinated Dibenzo-p-Dioxins, and Dibenzofurans from Incineration of Nanomaterials

Disposal of some nanomaterial-laden waste through incineration is inevitable, and nanomaterials' influence on combustion byproduct formation under high-temperature, oxidative conditions is not well understood. This work reports the formation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated-dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from incineration of paper and plastic waste containing various nanomaterials, including titania, nickel oxide, silver, ceria, iron oxide, quantum dots, and C60-fullerene, in a laboratory-scale furnace. The presence of nanomaterials in the waste stream resulted in higher emissions of some PAH species and lower emissions of others, depending on the type of waste. The major PAH species formed were phenanthrene and anthracene, and emissions were sensitive to the amount of nanomaterials in the waste. Generally, there were no significant differences in emission factors for the larger PAH species when nanomaterials were added to the waste. The total PAH emission factors were on average ~6 times higher for waste spiked with nanomaterials v. their bulk counterparts. Emissions of chlorinated dioxins from poly(vinyl chloride) (PVC) waste were not detected; however, chlorinated furans were formed at elevated concentrations with wastes containing silver and titania nanomaterials, and toxicity was attributable mainly to 2,3,4,7,8-pentachlorodibenzofuran. The combination of high specific surface area and catalytic, including electrocatalytic, properties of nanomaterials might be responsible for affecting the formation of toxic pollutants during incineration.