Effects Of Polycyclic Aromatic Hydrocarbons Research Articles

A systematic review on the effects of polycyclic aromatic hydrocarbons on cardiometabolic impairment

Background:Various epidemiological studies have shown that exposure to environmental pollutants including polycyclic aromatic hydrocarbons (PAHs) might increase the risk of cardiovascular diseases (CVDs) and their risk factors. This study aims to systematically review the association of PAH exposure with metabolic impairment.Methods:Data were collected by searching for relevant studies in international databases using the following keywords: “polycyclic aromatic hydrocarbon” + “cardiovascular disease,” PAH + CVD, polycyclic aromatic hydrocarbon and “air pollutant” + “CVD,” and the desired data were extracted and included in the study according to the systematic review process.Results:From the 14 articles included in the present systematic review, eight articles were conducted on the relationship between PAH and CVDs, four articles were conducted to examine the association of PAH exposure with blood pressure (BP), and two articles investigated the link between PAH and obesity.Conclusions:Most studies included in this systematic review reported a significant positive association of PAH exposure with increased risk of CVDs and its major risk factors including elevated BP and obesity. These findings should be confirmed by longitudinal studies with long-term follow-up.

Spliced leader-based analyses reveal the effects of polycyclic aromatic hydrocarbons on gene expression in the copepod Pseudodiaptomus poplesia

Polycyclic aromatic hydrocarbons (PAHs) are a group of toxic and carcinogenic pollutants that can adversely affect the development, growth and reproduction of marine organisms including copepods. However, knowledge on the molecular mechanisms regulating the response to PAH exposure in marine planktonic copepods is limited. In this study, we investigated the survival and gene expression of the calanoid copepod Pseudodiaptomus poplesia upon exposure to two PAHs, 1, 2-dimethylnaphthalene (1, 2-NAPH) and pyrene. Acute toxicity responses resulted in 96-h LC50 of 788.98μgL−1 and 54.68μgL−1 for 1, 2-NAPH and pyrene, respectively. Using the recently discovered copepod spliced leader as a primer, we constructed full-length cDNA libraries from copepods exposed to sublethal concentrations and revealed 289 unique genes of diverse functions, including stress response genes and novel genes previously undocumented for this species. Eighty-three gene families were specifically expressed in PAH exposure libraries. We further analyzed the expression of seven target genes by reverse transcription-quantitative PCR in a time-course test with three sublethal concentrations. These target genes have primary roles in detoxification, oxidative defense, and signal transduction, and include different forms of glutathione S-transferase (GST), glutathione peroxidases (GPX), peroxiredoxin (PRDX), methylmalonate-semialdehyde dehydrogenase (MSDH) and ras-related C3 botulinum toxin substrate (RAC1). Expression stability of seven candidate reference genes were evaluated and the two most stable ones (RPL15 and RPS20 for 1, 2-NAPH exposure, RPL15 and EF1D for pyrene exposure) were used to normalize the expression levels of the target genes. Significant upregulation was detected in GST-T, GST-DE, GPX4, PRDX6 and RAC1 upon 1, 2-NAPH exposure, and GST-DE and MSDH upon pyrene exposure. These results indicated that the oxidative stress was induced and that signal transduction might be affected by PAH exposure in P. poplesia. However, gene upregulation was followed by a reduction in expression level towards 96h, indicating a threshold value of exposure time that leads to depressed gene expression. Prolonged exposure may cause dysfunction of detoxification and antioxidant machinery in P. poplesia. The transcriptional responses of GST-T, GPX2 and GPX4 upon pyrene exposure were minimal. Our results reveal the different sensitivity of P. poplesia to two PAHs at both the individual and transcriptional levels. As the first attempt, this study proved that copepod spliced leader is useful for obtaining full-length cDNA in P. poplesia exposed to PAHs and provided a valuable gene resource for this non-model species. This approach can be applied to other calanoid copepods exposed to various stressors, particularly under field conditions.

PAHs Exposure Assessment for Highway Toll Station Workers Through Personal Particulate Sampling and Urinary Biomonitoring in Tianjin, China

ABSTRACTHighway toll station workers' occupational exposure levels and health effects of polycyclic aromatic hydrocarbons (PAHs) have been analyzed through personal particulate sampling and urinary biomonitoring during March–May, 2014 in Tianjin, China. Personal particulate samples were collected during highway toll station workers' day shift working time (from 9:00 a.m. to 5:00 p.m.). Pre-shift and post-shift spot urine samples were collected on each participant. In personal particulate samples, 16 priority PAHs suggested by USEPA were measured, and in the urine samples oxidative stress biomarker (8-OHdG) was analyzed. The measured mean occupational exposed concentration of PM2.5 was 230.73 μg m−3, and the mean p-PAHs exposed concentration was 319.90 ng m−3 for the selected workers. Urinary concentrations of 8-OHdG increased by two times following an 8-h work shift in participants. Significant positive associations were found between post-work shift urinary 8-OHdG and p-PAH concentrations. Our finding indicated that personal air exposures to PAHs originating from traffic emissions are important in increasing oxidative burdens in human body.

Effects of polycyclic aromatic hydrocarbons and their mixtures on the activation of the human nuclear receptors AhR and CAR

Effects of polycyclic aromatic hydrocarbons and their mixtures on the activation of the human nuclear receptors AhR and CAR

Biological effects of polycyclic aromatic hydrocarbons (PAH) and their first metabolic products in in vivo exposed Atlantic cod (Gadus morhua)

ABSTRACTThe monitoring of the presence of polycyclic aromatic hydrocarbons (PAH) in the aquatic environment is a worldwide activity since some of these compounds are well-established carcinogens and mutagens. Contaminants in this class are in fact regarded as priority hazardous substances for environmental pollution (Water Framework Directive 2000/60/EC). In this study, Atlantic cod (Gadus morhua) was selected to assess in vivo effects of two PAH and their first metabolic products, namely, the corresponding trans-dihydrodiols, using biological markers. Fish were exposed for 1 wk to a single PAH (naphthalene or chrysene) and its synthetic metabolites ((1R,2R)-1,2-dihydronaphthalene-1,2-diol and (1R,2R)-1,2-dihydrochrysene-1,2-diol) by intraperitoneal injection in a continuous seawater flow system. After exposure, PAH metabolism including PAH metabolites in bile and ethoxyresorufin O-deethylase (EROD) activity, oxidative stress glutathione S-transferases (GST) and catalase (CAT) activities, and genotoxicity such as DNA adducts were evaluated, as well as general health conditions including condition index (CI), hepatosomatic index (HSI), and gonadosomatic index (GSI). PAH metabolite values were low and not significantly different when measured with the fixed-wavelength fluorescence screening method, while the gas chromatography–mass spectroscopy (GC-MS) method showed an apparent dose response in fish exposed to naphthalene. DNA adduct levels ≥0.16 × 10−8 relative adduct level (RAL) were detected. It should be noted that 0.16 × 10−8 RAL is considered the maximal acceptable background level for this species. The other biomarkers activities of catalase, GST, and EROD did not display a particular compound- or dose-related response. The GSI values were significantly lower in some chrysene- and in both naphthalene- and naphthalene diol-exposed groups compared to control.

Spatio-temporal distribution, source, and genotoxic potential of polycyclic aromatic hydrocarbons in estuarine and riverine sediments from southern India

In order to categorize the distribution, source, and effects of polycyclic aromatic hydrocarbons (PAHs) in aquatic systems of southern India, chemical and toxicological analyses were performed on surface and core sediments, collected from Adyar river, Cooum river, Ennore estuary, and Pulicat lake near Chennai city. The total PAH concentration in surface sediment ranged from 13 to 31,425ng/g with a mean value of 4320ng/g; the concentration was markedly higher in Cooum river compared to that at other sites. The historical PAH dissemination in core samples in the Cooum river, Ennore estuary, and Pulicat lake ranged from 30 to 31,425ng/g, from 8.6 to 910ng/g, and from 62 to 546ng/g, respectively. Surface sediments were predominantly contaminated with low molecular weight (LMW) PAHs. Historical profiles suggest that PAH contamination in the area is now greater than it had been in the past. PAH accumulation in Pulicat lake was distinct from that at other locations where high molecular weight (HMW) PAHs were predominant. DNA damage in HepG2 cells treated with sediment extracts from different locations showed a good correlation with their respective total PAH levels. Statistical analysis revealed that 3-ring and 4-ring PAHs may synergistically contribute to the genotoxic potency compared to others in sediments. The study also showed that a majority of PAHs in the study area indicated a petrogenic origin. Based on the enrichment and toxicological assessment of PAHs in sediments, Cooum river was shown to suffer the highest biological impairment among the studied water bodies.

Short-term exposure to benzo[a]pyrene causes oxidative damage and affects haemolymph steroid levels in female crab Portunus trituberculatus

Concern has increased regarding the adverse effects of polycyclic aromatic hydrocarbons (PAHs) on reproduction. However, limited information is available on the effects of PAHs in crustacean. In order to determine whether benzo[a]pyrene (B[a]P) could cause reproductive toxicity on the swimming crab Portunus trituberculatus, sexually mature female crabs were exposed to environmentally relevant concentrations of B[a]P (0, 0.1, 0.5 and 2.5 μg/L) for 10 days. B[a]P treatments resulted in high accumulation in ovary, and induced oxidative stress in a dose-dependent manner on ovary of crab. Furthermore, the haemolymph estradiol (E2) and testosterone (T) levels were significantly decreased. Histological investigation also revealed the reproductive toxicity caused by B[a]P. The results demonstrated that waterborne exposure to B[a]P caused oxidative damage and disrupted sex steroids in female crab P. trituberculatus, ultimately resulting in histological alternation.

Diversity of organotrophic bacteria, activity of dehydrogenases and urease as well as seed germination and root growth Lepidium sativum, Sorghum saccharatum and Sinapis alba under the influence of polycyclic aromatic hydrocarbons.

Polycyclic aromatic hydrocarbons are organic compounds with highly toxic, carcinogenic, and mutagenic properties, which adversely affect the basic biological parameters of the soil, including the count of microorganisms, and the enzymatic activity. In addition to disturbances to the biological activity of the soil, PAHs may also exhibit toxic effects on plants. In view of the above, the study involved testing aimed at the determination of the effects of polycyclic aromatic hydrocarbons in a form of naphthalene, phenanthrene, anthracene and pyrene on the count, colony development (CD) index, ecophysiological (EP) diversity index of organotrophic bacteria, and the activity of soil dehydrogenases and soil urease. Moreover, an attempt was made to determine the soil’s resistance based on the activity of the above-listed enzymes, and the effect of polycyclic aromatic hydrocarbons on seed germination and root growth was assessed by Lepidium sativum, Sorghum saccharatum, and Sinapis alba. In addition, the species of bacteria found in a soil subjected to strong pressure of polycyclic aromatic hydrocarbons were isolated. The experiment was performed in a laboratory on samples of loamy sand. Polycyclic aromatic hydrocarbons were introduced into the soil in an amount of 0, 1000, 2000, and 4000 mg kg−1 of soil dry matter. Germination and growth of cress (L. sativum), white mustard (S. alba), and sweet sorghum (S. saccharatum) were determined using Phytotoxkit tests. It was found that the tested PAHs increased the average colony counts of organotrophic soil bacteria; pyrene did so to the greatest extent (2.2-fold relative to non-contaminated soil), phenanthrene to the smallest extent (1.4-fold relative to non-contaminated soil). None of the PAHs changed the value of the bacterial colony development (CD) index, while anthracene and pyrene increased the value of the eco-physiological (EP) diversity indicator. PAHs lowered the activity of the tested enzymes. The activity of dehydrogenases was dependent on a greater extent by the type of hydrocarbon (54.56 %) rather than by the dose (10.64 %), while for the activity of urease, it was the opposite. The greater extent was dependent on dose (95.42 %) rather than by type (0.21 %). Dehydrogenases are characterised by greater resistance to the action of PAHs than urease. Based on seed germination and root growth, it has shown that S. alba is best suited, being the most vulnerable plant, while S. saccharatum is the least suited. Subjecting a soil to strong pressure of PAHs leads to disturbances to the biological parameters of the soil, seed germination, and root growth L. sativum, S. saccharatum, and S. alba.

Air pollution from polycyclic aromatic hydrocarbons generated by human activities and their health effects in China

The key factors that influence the health effects of polycyclic aromatic hydrocarbons (PAH) air emissions generated by human activities in China were identified in this study by considering the emission amounts, environmental fates, exposure, and damage at the national level. Results showed that the most significant substances affecting overall human health included benzo(a)pyrene (BaP), dibenz(a,h)anthracene (DahA), and fluoranthene (Flu), which are mainly generated from aluminum production, biomass indoor burning, and bituminous coal consumption for domestic use. Approximately 10% of the BaP, DahA, and Flu emissions corresponded to over 80% of all recorded human health effects and showed significant positive linear relationships with mortality from malignant tumors, as well as with the nervous system, heart, and cerebral-vascular diseases. Increasing aluminum recycling, biomass utilization, national pipeline gas penetration rate, and national heating coverage rate are effective approaches for reducing the overall health impact generated by PAH pollution.

Exposure to PAHs reduced the number and suppressed the function of regulatory T cells in newborns.

Objective To investigate the effects of polycyclic aromatic hydrocarbons (PAHs) on regulatory T (Treg) cells in newborns. Methods Blood samples were taken from the umbilical cord of seven newborn babies. CD4+ CD25+ T cells were isolated and treated with or without 300 nmol/L of phenanthrene for 72 hours in the presence of 100 IU/ml of IL-2. The expression of forkhead box P3 (Foxp3), signal transducer and activator of transcription 3 (STAT3) and STAT5 were analyzed by 8-color flow cytometry. RT-PCR was performed to detect the expression of DNA (cytosine-5)-methyltransferase 1 (DNMT1), DNMT3a, DNMT3b and IL-4 at mRNA level. Pyrosequencing in combination with bisulphite sequencing was used to evaluate the methylation within the promoter and the Treg-specific demethylated region (TSDR) of Foxp3 locus. Treg cells were cultured for 7 hours with autologous Tresp at Tresp/Treg ratios of 1∶1, 2∶1, 4∶1 and 8∶1 and stimulated with anti-CD3/CD28 beads and IL-2 for the evaluation of the immunosuppressive activities of Treg cells. Results (1) PAHs inhibited the expression of Foxp3 and the function of Treg cells collected from newborns. (2) PAHs significantly decreased the expression of STAT5 and Foxp3, but increased the expression of STAT3 (P<0.05). (3)PAHs enhanced the methylation of the promoter and the TSDR within Foxp3 gene. (4) The transcription levels of DNMT1, DNMT3a and DNMT3b in PAHs treated group were significantly higher than those of the control group (P<0.05). (5) More IL-4 was secreted by PAHs treated CD4+ CD25+ T cells, indicating that IL-4 was negatively correlated with STAT5, but positively correlated with STAT3. Conclusion PAHs decreased the number and inhibited the function of Treg cells in newborns. The possible mechanism might be related to the abnormal expression of STAT3 and STAT5 induced by IL-4 as well as the methylation within Foxp3 gene. Key words: PAHs; DNA methylation; STAT3/STAT5 transcription factor; Regulatory T cell; IL-4

Impact of hydraulic loading on removal of polycyclic aromatic hydrocarbons (PAHs) from vertical-flow wetland

The effects of polycyclic aromatic hydrocarbons (PAHs) removal on lab-simulated vertical wetland systems, each containing eight dominant species, under continuous- and intermittent-flow feeding modes, were determined. The main results were: (1) PAHs removal effect was greater in intermittent-flow system than in continuous-flow system, with the exception of the floating plant Hydrilla verticillata wetland. This may be due to pollutants remaining stable for longer duration under intermittent-flow mode, which is conducive to microbial, plant, and water absorption of PAHs, as well as to microbial decomposition and absorption by plant roots; (2) absorption and degradation rates of PAHs varied among wetland body plants in different periods with removal efficiencies of 30%–70% observed following the first and fifth cycles, and under high-performance degradation conditions; (3) mean removal rates of PAHs by hydrophytes under continuous-flow mode were as follows: H. verticillata (34.4%), Arundo donax (Gramineae) (33.2%), Phragmites australis (28.7%), Ipomoea aquatica Forsk (Convolvulaceae) (28.5%), Zizania aquatic (27.6%), Calla palustris (Araceae) (27.2%), Acorus calamus (26.8%), and Hardy canna (17.9%); (4) average rates of PAHs removal by hydrophyte under intermittent-flow mode were as follows: A. donax (40.5%), Z. aquatic (37.9%), A. calamus (37.0%), P. australis (36.9%), Hardy canna (34.6%), C. palustris (33.9%), I. aquatica (31.2%), and H. verticillata (29.3%).

A comprehensive study of the impact of polycyclic aromatic hydrocarbons (PAHs) contamination on salt marsh plants Spartina alterniflora: implication for plant-microbe interactions in phytoremediation.

These pot experiments aimed to investigate the effects of polycyclic aromatic hydrocarbons (PAHs) on plant uptake, rhizophere, endophytic bacteria, and phytoremediation potentials of contaminated sediments. Salt marsh plant Spartina alterniflora was selected and cultivated in phenanthrene (PHE)- and pyrene (PYR)-contaminated sediments (for 70 days). The results indicated that the amount of PHE removed from the sediments ranged from 13 to 36 %, while PYR ranged from 11 to 30 %. In rhizophere sediment, dehydrogenase activities were significantly (P < 0.05) enhanced by higher concentration of PHE treatments, while polyphenol oxidase activities were prohibited more than 10 % in non-rhizophere sediment. Compared with the control, PHE treatments had also significantly (P < 0.05) lower total microbial biomass; especially for gram-negative bacteria, this decrease was more than 24 %. However, the PYR treatments had little effect on the dehydrogenase, polyphenol oxidase, and total phospholipid fatty acid analysis (PLFA) biomass. The greatest abundance of PAH-ring hydroxylating dioxygenases isolated from gram-negative bacteria (PAH-RHDα-GN) of rhizoplane and endophyte in roots were found at high concentration of PHE treatments and increased by more than 100- and 3-fold, respectively. These results suggested that PAH pollution would result in the comprehensive effect on S. alterniflora, whose endophytic bacteria might play important roles in the phytoremediation potential of PAH-contaminated sediments.

English

Effects of polycyclic aromatic hydrocarbons and small related molecules on the morphology of fission yeast (Schizosaccharomyces pombe) are described. Polycyclic aromatic hydrocarbons are important environmental pollutants that act as carcinogens via several mechanisms of action. Fission yeast is a useful model organism for revealing the mechanisms by which these molecules affect the cell. None of the molecules studied affected cell length of wildtype or a rad26D mutant yeast relative to control, indicating that none of these operate like known genotoxins that lengthen the cell. Five compounds are shown to decrease cell width in wildtype fission yeast, but not in the rad26D strain. These results indicate that machinery controlling the cell’s width is affected by these molecules, and that this change is not detected when the rad26 protein is absent. These observations were made using imaging flow cytometry, which captures tens of thousands of two-dimensional cell images in a short time and provides statistically rigorous data on large cell populations. Key words: Fission yeast, Schizosaccharomyces pombe, hydrocarbon, polycyclic aromatic hydrocarbon (PAH), morphology, imaging flow cytometry.

Effects of polycyclic aromatic hydrocarbons on microbial community structure and PAH ring hydroxylating dioxygenase gene abundance in soil.

Development of successful bioremediation strategies for environments contaminated with recalcitrant pollutants requires in-depth knowledge of the microorganisms and microbial processes involved in degradation. The response of soil microbial communities to three polycyclic aromatic hydrocarbons, phenanthrene (3-ring), fluoranthene (4-ring) and benzo(a)pyrene (5-ring), was examined. Profiles of bacterial, archaeal and fungal communities were generated using molecular fingerprinting techniques (TRFLP, ARISA) and multivariate statistical tools were employed to interpret the effect of PAHs on community dynamics and composition. The extent and rate of PAH removal was directly related to the chemical structure, with the 5-ring PAH benzo(a)pyrene degraded more slowly than phenathrene or fluoranthene. Bacterial, archaeal and fungal communities were all significantly affected by PAH amendment, time and their interaction. Based on analysis of clone libraries, Actinobacteria appeared to dominate in fluoranthene amended soil, although they also represented a significant portion of the diversity in phenanthrene amended and unamended soils. In addition there appeared to be more γ-Proteobacteria and less Bacteroidetes in soil amended with either PAH compared to the control. The soil bacterial community clearly possessed the potential to degrade PAHs as evidenced by the abundance of PAH ring hydroxylating (PAH-RHDα) genes from both gram negative (GN) and gram positive (GP) bacteria in PAH-amended and control soils. Although the dioxygenase gene from GP bacteria was less abundant in soil than the gene associated with GN bacteria, significant (p < 0.001) increases in the abundance of the GP PAH-RHDα gene were observed during phenanthrene and fluoranthene degradation, whereas there was no significant difference in the abundance of the GN PAH-RHDα gene during the course of the experiment. Few studies to-date have examined the effect of pollutants on more than one microbial community in soil. The current study provides information on the response of soil bacterial, archaeal and fungal communities during the degradation of three priority pollutants and contributes to a knowledge base that can inform the development of effective bioremediation strategies for contaminated sites.

Toxicological effects of polycyclic aromatic hydrocarbons and their derivatives on respiratory cells

Polycyclic aromatic hydrocarbons (PAHs) are found in ambient aerosols and particulate matter. Experimental studies have shown that PAHs and related chemicals can induce toxicological effects. The present study aimed to investigate the effects of PAHs and their derivatives on the respiratory and immune systems and the underlying mechanisms. The human bronchial epithelial cell line BEAS-2B was exposed to PAHs and their derivatives, and the cytotoxicity and proinflammatory protein expression were then investigated. A cytotoxic effect was observed in BEAS-2B exposed to PAH derivatives such as naphthoquinone (NQ), phenanthrenequinone (PQ), 1-nitropyrene (1-NP), and 1-aminopyrene (1-AP). In addition, 1,2-NQ and 9,10-PQ showed more effective cytotoxicity than 1,4-NQ and 1,4-PQ, respectively. Pyrene showed a weak cytotoxic effect. On the other hand, naphthalene and phenanthrene showed no significant effects. Pyrene, 1-NP, and 1-AP also increased intercellular adhesion molecule-1 expression and interleukin-6 production in BEAS-2B. The increase was partly suppressed by protein kinase inhibitors such as the epidermal growth factor receptor-selective tyrosine kinase inhibitor and nuclear receptor antagonists such as the thyroid hormone receptor antagonist. The present study suggests that the toxicological effects of chemicals may be related to the different activities resulting from their structures, such as numbers of benzene rings and functional groups. Furthermore, the chemical-induced increase in proinflammatory protein expression in bronchial epithelial cells was possibly a result of the activation of protein kinase pathways and nuclear receptors. The increase may partly contribute to the adverse health effects of atmospheric PAHs.

Levels and neurodevelopmental effects of polycyclic aromatic hydrocarbons in settled house dust of urban dwellings on preschool–aged children in Nanjing, China

This study investigated levels and possible determinants of polycyclic aromatic hydrocarbons (PAHs) in settled house dust of urban dwellings with preschool–aged children in Nanjing, China. The possible neurodevelopmental effects of house–dust PAHs on the children were also investigated. Settled house dust was collected from 203 urban houses. Fifteen PAHs were measured using an HPLC with a fluorescence detector and wavelength programming. The Child Behavior Checklist and the Gesell Development Inventory were used to evaluate the overall development of the children. PAHs were detected in settled house dust of >90% of houses, where high molecular weight PAHs predominated. Most PAHs with two or three rings were found at significantly higher levels in indoor compared with outdoor dust. PAH isomeric ratios showed that PAHs with four or more rings might be derived from outdoor coal burning sources. Naphthalene was found at lower concentrations in houses with more hours of natural ventilation, while pyrene, chrysene (Chr) and benzo[k]fluoranthene (BkF) were present at higher concentrations in these houses. A higher floor level correlated with lower levels of PAHs, especially those with four or more rings, while older houses had higher PAH levels. Benzo[a]pyrene (BaP) and indeno[1,2,3–cd]pyrene levels were positively associated with most behavioral problem scores. Higher BaP and benzo[g,h,i]perylene levels showed lower Gesell language development quotient (DQs), and higher Chr and BkF were associated with lower Gesell social skill DQs. In conclusion, 15 PAHs are ubiquitous in urban settled house dust, where outdoor coal burning and indoor cooking oil fumes are the two main sources of PAHs in Nanjing, China. Natural ventilation, floor level and residence age potentially influence house dust PAH levels. The potential adverse effect of postnatal exposure to PAHs on the behavior and neurodevelopment of preschool–aged children requires follow up in larger studies.

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.

Gas-particle distributions, sources and health effects of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) in Venice aerosols

Air samples were collected in Venice during summer 2009 and 2012 to measure gas and particulate concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs). PCB-11, considered a marker for non-Aroclor contamination of the environment, was found for the first time in the Venetian lagoon and in Europe. An investigation on sources has been conducted, evidencing traffic as the major source of PAHs, whereas PCBs have a similar composition to Aroclor 1248 and 1254; in 2009 a release of PCN-42 has been hypothesized. Toxicological evaluation by TCA and TEQ methods, conducted for the first time in Venice air samples, identified BaP, PCB-126 and PCB-169 as the most important contributors to the total carcinogenic activity of PAHs and the total dioxin-like activity of PCBs and PCNs.

The Effect of Polycyclic Aromatic Hydrocarbons on the Structure of Organotrophic Bacteria and Dehydrogenase Activity in Soil

The objective of this article was to determine the structure of microbial communities and the activity of dehydrogenases in soil samples contaminated with four polycyclic aromatic hydrocarbons (PAHs), i.e., naphthalene, phenanthrene, anthracene, and pyrene, in the amount of 0, 1000, 2000, and 4000 mg kg−1soil DM. Organic substances—cellulose, sucrose, and compost—were added to the samples in the amount of 0 and 9 g kg−1soil DM. The experiment was performed in a laboratory on samples of loamy sand. Indices of colony development (CD) and eco-physiological diversity (EP) of organotrophic bacteria, soil resistance (RS), and soil resilience (RL) were calculated. Soil contamination with PAHs differentiated the structure of organotrophic bacteria, and the lowest CD and EP values were noted in soil samples containing pyrene. PAHs inhibited the activity of dehydrogenases, and pyrene exerted the most inhibitory effect on enzyme activity. Dehydrogenase activity was determined mainly by the applied PAH dose, the date of analysis and the type of organic substance added to soil. Low RL values indicate that exposure to PAHs induces long-term changes in dehydrogenase activity.

Oxidative stress responses of gulf killifish exposed to hydrocarbons from the Deepwater Horizon oil spill: Potential implications for aquatic food resources

Ecosystem effects of polycyclic aromatic hydrocarbons (PAHs) remain under investigation following the Gulf of Mexico Deepwater Horizon oil spill. Fundulus grandis, an established indicator of aquatic ecosystem health, was investigated because this species shares genes and biochemical pathways with higher trophic-level fish and plays an important role in the gulf food chain. Oxidative stress responses including hepatic cytochrome P4501A (CYP1A) and serum antioxidant capacity were evaluated in fish exposed to PAHs. Fish were exposed to water-accommodated fractions (WAFs) of crude oil (7.0 ± 0.10 mg/L C6-C28) after which solutions were diluted below the level of detection over 8 h using 15 ppt aerated artificial seawater. Before euthanasia, fish remained in aquaria for 12 h, 24 h, or 48 h. Three replicate experiments were conducted at each time point using unexposed fish as experimental controls. Significant differences (p < 0.05) in CYP1A induction were observed in exposed versus control fish at 24 h. Expression of CYP1A increased by 25%, 66%, and 23% in exposed fish at 12 h, 24 h, and 48 h, respectively. Significant increases were observed in antioxidant capacity of nonenzymatic antioxidants in exposed versus control fish at each time point. Given the activity of CYP1A, radicals formed during PAH detoxification likely resulted in increased oxidant load requiring elevated antioxidant defenses. Research is needed to determine the duration of oxidative stress responses considering the potential for lipid oxidation in exposed fish or species feeding on exposed fish.