Bitumen fumes: review of work on the potential risk to workers and the present knowledge on its origin

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

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

Chemical characterization and anaerobic treatment of bitumen fume condensate using a membrane bioreactor

Bitumen fume condensate (BFC) is a hazardous wastewater generated at asphalt reclamation and production sites. BFC contains a wide variety of potentially toxic organic pollutants that negatively affect anaerobic processes. In this study, we chemically characterized BFC produced at an industrial site and evaluated its degradation under anaerobic conditions. Analyses identified about 900 compounds including acetate, polycyclic aromatic hydrocarbons, phenolic compounds, and metal ions. We estimated the half maximal inhibitory concentrations (IC₅₀) of methanogenesis of 120, 224, and 990 mgCOD·L^-1 for three types of anaerobic biomass, which indicated the enrichment and adaptation potentials of methanogenic biomass to the wastewater constituents. We operated an AnMBR (7.0 L, 35 °C) for 188 days with a mixture of BFC, phenol, acetate, and nutrients. The reactor showed a maximum average COD removal efficiency of 87.7 ± 7.0 %, that corresponded to an organic conversion rate of 286 ± 71 mgCOD^-1·L^-1d^-1. The microbial characterization of the reactor's biomass showed the acetoclastic methanogen Methanosaeta as the most abundant microorganism (43 %), whereas the aromatic and phenol degrader Syntrophorhabdus was continuously present with abundances up to 11.5 %. The obtained results offer the possibility for the application of AnMBRs for the treatment of BFC or other petrochemical wastewater.

Sample Preparation and Analytical Methods for Identifying Organic Compounds in Bituminous Emissions

Bitumen is a major construction material that can emit harmful fumes when heated. These fumes pose health risks to workers and communities near construction projects or asphalt mixing plants. The chemical complexity of bitumen fumes and the increasing use of additives add to the difficulty of analytically quantifying the harmful chemicals emitted using a single technique. Research on bitumen emissions consists of numerous sample preparation and analytical methods. There are a range of considerations to be made when deciding on an appropriate sample preparation method and instrumental configuration to optimise the analysis of specific organic contaminants in emissions. Researchers investigating emissions from bituminous materials may need to consider a range of analytical techniques to quantify harmful chemicals and assess the efficacy of new additives. This review summarises the primary methodologies for sample preparation and analytical techniques used in bitumen research and discusses future challenges and solutions.

Collection of polycyclic aromatic sulfur heterocycles from asphalt fumes and quantification by an HPLC-DAD method

A chromatographic method is described for the separation and quantification of polycyclic aromatic sulfur heterocycles (PASHs) using liquid chromatography coupled with diode array detection (DAD). The PASHs that were investigated in this study were chosen based on their similarity in molecular weight, volatility and polarity of their PAH analogues. The chromatographic separation of the compounds was optimized, and their analytical characteristics were evaluated. The limits of detection and quantification ranged from 0.05 for 2,3,4,7-tetramethylbenzothiophene to 2.16 μg L-1 for thieno[2,3-b]thiophene and from 0.16 for 2,3,4,7-tetramethylbenzothiophene to 6.53 μg L-1 for thieno[2,3-b]thiophene, respectively. Recoveries ranged from 84.9 for benzo[b]benzo[4,5]thieno[2,3-d]thiophene to 110% for dinaphtho[2,1-b:1',2'-d]thiophene. Intermediate precisions and repeatabilities lie between 1.4 and 3.0%, and 0.3 and 1.7%, respectively. The chromatographic method was applied for determination of PASHs directly in asphalt fumes, which were obtained by heating asphalt samples in a homemade closed system. The mutual interference of PAH analogues was also discussed. The method was successfully used for PASH determination in asphalt samples obtained from three different oil refineries in Brazil.

The development of a cell-based model for the assessment of carcinogenic potential upon long-term PM2.5 exposure

To assess the carcinogenic potential of PM2.5 exposure, we developed a cell-based experimental protocol to examine the cell transformation activity of PM2.5 samples from different regions in China. The seasonal ambient PM2.5 samples were collected from three megacities, Beijing (BJ), Wuhan (WH), and Guangzhou (GZ), from November 2016 to October 2017. The mean concentrations of PM2.5 were much higher in the winter season (BJ: 109.64 μg/m³, WH: 79.99 μg/m³, GZ: 49.99 μg/m³) than that in summer season (BJ: 42.40 μg/m³, WH: 25.82 μg/m³, GZ: 19.82 μg/m³). The organic extracts (OE) of PM2.5 samples from combined summer (S) (June, July, August) or winter (W) (November, December, January) seasons were subjected to characterization of chemical components. We treated human bronchial epithelial (HBE) cells expressing CYP1A1 (HBE-1A1) with PM2.5 samples at doses ranging from 0 to 100 μg/mL (0, 1.563, 3.125, 6.25, 12.5, 25, 50, 100 μg/mL) and determined the phenotype of malignant cell transformation. A dose-response relationship was analyzed by benchmark dose (BMD) modeling, and the potential were indicated by BMDL₁₀. The order of the carcinogenic risk of seasonal PM2.5 samples from high to low was BJ-W, WH-W, GZ-W, WH-S, BJ-S, and GZ-S. Notably, we found that the alteration in the lung cancer-related biomarkers, KRAS, PTEN, p53, c-Myc, PCNA, pAKT/AKT, and pERK/ERK was congruent with the activity of cell transformation and the content of specific components of polycyclic aromatic hydrocarbon (PAHs) bound to PM2.5. Taken together, we have successfully developed a cell-based alternative model for the evaluation of potent carcinogenicity upon long-term PM2.5 exposure.

Regulation of UGT2A1 by miR-196a-5p and miR-196b-5p

UDP-glucuronosyltransferase (UGT) 2A1 is an important enzyme in the detoxification of polycyclic aromatic hydrocarbons found in cigarette smoke. This enzyme is expressed in aerodigestive tract tissues including lung as both its wild-type and exon 4-deleted splice variant isoforms, with the latter acting as a negative regulator of wild-type UGT2A1 activity. UGT2A1 regulation may also be mediated by microRNA (miRNA). To identify miRNA important in the regulation of UGT2A1, expression analysis in tandem with in silico analysis suggested miR-196a-5p and miR-196b-5p as potential top candidates. Significant reductions in firefly luciferase activity were observed in human embryonic kidney cell line 293 cells cotransfected with the wild-type UGT2A1 3'-untranslated region (UTR)-containing luciferase plasmid and either miR-196a-5p (62%, P = 0.00080) or miR-196b-5p (60%, P = 0.00030) mimics. In pull-down assays, there was a 3.4- and 5.2-fold increase in miR-196a-5p (P = 0.054) and miR-196b-5p (P = 0.035), respectively, using the UGT2A1 3'-UTR biotinylated mRNA probe as compared with the β-actin coding region control mRNA probe. UGT2A1 mRNA was reduced by 25% (P = 0.058) and 35% (P = 0.023) in H146 and H1944 cells, respectively, after overexpression of the miR196a-5p mimic. A similar 32% (P = 0.030) and 41% (P = 0.016) reduction was observed after over-expression of the miR-196b-5p mimic. In H146 cells transfected with miRNA mimic together with a small interfering RNA (siRNA) specific for the UGT2A1 splice variant, a significant reduction in 3-hydroxy-benzo[a]pyrene-glucuronide formation was observed. The miR-196a-5p- and miR-196b-55p-treated cells exhibited reductions of 35% (P = 0.047) and 44% (P = 0.0063), respectively. These data suggest that miR-196a-5p and miR-196b-5p play an important role in UGT2A1 regulation within the lung and potentially other aerodigestive tract tissues.

A Case Study Describing a Community-Engaged Approach for Evaluating Polycyclic Aromatic Hydrocarbon Exposure in a Native American Community

In 2015, the Swinomish Indian Tribal Community (SITC) was impacted by an air toxic release from one of two nearby oil refineries. This experience motivated SITC members to learn more about their exposure to air toxics. On the invitation of SITC, this community-based study measured personal exposure to polycyclic aromatic hydrocarbons (PAHs) and conducted interviews with the volunteers to evaluate perceptions of the data and experience of participating. Non-smoking SITC members were recruited in March 2016 (N = 10) and January 2017 (N = 22) with seven volunteers participating both times. Volunteers wore a wristband passive sampler for 7 days and completed daily activity diaries. Wristbands were analyzed for 62 PAHs using gas chromatography mass spectrometry. Wilcoxon exact tests determined if the sum total PAHs (ΣPAH) differed by activity, proximity to the refineries, and time. Aggregated results were shared during community meetings, and volunteers received individual reports. Volunteers (N = 9) participated in individual interviews. All volunteers were exposed to different amounts and types of PAHs. Burning candles or using a wood stove and/or propane heating were associated with higher ΣPAH exposures. While ΣPAH was similar in both sampling periods, the composition of PAHs differed. More priority listed PAHs were detected in January (N = 17) versus March (N = 10). Among volunteers who participated in both sampling events, exposure to four PAHs significantly differed between seasons. Overall, volunteers reported that the study made them more aware of air pollution sources in their community. They also commented that the chemical nomenclature was difficult to understand, but appreciated the individual reports that allowed them to visually compare their data to the distribution of data collected in their community. For volunteers with lower exposures, these comparisons gave them relief. However, volunteers with higher exposures reported concern and several changed their behaviors to reduce their exposure to known PAH sources. This study provided an opportunity for SITC members to learn about their personal exposure to a class of air toxics within the context of their community. While the limitations of the study hindered the ability to identify sources of air toxics in the community, this activity appeared to raise awareness about ambient and indoor air pollution among the volunteers.

Street Dust-Bound Polycyclic Aromatic Hydrocarbons in a Saudi Coastal City: Status, Profile, Sources, and Human Health Risk Assessment

Polycyclic aromatic hydrocarbons (PAHs) in street dust pose a serious problem threatening both the environment and human health. Street dust samples were collected from five different land use patterns (traffic areas TRA, urban area URA, residential areas REA, mixed residential commercial areas MCRA and suburban areas SUA) in Jeddah, a Saudi coastal city, and one in in Hada Al Sham, a rural area (RUA). This study aimed to investigate the status, profile, sources of PAHs and estimate their human health risk. The results revealed an average concentration of total PAHs of 3320 ng/g in street dust of Jeddah and 223 ng/g in RUA dust. PAHs with high molecular weight represented 83.38% of total PAHs in street dust of Jeddah, while the carcinogenic PAH compounds accounted 57.84%. The highest average concentration of total PAHs in street dust of Jeddah was found in TRA (4980 ng/g) and the lowest in REA (1660 ng/g). PAHs ratios indicated that the principal source of PAHs in street dust of Jeddah is pyrogenic, mainly traffic emission. Benzo(a)anthracene/chrysene (BaA/CHR) ratio suggests that PAHs in street dusts of Jeddah come mainly from emission of local sources, while PAHs in RUA might be transported from the surrounding urban areas. The estimated Incremental Lifetime Cancer Risk (ILCR) associated with exposure to PAHs in street dusts indicated that both dermal contact and ingestion pathways are major contributed to cancer risk for both children and adults. Based on BaPequivalence concentrations of total PAHs, ILCRIngestion, ILCRdermal and cancer risk values for children and adults exposed to PAHs in street dust of different areas in Jeddah were found between 10-6 and 10-4, indicating potential risk. The sequence of cancer risk was TRA > URA > MCRA > SUA > REA. Only exposure to BaP and DBA compounds had potential risk for both children and adults.

Particle-Bound Polycyclic Aromatic Hydrocarbon in the Atmosphere of Heavy Traffic Areas in Greater Cairo, Egypt: Status, Source, and Human Health Risk Assessment

Airborne particulate samples were collected from three main squares (Ramsis, El Giza, and Sphinx) representing heavy traffic areas in Greater Cairo during the period of December 2015–February 2016, and analysed for polycyclic aromatic hydrocarbon (PAHs). The maximum concentrations of particle-bound PAHs were observed at El Giza, while the minimum levels were recorded at Sphinx. The levels of particle-bound PAHs in the square areas of Greater Cairo are higher than those found in many different locations in Egypt and around the world.The distribution of individual particle-bound PAHs as well as PAH categories, depending on the ring number in Ramsis, El Giza, and Sphinx, wasquite similar. This similarity implies similar emission sources of PAHs in the three square areas, with vehicle exhaust emissions being the dominant one. Benzo[b]fluoranthene (BbF), benzo[ghi]perylene (BGP), and indeno[1,2,3-cd]pyrene(IND) were the most abundant PAH compounds. Diagnostic concentration ratios of PAH compounds in the three square locations suggest that both petrogenic and pyrogenic sources emit these compounds. Moreover, they originate mainly from traffic emissions in the study areas. Based on the calculated benzo[a]pyrene equivalent (BaPeq) for the individual particle-bound PAH compounds, health risks associated with the inhalation of these compounds were assessed. Total carcinogenic activity (TCA) for all measured PAHs represented 20.03% (El Giza), 20.40% (Ramsis), and 20.60% (Sphinx) of the total PAH concentrations. Benzo[a]pyrene (BaP) and dibenz[a,h]anthracene (DBA) were the highest contributors to the total health risks; these accounted for 42.72% and 38.50% (El Giza), 41.79% and 39.17% (Ramsis), and 42.92% and 37.78% (Sphinx) of the TCA of all PAH compounds, respectively. These results indicate the importance of BaP and DBA as surrogate compounds for PAHs in the atmosphere of square areas of Greater Cairo.

Occupational exposure to asphalt fume can cause oxidative DNA damage among road paving workers

OBJECTIVES

We designed the present study to determine the effect of occupational exposure to asphalt fumes on oxidative status and DNA damage in road paving workers.

METHODS

Sixty road paving workers exposed to asphalt fumes and forty non-exposed control subjects were recruited. Occupational exposure to PAHs was assessed by urinary 1-hydroxypyrene (1-OHP) excretion. Serum thiol disulfide homeostasis (TDH), total oxidant status (TOS) and total antioxidant status (TAS) and urinary 8-hydro-deoxyguanosine (8-OH-dG) level were evaluated by automated colourimetric method.

RESULTS

The urinary concentrations of 1-OHP and 8-OH-dG were significantly higher in the exposed group than in the control group (P < 0.001). Disulfide/thiol ratio, TOS, and TAS were also significantly higher for the asphalt workers. A positive correlation existed between urinary 1-OHP and 8-OH-dG, TOS and TAS.

CONCLUSION

Study results indicate that exposure to PAHs induces oxidative stress and causes genotoxic effects in asphalt workers.

Human health risk assessment and PAHs in a stretch of river Ganges near Kanpur

The presence of 13 polycyclic aromatic hydrocarbons (PAHs) was measured in a small stretch of river Ganges in Kanpur, using high-performance liquid chromatography equipped with photodiode array detector (HPLC/PDA). Non-carcinogenic risk on human health was calculated in the form of hazardous index. Carcinogenic risk was calculated as chronic daily intake and incremental lifetime cancer risk (ILCR) with the help of monitored PAHs in river water. Due to non-availability of reference dose (RfD) values for all the 13 PAHs, the combined hazardous index for three PAHs was calculated. These values in winter, pre-monsoon, and post-monsoon period varied from 6.37 × 10^-3 (Bithoor) to 1.12 × 10^-2 (Jajmau), 2.89 × 10^-3 (Bithoor) to 8.52 × 10^-3 (Annandeshwar Temple), and 1.80 × 10^-3 (Massacre Ghat) to 6.67 × 10^-3 (Jajmau), respectively. In this study, the carcinogenic risk due to PAHs was calculated in the form of ILCR. ILCR due to benzo(a)pyrene (BaP) varied from 1.39 × 10^-6 (Massacre Ghat) to 1.45 × 10^-5 (Jajmau). ILCR was also calculated with the help of BaP_eq for five age groups of people (adults, teenagers, children, toddlers, and infants). The outcome of the study indicates that there is a need to control pollution of the river water to maintain its quality. Continuous discharge of PAHs into the river poses both human health risk and ecological risk.

Oxidation and adduct formation of xenobiotics in a microfluidic electrochemical cell with boron doped diamond electrodes and an integrated passive gradient rotation mixer

Reactive xenobiotic metabolites and their adduct formation with biomolecules such as proteins are important to study as they can be detrimental to human health. Here, we present a microfluidic electrochemical cell with integrated micromixer to study phase I and phase II metabolism as well as protein adduct formation of xenobiotics in a purely instrumental approach. The newly developed microfluidic device enables both the generation of reactive metabolites through electrochemical oxidation and subsequent adduct formation with biomolecules in a chemical microreactor. This allows us to study the detoxification of reactive species with glutathione and to predict potential toxicity of xenobiotics as a result of protein modification. Efficient mixing in microfluidic systems is a slow process due to the typically laminar flow conditions in shallow channels. Therefore, a passive gradient rotation micromixer has been designed that is capable of mixing liquids efficiently in a 790 pL volume within tens of milliseconds. The mixing principle relies on turning the concentration gradient that is initially established by bringing together two streams of liquid, to take advantage of the short diffusion distances in the shallow microchannels of thin-layer flow cells. The mixer is located immediately downstream of the working electrode of an electrochemical cell with integrated boron doped diamond electrodes. In conjunction with mass spectrometry, the two microreactors integrated in a single device provide a powerful tool to study the metabolism and toxicity of xenobiotics, which was demonstrated by the investigation of the model compound 1-hydroxypyrene.

Thiol/disulfide homeostasis in asphalt workers

The aim of this study was to investigate thiol/disulfide homeostasis in asphalt workers who are exposed to polycyclic aromatic hydrocarbons occupationally. The study was carried out in 34 nonsmoker asphalt workers. Additionally, 35 healthy nonsmoker volunteers were recruited as control group. Thiol and disulfide concentrations were determined using the novel automated measurement method. Levels of urinary 1-OH-pyrene were analyzed by liquid chromatography. Disulfide/thiol ratio was significantly higher in exposed group (p = .034). Also, a positive correlation was detected between disulfide/thiol ratio and 1-OH-pyrene values (r = .249, p = .036). Thiol/disulfide homeostasis was found to be disturbed in asphalt workers. The novel test used in this study may be useful for evaluating the oxidative status in polycyclic aromatic hydrocarbon (PAH) exposure.

Biological impact of environmental polycyclic aromatic hydrocarbons (ePAHs) as endocrine disruptors

Polycyclic aromatic hydrocarbons (PAHs) are often detected in the environment and are regarded as endocrine disruptors. We here designated mixtures of PAHs in the environment as environmental PAHs (ePAHs) to discuss their effects collectively, which could be different from the sum of the constituent PAHs. We first summarized the biological impact of environmental PAHs (ePAHs) found in the atmosphere, sediments, soils, and water as a result of human activities, accidents, or natural phenomena. ePAHs are characterized by their sources and forms, followed by their biological effects and social impact, and bioassays that are used to investigate their biological effects. The findings of the bioassays have demonstrated that ePAHs have the ability to affect the endocrine systems of humans and animals. The pathways that mediate cell signaling for the endocrine disruptions induced by ePAHs and PAHs have also been summarized in order to obtain a clearer understanding of the mechanisms responsible for these effects without animal tests; they include specific signaling pathways (MAPK and other signaling pathways), regulatory mechanisms (chromatin/epigenetic regulation, cell cycle/DNA damage control, and cytoskeletal/adhesion regulation), and cell functions (apoptosis, autophagy, immune responses/inflammation, neurological responses, and development/differentiation) induced by specific PAHs, such as benz[a]anthracene, benzo[a]pyrene, benz[l]aceanthrylene, cyclopenta[c,d]pyrene, 7,12-dimethylbenz[a]anthracene, fluoranthene, fluorene, 3-methylcholanthrene, perylene, phenanthrene, and pyrene as well as their derivatives. Estrogen signaling is one of the most studied pathways associated with the endocrine-disrupting activities of PAHs, and involves estrogen receptors and aryl hydrocarbon receptors. However, some of the actions of PAHs are contradictory, complex, and unexplainable. Although several possibilities have been suggested, such as direct interactions between PAHs and receptors and the suppression of their activities through other pathways, the mechanisms underlying the activities of PAHs remain unclear. Thus, standardized assay protocols for pathway-based assessments are considered to be important to overcome these issues.

PAH dynamics in roadside environments: Influence on the consistency of diagnostic ratio values and ecosystem contamination assessments

Roadside contamination (of air, soils and organisms) by polycyclic aromatic hydrocarbons (PAHs) was examined in an arable field and a mature forest (central France). Measured contents accounted for minute fractions of the cumulative vehicular exhaust emissions. The fate of vehicular PAHs was affected by many factors, including: atmospheric load dispersal, deposition on soils and vegetation, incorporation into water and organic matter cycles, and accumulation in species. Given these empirical results, we evaluated the consistency of a set of well-known diagnostic ratios. This effort has revealed that: i) most diagnostic ratio values vary considerably across roadside samples, including exhaust emissions; and ii) the first few meters from the carriageway or the road verge/forest interface or remote areas where surface water accumulates actually define turning or inflection points in the ratio profiles. These variations constitute a major obstacle to delimitating the extent of roadside contamination due to PAHs, in addition to raising questions over the applicability of ratios routinely used to designate sources. New ratios, namely (Flt+BkF)/(Pyr+BbF) and (Flt+BkF+BghiP)/Σ10PAH, have been specifically developed to address this challenge. The higher consistencies exhibited among environmental compartments as well as between surface soil and exhaust emissions still yield differentiated values relative to several industrial sources.

Biological effects and toxicity of diluted bitumen and its constituents in freshwater systems

Approximately 50 billion cubic meters of bitumen resides within the oil sands region of Alberta, Canada. To facilitate the transport of bitumen from where it is extracted to where it is processed, the bitumen is diluted with natural gas condensate ('dilbit'), synthetic crude from hydrocracking bitumen ('synbit'), or a mixture of both ('dilsynbit'). A primary consideration for the effects of diluted bitumen products on freshwater organisms and ecosystems is whether it will float on the water surface or sink and interact with the stream or lake sediments. Evidence from a spill near Kalamazoo, MI, in 2010 and laboratory testing demonstrate that the nature of the spill and weathering of the dilbit, synbit or dilsynbit prior to and during contact with water will dictate whether the product floats or sinks. Subsequent toxicological data on the effects of dilbit and other diluted bitumen products on freshwater organisms and ecosystems are scarce. However, the current literature indicates that dilbit or bitumen can have significant effects on a wide variety of toxicological endpoints. This review synthesizes the currently available literature concerning the fate and effects of dilbit and synbit spilled into freshwater, and the effects of bitumen and bitumen products on aquatic organisms and ecosystems. Dilbit is likely to provide ecological impacts that are similar to and extend from those that follow from exposure to lighter crude oil, but the prospect of bitumen settling after binding to suspended sediments elevates the risk for benthic impacts in streams and lakes.

Multi-pathway assessment of human health risk posed by polycyclic aromatic hydrocarbons

To assess aggregate exposure to polycyclic aromatic hydrocarbons (PAHs) via several environmental media and pathways, a probabilistic framework for multi-pathway health risk assessment that integrates PAHs potency equivalence factors, risk estimation modeling, and Monte Carlo simulation was applied to a case study in Nanjing, which is an important industrial city in China. Incremental lifetime risk of additional cancers posed by exposure to 16 USEPA priority PAHs in air, water, soil, and fish was assessed. Risks to three age groups, infants, children, and adults, through various exposure pathways, including oral ingestion, dermal absorption, and inhalation, were estimated. Results of the analysis of risk indicated that B[a]P, B[b]F, and BA were the predominant PAHs pollutants in Nanjing. Risk of additional cancer for local adults was on average 2.62 × 10(-5). The risks were primarily due to ingestion of fish and inhalation, which contributed 99 % of the total risks. By contrast, risk to infants was essentially negligible. Results of a sensitivity analysis indicated that the input variables of concentration of PAHs in fish (C f), the body weight (BW), and the ingestion rate of fish (IRf) were the major influences on estimates of risks.

Chronic dietary exposure of zebrafish to PAH mixtures results in carcinogenic but not genotoxic effects

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants that can be present at high levels as mixtures in polluted aquatic environments. Many PAHs are potent mutagens and several are well-known carcinogens. Despite numerous studies on individual compounds, little is known about the toxicity of PAHs mixtures that are encountered in environmental situations. In the present work, zebrafish were continuously fed from 5 days post-fertilisation to 14 months post-fertilisation (mpf) with a diet spiked with fractions of either pyrolytic (PY), petrogenic light oil (LO), or petrogenic heavy oil (HO) origin at three concentrations. A decrease in survival was identified after 3 mpf in fish fed with the highest concentration of HO or LO, but not for PY. All PAH fractions caused preneoplastic and neoplastic disorders in long-term-exposed animals. Target tissues were almost exclusively of epithelial origin, with the bile duct epithelium being the most susceptible to chronic exposure to all PAH fractions, and with germ cells being the second most responsive cells. Significantly higher incidences of neoplasms were observed with increasing PAH concentration and exposure duration. The most severe carcinogenic effects were induced by dietary exposure to HO compared to exposure to LO or PY (45, 30 and 7 %, respectively, after 9 to 10 months of exposure to an intermediate concentration of PAHs). In contrast, earliest carcinogenic effects were detected as soon as 3 mpf after exposure to LO, including the lowest concentration, or to PY. PAH bioactivation and genotoxicity in blood was assessed by ethoxyresorufin-O-deethylase activity quantification and comet and micronuclei assays, respectively, but none of these were positive. Chronic dietary exposure of zebrafish to PAH mixtures results in carcinogenotoxic events that impair survival and physiology of exposed fish.

Silicone wristbands as personal passive samplers

Active-sampling approaches are commonly used for personal monitoring, but are limited by energy usage and data that may not represent an individual's exposure or bioavailable concentrations. Current passive techniques often involve extensive preparation, or are developed for only a small number of targeted compounds. In this work, we present a novel application for measuring bioavailable exposure with silicone wristbands as personal passive samplers. Laboratory methodology affecting precleaning, infusion, and extraction were developed from commercially available silicone, and chromatographic background interference was reduced after solvent cleanup with good extraction efficiency (>96%). After finalizing laboratory methods, 49 compounds were sequestered during an ambient deployment which encompassed a diverse set of compounds including polycyclic aromatic hydrocarbons (PAHs), consumer products, personal care products, pesticides, phthalates, and other industrial compounds ranging in log K(ow) from -0.07 (caffeine) to 9.49 (tris(2-ethylhexyl) phosphate). In two hot asphalt occupational settings, silicone personal samplers sequestered 25 PAHs during 8- and 40-h exposures, as well as 2 oxygenated-PAHs (benzofluorenone and fluorenone) suggesting temporal sensitivity over a single work day or week (p < 0.05, power =0.85). Additionally, the amount of PAH sequestered differed between worksites (p < 0.05, power = 0.99), suggesting spatial sensitivity using this novel application.

On the antiquity of cancer: evidence for metastatic carcinoma in a young man from ancient Nubia (c. 1200 BC)

Cancer, one of the world’s leading causes of death today, remains almost absent relative to other pathological conditions, in the archaeological record, giving rise to the conclusion that the disease is mainly a product of modern living and increased longevity. This paper presents a male, young-adult individual from the archaeological site of Amara West in northern Sudan (c. 1200BC) displaying multiple, mainly osteolytic, lesions on the vertebrae, ribs, sternum, clavicles, scapulae, pelvis, and humeral and femoral heads. Following radiographic, microscopic and scanning electron microscopic (SEM) imaging of the lesions, and a consideration of differential diagnoses, a diagnosis of metastatic carcinoma secondary to an unknown soft tissue cancer is suggested. This represents the earliest complete example in the world of a human who suffered metastatic cancer to date. The study further draws its strength from modern analytical techniques applied to differential diagnoses and the fact that it is firmly rooted within a well-documented archaeological and historical context, thus providing new insights into the history and antiquity of the disease as well as its underlying causes and progression.

A Study on Modified Methylnaphthalene Sulfonate Formaldehyde Condensates: Synthesis, Structures and Asphalt Emulsification

The novel surfactants of sulfonated methylnaphthalene-formaldehyde condensates modified with poly (ethyleneglycol) monooctylphenyl ether (OP-10), 4-octylphenol or octadecylamine were synthesized as anionic emulsifier for the preparation of asphalt emulsions and cement mortar. The experimental results revealed that the modified methylnaphthalene sulfonate formaldehyde condensates (MSFC-OP10, MSFC-OCP and MSFC-OAM) containing a substantial amount of hydrophobic and lipophilic groups in the main chain would exhibit a superior effect both in dispersability and emulsifying property. When cement is mixed with the emulsified asphalt containing MSFC-OP10, MSFC-OCP or MSFC-OAM, the free as-synthesized condensates in the emulsified asphalt exhibited a fairly good dispersing performance and this emulsified asphalt appeared to be relatively stable as well. The presence of either MSFC-OP10, MSFC-OCP or MSFC-OAM in the asphalt emulsion would not only markedly improve its stability, delay its demulsification process, but also would upgrade and restrain both the settlement and stratification of the mixed mastics.

A review of the technological solutions for the treatment of oily sludges from petroleum refineries

The activities of the oil industry have several impacts on the environment due to the large amounts of oily wastes that are generated. The oily sludges are a semi-solid material composed by a mixture of clay, silica and iron oxides contaminated with oil, produced water and the chemicals used in the production of oil. Nowadays both the treatment and management of these waste materials is essential to promote sustainable management of exploration and exploitation of natural resources. Biological, physical and chemical processes can be used to reduce environmental contamination by petroleum hydrocarbons to acceptable levels. The choice of treatment method depends on the physical and chemical properties of the waste as well as the availability of facilities to process these wastes. Literature provides some operations for treatment of oily sludges, such as landfilling, incineration, co-processing in clinkerization furnaces, microwave liquefaction, centrifugation, destructive distillation, thermal plasma, low-temperature conversion, incorporation in ceramic materials, development of impermeable materials, encapsulation and biodegradation in land farming, biopiles and bioreactors. The management of the technology to be applied for the treatment of oily wastes is essential to promote proper environmental management, and provide alternative methods to reduce, reuse and recycle the wastes.

Gas-particle concentration, distribution, and health risk assessment of polycyclic aromatic hydrocarbons at a traffic area of Giza, Egypt

Atmospheric particulate and gaseous polycyclic aromatic hydrocarbons (PAHs) samples were collected from an urban area in Dokki (Giza) during the summer of 2007 and the winter of 2007-2008. The average concentrations of PAHs were 1,429.74 ng/m(3) in the particulate phase, 2,912.56 ng/m(3) in the gaseous phase, and 4,342.30 ng/m(3) in the particulate + gaseous phases during the period of study. Dokki has high level concentrations of PAH compounds compared with many polluted cities in the world. The concentrations of PAH compounds in the particulate and gaseous phases were higher in the winter and lower in the summer. Total concentrations of PAHs in the particulate phase and gaseous phase were 22.58% and 77.42% in summer and 36.97% and 63.03% in winter of the total (particulate + gaseous) concentrations of PAHs, respectively. The gaseous/particulate ratios of PAHs concentration were 3.43 in summer and 1.71 in winter. Significant negative correlation coefficients were found between the ambient temperature and concentrations of the total PAHs in the particulate and gaseous phases. The distribution of individual PAHs and different categories of PAHs based on aromatic ring number in the particulate and gaseous phases during the summer and winter were nearly similar, indicating similar emission sources of PAHs in both two seasons. Benzo(b)fluoranthene in the particulate phase and naphthalene in the gaseous phase were the most abundant compounds. Diagnostic concentration ratios of PAH compounds indicate that these compounds are emitted mainly from pyrogenic sources, mainly local vehicular exhaust emissions. Health risks associated with the inhalation of individual PAHs in particulate and gaseous phases were assessed on the basis of its benzo(a)pyrene equivalent concentration. Dibenzo(a,h)anthracene and benzo(a)pyrene in the particulate phase and benzo(a)pyrene and benzo(a)anthracene in the gaseous phase were the greatest contributors to the total health risks. The relative mean contributions of the total carcinogenic activity (concentrations) of all PAHs to the total concentrations of PAHs were 29.37% and 25.15% in the particulate phase and 0.76% and 0.92% in the gaseous phase during the summer and winter, respectively. These results suggest that PAHs in the particulate phase in the ambient air of Dokki may pose a potential health risk.

Comparative modeling approaches for personal exposure to particle-associated PAH

Several models for simulation of personal exposure (PE) to particle-associated polycyclic aromatic hydrocarbons (PAH) have been developed and tested. The modeling approaches include linear regression models (Model 1), time activity weighted models (Models 2 and 3), a hybrid model (Model 4), a univariate linear model (Model 5), and machine learning technique models (Model 6 and 7). The hybrid model (Model 4), which utilizes microenvironment data derived from time-activity diaries (TAD) with the implementation of add-on variables to account for external factors that might affect PE, proved to be the best regression model (R(2) for B(a)P = 0.346, p < 0.01; N = 68). This model was compared with results from two machine learning techniques, namely decision trees (Model 6) and neural networks (Model 7), which represent an innovative approach to PE modeling. The neural network model was promising in giving higher correlation coefficient results for all PAH (R(2) for B(a)P = 0.567, p < 0.01; N = 68) and good performance with the smaller test data set (R(2) for B(a)P = 0.640, p < 0.01; N = 23). Decision tree accuracies (Model 6) which assess how precisely the algorithm can determine the correct classification of a PE concentration range indicate good performance, but this is not comparable to the other models through R(2) values. Using neural networks (Model 7) showed significant improvements over the performance of hybrid Model 4 and the univariate general linear Model 5 for test samples (not used in developing the models). The worst performance was given by linear regression Models 1 to 3 based solely on home and workplace concentrations and time-activity data.

Bitumen products induce skin cell apoptosis in chronically exposed road pavers

BACKGROUND

Worker's exposure to bitumen fumes, via inhalation and skin contamination, is related to adverse effects including an increased risk of lung, stomach and non-melanoma skin cancers and leukaemia. The two major mechanisms regulating apoptosis include the mitochondria-mediated intrinsic pathway and the extrinsic pathway induced by death signalling ligands. In a previous study, we showed activation of apoptosis-regulating proteins BAX and BCL-2 in road pavers chronically exposed to bitumen fumes. These molecules play a central role in activation of programmed cell death by the intrinsic pathway. In this study, we hypothesized that the apoptosis mechanism could be activated in the skin of road pavers chronically exposed to bitumen fumes also through the extrinsic pathway, via mediation by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its death receptor, DR5.

METHODS

Skin punch biopsies from 16 occupationally exposed workers and a control group were processed immunohistochemically for TRAIL and DR5. Activation of programmed cell death was also investigated by expression of caspase-3 and visualization of DNA strand breaks.

RESULTS AND CONCLUSION

TRAIL, DR5 and caspase-3 overexpression and enhanced Terminal Deoxynucleotidyl Transferase Mediated dUTP Nick End Labeling (TUNEL) positivity were found in chronically bitumen-exposed skin, suggesting activation of apoptosis as a defence mechanism.

Polycyclic aromatic hydrocarbons (PAHs) in atmospheric urban area: monitoring on various types of sites

The air quality over the Toulouse urban area (France) is recorded daily by the regional "Midi-Pyrénées" atmospheric pollution measurements network (ORAMIP). Relevant data is collected from about 100 analysers spread over more than thirty stations. The regulations covering major indicators of atmospheric pollution (ozone, nitrogen dioxide, sulphur dioxide) have been updated in recent years to include additional compounds like polycyclic aromatic hydrocarbons (PAHs). The ORAMIP, in partnership with the ENSIACET has undertaken background PAH average concentration measurements over the urban agglomeration of Toulouse during spring 2006 for various types of sites (traffic, urban, industrial). The sampling was performed using a low volume air sampler equipped with quartz fiber filters and polyurethane foams For the two urban sites, total atmospheric concentrations between 12 and 20 ng/m(3) have been obtained, whereas for the industrial site the values averaged 22 ng/m(3). In addition, and regardless of site, the average concentrations of benzo[a]pyrene, at present the only regulated PAH, were always less than the 1 ng/m(3) limit.

Vertical distribution and environmental significance of sulfur and oxygen heterocyclic aromatic hydrocarbons in soil samples collected from Beijing, China

Vertical distribution of the concentration and composition of some sulfur and oxygen heterocyclic aromatic hydrocarbons (SOHAHs), such as, fluorene, dibenzofuran, dibenzothiophene and their alkyl homologues in 10 soil profiles in Beijing have been investigated. The results showed that the concentrations and composition of SOHAHs in topsoil (0-30cm) from different profiles are different. The concentrations of SOHAHs in topsoils are much higher than that in bottom soils where the concentrations are relatively constant. The fingerprints of SOHAHs from same profile are similar in topsoil samples, which are obviously different at the deep part, which suggested that the sources of these compounds are consistent in topsoil and are discriminating between surface and bottom soils. The main sources of SOHAHs in surface soil were fossil fuel combustion, petroleum and wastewater irrigation, while those at deep part were likely derived from the degradation products of soil organic matters.

Genotoxic effects of fumes from asphalt modified with waste plastic and tall oil pitch

As the use of recycled materials and industrial by-products in asphalt mixtures is increasing, we investigated if recycled additives modify the genotoxicity of fumes emitted from asphalt. Fumes were generated in the laboratory at paving temperature from stone-mastic asphalt (SMA) and from SMA modified with waste plastic (90% polyethylene, 10% polypropylene) and tall oil pitch (SMA-WPT). In addition, fumes from SMA, SMA-WPT, asphalt concrete (AC), and AC modified with waste plastic and tall oil pitch (AC-WPT) were collected at paving sites. The genotoxicity of the fumes was studied by analysis of DNA damage (measured in the comet assay) and micronucleus formation in human bronchial epithelial BEAS 2B cells in vitro and by counting mutations in Salmonella typhimurium strains TA98 and YG1024. DNA damage was also assessed in buccal leukocytes from road pavers before and after working with SMA, SMA-WPT, AC, and AC-WPT. The chemical composition of the emissions was analysed by gas chromatography/mass spectrometry. The SMA-WPT fume generated in the laboratory induced a clear increase in DNA damage in BEAS 2B cells without metabolic activation. The laboratory-generated SMA fume increased the frequency of micronucleated BEAS 2B cells without metabolic activation. None of the asphalt fumes collected at the paving sites produced DNA damage with or without metabolic activation. Fumes from SMA and SMA-WPT from the paving sites increased micronucleus frequency without metabolic activation. None of the asphalt fumes studied showed mutagenic activity in Salmonella. No statistically significant differences in DNA damage in buccal leukocytes were detected between the pre- and post-shift samples collected from the road pavers. However, a positive correlation was found between DNA damage and the urinary metabolites of polycyclic aromatic hydrocarbons (PAHs) after work shift, which suggested an association between occupational exposures during road paving and genotoxic effects. Our results indicate that fumes from SMA and SMA-WPT contain direct-acting genotoxic components.

Monitoring of environmental exposure to polycyclic aromatic hydrocarbons: a review

Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic compounds with two or more fused aromatic rings. They have a relatively low solubility in water, but are highly lipophilic. Most of the PAHs with low vapour pressure in the air are adsorbed on particles. When dissolved in water or adsorbed on particulate matter, PAHs can undergo photodecomposition when exposed to ultraviolet light from solar radiation. In the atmosphere, PAHs can react with pollutants such as ozone, nitrogen oxides and sulfur dioxide, yielding diones, nitro- and dinitro-PAHs, and sulfonic acids, respectively. PAHs may also be degraded by some microorganisms in the soil. PAHs are widespread environmental contaminants resulting from incomplete combustion of organic materials. The occurrence is largely a result of anthropogenic emissions such as fossil fuel-burning, motor vehicle, waste incinerator, oil refining, coke and asphalt production, and aluminum production, etc. PAHs have received increased attention in recent years in air pollution studies because some of these compounds are highly carcinogenic or mutagenic. Eight PAHs (Car-PAHs) typically considered as possible carcinogens are: benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene (B(a)P), dibenzo(a,h)anthracene, indeno(1,2,3-cd)pyrene and benzo(g,h,i)perylene. In particular, benzo(a)pyrene has been identified as being highly carcinogenic. The US Environmental Protection Agency (EPA) has promulgated 16 unsubstituted PAHs (EPA-PAH) as priority pollutants. Thus, exposure assessments of PAHs in the developing world are important. The scope of this review will be to give an overview of PAH concentrations in various environmental samples and to discuss the advantages and limitations of applying these parameters in the assessment of environmental risks in ecosystems and human health. As it well known, there is an increasing trend to use the behavior of pollutants (i.e. bioaccumulation) as well as pollution-induced biological and biochemical effects on human organisms to evaluate or predict the impact of chemicals on ecosystems. Emphasis in this review will, therefore, be placed on the use of bioaccumulation and biomarker responses in air, soil, water and food, as monitoring tools for the assessment of the risks and hazards of PAH concentrations for the ecosystem, as well as on its limitations.

Determination of airborne polycyclic aromatic hydrocarbons at an airport by gas chromatography–mass spectrometry and evaluation of occupational exposure

The aim of this study was to determine airborne polycyclic aromatic hydrocarbons (PAHs) and biphenyl at an airport by gas chromatography-mass spectrometry and to evaluate occupational exposure by environmental monitoring. A total of 12 samplings were carried out in three areas: (1) a handling area where baggage was unloaded manually from vehicles onto conveyor belts (n=5); (2) the runway with plane and motor vehicle traffic (n=5) and (3) a departure lounge (n=2). PAHs levels were in most cases low. The higher levels found refer to naphthalene (130-13,050 ng/m3) and to its methyl-substitutes 2-methylnaphthalene (64-28,500 ng/m3) and 1-methylnaphthalene (24-35,300 ng/m3), and biphenyl (24-1610 ng/m3). A method was used to quantify twenty-four airborne PAHs, and biphenyl, and to detect a variety of other chemical compounds by means of the deconvolution program AMDIS. After sampling air on quartz filter and PUF and XAD-2 sorbents; extraction with dichloromethane, and concentration and purification on silica cartridges, analyses were carried out by gas chromatography-ion trap mass spectrometry. We used 20 deuterated PAHs to quantify both the 24 native PAHs and biphenyl. The native substances had been subdivided into small groups and in this way, their volatility was adequately reflected by the D-PAH present in each group. The limit of detection was 0.1 ng/m3 for all the PAHs, and a linear range of at least about three-fold the maximum level studied (naphthalene) was obtained both for D-PAHs and the native PAHs. A good recovery pattern was obtained for D-PAHs on quartz filters, PUF and XAD-2.

Emissions of tar-containing binders: a laboratory study

In Switzerland, hot recycling of tar-containing pavements is a subject of much dispute between environmentalists, road authorities and constructors. The main reason for this controversy comes from a lack of knowledge about the amount of hazardous compounds emitted, especially polycyclic aromatic hydrocarbons (PAHs), and the resulting health risk for road workers. On this background we decided to initiate a research project to study the emission behaviour of tar-containing materials. Mixtures of tar and bitumen with variable PAH content were heated in an open reactor flask at different temperatures to identify and quantify the key parameters of PAH emissions. The expected linear correlation between PAH concentration in the fumes and in the binder was found only for binder mixtures with PAH concentrations above 5000 ppm. This was traced back to the problem that a change of the PAH content in the binder was always accompanied by a change of other parameters, like viscosity. In the experiments with temperature variation, emissions of individual PAHs correlated well with vapor pressure. However, for Naphthalene and, in a lesser degree, for 3-ring PAHs too, a partial depletion of these compounds in the vapour was observed in some experiments. The effect is a slower increase with temperature for these compounds compared to 4-6-ring PAHs. This is one reason why the commonly used set of EPA-PAHs, which includes naphthalene and 3-ring PAHs, is considered inappropriate for the assessment of the health hazard in the case of tar-containing materials in hot recycling.

Exposure evaluation to airborne polycyclic aromatic hydrocarbons in an italian airport

The aim of this study was to use environmental monitoring to evaluate occupational exposure to polycyclic aromatic hydrocarbons (PAHs) and biphenyl in an Italian airport. Air was sampled using a quartz fiber filter, a polyurethane foam, and an XAD-2 layer. After extraction with dichloromethane, concentration and purification analyses of 25 PAHs (including biphenyl) were carried out by gas chromatography-ion trap mass spectrometry. In winter 2005, 12 air samples were taken at 120 L/min for 24 hours in three different areas of the airport. PAH levels were found to be generally low. In all investigated areas, the higher levels refer to naphthalene (130-13,050 ng/m), 2-methylnaphthalene (64-28,500 ng/m), 1-methylnaphtalene (24-35,300 ng/m), and biphenyl (24-1610 ng/m). However, in some instances, for compounds such as benzo[b+j+k]fluoranthene and benzo[a]pyrene, two high-boiling PAHs, the levels found (54.2 ng/ m and 8.6 ng/m, respectively) can be considered of some concern.

Assessment of DNA Damage in WBCs of Workers Occupationally Exposed to Fumes and Aerosols of Bitumen

We conducted a cross-shift study with 66 bitumen-exposed mastic asphalt workers and 49 construction workers without exposure to bitumen. Exposure was assessed using personal monitoring of airborne bitumen exposure, urinary 1-hydroxypyrene (1-OHP), and the sum of 1-, 2 + 9-,3-,4-hydroxyphenanthrene (OHPH). Genotoxic effects in WBC were determined with nonspecific DNA adduct levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) and the formation of DNA strand breaks and alkali-labile sites. Concentration of fumes and aerosols of bitumen correlated significantly with the concentrations of 1-OHP and OHPH after shift (r(s) = 0.27; P = 0.03 and r(s) = 0.55; P < 0.0001, respectively). Bitumen-exposed workers had more DNA strand breaks than the reference group (P < 0.0001) at both time points and a significant correlation with 1-OHP and OHPH in the postshift urines (r(s) = 0.32; P = 0.001 and r(s) = 0.27; P = 0.004, respectively). Paradoxically, we measured higher levels of DNA strand breaks, although not significant, in both study groups before shift. 8-OxodGuo adduct levels did not correlate with DNA strand breaks. Further, 8-oxodGuo levels were associated neither with personal exposure to bitumen nor with urinary metabolite concentrations. Significantly more DNA adducts were observed after shift not only in bitumen-exposed workers but also in the reference group. Only low-exposed workers had significantly elevated 8-oxodGuo adduct levels before as well as after shift (P = 0.0002 and P = 0.02, respectively). Our results show that exposure to fumes and aerosols of bitumen may contribute to an increased DNA damage assessed with strand breaks.

Genotoxic effects of bitumen fumes in Big Blue transgenic rat lung

Road paving workers are exposed to bitumen fumes (CAS No. 8052-42-4), a complex mixture of volatile compounds and particles containing carcinogenic and non-carcinogenic polycyclic aromatic hydrocarbons. However, epidemiological and experimental animal studies failed to draw unambiguous conclusions concerning their toxicity. In order to gain better insights on their genotoxic potential, we used an experimental design able to generate bitumen fumes at road paving temperature (temperature: 170 degrees C, total particulate matter: 100mg/m3) and perform a nose-only exposure of Big Blue transgenic rodents 6h/day for five consecutive days. The mutagenic properties of bitumen fumes were determined by analyzing the mutation frequency and spectrum of the neutral reporter gene cII inserted into the rodent genome. We previously observed in mouse lung, that bitumen fumes did not induce an increase of cII mutants, a modification of the mutation spectrum, nor the formation of DNA adducts. Since DNA adducts were found in the lungs of rats exposed to asphalt fumes in similar conditions, we decided to carry out an analogous experiment with Big Blue rats. A DNA adduct was detected 3 and 30 days after the end of treatment suggesting that these genetic alterations were quite steady. Thirty days after exposure, the cII mutant frequency was similar in control and exposed rats. In addition, a slight but not significant modification of the mutation spectrum associated with an increase of G:C to T:A and A:T to C:G transversions was noticeable in the treated animals. Then, these data failed to demonstrate a pulmonary mutagenic potential for bitumen fumes generated at road paving temperature in our experimental conditions despite the presence of a DNA adduct. These results may provide information concerning the pulmonary mechanism of action of this aerosol and may contribute to the occupational health hazard assessment.

Road pavers’ occupational exposure to asphalt containing waste plastic and tall oil pitch

Waste plastic (WP) and tall oil pitch (T), which are organic recycled industrial by-products, have been used as a binder with bitumen in stone mastic asphalt (SMA) and asphalt concrete (AC). We compared the exposure over one workday in 16 road pavers participating in a survey at four paving sites, using mixes of conventional asphalt (SMA, AC) or mixes containing waste material (SMA-WPT, AC-WPT). The concentrations of 11 aldehydes in air were 515 and 902 microg m(-3) at the SMA-WPT and AC-WPT worksites, being 3 and 13 times greater than at the corresponding worksites laying conventional asphalt. Resin acids (2-42 microg m(-3)), which are known sensitizers, were detected only during laying of AC-WPT. The emission levels (microg m(-3)) of total particulates (300-500), bitumen fumes (60-160), bitumen vapour (80-1120), naphthalene (0.59-1.2), phenanthrene (0.21-0.32), pyrene (<0.015-0.20), benzo(a)pyrene (<0.01) and the sum of 16 PAHs (polycyclic aromatic hydrocarbons, 1.28-2.00) were similar for conventional and WPT asphalts. The dermal deposition of 16 PAHs on exposure pads (on workers' wrist) was low in all pavers (0.7-3.5 ng cm(-2)). Eight OH-PAH biomarkers of naphthalene, phenanthrene and pyrene exposures were quantified in pre- and post-shift urine specimens. The post-shift concentrations (mean +/- SD, micromol mol(-1) creatinine) of 1- plus 2-naphthol; 1-,2-,3-,4- plus 9-phenanthrol; and 1-hydroxypyrene were, respectively, for asphalt workers: 18.1+/- 8.0, 2.41 +/- 0.71 and 0.66+/- 0.58 (smokers); 6.0+/- 2.3, 1.70+/- 0.72 and 0.27+/- 0.15 (non-smokers); WPT asphalt workers: 22.0+/- 9.2, 2.82+/- 1.11 and 0.76+/- 0.18 (smokers); 6.8+/- 2.6, 2.35+/- 0.69 and 0.46+/- 0.13 (non-smokers). The work-related uptake of PAHs was low in all pavers, although it was significantly greater in smokers than in non-smokers. The WPT asphalt workers complained of eye irritation and sore throat more than the pavers who had a much lower exposure to aldehydes and resin acids.

DNA damage measured by the single-cell gel electrophoresis (Comet) assay in mammals fed with mussels contaminated by the 'Erika' oil-spill

This research aimed to estimate potential genotoxicity for consumers resulting from the ingestion of seafood contaminated with polycyclic aromatic hydrocarbons (PAHs) released into the marine environment after the 'Erika' shipwreck along the coasts of south Brittany, in France. Mussels (Mytilus sp.) collected from sites on the Atlantic coast that were affected by the oil slick in various degrees, were used to feed rats daily for 2 and 4 weeks. DNA damage was measured by use of the Comet assay in the liver, bone marrow and blood of rats receiving food contaminated with 312 microg of 16PAHs/kg dry weight (d.w.) equivalent to 33.8 microg TEQs (toxic equivalent quantities to benzo(a)pyrene (BaP))/kg d.w. mussels, 569 microg/kg d.w. (83.6 microg TEQs/kg) and 870 microg/kg d.w. (180.7 microg TEQs/kg). A dose-effect-time relationship was observed between the amount of DNA damage in the liver and bone marrow of the rats and the PAH contamination level of the mussels. Genotoxicity increased during the period between 15 and 30 days in rats that received food at the highest two PAH levels. On the other hand, no significant change in liver and bone marrow of rats fed with mussels containing 33.8 microg TEQs/kg d.w. was recorded at 30 days compared with 15 days, indicating efficient DNA repair capacity at low levels of exposure. No signs of genotoxicity were found in peripheral blood. Globally, the observed effects were rather moderate. These results show that oil-contaminated food caused DNA damage in predators, and underline the bioavailability to consumers of pollutants in mussels contaminated with fuel oil. The usefulness of the Comet assay as a sensitive tool in biomonitoring studies analyzing responses of PAH transfer through food webs was also confirmed.

Genotoxicity related to transfer of oil spill pollutants from mussels to mammals via food

Heavy fuel oils containing high levels of polycyclic aromatic hydrocarbons (PAHs) were released into the marine environment after the Erika oil spill on the Atlantic coast. As highly condensed PAH pollutants can bioaccumulate in invertebrates, their transfer to vertebrates through the food chain was of concern. This study aimed to estimate potential genotoxic effects in rats fed for 2 or 4 weeks with the marine mussel Mytilus edulis contaminated by oil pollutants. Two levels of PAH contamination were studied, around 100 and 500 microg of total PAHs/kg dry weight (d.w.) in mussels. Genotoxic damage in rats was investigated by single-cell gel electrophoresis (Comet assay) and micronucleus assays in liver, bone marrow, and peripheral blood. DNA damage was observed in the liver of rats fed with the most contaminated mussels (500 microg PAHs/kg d.w.).DNA damage also was observed in the bone marrow but less than that in the liver. A small increase in micronuclei frequency was registered as well. This work underlines the bioavailability of pollutants in fuel-oil-contaminated mussels to consumers and the usefulness of the Comet assay as a sensitive tool in biomonitoring to analyze responses to PAH transfer in food. The occurrence of substituted PAHs and related compounds such as benzothiophenes in addition to nonsubstituted PAHs in fuel oils and mussels raised the question of whether they were implicated in the genotoxic effects registered in rats.

Exposure to asphalt fumes activates activator protein-1 through the phosphatidylinositol 3-kinase/Akt signaling pathway in mouse epidermal cells

Occupational exposure to asphalt fumes may pose a health risk. Experimental studies using animal and in vitro models indicate that condensates from asphalt fumes are genotoxic and can promote skin tumorigenesis. Enhanced activity of activator protein-1 (AP-1) is frequently associated with the promotion of skin tumorigenesis. The current study investigated the effect of exposure to asphalt fumes on AP-1 activation in mouse JB6 P+ epidermal cells and the skin of transgenic mice expressing the AP-1 luciferase reporter gene. Asphalt fumes were generated from a dynamic generation system that simulated road-paving conditions. Exposure to asphalt fumes significantly increased AP-1 activity in JB6 P+ cells as well as in cultured keratinocytes isolated from transgenic mice expressing AP-1 reporter. In addition, topical application of asphalt fumes by painting the tail skin of mice increased AP-1 activity by 14-fold. Exposure to asphalt fumes promoted basal as well as epidermal growth factor-stimulated anchorage-independent growth of JB6 P+ cells in soft agar. It activated phosphatidylinositol 3-kinase and induced phosphorylation of Akt at Ser-473/Thr-308, and concurrently activated downstream p70 S6 kinase as well as glycogen synthase kinase-3beta. Asphalt fumes transiently activated c-Jun NH2-terminal kinases without affecting extracellular signal-regulated kinases and p38 mitogen-activated protein kinases. Further study indicated that blockage of phosphatidylinositol 3-kinase activation eliminated asphalt fume-stimulated AP-1 activation and formation of anchorage-independent colonies in soft agar. This is the first report showing that exposure to asphalt fumes can activate AP-1 and intracellular signaling that may promote skin tumorigenesis, thus providing important evidence on the potential involvement of exposure to asphalt fumes in skin carcinogenesis.

Urinary Benzo[a]pyrene and Its Metabolites as Molecular Biomarkers of Asphalt Fume Exposure Characterized by Microflow LC Coupled to Hybrid Quadrupole Time-of-Flight Mass Spectrometry

As a step to study the health effects of asphalt fume exposure, an analytical method was developed to characterize benzo[a]pyrene and its hydroxy metabolites in the urine of asphalt fume-exposed rats. This method is based on microflow liquid chromatography (LC) coupled to hybrid quadrupole orthogonal acceleration time-of-flight mass spectrometry (Q-TOFMS). Twenty-four female Sprague-Dawley rats were used in the experiment, with 8 as controls and 16 exposed to asphalt fumes in a whole-body inhalation chamber for 10 days (4 h/day). Generated at 150 degrees C, the asphalt fume concentration in the animal exposure chamber ranged 76-117 mg/m(3). In the urine of the asphalt fume-exposed rats, benzo[a]pyrene and its metabolites of 3-hydroxybenzo[a]pyrene, benzo[a]pyrene-7,8-dihydrodiol(+/-), and benzo[a]pyrene-7,8,9,10-tetrahydrotetrol(+/-) were identified, and their concentrations were determined at 2.19 +/- 0.49, 16.17 +/- 0.3, 6.28 +/- 0.36, and 29.35 +/- 0.26 ng/100 mL, respectively. The metabolite concentrations from the controlled group, however, were either under the detection limits or at a relatively very low level (0.19 +/- 0.41 ng/100 mL for benzo[a]pyrene-7,8,9,10-tetrahydrotetrol metabolite). The results clearly indicate that the benzo[a]pyrene and its hydroxy metabolites were significantly elevated (p < 0.001) in the urine of asphalt fume-exposed rats relative to controls. The study also demonstrated that the combination of microflow LC separation and collision-induced dissociation leading to a characteristic fragmentation pattern by hybrid Q-TOFMS offers a distinct advantage for the identifications and characterizations of the benzo[a]pyrene metabolites.