THE SIGNIFICANCE OF POLYCYCLIC AROMATIC HYDROCARBONS AS ENVIRONMENTAL CARCINOGENS. 35 YEARS RESEARCH ON PAH—A RETROSPECTIVE

Phenanthrene-Induced Cytochrome P450 Genes and Phenanthrene Tolerance Associated with Arabidopsis thaliana CYP75B1 Gene

Polycyclic aromatic hydrocarbons (PAHs) form an important group of organic pollutants due to their distribution in the environment and their carcinogenic and/or mutagenic effects. In order to identify at the molecular level some of the players in the biodegradation and tolerance response to PAHs in plants, we have phenotyped 32 Arabidopsis thaliana T-DNA mutant lines corresponding to 16 cytochrome P450 (CYP) genes that showed to be differentially expressed under contrasted stress conditions induced by phenanthrene, a 3-ring PAH. This screening has allowed us to identify CYP75B1 (At5g07990) T-DNA mutants as the only ones being sensitive to phenanthrene-induced stress, supporting that CYP75B1 protein is necessary for PAH tolerance. CYP75B1 codes for a 3'flavonol hydroxylase. CYP75B1 gene was heterologously expressed on yeast in order to investigate whether it affects the A. thaliana response to phenanthrene by participating in its metabolization. Heterologously-produced CYP75B1 enzyme shows to be catalytically efficient against its physiological substrates (e.g., naringenin) but unable to metabolize phenanthrene or 9-phenanthrenol. In contrast, CYP75B1 seems rather involved in phenanthrene tolerance as a crucial element by regulating concentration of antioxidants through the production of 3'-hydroxylated flavonoids such as quercetin and cyanidin. In particular, we report a highly increased generation of reactive oxygen species (H2O2 and singlet oxygen) in cyp75b1 mutants compared to control plants in response to phenanthrene treatment. Overall, CYP75B1 shows to play an important role in the response to the deleterious effects of phenanthrene exposure and this is related to oxidative stress sensitivity rather than metabolization.

Benzo[a]pyrene in Moscow road dust: pollution levels and health risks

Benzo[a]pyrene (BaP) is one of the priority pollutants in the urban environment. For the first time, the accumulation of BaP in road dust on different types of Moscow roads has been determined. The average BaP content in road dust is 0.26 mg/kg, which is 53 times higher than the BaP content in the background topsoils (Umbric Albeluvisols) of the Moscow Meshchera lowland, 50 km east of the city. The most polluted territories are large roads (0.29 mg/kg, excess of the maximum permissible concentration (MPC) in soils by 14 times) and parking lots in the courtyards (0.37 mg/kg, MPC excess by 19 times). In the city center, the BaP content in the dust of courtyards reaches 1.02 mg/kg (MPC excess by 51 times). The accumulation of BaP depends on the parameters of street canyons formed by buildings along the roads: in short canyons (< 500 m), the content of BaP reaches maximum. Relatively wide canyons accumulate BaP 1.6 times more actively than narrow canyons. The BaP accumulation in road dust significantly increases on the Third Ring Road (TRR), highways, medium and small roads with an average height of the canyon > 20 m. Public health risks from exposure to BaP-contaminated road dust particles were assessed using the US EPA methodology. The main BaP exposure pathway is oral via ingestion (> 90% of the total BaP intake). The carcinogenic risk for adults is the highest in courtyard areas in the south, southwest, northwest, and center of Moscow. The minimum carcinogenic risk is characteristic of the highways and TRR with predominance of nonstop traffic.

Unravelling the molecular mechanism of mutagenic factors impacting human health

Environmental mutagens are chemical and physical substances in the environment that has a potential to induce a wide range of mutations and generate multiple physiological, biochemical, and genetic modifications in humans. Most mutagens are having genotoxic effects on the following generation through germ cells. The influence of germinal mutations on health will be determined by their frequency, nature, and the mechanisms that keep a specific mutation in the population. Early prenatal lethal mutations have less public health consequences than genetic illnesses linked with long-term medical and social difficulties. Physical and chemical mutagens are common mutagens found in the environment. These two environmental mutagens have been associated with multiple neurological disorders and carcinogenesis in humans. Thus in this study, we aim to unravel the molecular mechanism of physical mutagens (UV rays, X-rays, gamma rays), chemical mutagens (dimethyl sulfate (DMS), bisphenol A (BPA), polycyclic aromatic hydrocarbons (PAHs), 5-chlorocytosine (5ClC)), and several heavy metals (Ar, Pb, Al, Hg, Cd, Cr) implicated in DNA damage, carcinogenesis, chromosomal abnormalities, and oxidative stress which leads to multiple disorders and impacting human health. Biological tests for mutagen detection are crucial; therefore, we also discuss several approaches (Ames test and Mutatox test) to estimate mutagenic factors in the environment. The potential risks of environmental mutagens impacting humans require a deeper basic knowledge of human genetics as well as ongoing research on humans, animals, and their tissues and fluids.

Main features and contamination of sealed soils in the east of Moscow city

The aim of this paper is to characterize the main properties and level of pollution of sealed soils in different land use zones of the Eastern administrative district (EAD) of Moscow. In 2016-2017 overall, 47 samples were taken from 35 soil pits. The list of soil properties analyzed included actual acidity, organic carbon content, particle-size distribution, and degree of salinity. Pollution of sealed soils with petroleum products (PPs), benzo[a]pyrene (BaP) and heavy metals and metalloids (HMMs) was evaluated. Sealed soils are characterized by the medium organic matter content (2.24%), alkaline reaction (pH 8.0), sandy loamy texture, and the absence of soluble salts in the upper part of the profile. The pronounced technogenic anomalies of hydrocarbons are mainly formed in the sealed soils of the industrial and traffic land use zones. The mean content of BaP in the sealed soils is 56 times higher than that in the background soils, it exceeds MPC by 9.5 times. The concentrations of most HMMs in the sealed soils exceed the background level by two-four times. The most intense accumulation of As, Ba, Cr, Cu, Ni, Pb, Sb, and Sn takes place in the industrial zone with the high degree of sealing. The hygienic standards for BaP and PPs contents approved in the Russian Federation in the sealed soils of EAO are exceeded by almost ten times. Maximum permissible concentrations are also exceeded for a large group of HMMs. The high contamination of the sealed soils can create dangerous ecological situation in the EAD if road covering will be removed and pollutants begin to migrate.

Seaweed as bioindicators of organic micropollutants polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs)

This study highlights the role of seaweed as important indicators of pollutants as they respond immediately to change in water chemistry and have high survival capabilities. Concentration and risk assessment of 13 polycyclic aromatic hydrocarbons (PAHs), as well as 20 organochlorine pesticides (OCPs), were examined in the seaweed from El-Mex Bay, Mediterranean Sea during spring and autumn seasons. The green alga Ulva compressa had a maximum ability to accumulate both PAHs and OCPs. In general, the content of the tested micropollutants in the collected seaweed is correlated to their species, morphology, concentration, and nature of pollutant. Naphthalene (NAP) and benzo a pyrene were the predominant polycyclic aromatic hydrocarbons in all species with mean concentrations of 68.57 and 56.14 ng g^-1, respectively. The results of the current study showed that the contribution of the different fractions of PAHs from the total concentration was as follows: fossil-fuel derived polycyclic aromatic hydrocarbons (∑PAH_F; 49.32%) > combustion-derived polycyclic aromatic hydrocarbons (PAH_COMB; 30.83%) > carcinogenic fractions (PAH_CARC; 19.86%). A maximum PAH_CARC (30.38%) was recorded in Ulva fasciata. For OCPs, the presence of 1,1-dichloro-2, 2-bis (4-chlorophenyl) ethane (DDD) (ND-27.8 ng g^-1) rather than DDT; 1,1,1-trichloro-2, 2-bis (4-chlorophenyl) ethane was an indication for biotransformation involving the reductive dichlorination of DDT to more recalcitrant and toxic DDD. Endrin ketone has the highest mean hazard quotient (0.376). The cancer risk values of most PAHs and OCPs were in the range from 10^-4 to 10^-3 recommending precautionary measures. The results explained that the present algal species play a vital role in the uptake of organic pollutants and act as biomarkers for micropollutants in the ecosystem.

Reduction in Toxicity of Polystyrene Nanoplastics Combined with Phenanthrene through Binding of Jellyfish Mucin with Nanoplastics

Mucin (Mu), a biological substance extracted from jellyfish (Aurelia aurita), was used to reduce the toxic effect of polystyrene nanoplastics (PS-NP) combined with phenanthrene (Phe) in the aquatic environment of zebrafish (Danio rerio), among other aquatic organisms. Mu showed a high binding capacity, as it bound to 92.84% and 92.87% of the PS-NPs (concentration of 2.0 mg/L) after 0.5 h and 8 h, respectively. A zebrafish embryo development test was conducted to check for any reduction in toxicity by Mu. When exposed to PS-NP + Mu and PS-NP + Phe + Mu, respectively, the hatching rates were 88.33 ± 20.21% and 93.33 ± 2.89%, respectively; these results were not significantly different from those of the control group. However, the hatching rate with the addition of Mu increased, compared to that of the PS-NP (71.83 ± 13.36%) and Phe (37.50 ± 19.83%) treatments, and the morphological abnormality rate decreased. The presence of Mu was also found to obstruct the absorption of PS-NP and PS-NP + Phe by the zebrafish. When zebrafish embryos were exposed to PS-NP at a concentration of 5.0 mg/L, the hatching rate differed significantly from that of the control group, and the expression of CAT and p53 genes increased significantly, but the expression of Bcl-2 decreased significantly. An mRNA sequence analysis revealed that the gene expression levels of the test group containing Mu were similar to those of the control group. These results infer that Mu can be used as a biological material to collect and remove PS-NPs from aquatic environments and reduce toxicity.

Assessment of polycyclic aromatic hydrocarbons in seafood collected from coastal aquaculture ponds in Taiwan and human health risk assessment

The level and distribution of 16 USEPA Polycyclic aromatic hydrocarbon (PAHs) in aquaculture farmed fish (Mugil cephalus and Oreochromis mossambicus) and shellfish (Corbicula fluminea Formosa and Meretrix lusoria) were determined in Taiwan and then assessed cancer and non-cancer risks for those consuming these kinds of seafood. Results indicated that C. fluminea Formosa accumulated the highest average concentration of total PAHs (43.0 ± 11.3 ng/g wet weight) while M. lusoria contained the lowest concentration (20.0 ± 5.8 ng/g) among all species. The low-molecular-weight PAHs were dominant for both fish and shellfish, which consistent with other studies. Notably, parts of high-molecular-weight PAHs were found in shellfish whereas that was little in fish. The calculated hazard quotients (HQ) of all PAHs were smaller than 1 and the incremental lifetime cancer risks (ILCR) for Benzo[a]pyrene were below 1 × 10^-5, suggesting that PAHs in the collected seafood could pose a low hazard to residents. Although the results indicated that the studied seafood is safe for human consumption, children and seniors post relatively higher risks, suggesting that it needs to continue monitoring and control the PAHs concentration in seafood and the associated environments.

Accessing Polycyclic Heteroarenes Enabled by Copper-Catalyzed Aerobic Oxidative C-H/C-H [4 + 2] Annulation of 3-Arylindole Derivatives

Several polycyclic aromatic hydrocarbons are delivered at room temperature by copper-catalyzed aerobic oxidative C-H/C-H [4 + 2] annulation of alkyl-substituted 3-arylindole derivatives. Specifically, dual aryl C-H functionalization is furnished under mild conditions through the 1,2-migration of copper catalyst and regioselective alkyne insertion. Mechanistic experiments demonstrate that the C-H bond cleavage on the indole and phenyl rings is not involved in the rate-limiting step.

Substituted Two- to Five-Ring Polycyclic Aromatic Compounds Are Potent Agonists of Atlantic Cod (Gadus morhua) Aryl Hydrocarbon Receptors Ahr1a and Ahr2a

Polycyclic aromatic hydrocarbons (PAHs) are among the most toxic and bioavailable components found in petroleum and represent a high risk to aquatic organisms. The aryl hydrocarbon receptor (Ahr) is a ligand-activated transcription factor that mediates the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and other planar aromatic hydrocarbons, including certain PAHs. Ahr acts as a xenosensor and modulates the transcription of biotransformation genes in vertebrates, such as cytochrome P450 1A (cyp1a). Atlantic cod (Gadus morhua) possesses two Ahr proteins, Ahr1a and Ahr2a, which diverge in their primary structure, tissue-specific expression, ligand affinities, and transactivation profiles. Here, a luciferase reporter gene assay was used to assess the sensitivity of the Atlantic cod Ahrs to 31 polycyclic aromatic compounds (PACs), including two- to five-ring native PAHs, a sulfur-containing heterocyclic PAC, as well as several methylated, methoxylated, and hydroxylated congeners. Notably, most parent compounds, including naphthalene, phenanthrene, and partly, chrysene, did not act as agonists for the Ahrs, while hydroxylated and/or alkylated versions of these PAHs were potent agonists. Importantly, the greater potencies of substituted PAH derivatives and their ubiquitous occurrence in nature emphasize that more knowledge on the toxicity of these environmentally and toxicologically relevant compounds is imperative.

Indoor wood combustion, carcinogenic exposure and esophageal cancer in southwest Kenya

BACKGROUND

Exposure to polycyclic aromatic hydrocarbons (PAHs) is a risk factor for esophageal squamous cell carcinoma (ESCC) in high-incidence areas of China, Iran and Brazil, but PAH assessments have not been conducted in East Africa, another ESCC hot spot.

OBJECTIVE

To evaluate demographic or lifestyle factors associated with the PAH biomarker concentrations in the study population, and whether PAH metabolite concentrations showed any associations with esophageal precancerous lesions.

METHODS

We recruited a community-based sample of 289 asymptomatic adults from a rural area of Kenya and performed Lugol's chromoendoscopy to detect esophageal squamous dysplasia (ESD); participants completed a questionnaire and provided a spot urine specimen. We analyzed urine for seven hydroxylated metabolites of naphthalene, fluorene, phenanthrene, and pyrene at the U.S. National Center for Environmental Health, and compared creatinine-corrected PAH metabolite concentrations with questionnaire data and the presence of ESD.

RESULTS

PAH metabolite concentrations among never tobacco users in these rural Kenya residents were 2.4-28.1 times higher than those reported from never tobacco users in Iran, Brazil and the USA. Female sex, cooking indoors, having no post-primary education, and age <50, but not tobacco use, were positively and significantly associated with PAH metabolite concentrations. Almost all participants used wood as cooking fuel. Nine participants had advanced ESD. Adjusted logistic regression showed a significant association between 2-hydroxynaphthalene (OR = 4.19, 95%CI: 1.01-17.47) and advanced ESD. All other PAH metabolites had positive but non-significant associations with advanced ESD.

CONCLUSIONS

Urinary PAH metabolite concentrations among never tobacco users are markedly higher in this group from Kenya than in other populations and are associated with indoor cooking with wood on open, unvented stoves. These metabolite concentrations were also associated with the presence of advanced esophageal dysplasia. Our findings underline the importance of assessing alternative cooking conditions to reduce PAH exposure in this population.

Synthesis of trans-dihydronaphthalene-diols and evaluation of their use as standards for PAH metabolite analysis in fish bile by GC-MS

Phenols and trans-1,2-dihydro-1,2-diols are metabolites commonly formed in vivo in fish upon exposure to polycyclic aromatic hydrocarbons (PAHs). These metabolites are excreted via the bile and gas chromatography-mass spectrometry (GC-MS) analysis of bile is becoming more frequently used for evaluating PAH exposure levels in fish. Current protocols focus on the detection and quantification of phenols formed during in vivo oxidation of PAHs, leaving out analyses and quantification of other oxidation products such as trans-1,2-dihydro-1,2-diols, potentially underestimating exposure levels. Herein, four trans-1,2-dihydro-1,2-diols, namely trans-1,2-dihydronaphthalene-1,2-diol, trans-6-methyl-1,2-dihydronaphthalene-1,2-diol, trans-5,7-dimethyl-1,2-dihydronaphthalene-1,2-diol, and trans-4,6,7-trimethyl-1,2-dihydronaphthalene-1,2-diol, were successfully prepared and used as standards in the GC-MS analysis, aiming to further develop this qualitative and quantitative analytical method for the determination of PAH exposures. This study shows that the currently used GC-MS analysis, including sample workup, is not suitable for determining the quantity of the corresponding diols derived from naphthalene and methylated naphthalenes. Alternative approaches are needed to provide a correct estimate of PAH exposure levels.

Formation and distribution of phenanthrene and its metabolites (monohydroxy-phenanthrenes) in Korean rockfish (Sebastes schlegelii)

This study investigated the tissue distribution of phenanthrene (PHE) and the formation of monohydroxy-phenanthrene (OH-PHE) metabolites in Korean rockfish (Sebastes schlegelii). PHE was intragastrically administered to two groups of rockfish. The first group was exposed to PHE at a low dose (10 mg/kg body weight) and the second group was exposed at a high dose (30 mg/kg body weight). The rockfish were analyzed and the levels of PHE were higher in the liver, followed by muscle, and then bile. PHE concentrations in the liver, muscle, and bile were 1.4-26, 0.10-2.01, and not detected (ND)-0.13 μg/g wet weight, respectively. All five monohydroxylated PHE metabolites (1-OH-PHE, 2-OH-PHE, 3-OH-PHE, 4-OH-PHE, and 9-OH-PHE) were detected only in bile. Among these OH-PHE metabolites, 3-OH-PHE was found at the highest concentration from all fish bile samples in both PHE exposure groups, indicating that regioselective OH-PHE formation occurs in rockfish and 3-OH PHE could be a good biomarker of exposure of Korean rockfish to PHE. Suspect screening analysis of the rockfish bile was performed by LC-QTOF/MS, and the formation of two OH-PHE-DNA adducts (thymine-OH-PHE and cytosine-OH-PHE) were identified in the bile sample collected 6 h after rockfish were exposed to the high PHE dose, indicating that OH-PHE metabolites may be toxic to fish. This is the first report on the formation characteristics of OH-PHE metabolites in rockfish and their use as biomarkers of exposure of rockfish to parent PHE.

Toxicities of Polycyclic Aromatic Hydrocarbons for Aquatic Animals

Polycyclic aromatic hydrocarbons (PAHs) are organic compounds that are widely distributed in the air, water, and soil. Recently, the amount of PAHs derived from fuels and from incomplete combustion processes is increasing. In the aquatic environment, oil spills directly cause PAH pollution and affect marine organisms. Oil spills correlate very well with the major shipping routes. Furthermore, accidental oil spills can seriously impact the marine environment toxicologically. Here, we describe PAH toxicities and related bioaccumulation properties in aquatic animals, including invertebrates. Recent studies have revealed the toxicity of PAHs, including endocrine disruption and tissue-specific toxicity, although researchers have mainly focused on the carcinogenic toxicity of PAHs. We summarize the toxicity of PAHs regarding these aspects. Additionally, the bioaccumulation properties of PAHs for organisms, including invertebrates, are important factors when considering PAH toxicity. In this review, we describe the bioaccumulation properties of PAHs in aquatic animals. Recently, microplastics have been the most concerning environmental problem in the aquatic ecosystem, and the vector effect of microplastics for lipophilic compounds is an emerging environmental issue. Here, we describe the correlation between PAHs and microplastics. Thus, we concluded that PAHs have a toxicity for aquatic animals, indicating that we should emphasize the prevention of aquatic PAH pollution.

Leaching of polycyclic aromatic hydrocarbons (PAHs) from coal dumps reclaimed with apple trees: a mechanistic insight

Polycyclic aromatic hydrocarbons (PAHs) have been identified as compounds that can be incorporated to run-off waters or to aquifers becoming a real threat not only to aquatic organisms but also to humans due to its carcinogenic and mutagenic activity. This work studies the presence of PAHs in a coal dump pile located in the north of Spain (Asturias), downhill a spoil pile of a cinabrium mine. This unique site gives the opportunity to assess whether acid waters have more potential to leach PAHs than normal rainwater (acidified when it gets in contact with coal spoil). The distribution of PAHs and methyl PAHs has shown that their abundance is higher in the path of acid waters which could be caused by the ability of acid water to break bonds of coal macromolecules. This chemical reaction liberates PAHs of less molecular weight that can be detected by GC-MS. Moreover, less soluble PAHs are concentrated on the acid water circulation area and more soluble PAHs more leached by acid water that rainwater, which indicates that PAHs dissolve more in acid waters than in normal rainwater. In addition, this coal spoil pile has been reclaimed with apple trees to make cider for human consumption. Up to 152 different compounds were identified in the tree samples, but neither PAHs nor methyl PAHs were found, pointing to a possible retention of the PAHs in the roots zone. Apple trees in the acid waters path show more concentration in waxes and flavour compounds, indicating a more mature apple.

Inland navigation: PAH inventories in soil and vegetation after EU fuel regulation 2009/30/EC

In January 2011, fuel quality in inland water vessels was changed by EU regulation 2009/30/EC, aiming at improving air quality along waterways. We hypothesized that the implementation of this regulation both lowered the total deposition of polycyclic aromatic hydrocarbons (PAHs) and changed their composition in river valleys. We analyzed parent-, alkylated- and thio-PAHs in soil and vine leaves, at two waterways (Rhine and Moselle, Germany), as well as in one ship-free reference area (Ahr, Germany). Samples were taken annually (2010-2013) in transects perpendicular to the rivers. We did not find any relation of PAH concentration and composition on vine leaves to inland navigation, likely because atmospheric exchange processes distorted ship-specific accumulation patterns. We did find, however, an accumulation of ship-borne PAHs in topsoil near the waterways (1543±788 and 581±252ngg^-1 at Moselle and Rhine, respectively), leading to larger PAH concentrations at the Moselle Valley than at the reference area (535±404ngg^-1) prior to EU fuel regulation. After fuel regulation, the PAH concentrations decreased in topsoils of the Moselle and Rhine Valley by 35±9 and 62±28%, respectively. These changes were accompanied by increasing proportions of dibenzothiophene (DBT) and low molecular weight PAHs. Both, changes in PAH concentrations and composition were traceable within 200 and 350m distance to the river front of Moselle and Rhine, respectively, and likely favored by erosion of topsoil in vineyards. We conclude that the EU regulation was effective in improving soil and thus also air quality within only three years. The impact was greater and spatially more relevant at the Rhine, which may be attributed to the larger traffic volume of inland navigation.

Rhodium(iii)-catalyzed oxidative bicyclization of 4-arylbut-3-yn-1-amines with internal alkynes through C–H functionalization

A new Rh(iii)-catalyzed oxidative bicyclization through C–H functionalization is presented for the synthesis of benzo[g]indoles.

The determination of polycyclic aromatic hydrocarbons in the urine of non-smoking Polish pregnant women

The aim of this study was to characterize the PAH exposure level among the non-smoking Polish pregnant women and to identify the minimal set of PAH metabolites that specifically reflect environmental PAH exposure. The study population consisted of 210 non-smoking pregnant women. The urine sample was used for analysis of the following PAH metabolites: 1-, 2-, 3-, 4-, 9-hydroxyphenanthrene (1-, 2-, 3-, 4-, 9-OH-PHE), 1-hydroxypyrene (1-OH-PYR), 1,6+1,8-dihydroxypyrene (DI-OH-PYR), phenanthrene trans-1,2-dihydrodiol (PHE-1,2-diol) and phenanthrene trans-9,10-dihydrodiol (PHE-9,10-diol). The analysis of all the biomarkers was performed by gas chromatography-mass spectrometry after their derivatization. The mean PAH metabolite concentrations were in the range of 0.15 (± 0.2) μg/g creatinine for 9-OH-PHE to 5.9 (± 10.6) μg/g creatinine for PHE-9,10-diol. Women living in the city center had higher concentrations of 1-OH-PHE (β=0.6; p=0.04), 3-OH-PHE (β=0.8; p=0.02), 9-OH-PHE (β=0.9; p=0.02), and DI-OH-PYR (β=1.0; p=0.006) than those living outside the city center. The usage of coal for residential heating was a significant predictor of all PAH metabolites except for 9-OH-PHE (p=0.1) and PHE-9,10-diol (p=0.08). With the increasing cotinine levels we observed a significant increase in the concentrations of the following PAH metabolites: 3-OH-PHE (β=0.2; p=0.007), 4-OH-PHE (β=0.3; p=0.002), PHE-1,2-diol (β=0.3; p<0.001), 1-OH-PYR (β=0.2; p=0.01). High-density housing, usage of coal for residential heating, cotinine level in saliva, season of urine collection and distance from the place of residence to the main road explained 26% of the variance of 3-OH-PHE and 21% of the variance of 1-OH-PHE. 2-OH-PHE, 3-OH-PHE, 9-OH-PHE and PHE-9,10-diol are sufficient to predict environmental PAH exposure. The urinary PAH biomarker levels found in this study indicate that non-smoking Polish pregnant women suffer from a higher PAH exposure than those in other western countries. This higher PAH exposure level probably poses a significant health risk for the newborns and young children and will require further attention in the future.

Persistent activation of DNA damage signaling in response to complex mixtures of PAHs in air particulate matter

Complex mixtures of polycyclic aromatic hydrocarbons (PAHs) are present in air particulate matter (PM) and have been associated with many adverse human health effects including cancer and respiratory disease. However, due to their complexity, the risk of exposure to mixtures is difficult to estimate. In the present study the effects of binary mixtures of benzo[a]pyrene (BP) and dibenzo[a,l]pyrene (DBP) and complex mixtures of PAHs in urban air PM extracts on DNA damage signaling was investigated. Applying a statistical model to the data we observed a more than additive response for binary mixtures of BP and DBP on activation of DNA damage signaling. Persistent activation of checkpoint kinase 1 (Chk1) was observed at significantly lower BP equivalent concentrations in air PM extracts than BP alone. Activation of DNA damage signaling was also more persistent in air PM fractions containing PAHs with more than four aromatic rings suggesting larger PAHs contribute a greater risk to human health. Altogether our data suggests that human health risk assessment based on additivity such as toxicity equivalency factor scales may significantly underestimate the risk of exposure to complex mixtures of PAHs. The data confirms our previous findings with PAH-contaminated soil (Niziolek-Kierecka et al., 2012) and suggests a possible role for Chk1 Ser317 phosphorylation as a biological marker for future analyses of complex mixtures of PAHs.

Comprehensive profiling of coal tar and crude oil to obtain mass spectra and retention indices for alkylated PAH shows why current methods err

Investigators use C(1) to C(4) substituted polycyclic aromatic hydrocarbons (PAH) to assess ecological risk and to track fossil fuels and related pollutants in the environment. To quantify these compounds gas chromatography/mass spectrometry (GC/MS) is used. This work demonstrates single ion monitoring (SIM) or extraction (SIE) of full scan data produces inaccurate and imprecise concentration estimates due to incorrect homologue peak assignments. Profiling of coal tar and crude oil by automated sequential GC-GC/MS provided the retention windows and spectral patterns for each homologue to correctly quantify these compounds. Simultaneous pulsed flame photometric (sulfur-specific) detection differentiated PAH from polycyclic aromatic sulfur heterocycles and their alkylated homologues when they eluted within the same retention windows and had common ions. Differences between SIE and spectral deconvolution of GC/MS data based on multiple fragmentation patterns per homologue ranged from a few percent for C(1) compounds to hundreds of percent for the higher alkylated homologues. Findings show current methods produce poor quality data adversely affecting forensic investigations, risk assessments, and weathering studies.

Efficiency of butyl rubber sorbent to remove the PAH toxicity

Large amounts of polycyclic aromatic hydrocarbons (PAHs) have been released to the marine environment as a result of oil spills and from other sources including wastewaters, surface runoff, industrial processes, atmospheric deposition, biosynthesis, and natural events such as forest fires. PAHs have been known to affect a variety of biological processes and can be potent cell mutagens/carcinogens and toxic. In this study, PAH toxicity removal was investigated by using a novel macroporous butyl rubber (BR) sorbent. To find out the toxicity removal efficiency of the sorbents, the toxicity tests with Vibrio fisheri (luminescence bacteria) and Phaeodactylum tricornutum (marine algae) were applied to the acenaphthene (Ace) and phenanthrene (Phen) solutions in seawater (Ace: 500- 1000 μg/L; Phen; 100-1000 μg/L) before and after sorbent applications. Additionally, lysosomal stability and filtration rate biomarker techniques were applied to the mussels (Mytilus galloprovincialis) exposed to 1000 μg/L Phen solution and bioaccumulation was measured. The results showed that the toxicity of the PAH solutions decreased 50-100 percent depending on the concentration of the solutions and organisms. Phaeodactylum was found as the most sensitive organism to Phen and Ace. Since the application of BR sorbent removed the Phen from the solution, the bioaccumulated Phen amount in the mussels decreased accordingly.

Antagonism of phenanthrene cytotoxicity for human embryo lung fibroblast cell line HFL-I by green tea polyphenols

Polycyclic aromatic hydrocarbons (PAHs) have been detected in some commercial teas around the world and pose a threat to tea consumers. However, green tea polyphenols (GTP) possess remarkable antioxidant and anticancer effects. In this study, the potential of GTP to block the toxicity of the model PAH phenanthrene was examined in human embryo lung fibroblast cell line HFL-I. Both GTP and phenanthrene treatment individually caused dose-dependent inhibition of cell growth. A full factorial design experiment demonstrated that the interaction of phenanthrene and GTP significantly reduced growth inhibition. Using the median effect method showed that phenanthrene and GTP were antagonistic when the inhibitory levels were less than about 50%. Apoptosis and cell cycle detection suggested that only phenanthrene affected cell cycle significantly and caused cell death; GTP lowered the mortality of HFL-I cells exposed to phenanthrene; However, GTP did not affect modulation of the cell cycle by phenanthrene.