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PubMed2001

Multimedia analysis of PAHs and nitro-PAH daughter products in the Los Angeles Basin.

Polycyclic aromatic hydrocarbons (PAHs) that are released into the atmosphere may have health consequences that can be compounded by their nitro-PAH atmospheric transformation products. The available literature suggests that some of the atmospheric nitro-PAH daughter products may increase the overall environmental health risk associated with PAHs. Therefore, an important issue is whether there is merit in considering atmospheric transformation products of air toxins when conducting environmental health-risk analyses. To illustrate the above issue, a comparative analysis of the potential risk that may be imposed by PAHs and their daughter products was carried out for the Los Angeles Basin. The analysis consisted of first assessing the multimedia environmental concentration of selected PAHs and nitro-PAHs using a spatial-compartmental modeling approach coupled with available monitoring data. Multimedia concentrations were then used to estimate chemical media-specific mutagenic densities as well as average daily intake from multiple pathways, followed by cancer risk for the known carcinogens among the study chemicals. The analysis revealed that mutagenic densities of the nitro-PAH daughter products can significantly exceed those of the parent PAHs. The results of this study suggest that there is merit in further investigation of the potential contribution of nitro-PAHs to the overall environmental health risk associated with airborne PAHs.

Air Pollutants↗

PubMed1993

HPRT and glycophorin A mutations in foundry workers: relationship to PAH exposure and to PAH-DNA adducts.

Mutations were evaluated in workers in an iron foundry with exposure to polycyclic aromatic hydrocarbons (PAHs), measured by personal and area monitoring, ranging from < 5 to 60 ng/m3 of benzo[a]pyrene (B[a]P). Mutation at the hypoxanthine guanine phosphoribosyl transferase (HPRT) and glycophorin A (GPA) loci (measures of molecular effect in lymphocytes and erythrocytes respectively) were assessed to demonstrate their relationship to external exposure at lower levels than previously analyzed in foundry workers at this plant (< 50-200 ng/m3). The relationship between mutations and PAH-DNA adducts measured by immunoassay (as a measure of the biologically effective dose) was also investigated. The markers were analyzed for dose-response and interindividual variability. Workers were classified into three exposure categories (low, medium and high). PAH-DNA adduct values for the low, medium and high exposure groups were 5.19, 6.10 and 9.57 x 10(-8) nucleotides respectively (r = 0.28; P = 0.08). HPRT mutant frequencies (adjusted for age and cloning efficiency) for the low, medium and high exposure groups were 1.04, 1.13 and 1.82 x 10(-6) cells respectively and demonstrated an upward trend with increasing exposure that was of borderline significance (r = 0.46, P = 0.06). In contrast, HPRT mutations were highly correlated with PAH-DNA adducts (r = 0.67; P = 0.004). Interindividual variability in mutant frequencies ranged from 1.5- to 4.5-fold within the three exposure categories. With respect to GPA variants, NN frequency (Vf) in erythrocytes (which reflects chromosomal loss and duplication, recombination or gene conversion) was not positively correlated with PAH exposure. The level of N0 Vf (arising from small-scale structural mutations in the GPA gene or from larger-scale chromosomal rearrangements or deletions) increased slightly, but not significantly, over the three exposure groups from 8.2 to 10.7 to 11.8/10(6) cells (P = 0.32). Interindividual variation in GPA NN Vf ranged from 2- to 18-fold and in GPA N0 from 4- to 5-fold. NN and N0 Vf were highly correlated (P = 0.001) but no correlation was seen between GPA and HPRT or between GPA and PAH-DNA adducts. Thus, the most interesting and novel finding is that, even at relatively low exposures to PAH, HPRT mutations were increased in parallel with PAH-DNA adducts. The observed association between PAH-DNA adducts and HPRT gene mutation in humans is consistent with experimental data for PAHs. These results support the use of both biomonitoring and personal ambient monitoring in further molecular epidemiology studies.

Adult↗

PubMed2005

PAH degradation capacity of soil microbial communities--does it depend on PAH exposure?

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants of the environment. But is their microbial degradation equally wide in distribution? We estimated the PAH degradation capacity of 13 soils ranging from pristine locations (total PAHs approximately 0.1 mg kg(-1)) to heavily polluted industrial sites (total PAHs approximately 400 mg kg(-1)). The size of the pyrene- and phenanthrene-degrading bacterial populations was determined by most probable number (MPN) enumeration. Densities of phenanthrene degraders reflected previous PAH exposure, whereas pyrene degraders were detected only in the most polluted soils. The potentials for phenanthrene and pyrene degradation were measured as the mineralization of (14)C-labeled spikes. The time to 10% mineralization of added (14)C phenanthrene and (14)C pyrene was inversely correlated with the PAH content of the soils. Substantial (14)C phenanthrene mineralization in all soils tested, including seven unpolluted soils, demonstrated that phenanthrene is not a suitable model compound for predicting PAH degradation in soils. (14)C pyrene was mineralized by all Danish soil samples tested, regardless of whether they were from contaminated sites or not, suggesting that in industrialized areas the background level of pyrene is sufficient to maintain pyrene degradation traits in the gene pool of soil microorganisms. In contrast, two pristine forest soils from northern Norway and Ghana mineralized little (14)C pyrene within the 140-day test period. Mineralization of phenanthrene and pyrene by all Danish soils suggests that soil microbial communities of inhabited areas possess a sufficiently high PAH degradation capacity to question the value of bioaugmentation with specific PAH degraders for bioremediation.

Bacteria↗

PubMed2000

Isolation of adherent polycyclic aromatic hydrocarbon (PAH)-degrading bacteria using PAH-sorbing carriers.

Two different procedures were compared to isolate polycyclic aromatic hydrocarbon (PAH)-utilizing bacteria from PAH-contaminated soil and sludge samples, i.e., (i) shaken enrichment cultures in liquid mineral medium in which PAHs were supplied as crystals and (ii) a new method in which PAH degraders were enriched on and recovered from hydrophobic membranes containing sorbed PAHs. Both techniques were successful, but selected from the same source different bacterial strains able to grow on PAHs as the sole source of carbon and energy. The liquid enrichment mainly selected for Sphingomonas spp., whereas the membrane method exclusively led to the selection of Mycobacterium spp. Furthermore, in separate membrane enrichment set-ups with different membrane types, three repetitive extragenic palindromic PCR-related Mycobacterium strains were recovered. The new Mycobacterium isolates were strongly hydrophobic and displayed the capacity to adhere strongly to different surfaces. One strain, Mycobacterium sp. LB501T, displayed an unusual combination of high adhesion efficiency and an extremely high negative charge. This strain may represent a new bacterial species as suggested by 16S rRNA gene sequence analysis. These results indicate that the provision of hydrophobic sorbents containing sorbed PAHs in the enrichment procedure discriminated in favor of certain bacterial characteristics. The new isolation method is appropriate to select for adherent PAH-degrading bacteria, which might be useful to biodegrade sorbed PAHs in soils and sludge.

Bacterial Adhesion↗

PubMedDate not supplied

Quantification of polycyclic aromatic hydrocarbons (PAHs) in human hair by HPLC with fluorescence detection: a biological monitoring method to evaluate the exposure to PAHs.

A high-performance liquid chromatographic (HPLC) method with fluorescence detection was developed for the quantification of polycyclic aromatic hydrocarbons (PAHs) in human hair. Fifteen kinds of PAHs classified as priority pollutants by the US EPA were quantified with four perdeuterated PAHs as internal standards. After 50 mg hair samples were washed with n-hexane to remove external contamination of PAHs, the samples were digested in 2.5 M sodium hydroxide. The digests were extracted with n-hexane and then analyzed by HPLC. Eleven kinds of PAHs were identified in hair samples of 20 subjects, and 10 kinds of PAHs were eventually quantified using the internal standards. For anthracene, chrysene and benzo[k]fluoranthene, significant differences were observed between smokers and non-smokers. Although benzo[b]fluoranthene, dibenz[a,h]anthracene, benzo[ghi]perylene and indeno[1,2,3-cd]pyrene were observed in the particulates of indoor and outdoor air, they were not detected in all hair samples. The analysis of PAHs in human hair should be useful as a new biomarker to evaluate the exposure to PAHs.

Chromatography, High Pressure Liquid↗

PubMed2003

Bioaccumulation and critical body residue of PAHs in the amphipod, Diporeia spp: additional evidence to support toxicity additivity for PAH mixtures.

Polycyclic aromatic hydrocarbons (PAHs) are considered to act additively when exposed as congener mixtures. Additive internal concentrations at the site of toxic action is the basis for recent efforts to establish a sum PAH guideline for sediment-associated PAH toxicity. This study determined the toxicity of several PAH congeners on a body residue basis in Diporeia spp. These values were compared to the previously established LR(50) value for a PAH mixture based on the molar sum of PAH congeners and demonstrated similar LR(50) values for individual PAH. These results support the contention that the PAH act at the same molar concentration whether present as individual compounds or in mixture. Aqueous exposures were conducted for 28 d, and the water was exchanged daily to maintain the exposure concentration. The concentration in the exposures declined by an average of 22% between water exchanges across all compounds, and ranged from 11% to 32%. The toxicokinetics were determined using both time-weighted-average (TWA) and time-variable water concentrations and were not statistically different between the two source functions. Toxicity was determined for both mortality and immobility (failure to swim on prodding) and on both a TWA water concentration and a body residue basis. The LC(50) values ranged from 1757 microg l(-1) for naphthalene after 10 d exposure to 79.1 microg l(-1) for pyrene after 28 d exposure, and the EC(50) ranged from 1587 microg l(-1) for naphthalene after 10 d exposure to 38.2 microg l(-1) for pyrene after 28 d exposure. The LR(50) values for all congeners at all lengths of exposure were essentially constant and averaged 7.5+/-2.6 micromol g(-1), while the ER(50) for immobility averaged 2.6+/-0.6 micromol g(-1). The bioconcentration factor declined with increasing exposure concentration and was driven primarily by a lower uptake rate with increasing dose, while the elimination remained essentially constant for each compound.

Amphipoda↗

PubMed2003

PCB and PAH speciation among particle types in contaminated harbor sediments and effects on PAH bioavailability.

This research provides particle-scale understanding of PCB and PAH distribution in sediments obtained from three urban locations in the United States: Hunters Point, CA; Milwaukee Harbor, WI; and Harbor Point, NY. The sediments comprised mineral grains (primarily sand, silt, and clays) and carbonaceous particles (primarily coal, coke, charcoal, pitch, cenospheres, and wood). The carbonaceous sediment fractions were separated from the mineral fractions based on their lower density and were identified by petrographic analysis. In all three sediments, carbonaceous particles contributed 5-7% of the total mass and 60-90% of the PCBs and PAHs. The production of carbonaceous particles is not known to be associated with PCB contamination, and it is very unlikely that these particles can be the source of PCBs in the environment Thus, it appears that carbonaceous particles preferentially accumulate PCBs acting as sorbents in the aqueous environment if PCBs are released directly to the sediment or if deposited as airborne soot particles. Aerobic bioslurry treatment resulted in negligible PAH loss from the carbonaceous coal-derived material in Milwaukee Harbor sediment but resulted in 80% of the PAHs being removed from carbonaceous particles in Harbor Point sediment. Microscale PAH extraction and analysis revealed that PAHs in Harbor Point sediment were associated mainly with coal tar pitch residue. PAHs present in semisolid coal tar pitch are more bioavailable than PAHs sorbed on carbonaceous particles such as coal, coke, charcoal, and cenosphere. Results of this study illustrate the importance of understanding particle-scale association of hydrophobic organic contaminants for explaining bioavailability differences among sediments.

Adsorption↗

PubMed1999

Interstellar PAH emission in the 11-14 micron region: new insights from laboratory data and a tracer of ionized PAHs.

The Ames infrared spectral database of isolated, neutral and ionized polycyclic aromatic hydrocarbons (PAHS) shows that aromatic CH out-of-plane bending frequencies are significantly shifted upon ionization. For solo- and duet-CH groups, the shift is pronounced and consistently toward higher frequencies. The solo-CH modes are blueshifted by an average of 27 cm-1 and the duet-CH modes by an average of 17 cm-1. For trio- and quartet-CH groups, the ionization shifts of the out-of-plane modes are more erratic and typically more modest. As a result of these ionization shifts, the solo-CH out-of-plane modes move out of the region classically associated with these vibrations in neutral PAHS, falling instead at frequencies well above those normally attributed to out-of-plane bending, vibrations of any type. In addition, for the compact PAHs studied, the duet-CH out-of-plane modes are shifted into the frequency range traditionally associated with the solo-CH modes. These results refine our understanding of the origin of the dominant interstellar infrared emission feature near 11.2 microns, whose envelope has traditionally been attributed only to the out-of-plane bending of solo-CH groups on PAHS, and provide a natural explanation for the puzzling emission feature near 11.0 microns within the framework of the PAH model. Specifically, the prevalent but variable long-wavelength wing or shoulder that is often observed near 11.4 microns likely reflects the contributions of duet-CH units in PAH cations. Also, these results indicate that the emission between 926 and 904 cm-1 (10.8 and 11.1 microns) observed in many sources can be unambiguously attributed to the out-of-plane wagging, of solo-CH units in moderately sized (fewer than 50 carbon atom) PAH cations, making this emission an unequivocal tracer of ionized interstellar PAHS.

Astronomical Phenomena↗

PubMed1978

Influence of glomerular filtration rate on renal PAH secretion rate in the rat kidney. Dependency of PAH extraction on renal filtration fraction.

PAH secretion (TPAH) was studied in rats at spontaneously occurring glomerular filtration rate (GFR). At saturated transport, TPAH was found to be correlated to GFR. This relationship was also observed at unsaturated transport where TPAH depends upon the PAH concentration in arterial plasma. However, no significant correlation between TPAH and renal PAH load or renal plasma flow rate was found when the effects of GFR were removed by partial correlation analysis. A dependency of TPAH on GFR explains the correlations found between filtration fraction (FF) and renal PAH extraction (EPAH) or renal tubular PAH extraction fraction (EPAH--FFPAH). Thus, even at low PAH concentration in a. plasma, renal PAH extraction may only be assumed to be constant if the filtration fraction is constant.

Aminohippuric Acids↗

PubMed1997

Determination of polycyclic aromatic hydrocarbons (PAH) and their metabolites in blood, feces, and urine of rats orally exposed to PAH contaminated soils.

Polycyclic aromatic hydrocarbons (PAH) have become an ubiquitous upper soil component as a consequence of industrialization involving a multitude of combustion processes. Ingestion of PAH contaminated soil is considered to be a major exposure route, specifically for small children living on these soils. Health risk assessment is based on extrapolations from data obtained via studies performed with pure chemicals. Additionally it is assumed that after oral intake all PAH present in the soil will be absorbed by the human body. Interactions with the soil matrix, however, may modulate the bioavailability of PAH. In this study, we examined the absorption and excretion of PAH in rats orally exposed either to industrially contaminated soils or pure model compounds as anthracene, pyrene and benzo(a)pyrene (B[a]P). The model compounds and the metabolites, 1-hydroxypyrene (1-OH-pyrene) and 3-hydroxybenzo(a)pyrene (3-OH-B[a]P), were measured in blood, feces or urine by means of HPLC with fluorescence detection. Because of rapid biotransformation only minimal levels of unmetabolized anthracene, pyrene and B[a]P in blood could be detected. The pharmacokinetic parameters were nonlinear and suggestive of enterohepatic cycling. Only low levels of the compounds were excreted unchanged in feces whereas the levels of the metabolites were considerably higher in feces and urine. These results indicate that the dosed PAH are largely absorbed by the gastrointestinal tract, subsequently metabolized and excreted as metabolites via urine and feces. Significant differences between the soil-treated group and the pure mixture-treated group could be observed; the soil-treated group showed higher fecal excretion of unchanged pyrene (0.5 versus 0.2% of the original dose) and B[a]P (1 versus 0.3%), lower excretion of 1-OH-pyrene in feces (5.1 versus 17. 0%), and lower excretion of 1-OH-pyrene in urine (0.2 versus 3.4%). The fecal excretion of 3-OH-B[a]P between the two groups was similar (8.8 versus 8.8%). These results suggest that the soil matrix is capable of reducing the absorption of at least pyrene. Therefore, exposure risk assessment models assuming complete bioavailability of soilmatrix-bound PAH probably overestimate the endogenous dose.

Administration, Oral↗

PubMed2005

Genotoxic risk assessment in white blood cells of occupationally exposed workers before and after alteration of the polycyclic aromatic hydrocarbon (PAH) profile in the production material: comparison with PAH air and urinary metabolite levels.

OBJECTIVE: Workers in various industries can be exposed to polycyclic aromatic hydrocarbons (PAHs). The relationship between biomarkers of genotoxic risk, PAH compounds in air (ambient monitoring) and PAH metabolites in urine (internal exposure) were studied in 17 workers exposed to PAHs in a fireproof-material producing plant before and 3 months after the PAH profile was altered in the binding pitch. METHODS: Two biomarkers of exposure, specific DNA adducts of (+/-)-r-7,t-8-dihydroxy-t-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE) and non-specific DNA adduct of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) were determined in white blood cells (WBCs). In addition, DNA strand breaks were analysed in lymphocytes by single-cell gel electrophoresis in a genotoxic risk assessment. Sixteen PAH compounds in air were determined by personal air sampling, and hydroxylated metabolites of phenanthrene, pyrene and naphthalene were determined in urine. RESULTS: After substitution of the binding pitch the concentrations of benzo[a]pyrene in air decreased (P<0.01). No changes could be observed for pyrene, while levels of phenanthrene (P=0.0013) and naphthalene (P=0.0346) in air increased. Consequently, median DNA adduct rates of anti-BPDE decreased after alteration of the production material (from 0.9 to <0.5 adducts/10(8) nucleotides). No changes in the excretion of 1-hydroxypyrene in urine could be determined, whereas increased levels of 1-, 2+9-, 3- and 4-hydroxyphenanthrene (P<0.0001) and 1-naphthol and 2-naphthol (P=0.0072) were found in urine. In addition, a statistically significant increase in DNA strand break frequencies (P<0.01) and elevated 8-oxodGuo adduct levels (P=0.7819, not statistically significant) were found in the WBCs of exposed workers 3 months after the PAH profile in the binding pitch had been altered. CONCLUSION: The results presented here show that the increased concentration of naphthalene and/or phenanthrene in the air at the work place could induce the formation of DNA strand breaks and alkali-labile sites in WBCs of exposed workers.

Adult↗

PubMed1997

Determination of urinary metabolites of polycyclic aromatic hydrocarbons (PAH) for the risk assessment of PAH-exposed workers.

A method for the simultaneous determination of urinary phenanthrene, fluoranthene, pyrene, chrysene and benzo[a]pyrene metabolites has been developed for individual risk assessment at polycyclic aromatic hydrocarbon (PAH)-burdened workplaces. The concentration of urinary metabolites as a measure for individual PAH exposure takes account not only of PAH masses resorbed by the respiratory tract but also those incorporated percutaneously. The method allows the determination of 25 different components with a low margin of error; the individual metabolite profiles thereby allow conclusions on the individual characteristics of PAH-oxidizing enzymes (monooxygenases). The coefficients of variation are lower than 10%. After enzymatic treatment of the urine with glucuronidase and arylsulfatase one part of the benzene or toluene extract is treated with diazomethane to convert phenols into methylethers, while another part is used to convert dihydrodiols into phenols. After further purification the metabolites are determined by means of a combination of gas chromatography and mass spectrometry. The PAH exposure of cock plant workers during several consecutive days resulted in fairly constant individual urinary metabolite profiles which, however, exhibited significant inter-individual variability. This held true also for Wistar rats exposed to tar pitch aerosol on 5 days during a period of 10 days. It was also demonstrated that in the case of coke plant workers there is a correlation between inhaled PAH and metabolites excreted. Mass relationships between inhaled PAH and metabolites excreted were found to differ from one individual to another.

Administration, Inhalation↗

PubMed1991

Correlations between 15 polycyclic aromatic hydrocarbons (PAH) and the mutagenicity of the total PAH fraction in ambient air particles in La Spezia (Italy).

Airborne particulate matter has been monitored 4 times a month for 1 year (1988) in the city of La Spezia (Italy). The polycyclic aromatic hydrocarbon (PAH) fractions were extracted, purified and characterized for the content of 15 individual PAH. In general when concentrations of individual PAH were compared statistical correlation was obtained. Mutagenicity studies were performed by the use of the Ames plate test with the Salmonella strains TA98, TA100, TA98NR and TA98DNP6 with and without metabolic activation (S9 mix). The TA98 strain was by far the most responsive and the S9 mix was absolutely required as expected when PAH are assayed. Besides mutagenicity, toxicity was also considered and it proved to be correlated with mutagenicity in TA98, +S9. The TA98NR and TA98DNP6 strains showed no appreciable differences from the parental strain TA98 indicating the absence of significant amounts of direct-acting nitro derivatives in our PAH samples. Of the 15 PAH considered in this study the amounts of cyclopental[c,d]pyrene (CPP) correlated best with mutagenicity. The role of CPP in contributing to the indirect mutagenicity of urban air PAH samples is discussed.

Air Pollutants↗

PubMed1999

Urinary 1-hydroxypyrene and other PAH metabolites as biomarkers of exposure to environmental PAH in air particulate matter.

Humans are exposed to polycyclic aromatic hydrocarbons (PAHs) from occupational, environmental, medicinal and dietary sources. PAH metabolites in human urine can be used as biomarkers of internal dose to assess recent exposure to PAHs. The most widely used urinary PAH metabolites are 1-hydroxypyrene (1-OHP) or 1-hydroxypyrene-O-glucuronide (1-OHP-gluc), the major form of 1-OHP in human urine, because of their relatively high concentration and prevalence in urine and their relative ease of measurement. Elevated levels of 1-OHP or 1-OHP-gluc have been demonstrated in smokers, in patients receiving coal tar treatment (vs. pre-treatment), in postshift road pavers or coke oven workers, and in subjects ingesting charbroiled meat. This metabolite is found (at low levels) in most human urine samples, even in persons without apparent occupational or smoking exposure. Recent studies suggest that environmental exposure to PAHs (and air particles) is associated with increased excretion of 1-OHP-gluc or 1-OHP. These findings raise the possibility of using urinary concentration of 1-OHP-gluc, or another PAH metabolite, as a surrogate biomarker of exposure to airborne fine (sooty) particulate matter--the major source of PAHs in polluted air. Reported associations between ambient particulate matter concentrations and health effects among adults and children, including respiratory disease and mortality, indicate the need for biomarkers of fine particle exposure. If validated, such biomarkers would be useful in supplementing and refining exposure information obtained by ambient monitoring.

Adult↗

PubMed1999

Assessment of the bioavailability of PAHs in rats exposed to a polluted soil by natural routes: induction of EROD activity and DNA adducts and PAH burden in both liver and lung.

In order to assess bioavailability of polycyclic aromatic hydrocarbons (PAHs) present in soils, male laboratory rats were exposed to litters of control and polluted soils. After 88+/-2 h of exposure, several biomarkers were measured in both liver and lung. When rats were exposed to SIV soil, contaminated by a mixture of at least 13 PAHs, (1) only 2 or 3 PAH compounds were detected in liver and lung; (2) cytochrome P450-dependent monooxygenase activity, followed by 7-ethoxyresorufin O-deethylase (EROD) activity measurement, was highly induced in liver (13-fold-induction) and lung (up to 78-fold); and (3) DNA adducts were significantly increased. For what concerns soil artificially contaminated by only one PAH (phenanthrene or B[a]P), EROD activity was not or fully induced, respectively. These results demonstrate the occurrence of a high bioavailability of PAHs to mammals in natural conditions of exposure. First results concerning DNA adducts must be profound, but they already show that a short exposure of mammals to PAH-polluted soils can lead to potential genotoxic effects. EROD activity can be used as a sensitive biomarker in both liver and lung of rats maintained on litters of soils in the laboratory, and such a test can be used routinely to contribute to risk assessment.

Animals↗

PubMed1996

PAH-pools in soils along a PAH-deposition gradient.

The objectives of this study are to characterize different PAH-pools (soil horizons, microsites influenced by stem flow, aggregate core and surface fractions, particle size fractions) in soils affected by depositions. Three forest soils affected by the emissions of an aluminium plant near Ziar/Central Slovakia were sampled to analyze 20 PAHs. The organic layers have high concentrations of PAHs (40-200 mg kg(-1)), decreasing as soil depth and distance from the aluminium plant increases. At the two sites nearest to the plant PAH-concentrations are higher in microsites affected by stem flow than in microsites not influenced by stem flow. They are also higher in aggregate surface fractions than in aggregate core fractions and in bulk soil samples than in aggregates. Sand- and siltsize particles contain decreasing percentages of the sum PAH-concentrations as distance from the plant increases. This microscale heterogeneity affects PAH-availability and has to be considered when assessing environmental risks.

Journal Article↗

PubMed2006

Applicability of the bioluminescence inhibition test in the 96-well microplate format for PAH-solutions and elutriates of PAH-contaminated soils.

The use of conventional plastic microplates for a miniaturised luminescent bacteria test may result in an underestimation of the toxicity for poorly water soluble highly adsorbing toxicants such as PAHs. In this study, the suitability of microplates for testing elutriates of PAH-contaminated soils was investigated. The LUMIStox test was performed as the standard test in the miniaturised format using contaminated soil elutriates and aqueous solutions of four selected PAHs (viz. naphthalene (NAP), acenaphthene (ACE), fluorene (FLU), and phenanthrene (PHE)). For the aqueous PAH-solutions, we observed reduced light inhibition values for the miniaturised bioassay when using black microplates made of polypropylene (PP) and polystyrene (PS) compared to the standard LUMIStox test. This phenomenon was most likely due to adsorption of toxicants to the microplate surfaces with PAHs of lower water solubility being significantly more affected; however, after minimizing the exposure of samples to plastic surfaces, polystyrene microplates revealed equivalent performance (>80% 'relative' light inhibition) to the standard glass cuvette test system. For soil elutriates, black microplates again exhibited slightly lower light inhibition values while white plates made of PS and Barex resulted in a pronounced overestimation of toxicity for a coloured soil elutriate. In general, microplates were applicable for testing elutriates of PAH-contaminated soils. In cases where samples are coloured or turbid, the application of black microplates is recommended.

Aliivibrio fischeri↗

PubMed2006

Formation of genotoxic nitro-PAH compounds in fish exposed to ambient nitrite and PAH.

Mutagenic nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) have been known to arise in the environment through direct emissions from combustion sources and nitration of PAHs, primarily in the atmosphere. Here, we report the formation of nitro-PAH compounds in fish contaminated with PAH and exposed to nitrite (NO2-) in the ambient water. Electrospray ionization mass spectrometric analysis of the bile of the euryhaline fish Oreochromis mossambicus exposed simultaneously to field-relevant, sublethal concentrations of phenanthrene (1 microg/g) and NO2- (1 microM) and collision-induced dissociation of selected ions revealed the presence of two strongly genotoxic nitro-PAH metabolites, namely phenanthrene-6-nitro-1,2-dihydrodiol-3,4-epoxide (mass/charge [m/z] 273) and dihydrodihydroxy acetylamino nitrophenanthrene (m/z 359). These two metabolite peaks present only in the bile of fish exposed simultaneously to phenanthrene and NO2- constituted, respectively, about 3.1 and 2.7% of the highest peak among the putative unconjugated phenanthrene metabolites in the mass spectrum. The presence of the oxidized phenanthrene metabolite dihydroxyphenanthrene (m/z 233) in fish exposed to phenanthrene alone as well as phenanthrene plus NO2- suggested that oxidation of phenanthrene precedes nitration in the sequence of reactions leading to the formation of the observed nitrophenanthrene metabolites. However, the route of PAH administration seems to determine the nature of metabolites formed. Nearly 92% of the hepatic cells of the fish exposed to phenanthrene in the presence of NO2- were found to have suffered extensive DNA fragmentation on comet assay.

Animals↗