Photomutagenicity of 16 polycyclic aromatic hydrocarbons from the US EPA priority pollutant list

Profile of particulate-bound organic compounds in ambient environment of Srinagar: a high-altitude urban location in the North-Western Himalayas

Twenty-four hourly samples of total suspended particulate matter (TSPM) were collected once a week over 17 months in the ambient environment of Srinagar (altitude 1524 m), an urban montane location in the North-Western Himalayas. The samples were analyzed to identify and quantify the presence of diverse organic compounds (OCs) using thermal desorption gas chromatography mass spectroscopy (TD-GCMS). Non-polar organic compounds-n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and molecular tracers (retene and nicotine), were detected in the TSPM samples. Molecular diagnostic ratios, derived from the quantified n-alkanes and PAHs in TSPM, assisted in characterization of the contributing sources. Significant variation in the planetary boundary layer height (meters) with change in season (summer to winter) in this region, also, affected the observed variation in the temporal profile of TSPM-bound OCs. TSPM-bound OCs were predominantly contributed from petroleum and biomass combustion; to a lesser extent from biogenic sources. High concentrations of retene and nicotine, known molecular tracers for coniferous wood combustion and tobacco smoke, respectively, were detected in the winter samples. Seasonal variation in TSPM-bound retene corresponded with the periodicity of biomass burning activity in the region. The benzo(a)pyrene equivalent (BAPE) concentrations, a measure for the carcinogenicity of TSPM-bound PAHs was calculated and the value exceeded the prescribed international standards in winter. This finding poses a major health concern for the inhabitants of this region. High BAPE concentration of PAHs during winter was linked to fossil fuel and biomass combustion, where the prevalent meteorology and topography played a synergistic role.

Analysis of Parent/Nitrated Polycyclic Aromatic Hydrocarbons in Particulate Matter 2.5 Based on Femtosecond Ionization Mass Spectrometry

Particulate matter 2.5 (PM2.5), collected from ambient air in Fukuoka City, was analyzed by gas chromatography combined with multiphoton ionization mass spectrometry using an ultraviolet femtosecond laser (267 nm) as the ionization source. Numerous parent polycyclic aromatic hydrocarbons (PPAHs) were observed in a sample extracted from PM2.5, and their concentrations were determined to be in the range from 30 to 190 pg/m(3) for heavy PPAHs. Standard samples of nitrated polycyclic aromatic hydrocarbons (NPAHs) were examined, and the limits of detection were determined to be in the picogram range. The concentration of NPAH adsorbed on PM2.5 in the air was less than 900-1300 pg/m(3). Graphical Abstract ᅟ.

Influence of physical factors on polycyclic aromatic hydrocarbons (PAHs) content in vegetable oils

The aim of this study was to test the hypothesis about physical factors causing a significant decrease of polycyclic aromatic hydrocarbon (PAH) compounds in foodstuffs. For this purpose, extraction of 16 PAHs (prioritised by EPA) from selected foodstuffs (rapeseed oil and sunflower oil) was carried out. The changes in PAH content in oils exposed to selected physical factors (UV radiation, temperature and time) were observed. Oils under study were exposed to two types of UV radiation: direct and indirect (through a glass plate). In both experiments, a reduction of 16 PAHs in oils was recorded but in the latter a PAH reduction was not as high. In another experiment, the temperature of oils was raised to 40, 100 and 200°C. As a result, the content of PAHs has decreased significantly. In both cases, exposure to UV radiation and high temperature resulted in the reduction of PAHs, it was strongly correlated with the duration of experiments. The results showed relatively low contamination of oil with PAHs. Only for rapeseed oil, the level of said contamination was substantially higher than laid down limits.

Multiwall carbon nanotubes increase the microbial community in crude oil contaminated fresh water sediments

Since crude oil contamination is one of the biggest environmental concerns, its removal from contaminated sites is of interest for both researchers and industries. In situ bioremediation is a promising technique for decreasing or even eliminating crude oil and hydrocarbon contamination. However, since these compounds are potentially toxic for many microorganisms, high loads of contamination can inhibit the microbial community and therefore reduce the removal rate. Therefore, any strategy with the ability to increase the microbial population in such circumstances can be of promise in improving the remediation process. In this study, multiwall carbon nanotubes were employed to support microbial growth in sediments contaminated with crude oil. Following spiking of fresh water sediments with different concentrations of crude oil alone and in a mixture with carbon nanotubes for 30days, the microbial profiles in these sediments were obtained using FLX-pyrosequencing. Next, the ratios of each member of the microbial population in these sediments were compared with those values in the untreated control sediment. This study showed that combination of crude oil and carbon nanotubes can increase the diversity of the total microbial population. Furthermore, these treatments could increase the ratios of several microorganisms that are known to be effective in the degradation of hydrocarbons.

Compound amino acids added in media improved Solanum nigrum L. phytoremediating CD-PAHS contaminated soil

Cd hyperaccumulator Solanum nigrum L. was a promising plant used to simultaneously remediate Cd-PAHs combined pollution soil through its extra accumulation capacity and rhizosphere degradation. This article compared the strengthening remediation role of cysteine (Cys), glycine (Gly) and glutamic acid (Glu) with EDTA and TW80. The results showed that the addition of 0.03 mmol L(-1) Cys, Gly, and Glu didn't significantly impact (p < 0.05) shoot biomass of S. nigrum, but obviously increased Cd concentration. Therefore, Cd capacity (µg pot(-1)) in shoots of S. nigrum was significantly increased (p < 0.05) by 37.7% compared to the control without reagent added. At the meantime, the PAHs degradation ratio in rhizoshpere was increased by 34.5%. Basically, the improving role of Cys, Gly, and Glu was higher than EDTA and TW80. The main reasons of enhanced the accumulation of S. nigrum to Cd might lie in the addition of Cys, Gly, and Glu which reduced pH and increased extractable Cd concentration in rhizosphere and phytochelatines (PCs) concentration in leaves. As for the degradation of PAHs in rhizosphere, increased microorganism number might be play important role.

Developmental abnormalities and differential expression of genes induced in oil and dispersant exposed Menidia beryllina embryos

Exposure of fish embryos to relatively low concentrations of oil has been implicated in sub-lethal toxicity. The objective of this study was to determine the effects of the exposure of Menidia beryllina embryos at 30-48h post-fertilization to the water accommodated fractions of oil (WAF, 200ppm, v/v), dispersants (20ppm, v/v, Corexit 9500 or 9527), and mixtures of oil and each of the dispersants to produce chemically enhanced water accommodated fractions (CEWAFs) over a 72-hour period. The polyaromatic hydrocarbon (PAH) and benzene, toluene, ethylene and xylene (BTEX) constituents of the 5X concentrated exposure solutions (control, WAF, dispersants and CEWAFs) were determined and those of the 1× exposures were derived using a dilution factor. PAH, BTEX and low molecular weight PAH constituents greater than 1ppb were observed in WAF and the dispersants, but at much higher levels in CEWAFs. The WAF and CEWAFs post-weathering were diluted at 1:5 (200ml WAF/CEWAF: 800ml 25ppt saltwater) for embryo exposures. Mortality, heartbeat, embryo normalcy, abnormality types and severities were recorded. The qPCR assay was used to quantify abundances of transcripts of target genes for sexual differentiation and sex determination (StAR, dmrt-1, amh, cyp19b, vtg and chg-L,), growth regulation (ghr) and stress response (cyp1a and Hsp90); and gapdh served as the housekeeping gene. Temperature was 21±1.5°C throughout the experimental period, while mortality was low and not significantly different (p=0.68) among treatments. Heartbeat was significantly different (0.0034) with the lowest heartbeats recorded in Corexit 9500 (67.5beats/min) and 9527 (67.1beats/min) exposed embryos compared with controls (82.7beats/min). Significantly more treated embryos were in a state of deterioration, with significantly more embryos presenting arrested tissue differentiation compared with controls (p=0.021). Exposure to WAF, dispersants and CEWAF induced aberrant expression of all the genes, with star, dmrt-1, ghr and hsp90 being significantly down-regulated in CEWAF and cyp19b in Corexit 9527. The cyp1a and cyp19b were significantly up-regulated in CEWAFs and WAF, respectively. The molecular endpoints were most sensitive, especially the expression of star, cyp19b, cyp1a, hsp90 and could therefore be used as early indicators of long term effects of Corexit 9500 and 9527 usage in oil spill management on M. beryllina, a valid sentinel for oil pollution events.

Chemical characterization and spatial distribution of PAHs and heavy hydrocarbons in rural sites of Campania Region, South Italy

In this paper, the behaviour and distribution patterns of heavy hydrocarbons and several polycyclic aromatic hydrocarbon (PAH) priority pollutants, as listed by the US Environmental Protection Agency, were evaluated in 891 soil samples. The samples were collected in three expected polluted rural sites in Campania (southern Italy) as part of the LIFE11 ECOREMED project, funded by the European Commission, to test innovative agriculture-based soil restoration techniques. These sites have been selected because they have been used for the temporary storage of urban and building waste (Teverola), subject to illicit dumping of unknown material (Trentola-Ducenta), or suspected to be polluted by metals due to agricultural practices (Giugliano). Chemical analysis of soil samples allowed the baseline pollution levels to be determined prior to any intervention. It was found that these areas can be considered contaminated for residential use, in accordance with Italian environmental law (Law Decree 152/2006). Statistical analysis applied to the data proved that average mean concentrations of heavy hydrocarbons could be as high as 140 mg/kg of dry soil with peaks of 700 mg/kg of dry soil, for the Trentola-Ducenta site; the median concentration of analytical results for hydrocarbon (HC) concentration for the Trentola-Ducenta and Giugliano sites was 63 and 73.4 mg/kg dry soil, respectively; for Teverola, the median level was 35 mg/kg dry soil. Some PAHs (usually benzo(a)pyrene) also exceeded the maximum allowed level in all sites. From the principal component analysis applied to PAH concentrations, it emerged that pollutants can be supposed to derive from a single source for the three sites. Diagnostic ratios calculated to determine possible PAH sources suggest petroleum combustion or disposal practice. Our sampling protocol also showed large dishomogeneity in soil pollutant spatial distribution, even at a scale as small as 3.3 m, indicating that variability could emerge at very short spatial scales.

Monitoring of polycyclic aromatic hydrocarbons on agricultural lands surrounding Tehran oil refinery

Soil samples at two depths were collected and analyzed to determine the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs), organic carbon, and soil pH. The Σ16PAHs were 0.13 to 3.92 mg kg(-1) at depth 1 and 0.21 to 50.32 mg kg(-1)at depth 2. The averages of the PAH compounds indicate that the area is contaminated with oil, and this pollution was greater at depth 2. Interpolation maps showed that the southern region, especially at depth 2, has been contaminated more by anthropogenic activity. The diagnostic ratios indicate several sources of pollution of the agricultural soil. A comparison of average PAHs and standard values revealed that higher molecular weight compounds in the topsoil (InP and BghiP) and subsoil (BaA, BkF, BaP, DBA, and BghiP) exceed standard values for farmland. The pH interpolation map for both depths showed that most of the area has alkaline soil from long-term irrigation with untreated urban wastewater.

Active and passive biomonitoring suggest metabolic adaptation in blue mussels (Mytilus spp.) chronically exposed to a moderate contamination in Brest harbor (France)

Brest harbor (Bay of Brest, Brittany, France) has a severe past of anthropogenic chemical contamination, but inputs tended to decrease, indicating a reassessment of its ecotoxicological status should be carried out. Here, native and caged mussels (Mytilus spp.) were used in combination to evaluate biological effects of chronic chemical contamination in Brest harbor. Polycyclic aromatic hydrocarbon (PAH) contamination was measured in mussel tissues as a proxy of harbor and urban pollution. Biochemical biomarkers of xenobiotic biotransformation, antioxidant defenses, generation of reducing equivalents, energy metabolism and oxidative damage were studied in both gills and digestive glands of native and caged mussels. In particular, activities of glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), NADP-dependent isocitrate dehydrogenase (IDP), pyruvate kinase (PK) and phosphoenolpyruvate carboxykinase (PEPCK) were measured and lipid peroxidation was assessed by malondialdehyde (MDA) quantification. In addition, a condition index was calculated to assess the overall health of the mussels. Moderate PAH contamination was detected in digestive glands of both native and caged individuals from the exposed site. Modulations of biomarkers were detected in digestive glands of native harbor mussels indicating the presence of a chemical pressure. In particular, results suggested increased biotransformation (GST), antioxidant defenses (CAT), NADPH generation (IDP) and gluconeogenesis (PEPCK), which could represent a coordinated response against chemically-induced cellular stress. Lipid peroxidation assessment and condition index indicated an absence of acute stress in the same mussels suggesting metabolic changes could, at least partially, offset the negative effects of contamination. In caged mussels, only GR was found modulated compared to non-exposed mussels but significant differences in oxidative stress and energy-related biomarkers were observed compared to native harbor mussels. Overall, these results suggested mussels chronically exposed to contamination have set up metabolic adaptation, which may contribute to their survival in the moderately contaminated harbor of Brest. Whether these adaptive traits result from phenotypic plasticity or genetic adaptation needs to be further investigated.

Health effects of soy-biodiesel emissions: bioassay-directed fractionation for mutagenicity

CONTEXT

Soy biodiesel is the predominant biodiesel in the USA, but there is little understanding of the classes of chemicals responsible for the mutagenicity of its emissions.

OBJECTIVE

We determined some of the chemical classes responsible for the mutagenicity of the particulate matter (PM) of the emissions from petroleum diesel (B0) and biodiesel containing increasing concentrations of soy methyl esters (B20, B50, and B100).

MATERIALS AND METHODS

We subjected organic extracts of the PM to bioassay-directed fractionation by sequential elution on silica gel with solvents of increasing polarity to produce four fractions per fuel. We injected these onto high performance liquid chromatography to produce 62 sub-fractions per fraction based on chemical polarity and evaluated all fractions and sub-fractions for mutagenicity in Salmonella. We correlated the results with the concentrations of 32 polycyclic aromatic hydrocarbons (PAHs) in the fractions.

RESULTS

The mutagenicity-emission factors of the fractions generally decreased with increasing concentrations of soy in the fuel. Despite the different chemical compositions of the fuels, the extractable organics of all four emissions had similar features: ∼60% of the mass was nonpolar, non-mutagenic compounds; most of the PAHs were polar; and most of the mutagenicity was due to weakly polar and polar compounds. Some of the mutagenicity of B20 was due to highly polar compounds.

CONCLUSIONS

The PM from soy biodiesel emissions was less mutagenic than that from petroleum diesel, and this reduction was associated with reduced concentrations of various weakly polar, polar, and highly polar mutagens, including PAHs, aromatic amines, nitroarenes, and oxy-PAHs.

Elucidation of fluoranthene degradative characteristics in a newly isolated Achromobacter xylosoxidans DN002

Strain DN002 isolated from petroleum-contaminated soil was identified as Achromobacter xylosoxidans based on morphological and biochemical properties and 16S rRNA phylogeny, and investigated for its potential to utilize numerous polycyclic aromatic hydrocarbons (PAHs) such as fluoranthene and pyrene as sole carbon and energy resource. Biodegradation studies showed that 500 mg(·)l(-1)fluranthene was degraded to 35.6 ± 0.3 mg(·)l(-1) by DN002 after 14 days incubation. During fluoranthene biodegradation, catechol 2,3 dioxygenase (C23O) activity was augmented 1.5 times more than catechol 1,2 dioxygenase (C12O), which indicated that C23O played a major role in fluoranthene degradation by DN002. Protein profiles were examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis and two-dimensional electrophoresis then analyzed by mass spectrometry induced by fluoranthene; a molecular mass range of 18 ∼ 66 kDa proteins were found upregulated compared with the uninduced control sample, including multiple isoenzymes of β-oxidation and dehydrogenases as well as dioxygenases. Besides, some new proteins, i.e., dihydrolipoamide succinyltransferase and aldehyde dehydrogenase family proteins and isocitrate lyase were also synthesized.

Quantification of PAHs and health risk via ingestion of vegetable in Khyber Pakhtunkhwa Province, Pakistan

This study was conducted to evaluate the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in the soil and vegetable irrigated with wastewater in 11 districts of Khyber Pakhtunkhwa (KPK) Province (Pakistan). The ∑16PAH ranged from 223 to 929 μg/kg in the soils with highest concentration in the soil of high urbanized district (Peshawar), while the lowest concentration in the soil of less urbanized district (Lakki Marwat). PAH concentrations in vegetable ranged from 51.6 to 402 μg/kg on dry weight bases (d.w). Naphthaene, phenanthrene, fluoranthene and pyrene were frequently observed in vegetable. The concentrations of higher molecular weight PAHs were lower in vegetable as compared to low molecular weight PAHs. The highest PAH concentrations were observed in leafy vegetable (lettuce>spinach). The highest TEQ value (7.2) was observed for pyrene following by naphthalene (4.9) for the samples collected from Mardan, while the lowest mean TEQ value (0.12) was found for acenaphthylene followed by benzo[k]fluoranthene (0.26) in Peshawar. The highest TEQ value was 4.1 for flouranthene followed by 3.8 for naphthalene in the KPK province. The uniqueness of this study is the quantification of PAHs in the soil and vegetable collected from a large area of KPK Province which are rapidly urbanizing.

Polycyclic aromatic hydrocarbon levels in European catfish from the upper Po River basin

Polycyclic aromatic hydrocarbons (PAHs) are a major concern in environmental studies as many of them have been labeled as probable carcinogens by the International Agency for Research on Cancer (IARC 1983). Due to their lipophilic properties and resistance to degradation, PAHs can accumulate in organic tissue. As a consequence, alarming concentrations of these compounds have been found in many aquatic species. The European catfish (Silurus glanis) is a top food chain predator that is considered to be a reliable bio-indicator of environmental pollution. From 2009 to 2011, 54 specimens of S. glanis were captured from four different sites covering the area of the Po River basin (Northern Italy). Fish muscles were analyzed in the laboratory to determine the levels of nine PAHs, namely naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, pyrene, benz[a]anthracene, chrysene, and benz[a]pyrene (BaP), which were detected by high-performance liquid chromatography (HPLC). The total average concentration of PAHs was 26.90 ± 49.50 ng g(-1) (min 0.60, max 275.75 ng g(-1)). Analysis showed that 9.20% of the fish muscles exceeded the maximum levels of 2 ng g(-1) set for BaP by European regulations (Commission Regulation (EC), 2006). Values measured for benz[a]pyrene ranged from 0.05 to 8.20 ng g(-1) (mean 1.07 ± 1.58 ng g(-1)). Chrysene and benz[a]anthracene, both considered potential human carcinogens (PAH2), were found at levels of 4.40 and 0.05 ng g(-1) (mean values), respectively. The highest mean concentration was recorded for anthracene (12.92 ng g(-1)), which has been recently included in the list of substances of very high concern (SVHC) as reported by the European Chemicals Agency (ECHA 1-9, 2009).

Cancer risk of incremental exposure to polycyclic aromatic hydrocarbons in electrocautery smoke for mastectomy personnel

Background

Electrocautery applications in surgical operations produce evasive odorous smoke in the cleanest operation rooms. Because of the incomplete combustion of electrical current in the tissues and blood vessels during electrocautery applications, electrocautery smoke (ES) containing significant unknown chemicals and biological forms is released. The potential hazards and cancer risk should be further investigated from the perspective of the occupational health of surgical staff.

Methods

The particle number concentration and the concentration of polycyclic aromatic hydrocarbons (PAHs) in ES were thoroughly investigated in 10 mastectomies to estimate the cancer risk for surgical staff. The particle number concentration and gaseous/particle PAHs at the surgeons’ and anesthetic technologists’ (AT) breathing heights were measured with a particle counter and filter/adsorbent samplers. PAHs were soxhlet-extracted, cleaned, and analyzed by gas chromatography/mass spectrometry.

Results

Abundant submicron particles and high PAH concentrations were found in ES during regular surgical mastectomies. Most particles in ES were in the size range of 0.3 to 0.5 μm, which may potentially penetrate through the medical masks into human respiration. The average particle/gaseous phase PAH concentrations at the surgeon’s breathing height were 131 and 1,415 ng/m³, respectively, which is 20 to 30 times higher than those in regular outdoor environments. By using a toxicity equivalency factor, the cancer risk for the surgeons and anesthetic technologists was calculated to be 117 × 10^-6 and 270 × 10^-6, respectively; the higher cancer risk for anesthetic technologists arises due to the longer working hours in operation rooms.

Conclusions

The carcinogenic effects of PAHs in ES on the occupational health of surgical staff should not be neglected. The use of an effective ES evacuator or smoke removal apparatus is strongly suggested to diminish the ES hazards to surgical staff.

Phytoremediation for co-contaminated soils of chromium and benzo[a]pyrene using Zea mays L

A greenhouse experiment was carried out to investigate the single effect of benzo[a]pyrene (B[a]P) or chromium (Cr) and the joint effect of Cr-B[a]P on the growth of Zea mays, its uptake and accumulation of Cr, and the dissipation of B[a]P over 60 days. Results showed that single or joint contamination of Cr and B[a]P did not affect the plant growth relative to control treatments. However, the occurrence of B[a]P had an enhancing effect on the accumulation and translocation of Cr. The accumulation of Cr in shoot of plant significantly increased by ≥ 79 % in 50 mg kg(-1) Cr-B[a]P (1, 5, and 10 mg kg(-1)) treatments and by ≥ 86 % in 100 mg kg(-1) Cr-B[a]P (1, 5, and 10 mg kg(-1)) treatments relative to control treatments. The presence of plants did not enhance the dissipation of B[a]P in lower (1and 5 mg kg(-1)) B[a]P contaminated soils; however, over 60 days of planting Z. mays seemed to enhance the dissipation of B[a]P by over 60 % in 10 mg kg(-1) single contaminated soil and by 28 to 41 % in 10 mg kg(-1)B[a]P co-contaminated soil. This suggests that Z. mays might be a useful plant for the remediation of Cr-B[a]P co-contaminated soil.

Passive sampling coupled to ultraviolet irradiation: a useful analytical approach for studying oxygenated polycyclic aromatic hydrocarbon formation in bioavailable mixtures

The authors investigated coupling passive sampling technologies with ultraviolet irradiation experiments to study polycyclic aromatic hydrocarbon (PAH) and oxygenated PAH transformation processes in real-world bioavailable mixtures. Passive sampling device (PSD) extracts were obtained from coastal waters impacted by the Deepwater Horizon oil spill and Superfund sites in Portland, Oregon, USA. Oxygenated PAHs were found in the contaminated waters with our PSDs. All mixtures were subsequently exposed to a mild dose of ultraviolet B (UVB). A reduction in PAH levels and simultaneous formation of several oxygenated PAHs were measured. Site-specific differences were observed with UVB-exposed PSD mixtures.

De-Risking of Stilbazulenyl Nitrone (STAZN), a Lipophilic Nitrone to Treat Stroke Using a Unique Panel of In Vitro Assays

In the present study, we used a comprehensive panel of in vitro assays to evaluate the efficacy and safety of stilbazulenyl nitrone (STAZN) as a lead compound to treat acute ischemic stroke. First, we measured neuroprotection in vitro using two different HT22 hippocampal nerve cell assays. Secondly, to de-risk drug development, we used CeeTox analysis with the H4IIE rat hepatoma cell line to determine the acute toxicity profile of STAZN. Third, STAZN was tested in microsomes from four species for measures of metabolic stability. Last, we determined the Ames test genotoxicity profile of STAZN using Salmonella typhimurium TA989 and TA100. In vitro, STAZN was neuroprotective against toxicity induced by iodoacetic acid, and oxytosis-induced glutathione depletion was initiated by glutamate, with an EC(50) value of 1-5 μM. Secondly, using CeeTox analysis, the estimated C(Tox) value (i.e., sustained concentration expected to produce toxicity in a rat 14-day repeat dose study) for STAZN was calculated to be 260 μM. Third, the half-life of STAZN in humans, dogs, and rats was 60-78 min. Last, the genotoxicity profile showed that STAZN did not induce bacterial colony growth under any conditions tested, indicating the lack of mutagenicity with this compound. STAZN appears to be a multi-target neuroprotective compound that has an excellent safety profile in both the CeeTox and Ames mutagenicity assays. STAZN may have significant potential as a novel neuroprotective agent to treat stroke and should be pursued in clinically relevant embolic stroke models.

UVA photoirradiation of benzo[a]pyrene metabolites: induction of cytotoxicity, reactive oxygen species, and lipid peroxidation

Benzo[ a]pyrene (BaP) is a prototype for studying carcinogenesis of polycyclic aromatic hydrocarbons (PAHs). We have long been interested in studying the phototoxicity of PAHs. In this study, we determined that metabolism of BaP by human skin HaCaT keratinocytes resulted in six identified phase I metabolites, for example, BaP trans-7,8-dihydrodiol (BaP t-7,8-diol), BaP t-4,5-diol, BaP t-9,10-diol, 3-hydroxybenzo[a]pyrene (3-OH-BaP), BaP (7,10/8,9)tetrol, and BaP (7/8,9,10)tetrol. The photocytotoxicity of BaP, 3-OH-BaP, BaP t-7,8-diol, BaP trans-7,8-diol- anti-9,10-epoxide (BPDE), and BaP (7,10/8,9)tetrol in the HaCaT keratinocytes was examined. When irradiated with 1.0 J/cm2 UVA light, these compounds when tested at doses of 0.1, 0.2, and 0.5 μM, all induced photocytotoxicity in a dose-dependent manner. When photoirradiation was conducted in the presence of a lipid (methyl linoleate), BaP metabolites, BPDE, and three related PAHs, pyrene, 7,8,9,10-tetrahydro-BaP trans-7,8-diol, and 7,8,9,10-tetrahydro-BaP trans-9,10-diol, all induced lipid peroxidation. The formation of lipid peroxides by BaP t-7,8-diol was inhibited by NaN3 and enhanced by deuterated methanol, which suggests that singlet oxygen may be involved in the generation of lipid peroxides. The formation of lipid hydroperoxides was partially inhibited by superoxide dismutase (SOD). Electron spin resonance spin trapping experiments indicated that both singlet oxygen and superoxide radical anion were generated from UVA photoirradiation of BPDE in a light dose responding manner.

Phototoxicity of herbal plants and herbal products

Plants are used by humans in daily life in many different ways, including as food, herbal medicines, and cosmetics. Unfortunately, many natural plants and their chemical constituents are photocytotoxic and photogenotoxic, and these phototoxic phytochemicals are widely present in many different plant families. To date, information concerning the phototoxicity and photogenotoxicity of many plants and their chemical constituents is limited. In this review, we discuss phototoxic plants and their major phototoxic constituents; routes of human exposure; phototoxicity of these plants and their constituents; general mechanisms of phototoxicity of plants and phototoxic components; and several representative phototoxic plants and their photoactive chemical constituents.

Structure-dependent lipid peroxidation by photoirradiation of pyrene and its mono-substituted derivatives

Pyrene, one of the most studied polycyclic aromatic hydrocarbons, can damage biological macromolecules and cause toxicity when irradiated by light. The effect of substituents, 1-amino, 1-hydroxy, 1-nitro, and 1-bromo, on light-induced lipid peroxidation is studied. Degradation kinetics and photoproduct analyses were conducted to test how these substituents affect the photoreaction. All five compounds have widely different photodegradation rates, with degradation half-lives, ranging from 8 min to 495 min. These rates parallel their light absorptivity. Four out of the five compounds induce lipid peroxidation when irradiated with UVA light, whereas 1-aminopyrene causes minimum or no lipid peroxidation. The relative amount of lipid peroxidation caused is: 1-bromopyrene > pyrene > 1-nitropyrene ≈ 1-hydroxypyrene > 1-aminopyrene. This relative lipid peroxidation is dependent on the substituent due to the following factors: light absorptivity, relative rates of the competing processes in the excited states, nature of the photoreaction, and nature of the photoproducts.

Pyrene exposure influences the thyroid development of Sebastiscus marmoratus embryos

Thyroid hormones play crucial roles in regulating development, morphogenesis, growth, and behavior in fishes. Some environmental pollutants have adverse effects on either development or function of the thyroid gland in fish. However, there are few reports on the effects of polycyclic aromatic hydrocarbons (PAHs) on fish thyroid. In the present study, rockfish (Sebastiscus marmoratus) embryos were exposed to pyrene (Py) for 5 days at the concentrations of 0.5, 5, and 50 nmol/L. The results showed that Py exposure decreased the expression of thyroid primordium markers, Pax2.1 and Nk2.1a as detected by quantitative PCR and in situ hybridization, and reduced the concentration of T(3), but not T(4). Thyroid receptor genes (TRα and TRβ) expression was down-regulated by Py. At the same time, Py exposure impaired the expression of thyroid development related genes, Fgfr2 and Hoxa3a expression, and altered the mRNA levels of thyroid function related genes, Deio1, Ttr, and Tg. In conclusion, the results demonstrated Py exposure inhibited thyroid development and influenced the function of thyroid system in rockfish embryos.

The Genotoxicity of Priority Polycyclic Aromatic Hydrocarbons (PAHs) Containing Sludge Samples

ABSTRACT In this research work we developed in vitro tests utilizing mammalian cell cultures, which can rapidly assess effect of exposure of oily sludge-derived chemicals on human and ecological health. Many of these are hazardous to health and environment due to their toxicity and/or accumulation potential in sediments as well as in organisms. Petroleum refinery and petrochemical industry-derived oily sludges contain toxic polycyclic aromatic hydrocarbons (PAHs), some of which are lipophilic in nature. Risk assessment of environmental samples suffers from inadequate availability of toxicity data, lack of knowledge about behavior of genotoxic substances in complex matrices, paucity of information on synergistic and antagonistic interactions of mixture of components, etc.; the literature describing the behavior of genotoxic substances in complex mixtures is sparse and sometimes contradictory. The present study aims at assessing the genotoxic potential of oily sludges collected from an integrated petroleum refinery and petrochemical industry located in the southwestern part of India and a petrochemical industry located in the western part of India using a battery of genotoxicity assays such as DNA damage/strand break, chromosomal aberration, p(53) protein induction, and apoptosis in CHO-K1 cell culture system. Exposure with different dose levels of sludge extracts (25, 50, 100 muL) in CHO-K1 cells could cause statistically significant level of (P < 0.001) DNA damage, chromosomal aberration, p(53) protein induction, and apoptosis in comparison to negative control treatment groups, and the genotoxicity was attributed to PAHs present in the sludge as identified by GC-MS. This implies that the sludges are genotoxic in nature in mammalian cells tested, and the exposure to these may pose a potential genotoxic risk to human beings.

Genotoxic effects in blood cells of Mus musculus and Iguana iguana living near coal mining areas in Colombia

Coal is a mixture of chemicals with the capacity of promoting biochemical changes that may lead to DNA damage. In this study, the comet assay in peripheral blood cells, and the micronucleus test in blood smears were used to evaluate potential genotoxic effects derived from exposure to coal mining activities on wild populations of Mus musculus and Iguana iguana. Four locations from Colombia were evaluated: La Loma and La Jagua de Ibirico, two municipalities located near coal mining fields at the Department of Cesar; and Valledupar and Arjona, cities used as reference sites, both localized at least 100 and 200km far from the mines, respectively. Compared to Valledupar and Arjona, animals collected in close proximity to coal mining areas showed highest percentages of DNA damage for both species, evidencing that living around coal mining fields may result in an increase of DNA lesions in blood cells of rodents and reptiles. The results for micronucleus test were conflicting. Mice from Arjona had greater number of cells with micronucleus than those from the other studied locations, probably as a result of infection found by blood parasites. In summary, it was demonstrated that animals living around coal mining areas have a greater chance of having DNA damage, as measured by the comet assay, than those from sites far from the coal dust source.

Phototoxicity and environmental transformation of polycyclic aromatic hydrocarbons (PAHs)-light-induced reactive oxygen species, lipid peroxidation, and DNA damage

Polycyclic aromatic hydrocarbons (PAHs) are a class of mutagenic and tumorigenic environmental contaminants. Although the mechanisms by which PAHs induce cancer in experimental animals have been extensively studied and the metabolic activation pathways have been determined, the environmental fate of PAHs and the phototoxicity exerted by PAHs, as well as their photoreaction products formed in the environment, have received much less attention. In this review, the formation of oxygenated PAHs, PAH quinones, nitro-PAHs, and halogenated PAHs from photoreaction of environmental PAHs are addressed. Upon light irradiation, PAHs and all PAH photoreaction products can absorb light energy to reach photo-excited states, which react with molecular oxygen, medium, and coexisting chemicals to produce reactive oxygen species (ROS) and other reactive intermediates, such as oxygenated PAHs and free radicals. These intermediates, including ROS, induce lipid peroxidation, and DNA damage including DNA strand breakage, oxidation to 8-oxo-2'-deoxyguanosine, and DNA-adducts. Since these toxicological endpoints are associated with age-related diseases, including cancer, environmental PAHs concomitantly exposed to sunlight may potentially promote human skin damage, leading to ageing and skin cancers. Thus, we suggest that (i) in addition to the widely recognized metabolic pathways, more attention must be paid to photoreaction as an important activation pathway for PAHs, (ii) risk assessment of environmental PAHs should take into consideration the complex photochemical reactions leading to mixtures of products that are also phototoxic; and (iii) the study of structure-toxicity relationships should be expanded to cover the complex photoreactions and extrinsic factors that affect phototoxicity endpoints.

Assessment of phenanthrene bioavailability in aged and unaged soils by mild extraction

It has become apparent that the threat of an organic pollutant in soil is directly related to its bioavailable fraction and that the use of total contaminant concentrations as a measure of potential contaminant exposure to plants or soil organisms is inappropriate. In light of this, non-exhaustive extraction techniques are being investigated to assess their appropriateness in determining bioavailability. To find a suitable and rapid extraction method to predict phenanthrene bioavailability, multiple extraction techniques (i.e., mild hydroxypropyl-β-cyclodextrin (HPCD) and organic solvents extraction) were investigated in soil spiked to a range of phenanthrene levels (i.e., 1.12, 8.52, 73, 136, and 335 μg g( - 1) dry soil). The bioaccumulation of phenanthrene in earthworm (Eisenia fetida) was used as the reference system for bioavailability. Correlation results for phenanthrene suggested that mild HPCD extraction was a better method to predict bioavailability of phenanthrene in soil compared with organic solvents extraction. Aged (i.e., 150 days) and fresh (i.e., 0 day) soil samples were used to evaluate the extraction efficiency and the effect of soil contact time on the availability of phenanthrene. The percentage of phenanthrene accumulated by earthworms and percent recoveries by mild extractants changed significantly with aging time. Thus, aging significantly reduced the earthworm uptake and chemical extractability of phenanthrene. In general, among organic extractants, methanol showed recoveries comparable to those of mild HPCD for both aged and unaged soil matrices. Hence, this extractant can be suitable after HPCD to evaluate risk of contaminated soils.

Chemical-assisted phytoremediation of CD-PAHs contaminated soils using Solanum nigrum L

A well-characterized cadmium (Cd) hyperaccumulating plant Solanum nigrum was grown in Cd and polycyclic aromatic hydrocarbons (PAHs) co-contaminated soil that was repeatedly amended with chemicals, including EDTA, cysteine (CY), salicylic acid (Sa), and Tween 80 (TW80), to test individual and combined treatment effects on phytoremediation of Cd-PAHs contaminated soils. Plant growth was negatively affected by exogenous chemicals except for EDTA. S. nigrum could accumulate Cd in tissues without assistant chemicals, while there was no visible effect on the degradation of PAHs. Cysteine had significant effects on phytoextraction of Cd and the highest metal extraction ratio (1.27%) was observed in 0.9 mmol/kg CY treatment. Both salicylic acid and Tween 80 had stimulative effects on the degradation of PAHs and there was the maximal degradation rate (52.6%) of total PAHs while 0.9 mmol/kg Sa was applied. Furthermore, the combined treatment T(0.1EDTA+0.9CY+0.5TW80) and T(0.5EDTA+0.9CY+03Sa) could not only increase the accumulation of Cd in plant tissues, but also promote the degradation of PAHs. These results indicated that S. nigrum might be effective in phytoextracting Cd and enhancing the biodegradation of PAHs in the co-contaminated soils with assistant chemicals.

Toxic effects of gold nanoparticles on Salmonella typhimurium bacteria

Nanometer-sized gold, due to its beautiful and bountiful color and unique optical properties, is a versatile material for many industrial and societal applications. We have studied the effect of gold nanoparticles on Salmonella typhimurium strain TA 102. The gold nanoparticles in solution prepared using the citrate reduction method is found not to be toxic or mutagenic but photomutagenic to the bacteria; however, careful control experiments indicate that the photomutagenicity is due to the co-existing citrate and Au³⁺ ions, not due to the gold nanoparticle itself. Au³⁺ is also found to be photomutagenic to the bacteria at concentrations lower than 1 µM, but toxic at higher concentrations. The toxicity of Au³⁺ is enhanced by light irradiation. The photomutagenicity of both citrate and Au³⁺ is likely due to the formation of free radicals, as a result of light-induced citrate decarboxylation or Au³⁺ oxidation of co-existing molecules. Both processes can generate free radicals that may cause DNA damage and mutation. Studies of the interaction of gold nanoparticles with the bacteria indicate that gold nanoparticles can be absorbed onto the bacteria surface but not able to penetrate the bacteria wall to enter the bacteria.

Assessment of pyrene bioavailability in soil by mild hydroxypropyl-β-cyclodextrin extraction

Bioavailability of organic pollutants in soil is currently a much-debated issue in risk assessment of contaminated sites. Ecorisk of an organic pollutant in soil is strongly influenced by the properties of the soil and its contamination history. To evaluate the effect of aging on the availability of pyrene, earthworm (Eisenia fetida) accumulation and chemical extraction by exhaustive and nonexhaustive techniques in soil spiked with a range of pyrene levels (1.07, 9.72, 88.4, 152, and 429 μg g⁻¹ dry soil) were measured in this study using both unaged (i.e., 0 days) and aged (i.e., 69, 150, and 222 days) soil samples. The results showed that the amount of pyrene accumulated by earthworms did not change greatly with aging time under different high-dose contamination levels, but changed significantly at lower concentrations. Moreover, aging (after 222 days) significantly decreased biological and chemical availability of pyrene. Furthermore, the relationship between earthworm bioaccumulation, hydroxypropyl-β-cyclodextrin (HPCD), and organic solvent extraction was investigated in order to find a suitable and rapid method to predict pyrene bioavailability. Results showed that, at different levels of pyrene, the mean values of earthworm uptake and HPCD extractability were 10-40% and 10-65%, respectively. Correlation (r² = 0.985) and extraction results for pyrene suggested that mild HPCD extraction was a better method to predict bioavailability of pyrene in soil compared with organic solvent extraction.

Degradation of phenanthrene and pyrene in spiked soils by single and combined plants cultivation

The present study was conducted to investigate the capability of four plant species (tall fescue, ryegrass, alfalfa, and rape seed) grown alone and in combination to the degradation of phenanthrene and pyrene (polycyclic aromatic hydrocarbons, PAHs) in spiked soil. After 65 days of plant growth, plant biomass, dehydrogenase activity, water-soluble phenolic (WSP) compounds, plant uptake and accumulation and residual concentrations of phenanthrene and pyrene were determined. Our results showed that presence of vegetation significantly enhanced the dissipation of phenanthrene and pyrene from contaminated soils. Higher degradation rates of PAHs were observed in the combined plant cultivation (98.3-99.2% phenanthrene and 88.1-95.7% pyrene) compared to the single plant cultivation (97.0-98.0% phenanthrene and 79.8-86.0% pyrene). Contribution of direct plant uptake and accumulation of phenanthrene and pyrene was very low compared to the plant enhanced dissipation. By contrast, plant-promoted biodegradation was the predominant contribution to the remediation enhancement. The correlation analysis indicates a negative relation between biological activities (dehydrogenase activity and WSP compounds) and residual concentrations of phenanthrene and pyrene in planted soils. Our results suggest that phytoremediation could be a feasible choice for PAHs contaminated soil. Moreover, the combined plant cultivation has potential to enhance the process.

Effects of UVA and visible light on the photogenotoxicity of benzo[a]pyrene and pyrene

This study investigated the role of UVA/visible light (U, 320-800 nm) and visible light (V, 400-800 nm) in the phototoxicity and photogenotoxicity of two ubiquitous polycyclic aromatic hydrocarbons (PAH): benzo[a]pyrene (BaP) and Pyrene (Pyr). These mechanisms were evaluated by the WST-1 test and the comet assay on normal human keratinocytes (NHK) and by the micronucleus test on CHO cells. The production of reactive oxygen species (ROS) was assessed through the induction of 8-oxodeoxyguanine (8-oxodG) lesions by immunofluorescence staining in NHK. Results of the WST-1 test revealed the phototoxic properties of BaP and Pyr after irradiation with U and V lights. BaP presented the highest phototoxic properties. Results of the comet assay showed that U- and V-irradiated BaP and Pyr induced increasing rates of DNA single-strand breaks in NHK, in a dose dependent manner. The tested PAH could also induce increased levels of micronuclei in CHO cells after U and V irradiations. Increasing 8-oxodG levels were detected after U and V irradiations in BaP- and Pyr-treated keratinocytes and confirmed the involvement of ROS in the photogenotoxicity of PAH. Overall, this study highlighted the existence of an alternative pathway of PAH genotoxicity that is induced by UVA and/or visible light. Visible light is suggested to photoactivate PAH by a mechanism which is mainly based on oxidative reactions.

Potential use of DNA adducts to detect mutagenic compounds in soil

In this study, three different soils with contrasting features, spiked with 300 mg benzo[a]pyrene (BaP)/kg dry soil, were incubated at 20 degrees C and 60% water holding capacity for 540 days. At different time points, BaP and DNA were extracted and quantified, and DNA adducts were quantified by (32)P-postlabelling. After 540 days incubation, 69.3, 81.6 and 83.2% of initial BaP added remained in Cruden Bay, Boyndie and Insch soils, respectively. Meanwhile, a significantly different amount of DNA-BaP adducts were found in the three soils exposed to BaP over time. The work demonstrates the concept that DNA adducts can be detected on DNA extracted from soil. Results suggest the technique is not able to directly reflect bioavailability of BaP transformation products. However, this new method provides a potential way to detect mutagenic compounds in contaminated soil and to assess the outcomes of soil remediation.

Light-Induced Toxic Effects of Tamoxifen: A Chemotherapeutic and Chemopreventive Agent

Tamoxifen is a powerful drug used to treat breast cancer patients, and more than 500,000 women in the U. S. are being treated with this drug. In our study, tamoxifen is found to be photomutagenic in Salmonella typhimurium TA102 at concentrations as low as 0.08 muM and reaches maximum photomutagenicity at 0.4 muM under a light dose equivalent to 20 min sunlight. These concentrations are comparable to the plasma tamoxifen concentration of 0.4 to 3 muM for patients undergoing tamoxifen therapy. The toxicity seems to be the result of DNA damage and/or lipid peroxidation caused by light irradiation of tamoxifen. The DNA damage caused by irradiation of PhiX174 DNA in the presence of tamoxifen appears to be formation of DNA-tamoxifen covalent adducts, not single strand/double strand cleavages, and there is no oxygen involvement. This is confirmed by EPR experiments that carbon-centerd radicals are formed by light irradiation of tamoxifen and there is no singlet oxygen formation. Although superoxide radical is formed, it is not involved in DNA damage.

Occurrence of polycyclic aromatic hydrocarbons in dust emitted from circulating fluidized bed boilers

Occurrence of polycyclic aromatic hydrocarbons (PAHs) in granulometric fractions of dust emitted from a hard coal fired circulating fluidized bed (CFB) boiler was investigated. The dust was sampled with the use of a Mark III impactor. In each fraction of dust, by using gas chromatography (GC), 16 selected PAHs and total PAHs were determined and the toxic equivalent B(a)P (TE B(a)P) was computed. The results, recalculated for the standard granulometric fractions, are presented as concentrations and content of the determined PAHs in dust. Distributions of PAHs and their profiles in the granulometric dust fractions were studied also. The PAHs in dust emitted from the CFB boiler were compared with those emitted from mechanical grate boilers; a distinctly lower content of PAHs was found in dust emitted from the former.

Phototoxicity of phenylenediamine hair dye chemicals in Salmonella typhimurium TA102 and human skin keratinocytes

Phenylenediamines (PD) are dye precursors used to manufacture hair dyes. The three PDs, 1,2-,1,3-, and 1,4-PD and three chlorinated PDs, 4-chloro-1,2-PD, 4-chloro-1,3-PD, and 4,5-dichloro-1,2-PD were studied for their mutagenic effect in Salmonella typhimurium TA 102, cytotoxicity in human skin keratinocyte cells, and for DNA cleavage. The results show that all six compounds are not toxic/mutagenic in TA 102 bacteria or skin cells, and do not cause DNA cleavage in PhiX 174 phage DNA. If the same tests are carried out by exposing them to light irradiation concurrently, all three chlorinated PDs cause mutation in TA 102 bacteria and single strand cleavage in PhiX174 phage DNA. This indicates that chlorination of the PDs makes these compounds more photochemically active and produces reactive species that cause DNA damage and mutation. For the photocytotoxicity test in skin cells, it appears there is no such structure-activity relationship. Two chlorinated PDs and two non-chlorinated PDs are cytotoxic at a fairly high concentration (1000microM) upon exposure to light irradiation.

Genotoxicity of combined exposure to polycyclic aromatic hydrocarbons and UVA--a mechanistic study

Solar UV radiation and benzo[a]pyrene (BaP) are two carcinogenic agents. When combined, their deleterious properties are synergistic. In order to get insights into the underlying processes, we carried out a mechanistic study within isolated DNA photosensitized to UVA radiation by either BaP, its diol epoxide metabolite (BPDE) or the tetraol arising from the hydrolysis of this last molecule. Measurement of the level of the oxidized base 8-oxo-7,8-dihydroguanine revealed that BaP is a poor sensitizer while BPDE and tetraol are more potent ones. None of these compounds was found to photosensitize formation of cyclobutane pyrimidine dimers through triplet energy transfer. On the basis of the distribution of oxidized DNA bases, we could show that photosensitization of DNA by BPDE involves electron abstraction (Type I) while tetraol acts mainly through singlet oxygen production (Type II). Under our experimental conditions, Type I was the major photosensitization process, which shows the lack of involvement of tetraol in the observed photo-oxidation reaction. Finally, we could show that the adducts, resulting from the alkylation of DNA by BPDE, are very potent sensitizers. Indeed, they are located in the close vicinity of the double helix and thus perfectly placed to induce oxidation reactions.

Accumulation of polycyclic aromatic hydrocarbons and heavy metals in lettuce grown in the soils contaminated with long-term wastewater irrigation

Accumulation of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) by crop plants from contaminated soils may pose health risks. A greenhouse pot experiment using lettuce (Lactuca satuva L.) as a representative vegetable was conducted to assess the concentrations of PAHs and HMs in vegetables grown in wastewater-contaminated soils. The concentrations of total PAHs were ranged from 1.5 to 3.4 mg kg(-1) in the contaminated soils, while 1.2 mg kg(-1) in the reference soil. Linear regression analyses showed that the relationships between soil and shoot PAH concentrations were stronger for LMW-PAHs (R(2) between 0.51 and 0.92) than for HMW-PAHs (R(2) 0.02 and 0.60), suggesting that translocation for LMW-PAHs is faster than HMW-PAHs. Furthermore, the data imply that root uptake was the main pathway for HMW-PAHs accumulation. The plant shoots were also highly contaminated with HMs, particularly Cd (0.4-0.9 mg kg(-1)), Cr (3.4-4.1 mg kg(-1)), Ni (11.7-15.1 mg kg(-1)) and Pb (2.3-5.3 mg kg(-1)), and exceed the guidance limits set by State Environmental Protection Administration (SEPA), China and the World Health Organization (WHO). This study highlights the potential health risks associated with cultivation and consumption of leafy vegetables on wastewater-contaminated soils.