Dose Of Polycyclic Aromatic Hydrocarbons Research Articles

Benchmark dose estimation of polycyclic aromatic hydrocarbons exposure base on Bayesian kernel machine regression

Objective: To explore benchmark dose (BMD) estimations of polycyclic aromatic hydrocarbons (PAHs) based on Bayesian kernel machine regression (BKMR) . Methods: A total of 155 adult residents of a coking plant in Shanxi Province who were surveyed in summer (June to August) from 2014 to 2019 were selected as the research objects. Fasting elbow vein blood of the subjects was collected in the morning for automatic analysis and detection of blood routine. Morning urine samples were collected for automatic analysis and detection of urine routine and urine creatinine detection. BKMR model combined with BMD method was used to calculate the acceptable doses of PAHs exposure on red blood cell damage in non-occupational population. Results: The concentration of hydroxylpolycyclic aromatic hydrocarbons (OH-PAHs) in the red blood cells abnormal group (n=117) was significantly higher than that in the normal group (n=38) (P<0.01). In the combined effect of OH-PAHs, 2-hydrol-naphthalene contributed the most, and the posterior inclusion probability (PIP) value was 0.9354. When OH-PAHs ≥P(55) concentration, the joint effect on the risk of red blood cell abnormalities increased as the concentration of the OH-PAHs mixture increased. When OH-PAHs were at P(65) and P(75) concentrations, respectively, the risk of red blood cell abnormalities in adults were 3.09 and 4.98 times that of OH-PAHs at P(50) concentrations, respectively. Compared with high concentration, low concentration of OH-PAHs exposure was more sensitive to red blood cell darmage. The acceptable doses of 8 kinds of OH-PAHs were 1.010 μmol/mol Cr (2-hydrol-naphthalene), 0.743 μmol/mol Cr (1-hydrol-naphthalene), 0.901 μmol/mol Cr (2-hydroxy-fluorene) and 0.775 μmol/mol Cr (1-hydroxy-phenanthrene), 0.737 μmol/mol Cr (1-hydroxy-pyrene), 0.607 μmol/mol Cr (9-hydroxy-fluorene), 0.713 μmol/mol Cr (2-hydroxy-phenanthrene) and 0.628 μmol/mol Cr (3-hydroxybenzo[a] pyrene), respectively. Conclusion: OH-PAHs mixture has positive combined effect on red blood cell damage in non-occupational population, and low concentration of OH-PAHs exposure is more sensitive to red blood cell damage. It is recommended that the exposure dose of PAHs should be controlled within 1 μmol/mol Cr.

Effectiveness of dermal cleaning interventions for reducing firefighters’ exposures to PAHs and genotoxins

Firefighters are exposed to carcinogenic and mutagenic combustion emissions, including polycyclic aromatic hydrocarbons (PAHs). Fire service and firefighter cancer advocacy groups recommend skin cleaning using wipes or washing with detergent and water after exposure to smoke, although these strategies have not been proven to reduce exposures to harmful combustion products such as PAHs. This study assessed dermal decontamination methods to reduce PAH exposures by firefighters participating in live fire training scenarios. Study participants (n = 88) were randomly assigned to an intervention group (i.e., two types of commercial skin wipes, detergent and water, or a control group who did not use any skin decontamination). PAHs were measured in personal air (during the fire) and dermal wipe samples (before and after fire suppression and after dermal decontamination). PAH metabolites and mutagenicity were measured in urine samples before and after fire suppression. Airborne PAH concentrations during the fire ranged between 200 and 3,970 μg/m3 (mean = 759 μg/m3, SD = 685 μg/m3). Firefighters had higher total PAHs and high-molecular-weight PAHs on their skin after the fire compared to before (1.3- and 2.2-fold, respectively, p < 0.01). Urinary PAH metabolites increased significantly following exposure to the training fires by 1.7 to 2.2-fold (depending on the metabolite, p < 0.001). Urinary mutagenicity did not differ significantly between pre- and post-fire for any of the decontamination methods. Detergent and water was the only intervention that removed a significant amount of total PAHs from the skin (0.72 ng/cm2 preintervention vs. 0.38 ng/cm2 postintervention, p < 0.01). However, fold changes in urinary PAH metabolites (i.e., pre- vs. post-exposure levels) did not differ among any of the dermal decontamination methods or the control group. These data suggest that despite on-site attempts to remove PAHs from firefighters’ skin, the examined interventions did not reduce the internal dose of PAHs. Future work should investigate preventing initial exposure using other interventions, such as improved personal protective equipment.

Competitive Metabolism of Polycyclic Aromatic Hydrocarbons (PAHs): An Assessment Using In Vitro Metabolism and Physiologically Based Pharmacokinetic (PBPK) Modeling.

Humans are routinely exposed to complex mixtures such as polycyclic aromatic hydrocarbons (PAHs) rather than to single compounds, as are often assessed for hazards. Cytochrome P450 enzymes (CYPs) metabolize PAHs, and multiple PAHs found in mixtures can compete as substrates for individual CYPs (e.g., CYP1A1, CYP1B1, etc.). The objective of this study was to assess competitive inhibition of metabolism of PAH mixtures in humans and evaluate a key assumption of the Relative Potency Factor approach that common human exposures will not cause interactions among mixture components. To test this objective, we co-incubated binary mixtures of benzo[a]pyrene (BaP) and dibenzo[def,p]chrysene (DBC) in human hepatic microsomes and measured rates of enzymatic BaP and DBC disappearance. We observed competitive inhibition of BaP and DBC metabolism and measured inhibition coefficients (Ki), observing that BaP inhibited DBC metabolism more potently than DBC inhibited BaP metabolism (0.061 vs. 0.44 µM Ki, respectively). We developed a physiologically based pharmacokinetic (PBPK) interaction model by integrating PBPK models of DBC and BaP and incorporating measured metabolism inhibition coefficients. The PBPK model predicts significant increases in BaP and DBC concentrations in blood AUCs following high oral doses of PAHs (≥100 mg), five orders of magnitude higher than typical human exposures. We also measured inhibition coefficients of Supermix-10, a mixture of the most abundant PAHs measured at the Portland Harbor Superfund Site, on BaP and DBC metabolism. We observed similar potencies of inhibition coefficients of Supermix-10 compared to BaP and DBC. Overall, results of this study demonstrate that these PAHs compete for the same enzymes and, at high doses, inhibit metabolism and alter internal dosimetry of exposed PAHs. This approach predicts that BaP and DBC exposures required to observe metabolic interaction are much higher than typical human exposures, consistent with assumptions used when applying the Relative Potency Factor approach for PAH mixture risk assessment.

Effect of soil contamination with polycyclic aromatic hydrocarbons from drilling waste on germination and growth of lawn grasses

In many studies, grasses were used to increase the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in soil because they are the most common plant species on the ground level and are quite resistant to contamination with these compounds. One of the main failures in PAH remediation in soil using plant species was the negative impact on germination and seedling growth. The objective of this study was to evaluate grass seed germination and seedling growth affected by drill cuttings to determine the resistance of selected grass species to the impact of PAH and their suitability for an effective phytoremediation of soils contaminated with waste that contain compounds from this group. In the study four grass species: tall fescue (Festuca arundinacea), red fescue (Festuca rubra), perennial ryegrass (Lolium perenne) and common meadow-grass (Poa pratensis). The germination energy of all species decreased as the amount of drill cuttings increased. Among the species studied, the highest germination energy and capacity were found in Lolium perenne (54.1 and 73.2 respectively), and the lowest – in Poa pratensis (16.7 and 23.3 respectively). With an increasing amount of drill cuttings, the root and seedling height were decreased. Festuca arundinacea seedlings were distinctly the highest and had the longest roots (96.7 and 52.7, respectively), while Poa pratensis seedlings showed the significantly slowest seedling and root elongation rate (30.4 and 12.4, respectively). However, the strongest decrease in seedling height and root length compared to the control was observed in Festuca rubra. Based on IC50, the greatest tolerance to the addition of drilling waste to the substrate was found for Festuca arundinacea and Festuca rubra. The conducted investigation indicates that Festuca arundinacea and Lolium perenne are grass species that are least sensitive to drilling waste in the substrate because no significant differences were found in root length and seedling height between the control soil and the soil where a PAH dose of 5% and 10% was applied.

Dose makes poison: Insights into the neurotoxicity of perinatal and juvenile exposure to environmental doses of 16 priority-controlled PAHs

Whether chronic exposure to environmental doses of polycyclic aromatic hydrocarbons (PAHs) can lead to neurotoxic effects is still unclear. Hence, the neurotoxic effects of perinatal and juvenile exposure to 16 priority-controlled PAHs were investigated. The mice were treated with 0, 0.5, 18.75, 50, 1875 μg/kg/day of PAHs corresponding to various population exposure concentrations from gestation to postnatal day 60. Urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) and hippocampal and cortical neurotransmitter levels were determined using liquid chromatography-tandem mass spectrometry. Typical indicators or outcome of neurotoxicity, including, spatial learning and memory ability, hippocampal long-term potentiation (LTP) and dendritic spine density were evaluated via Morris water maze tests, electrophysiological experiments and Golgi-Cox assays, respectively. The results showed that exposure to different levels of PAH could not increase oxidative DNA damage level. Mice exposed to 0.5, 50 and 1875 μg/kg/day PAHs had significantly longer escape latency than the control group only on the 1st day (p < 0.05). The number of platform crossings and the time spent in target quadrant were similar between the control and the PAHs-exposed mice. Compared with the control mice, only those exposed to 50 μg/kg/day PAHs had significantly lower LTP in hippocampal CA1 region and dendritic spine density in hippocampal DG region (p < 0.05). Except for serotonin, no significant difference in hippocampal and cortical neurotransmitter concentrations was observed between the control and PAHs-exposed groups. Taken together, perinatal and juvenile exposure to environmental doses of PAHs had no profound effect on spatial learning and memory abilities, hippocampal LTP, dendritic spines density, and neurotransmitter levels. These unexpected findings were quite different from previous in vivo studies which commonly used 2–3 orders of magnitude higher PAHs doses to treat animals. Thus, the environmental dose is a crucial reference for future toxicological research to reveal the actual toxic mechanisms and human health effects of PAHs exposure.

Comprehensive metabolomics insights into benzo[a]pyrene-induced metabolic reprogramming related to H460 cell invasion and migration

Polycyclic aromatic hydrocarbon exposure contributes most to the initiation and progression of lung cancer. Metabolic reprogramming is an important hallmark of tumors and essential for the malignant transformation and progression of lung cancer. However, benzo[a]pyrene-induced metabolic reprogramming of lung cancer cells during the invasion and migration is still unclear. Accordingly, benzo[a]pyrene (5 μg/L, within the range of the equivalent dose of polycyclic aromatic hydrocarbons in human blood), was used to induce the invasion and migration of large cell lung cancer H460 cells. Subsequently, an untargeted metabolomics approach using ultra-high-performance liquid chromatograph-mass spectrometry was conducted to discover benzo[a]pyrene-induced metabolic reprogramming of H460 cells and potential therapeutic targets. We showed that 117 of 202 identified metabolites were significantly altered in H460 cells upon benzo[a]pyrene exposure. Subsequent pathway analysis revealed that 31 metabolic pathways were significantly altered in benzo[a]pyrene-exposed H460 cells. Notably, 11 fatty acids (10–22 carbons) and 6 purine nucleotides accumulated, while acylcarnitines (6–18 carbons), most phospholipids (such as lysophosphatidylcholines, lysophosphatidylethanolamines, lysophosphatidylinositols and phosphatidylcholines) and sphingolipids (such as sphingomyelins and sphingosines) were decreased in benzo[a]pyrene-exposed H460 cells. Besides, 14 amino acid metabolic pathways were significantly altered in benzo[a]pyrene-exposed H460 cells, such as glutathione metabolism, alanine, aspartate and glutamate metabolism, tryptophan metabolism, and arginine and proline metabolism. Spearman correlation analysis and correlation networks demonstrated high correlations of fatty acids, acylcarnitines, phospholipids, sphingolipids, nucleotides and amino acids with H460 cell invasion and migration. This study suggests fatty acid metabolism, phospholipid metabolism, sphingolipid metabolism, amino acid metabolism and nucleotide metabolism as potential therapeutic targets for intervening the toxic effects of polycyclic aromatic hydrocarbons and related diseases. To our knowledge, decreases in acylcarnitines (6–18 carbons), phospholipids and sphingolipids, and accumulation of fatty acids and purine nucleotides are novel phenomena in benzo[a]pyrene-exposed large cell lung cancer cells.

EXPOSURE ASSESSMENT OF RAYONG OIL SPILL CLEANUP WORKERS.

In July of 2013, a pipeline connecting an offshore oil platform to a tanker caused crude oil to spill into the Sea of Rayong off the coast of Thailand. The resulting oil slick, estimated to be between 50 and 190 cubic meters (336-1,200 barrels), washed ashore one day later on the island of Samet. We conducted a study to quantify internal dose of polycyclic aromatic hydrocarbons (PAHs) and benzene in 1,262 oil spill cleanup workers, and to examine factors related to their dose. Frozen stored urine samples (n=1343) collected from the workers during the one month cleanup period were used to measure the concentration of 1-hydroxypyrene-glucuronide (1-OHPG), cotinine and creatinine. Data from questionnaires and urinary trans,trans-muconic acid (t,t-MA), a benzene metabolite, measured previously as part of a worker health surveillance plan, were linked with the laboratory data. The internal dose of urinary 1-OHPG was highest in individuals who worked during the first 3 days of cleanup work (median: 0.97 pmol/ml) and was 66.7% lower (median: 0.32 pmol/ml) among individuals who worked in the final week of the study (days 21-28). After adjusting for age, cotinineand creatinine by regression analysis, the decline in urinary 1-OHPG concentration with days of cleanup remained significant (P-trend <0.001). A decreasing trend by days of cleanup was also observed for detectable urinary t,t-MA percentage (P-trend <0.001). Rayong oil spill cleanup workers exhibited evidence of elevated levels of PAH and benzene exposure during the early weeks of cleanup, compared to near background levels 4 weeks after cleanup began. Long-term health monitoring of oil spill cleanup workers is advised.

Filaggrin variations are associated with PAH metabolites in urine and DNA alterations in blood

Dermal chemical exposure is common in many professions. The filaggrin protein is important for the skin barrier and variations in the filaggrin gene (FLG) may influence the uptake of chemicals via the skin, and consequently, the degree of systemic effects. The aim of this study was to investigate, in chimney sweeps with occupational exposure to polycyclic aromatic hydrocarbons (PAH) from soot, the influence of variation in FLG on internal PAH dose and DNA alterations, including epigenetic, previously linked to cancer and cardiovascular disease.We used TaqMan PCR to genotype 151 chimney sweeps and 152 controls for four FLG null variants (R501X, R2447X, S3247X and 2282del4) which cause impaired skin barrier, and FLG copy number variation (12th repeat, CNV12) which potentially is beneficial for the skin barrier. The internal dose of PAH was represented by urinary PAH metabolites (e.g. 1-hydroxypyrene and 3-hydroxybenzo[a]pyrene) that we measured by LC-MS/MS. We measured epigenetic alterations (methylation of AHRR and F2RL3) in blood by pyrosequencing; and DNA alterations (telomere length and mitochondrial DNA copy number) by real-time PCR. Hypomethylation of AHRR or F2RL3 is a risk factor for lung cancer and shorter telomere length a risk factor for cardiovascular disease.The frequencies of FLG null were 8.6 and 11.8% (p = 0.35), and CNV12 27.8 and 19.7% (p = 0.09) in chimney sweeps and controls, respectively. We found that among chimney sweeps working predominately with soot sweeping (high PAH exposure), CNV12 carriers had lower concentrations of PAH metabolites in urine compared with non-carriers (median 1-hydroxypyrene = 0.37 vs 0.86 μg/g creatinine respectively; p = 0.025 by linear regression models adjusted for age, BMI and smoking) compared to sweeps not carrying CNV12. Further, FLG null was associated with approximately 2.5% higher methylation of F2RL3 (cg03636183, p = 0.019 after adjustment for exposure group, age, BMI and smoking). FLG null was associated with approximately 7% shorter telomere length (p = 0.015, adjusted model).Our results suggest that FLG variations may influence the dose of PAH in highly exposed workers, possibly via dermal uptake. It also suggests that FLG variation may influence the degree of (epi)genotoxicity in the body. FLG variation is common in the working population and should be considered in risk assessment.

ETS Exposure and PAH Body Burden in Nonsmoking Italian Adults.

Active smoking is associated with increased body burden of polycyclic aromatic hydrocarbons (PAHs); the aim of this study was to assess whether environmental tobacco smoking (ETS) increases the internal dose of PAHs. In 344 nonsmoking Italian adults, out of 497 individuals selected as representative of the population of the town of Modena, ETS exposure was evaluated by a self-administered questionnaire and by the measurement of urinary cotinine (COT-U). PAH exposure was assessed by the measurement of urinary 1-hydroxypyrene (1-OHPYR) and of ten urinary PAHs. In all subjects, median (5th–95th percentile) COT-U was 0.47 (<0.1–3.91) µg/L. While 58 subjects reported to be ETS exposed (ETSQUEST), 38 individuals were identified as ETS exposed on the basis of a COT-U value of 1.78 (90% confidence interval 1.75–1.80) µg/L, previously derived as an upper reference value in not ETS exposed Italian adults (ETSCOT). Median COT-U levels were 1.38 (<0.1–9.06) and 3.63 (1.80–17.39) µg/L in ETSQUEST and in ETSCOT subjects, respectively. Significant correlations between COT-U and 1-OHPYR, and urinary anthracene, fluoranthene, pyrene, and chrysene were found among all subjects. Significantly higher levels of 1-OHPYR, and urinary fluorene, anthracene, and pyrene were found in ETSCOT individuals. The results of multiple linear regression analyses, taking into consideration diet and other sources of PAHs exposures such as the residence area/characteristics and traffic, confirmed that 1-OHPYR and urinary fluorene were affected by ETS exposure, even if ETS played a minor role.

The levels of polycyclic aromatic hydrocarbons (PAHs) in human milk and exposure risk to breastfed infants in petrochemical industrialized Lanzhou Valley, Northwest China

We investigated in this paper the presence of PAHs in human milk from lactating women residing in Lanzhou, a petrochemical industrialized valley city in Northwest China. The PAH concentration levels in human milk samples from 98 healthy women were determined by gas chromatography/mass spectrometry (GC/MS). The associations between the lifestyle factors and the PAHs levels of human milk were analyzed. Moreover, we applied principal component analysis (PCA) method to gain a better insight into the similarities or dissimilarities of the human milk PAH loads and different pathways of source exposure. In addition, the exposure risks of breastfed infants due to PAH ingestion via breast milk were assessed and the relative breast-feeding risk to the total intake dose of infants was addressed. The results showed that the average fat-normalized human milk ∑15PAHs concentrations for the lactating women residing in four districts of Lanzhou, namely, Xigu, Anning, Qilihe, and Chengguan were 320.40, 270.36, 374.04, and 259.84ng/g of fat, respectively. The ∑15PAHs of human milk from the lactating women of Qilihe District exhibited the highest concentration level, while the concentration level for women from Xigu District is the second highest for the observed human milk ∑15PAHs. And the corresponding BaPeq concentrations for women in Xigu, Anning, Qilihe, and Chengguan districts were 58.29, 47.95, 65.13, and 45.60ng/g of fat, respectively. A significant correlation was only found between human milk and living district environment (p < 0.05). Although the Spearman correlation analysis showed that there were no significant correlation existing between other lifestyle and human milk PAHs, we confirmed that consuming barbecue food could elevate PAHs levels in human milk: the barbecue intake frequency caused 10% fluctuation of ∑15PAHs concentration between high frequency and low frequency group in our study. Furthermore, the exposure to second-hand smoke can also increase the ∑15PAHs levels in human milk by 4 to 11% here. Ingestion doses of PAHs by infants (19.37-77.75ngkg-1day-1) were much higher than the inhalation doses (2.83-16.48ngkg-1day-1), which indicated that the ingestion is the main exposure risk pathway for infants. Since there are limited guidelines and standards for PAHs ingestion dose in human milk by infant, we compared the ingestion dose of BaP with the upper bound estimates of BaP dietary exposure of 108ngkg-1day-1 for toddlers of ages between 1.5 and 2.5years of age in the UK reported by Committee on Toxicity of Chemicals in Food (COT) and the data we obtained were lower than this upper bound. However, the estimated margin of exposure (MOE) values of BaP-MOE, PAH2-MOE, PAH4-MOE, and PAH8-MOE were smaller than 10,000 which indicated that there are potential hazard for breastfed infants consuming these human milk samples.

Inhalation exposure and health risks for newsagents exposed to atmospheric polycyclic aromatic hydrocarbons in Tehran, Iran

Many workers such as newsagents are exposed to polycyclic aromatic hydrocarbons (PAHs) found in urban atmosphere. The present study was designed to determine the levels of newsagents' inhalation exposure to PAHs found in ambient air of Tehran, Iran and to assess the health risks with the toxic equivalency factor (TEF) approach. Ninety personal exposure samples were collected during the summer season (representing warm period samples) and the fall season (representing cold period samples) of 2013. Sixteen priority PAHs from the United States Environmental Protection Agency (US EPA) pollutants list were selected for analysis of newsagents' personal daily exposure. Samples were analyzed by gas chromatography–mass spectrometry. The levels of benzo[a]pyrene (BaP) in the breathing zone air of newsagents in the summer and fall seasons were 0.122±0.036μg/m3 and 0.361±0.077μg/m3, respectively. The obtained benzo[a]pyrene equivalent BaP(eq) values of 16 USEPA PAHs were higher in the fall season than those obtained for summer season. Comparing the daily inhaled dose of PAHs in the summer and fall seasons showed that the highest daily inhaled dose (13μg) was calculated for benzo[a]anthracene in the cold period (fall seasons' samples). Special attention should be paid to protect newsagents in relation to PAH exposure.

Tracing biomarker of PAH-exposure and susceptibility factor (GSTM-polymorphism) among cancer patients in Pakistan

We studied cancer patients for possible PAH exposure, using urinary concentration of 1-hydroxypyrene (1-OHP) as a biomarker of internal dose of polycyclic aromatic hydrocarbons (PAHs). The subjects included in this study belonged to various socio-demographic backgrounds, and were diagnosed with cancer (i.e. lung, head and neck or digestive tract cancer). In general, we observed high concentration of urinary 1-OHP among digestive tract cancer patients, compared with the controls (CN) (mean 1.06, median 1.03 and mean 0.62, median 0.63 μmol/mol-Cr in digestive tract cancer patients and controls respectively). The concentrations of urinary 1-OHP were higher than the background level of PAHs; therefore, these groups could have been exposed to PAHs. Highest urinary 1-OHP concentration was observed in digestive tract cancer patients (median 1.25 μmol/mol-Cr) with GSTM-1 genotype. The results of PCA were consistent with qualitative and quantitative data analysis. The contribution of urinary 1-OHP eigenvector revealed a relatively high PAH-exposure among cancer patients compared with CN, while diet and age were influential parameters among cancer patients, which could have a strong link in cancer etiology in the selected exposure groups.

Morphological changes and growth of filamentous fungi in the presence of high concentrations of PAHs.

In this study, we evaluated the effect of low and high molecular weight polycyclic aromatic hydrocarbons (PAHs), i.e., Phenanthrene, Pyrene and Benzo[a]pyrene, on the radial growth and morphology of the PAH-degrading fungal strains Aspergillus nomius H7 and Trichoderma asperellum H15. The presence of PAHs in solid medium produced significant detrimental effects on the radial growth of A. nomius H7 at 4,000 and 6,000 mg L−1 and changes in mycelium pigmentation, abundance and sporulation ability at 1,000–6,000 mg L−1. In contrast, the radial growth of T. asperellum H15 was not affected at any of the doses tested, although sporulation was observed only up to 4,000 mg L−1 and as with the H7 strain, some visible changes in sporulation patterns and mycelium pigmentation were observed. Our results suggest that fungal strains exposed to high doses of PAHs significantly vary in their growth rates and sporulation characteristics in response to the physiological and defense mechanisms that affect both pigment production and conidiation processes. This finding is relevant for obtaining a better understanding of fungal adaptation in PAH-polluted environments and for developing and implementing adequate strategies for the remediation of contaminated soils.

Interactions between Potamogeton crispus L. and phenanthrene and pyrene in sediments

Information on the interaction between submerged macrophytes and organic contaminants in sediments is important for successful phytoremediation. In this study, the growth response and remedial function of Potamogeton crispus L. (P. crispus) to phenanthrene and pyrene in sediments were investigated. P. crispus was obtained by a tissue culture technique. Surface sediments (top 0–15 cm) were collected from the Haihe River, Tianjin, China. Six different concentrations of phenanthrene and pyrene (8–180 mg kg−1 dry sediment) were spiked in the sediments. At the end of the 54-day experiment, chlorophyll content, plant length and fresh weight, and root morphology were measured. Concentrations of phenanthrene and pyrene in P. crispus and sediments, as well as the activities of polyphenol oxidase in sediments, were analyzed. P. crispus growth was promoted by polycyclic aromatic hydrocarbons (PAHs) in sediments (range of 8–80 mg kg−1) and was not inhibited until the PAH concentration was increased to 180 mg kg−1. Root tip number was the most sensitive parameter. The presence of P. crispus evidently enhanced the removal of phenanthrene and pyrene from sediments by 18.3 − 34.1 and 14.1 − 27.8 %, respectively. The dissipation increments increased with increasing PAH concentration and showed similar values when PAH concentration was >48 mg kg−1. Plant accumulation of phenanthrene and pyrene counted for less than 1.05 and 2.46 % of the total increments, respectively. Moreover, the presence of P. crispus could improve the activities of polyphenol oxidase. A positive correlation between the dissipation increments of PAHs and the differences of polyphenol oxidase activities between planted and unplanted sediments was obtained. P. crispus could tolerate high doses of PAHs. The growth of P. crispus was stimulated by phenanthrene and pyrene in sediments over a large concentration range. Moreover, the presence of P. crispus enhanced the removal of PAHs, which was closely related to polyphenol oxidase activities as a result of plant growth stimulation. Therefore, P. crispus should be a suitable choice for phytoremediation of PAH-contaminated sediments.

Assessment of the levels of urinary 1-hydroxypyrene and air polycyclic aromatic hydrocarbon in PM2.5 for adult exposure to the petrochemical complex emissions

The relationship between external exposure and internal doses of polycyclic aromatic hydrocarbons (PAHs) has not been established for people living in industrial areas. This study was carried out to estimate the relationship between particle-phase PAH exposure and urinary 1-hydroxypyrene (1-OHP) levels among the adults living near a large petrochemical complex in Mailiao, Taiwan. We measured urinary 1-OHP in 781 residents above 35 years old and PM2.5 PAHs within a 20-km radius downwind from the petrochemical complex. Urinary 1-OHP was analyzed by high performance liquid chromatography, while 16 ambient particle-phase PAHs were measured by gas chromatography mass spectrometry. External exposures to individual PAHs at each study subject′s address were estimated by kriging interpolation from air sampling results and regressed against the subjects′ urinary 1-OHP levels, adjusting for confounding factors. The study population′s urinary 1-OHP levels ranged from 0.001 to 3.005μmol/mol-creatinine with significantly higher levels for females, grilled food consumers, and residents living close to roads. All 16 particle-phase PAHs were present in the study area with total PAH concentrations ranging from 0.111 to 1.982ng/m3. The spatial distribution of 4- and 5-ring PAHs identified high-concentration hotspots close to the complex in Mailiao. The multiple regression models showed that the adults′ urinary 1-OHP levels were significantly correlated with 5 out of the 16 PAHs, including benzo[a]anthracene, benzo[k]fluoranthene, fluoranthene, pyrene, and dibenzo[a,h]anthracene; a 0.01ng/m3 increase in the concentration of these 5 PAHs at the study subjects′ addresses was associated with a 20% elevation in urinary 1-OHP levels (μg/g-creatinine). Emissions from a petrochemical complex can elevate particle-phase PAH concentrations in surrounding areas and increase the urinary 1-OHP levels of adults living nearby.

Systemic exposure to PAHs and benzene in firefighters suppressing controlled structure fires.

Turnout gear provides protection against dermal exposure to contaminants during firefighting; however, the level of protection is unknown. We explored the dermal contribution to the systemic dose of polycyclic aromatic hydrocarbons (PAHs) and other aromatic hydrocarbons in firefighters during suppression and overhaul of controlled structure burns. The study was organized into two rounds, three controlled burns per round, and five firefighters per burn. The firefighters wore new or laundered turnout gear tested before each burn to ensure lack of PAH contamination. To ensure that any increase in systemic PAH levels after the burn was the result of dermal rather than inhalation exposure, the firefighters did not remove their self-contained breathing apparatus until overhaul was completed and they were >30 m upwind from the burn structure. Specimens were collected before and at intervals after the burn for biomarker analysis. Urine was analyzed for phenanthrene equivalents using enzyme-linked immunosorbent assay and a benzene metabolite (s-phenylmercapturic acid) using liquid chromatography/tandem mass spectrometry; both were adjusted by creatinine. Exhaled breath collected on thermal desorption tubes was analyzed for PAHs and other aromatic hydrocarbons using gas chromatography/mass spectrometry. We collected personal air samples during the burn and skin wipe samples (corn oil medium) on several body sites before and after the burn. The air and wipe samples were analyzed for PAHs using a liquid chromatography with photodiode array detection. We explored possible changes in external exposures or biomarkers over time and the relationships between these variables using non-parametric sign tests and Spearman tests, respectively. We found significantly elevated (P < 0.05) post-exposure breath concentrations of benzene compared with pre-exposure concentrations for both rounds. We also found significantly elevated post-exposure levels of PAHs on the neck compared with pre-exposure levels for round 1. We found statistically significant positive correlations between external exposures (i.e. personal air concentrations of PAHs) and biomarkers (i.e. change in urinary PAH metabolite levels in round 1 and change in breath concentrations of benzene in round 2). The results suggest that firefighters wearing full protective ensembles absorbed combustion products into their bodies. The PAHs most likely entered firefighters’ bodies through their skin, with the neck being the primary site of exposure and absorption due to the lower level of dermal protection afforded by hoods. Aromatic hydrocarbons could have been absorbed dermally during firefighting or inhaled during the doffing of gear that was off-gassing contaminants.

Assessing Risks to Sea Otters and the Exxon Valdez Oil Spill: New Scenarios, Attributable Risk, and Recovery

ABSTRACT The Exxon Valdez oil spill occurred more than two decades ago, and the Prince William Sound ecosystem has essentially recovered. Nevertheless, discussion continues on whether or not localized effects persist on sea otters (Enhydra lutris) at northern Knight Island (NKI) and, if so, what are the associated attributable risks. A recent study estimated new rates of sea otter encounters with subsurface oil residues (SSOR) from the oil spill. We previously demonstrated that a potential pathway existed for exposures to polycyclic aromatic hydrocarbons (PAHs) and conducted a quantitative ecological risk assessment using an individual-based model that simulated this and other plausible exposure pathways. Here we quantitatively update the potential for this exposure pathway to constitute an ongoing risk to sea otters using the new estimates of SSOR encounters. Our conservative model predicted that the assimilated doses of PAHs to the 1-in-1000th most-exposed sea otters would remain 1–2 orders of magnitude below the chronic effects thresholds. We re-examine the baseline estimates, post-spill surveys, recovery status, and attributable risks for this subpopulation. We conclude that the new estimated frequencies of encountering SSOR do not constitute a plausible risk for sea otters at NKI and these sea otters have fully recovered from the oil spill.

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

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

Quantifying long-term risks to sea otters from the 1989 ‘Exxon Valdez’ oil spill: Comment on Bodkin et al. (2012)

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 488:291-296 (2013) - DOI: https://doi.org/10.3354/meps10497 COMMENT Quantifying long-term risks to sea otters from the 1989 ‘Exxon Valdez’ oil spill: Comment on Bodkin et al. (2012) Mark A. Harwell*, John H. Gentile Harwell Gentile & Associates, LC, PO Box 291267, Port Orange, Florida 32129-1267, USA *Email: mharwell@ecologicalrisk.com ABSTRACT: Bodkin et al. (2012; Mar Ecol Prog Ser 447:273-287) assessed the frequency at which sea otters Enhydra lutris might encounter subsurface oil residues from the ‘Exxon Valdez’ oil spill. They concluded that a pathway exists for exposures of sea otters to residual oil in the intertidal zone, and imply that this pathway has delayed recovery of sea otters. We agree that the potential exposure pathway exists, and the Bodkin et al. (2012) estimates of the frequency of encountering subsurface oil residues (4 to 10 times per year) comport with our previously published studies (2 to 7 times per year). However, we disagree that this pathway constitutes a significant risk to sea otters. We discuss results from our quantitative ecological risk assessment using an individual-based model that specifically simulated this pathway of exposures to a population of 500000 sea otters. This conservative model predicted that assimilated doses of polycyclic aromatic hydrocarbons in subsurface oil residues to the 1-in-1000th most-exposed sea otters would be 1 to 2 orders of magnitude below the chronic effects thresholds that we established using USEPA data and methodology. When we artificially increased the rate of encountering subsurface oil residues, it required 4 to 10 encounters per day to reach effects levels. We conclude that the subsurface oil residues from the oil spill could not plausibly be responsible for any individual- or population-level effect on the sea otters at northern Knight Island. KEY WORDS: Sea otter · ‘Exxon Valdez’ oil spill · Ecological risk assessment · Enhydra lutris · Individual-based models Full text in pdf format PreviousNextCite this article as: Harwell MA, Gentile JH (2013) Quantifying long-term risks to sea otters from the 1989 ‘Exxon Valdez’ oil spill: Comment on Bodkin et al. (2012). Mar Ecol Prog Ser 488:291-296. https://doi.org/10.3354/meps10497 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 488. Online publication date: August 15, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

The mechanism of the antioxidant effect of smoked paprika from La Vera, Spain

This study aimed at further investigating the antioxidant effect of smoked paprika (Pimentón La Vera, Spain) in healthy subjects. Crossover study included male students (age 20.6 ± 1.7 years) who consumed smoked or non-smoked paprika (2 g/day, 20 times, over 30 days). After ingestion of smoked paprika, plasma malondialdehyde (MDA) levels were significantly (p < 0.01) reduced versus basal and non-smoked paprika ingestion values. Reduced glutathione (GSH) levels were increased and oxidised glutathione (GSSG) levels reduced significantly (p < 0.05) in paired subjects after consumption of smoked paprika. Smoked paprika significantly increased mRNA levels of glutathione peroxidase and cytochrome c oxydase versus non-smoked paprika ingestion. The low dose of polycyclic aromatic hydrocarbons (PAHs) contained in the smoked paprika could cause an activation of antioxidant defences as increasing activity of the GSH cycle and activating some antioxidant enzyme such as glutathione peroxidase and cytochrome c oxidase.