Polycyclic Aromatic Hydrocarbons Contamination Research Articles

Transformation and Degradation of PAH Mixture in Contaminated Sites: Clarifying Their Interactions with Native Soil Organisms

Soil contamination of polycyclic aromatic hydrocarbons (PAHs), especially caused by the mixture of two or more PAHs, raised great environmental concerns. However, research on the migration and transformation processes of PAHs in soils and their interactions with native communities is limited. In this work, soil samples from uncontaminated sites around the industrial parks in Handan, Hengshui, and Shanghai were artificially supplemented with three concentrations of anthracene (Ant), 9-chloroanthracene (9-ClAnt), benzopyrene (BaP), and chrysene (Chr). Ryegrass was planted to investigate the degradation of PAHs and its interaction with native soil organisms in the constructed ryegrass–microbe–soil microcosmic system. The bacterial and fungal communities in soil were affected by PAHs; their species diversity and relative abundance changed after exposure to different concentrations of PAHs, among which Lysobacter, Bacillus, Pseudomonas, and Massilia bacteria were correlated to the degradation of PAHs. On the 56th day, the contents of BaP, Chr, and Ant decreased with the degradation process, while the degradation of 9-ClAnt was limited. Nineteen intermediates, including hydroxylation and carboxylated compounds, were identified. The present research would help clarify the potential interactions between PAHs and native organisms in contaminated sites, providing fundamental information for evaluating the transformation risks of PAHs in the natural environment.

Development of a highly sensitive method based on QuEChERS and GC–MS/MS for the determination of polycyclic aromatic hydrocarbons in infant foods

Polycyclic aromatic hydrocarbons (PAHs) are environmental contaminants that can be found in various food products, including those intended for infants. Due to their potential health risks, it is crucial to develop sensitive analytical methods for the accurate determination of PAHs in infant foods. This study describes the development and validation of a highly sensitive method for the quantification of European PAH markers, namely benzo[a]pyrene, benzo[a]anthracene, chrysene, and benzo[b]fluoranthene, using gas chromatography–tandem mass spectrometry (GC–MS/MS), in baby food samples. The first step was the optimization of the sample preparation procedure, performed using different methods based on the QuEChERS approach, also testing different extraction solvents. Several factors such as extraction efficiency, selectivity, and recovery were evaluated to choose the most effective procedure for sample preparation. Furthermore, the GC–MS/MS method was optimized, evaluating parameters such as linearity, sensitivity, accuracy, and robustness using spiked infant food samples. The method demonstrated excellent linearities with a correlation coefficient higher than 0.999 over a wide concentration range, and limits of detection and limits of quantification in the range 0.019–0.036 μg/kg and 0.06–0.11 μg/kg, respectively. Extraction recoveries were between 73.1 and 110.7%, with relative standard deviations always lower than 8%. These findings are compliant with the indications of the European Commission (Reg. 836/2011). To assess the applicability of the method to official control activities, a survey was conducted on commercially available infant food products. Four markers were determined in commercial samples belonging to different food categories for infants and young children. The outcome of this monitoring showed that PAH contamination, in all samples, was below the quantification limits. In conclusion, the developed GC–MS/MS method provides a highly sensitive and reliable approach for the determination of PAHs in baby foods. The optimized sample preparation, instrumental parameters, and validation results ensure accurate quantification of 4 PAHs even at trace levels. This method could contribute to the assessment of PAH exposure in infants and it could support regulatory efforts to ensure the safety and quality of infant food products with regular monitoring.

Polycyclic Aromatic Hydrocarbons Contamination and Quality of Locally Produced Crude Palm Oil in South-South Zone, Nigeria

Background: Oil palm, Elaeis guineensis Jacq is a perennial crop mainly cultivated for its vegetable oil. The fatty acid composition of crude palm oil (CPO) is mostly composed of palmitic, stearic oleic, and linoleic acids. Objectives: This study evaluated the quality of locally produced CPO from six states of South-South zone, Nigeria. Methods: The parameters of CPOs were characterized by specific gravity (SG), acid value (AV), percentage of free fatty acid (%FFA), and saponification value (SV) and peroxide value (PV). Polycyclic aromatic hydrocarbons (PAHs) in CPO were quantified using standard procedures, the related risk due to daily consumption of 25 g was characterized by lifetime cancer risk (LCR) and margin of exposure (MOE). Results: The study observed that the mean values of the parameters were 0.931 SG; 5.01 mgKOH g-1 AV; 2.28% FFA; 177.27 mgKOH g-1 SV and 29.65 meqO2 kg-1 PV. Apart from %FFA, the others did not meet the requirements recommended by the Codex Alimentarius Commission of the joint WHO/FAO. Diagnostic ratios of PAHs suggested a mixture of petrogenic and pyrogenic origins. The MOEs showed low health concern while 16PAH-LCR values which ranged from 2.48E-04 - 4.48E-04 were unacceptable. The screening value 0.003 was significantly (p> 0.05) lower than the computed total BaP equivalent (BaPeq) values indicating potential human health concerns. It is recommended that CPO processing and storage methods should be properly monitored to prevent quality reduction and contamination, which might have adverse effect on consumers.

A current perspective on polycyclic aromatic hydrocarbons contamination and their bioremediation aspects

A current perspective on polycyclic aromatic hydrocarbons contamination and their bioremediation aspects

Genetic redundancy in the naphthalene-degradation pathway of Cycloclasticus pugetii strain PS-1 enables response to varying substrate concentrations.

Polycyclic aromatic hydrocarbon (PAH) contamination in marine environments range from low-diffusive inputs to high loads. The influence of PAH concentration on the expression of functional genes (e.g., those encoding ring-hydroxylating dioxygenases; RHDs), has been overlooked in PAH biodegradation studies. However, understanding marker-gene expression under different PAH loads can help monitor and predict bioremediation efficiency. Here, we followed the expression (via RNA sequencing) of Cycloclasticus pugetii strain PS-1 in cell suspension experiments under different naphthalene (100 and 30 mg L-1) concentrations. We identified genes encoding previously uncharacterized RHD subunits, termed rhdPS1α and rhdPS1β, that were highly transcribed in response to naphthalene-degradation activity. Additionally, we identified six RHD subunit-encoding genes that responded to naphthalene exposure. In contrast, four RHD subunit genes were PAH-independently expressed and three other RHD subunit genes responded to naphthalene starvation. Cycloclasticus spp. could, therefore, use genetic redundancy in key PAH-degradation genes to react to varying PAH loads. This genetic redundancy may restrict the monitoring of environmental hydrocarbon-degradation activity using single-gene expression. For Cycloclasticus pugetii strain PS-1, however, the newly identified rhdPS1α and rhdPS1β genes might be potential target genes to monitor its environmental naphthalene-degradation activity.

Polycyclic aromatic hydrocarbons (PAHs) pollution and risk assessment of soils at contaminated sites in China over the past two decades

With rapid urbanization in China, soil pollution at contaminated sites has emerged as a significant concern in the environmental protection plan. Moreover, extensive research has focused on the analysis of other major contaminants. However, over the past two decades, only a few studies have systematically analyzed polycyclic aromatic hydrocarbons (PAHs) in contaminated soils, particularly their source identification, contamination level assessment, and risk evaluation. This study addressed these research gaps by comprehensively evaluating soil PAHs contamination at these sites through the collection and screening of relevant literature data from the past 20 years using a “front page filtering” approach. The results suggested that the most contaminated sites in China were associated with petrochemical plants, steel mills, and coking plants. Coal/biomass burning emerged as the predominant source of PAHs pollution in the soils of contaminated sites across China. Overall, the soils of contaminated sites exhibited relatively low levels of PAHs contamination. The single-factor index method showed that benzo(a)pyrene (BaP) was the PAH monomer with the highest contamination level. Geographically, Northeast and North China exhibited relatively higher contamination levels and ecological risks. Moreover, PAHs posed significant health hazards, as they exhibited significantly high toxic effects on the respiratory system, carcinogenicity, aromatic hydrocarbon receptors, estrogen receptors, and antioxidant response elements. Additionally, children and youths faced higher health risks than adults. The findings from this study provide a solid basis for developing strategies to manage PAHs at contaminated sites in China.

Is Fucus a suitable biomonitoring organism for polycyclic aromatic hydrocarbon contamination? A study from the Faroe Islands

To evaluate seaweed as a biomonitoring organism, Fucus was sampled in the Faroe Islands. Nineteen PAHs, including the EPA 16, and four groups of alkylated PAHs were quantified using GC–MS analysis of extracts obtained using a modified QuEchERS method with ultrasonication in acetonitrile, back-extraction into hexane, and Florisil® cleanup. Samples from the harbor of Tórshavn collected at high tide were the most polluted with PAH concentrations between 1.3 × 102 and 1.7 × 102 ng/g wet weight. All samples contained a factor 10 higher concentrations of alkylated PAHs compared to their parent compounds. These results suggest that Fucus might be suitable as a biomonitoring organism for PAH pollution. Differences between samples collected in close proximity and on different days were observed (same range of RSD 14–120% and 60–102%, respectively), suggesting that water exchange, tide levels, and direct exposure to surface diesel pollution have a strong influence on pollutant uptake in Fucus. The findings stress the need for further evaluation of the sampling strategy.

ECOLOGICAL AND HUMAN HEALTH RISKS ASSOCIATED WITH SOIL POLLUTION BY PAHS AND HEAVY METALS IN THE NIGER DELTA

Despite the prevalence of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) in Niger Delta's crude oil regions, comprehensive research on their concentrations and combined risks in crude oil-contaminated soils is lacking. Our study focused on examining the concentration, source, spatial distribution, and health risk of 16 PAHs and 9different HMs in soils across a gradient of Niger Delta area Nigeria. The objective was to gain a comprehensive understanding of the HMs and PAHs' behavior in the environment and their potential impact on human health. The mean total concentrations of 16 PAHs (Σ16PAHs) were 779.58 ng/g for upland area, 749.46 ng/g for mid-slope area, and 679.37 ng g-1 for Low-land. The concentration of the HMs followed the order of Cu > Cd > Ni > Pb > Cr > Fe > Mn > Zn > Co, with Cu, Cd, Ni, and Pb exceeding the permissible levels. The study areas displayed varying concentrations of NO3-, PO42-, SO42- Ca, Na, and K, with some levels exceeding acceptable values, possibly influenced by crude oil contamination and the use of fertilizers. In the Niger Delta regions, the primary sources of soil PAH contamination include crude oil spills, natural crude oil seepage, and coal combustion. With this, the government of Nigeria should strengthen soil contamination monitoring, enforce spill regulations and promote eco-friendly farming.

Examining diverse remediation mechanisms of biochar in soil contaminated with polycyclic aromatic hydrocarbon (PAH) of various ring structures: A global meta-analysis

Biochar is a widely recognized solution for addressing polycyclic aromatic hydrocarbon (PAH) contamination. However, it is unclear how the different physicochemical properties of PAHs affect remediation mechanisms, thereby affecting the remediation efficiency of biochar. In this study, a meta-analysis of 56 studies with 2236 observations was conducted to quantify the contributions of the preparation parameters and physicochemical properties of biochar, soil properties, and application measures to remediation efficiency. The research results revealed that PAH contents in the contaminated soil were significantly reduced by an average of 24.99 % after the application of biochar. Random Forest analysis identified feedstock, biochar SSA, soil pH, and rate of biochar application to be the most critical factors among the four categories. The reduction of PAH contents in the contaminated soil first decreased from 37.61 % to 17.44 % and then increased to 40.29 % with an increase in the number of aromatic rings from 2 to 6. Our study results suggest that biochar prepared from bio-waste at low temperatures could be favorable for reducing the content of NAP in soil. Wood-derived biochar pyrolyzed at a relatively high temperature is recommended for remediation of soil contaminated with PAHs with 5 or 6 aromatic rings. Our study provides a new perspective and an optimized strategy for the remediation of PAH-contaminated soils with biochar.

Drivers distinguishing of PAHs heterogeneity in surface soil of China using deep learning coupled with geo-statistical approach

Although numerous studies have reported the influencing factors of polycyclic aromatic hydrocarbons (PAHs) in surface soil from source, process or soil perspectives, the mechanism of PAHs heterogeneity in surface soil are still not well understood. In this study, the effects of 16 PAHs in surface soil of China sampled between 2003 and 2020 with their 17 “source-process-sink” factors at 1 km resolution (N = 660)) were explored using deep learning (eXtreme Gradient Boosting) to mine key information from complex dataset under the optimized parameters (i.e., learning rate = 0.05, maximum depth = 5, sub-sample = 0.8). It was observed that top five factors of 16 PAH had the largest cumulative contribution (i.e., from 84.8% to 98.1%) on their soil concentrations. PAH emission was the predominant driver, and its effect on soil PAH increases with increasing logKow. Soil was the second driver, in which clay can promote the partition of PAHs with low or middle logKow. However, sand can accumulate those congeners with high logKow. Moreover, the deep learning plus geo-statistical models (with low deviation for testing dataset (N = 283)) were capable of predicting soil PAH concentrations using their drivers with high accuracy. This study improved the understanding of the environmental fate and spatial variability of soil PAHs, as well as provided a novel technique (i.e., deep learning coupled with geo-statistics) for accurate prediction of soil pollutants.

Distribution characteristics, source analysis and risk assessment of polycyclic aromatic hydrocarbons in sediments of Kuye River: a river in a typical energy and chemical industry zone.

This study systematically analyzed the distribution characteristics, sources, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in Kuye River sediments, located in an energy and chemical industry base in northern Shaanxi, China. The results that revealed the concentrations of 16 PAHs in the sediment ranged from 1090.04 to 32,175.68ng∙g-1dw, with the four-ring PAHs accounting for the highest proportion. Positive matrix factorization analysis (PMF) revealed the main sources of PAHs as incomplete fossil fuel combustion, biomass combustion, and traffic emissions. The total toxic equivalent concentration of BaP, risk quotient, and lifetime carcinogenic risk of PAHs suggested moderate to high contamination of PAHs in the area. The higher incremental lifetime carcinogenic risk (ILCR) indicated that PAH ingestion was the primary route of impact on public health, with children potentially being more susceptible to PAH exposure. This study can provide valuable theoretical support for implementing pollution prevention measures and ecological restoration strategies for rivers in energy and chemical industry areas.

Effects of Polycyclic Aromatic Hydrocarbons on the Composition of the Soil Bacterial Communities in the Tidal Flat Wetlands of the Yellow River Delta of China.

Polycyclic aromatic hydrocarbons (PAHs) are pervasive organic pollutants in coastal ecosystems, especially in tidal flat wetlands. However, the mechanisms through which PAHs impact the soil bacterial communities of wetlands featuring a simple vegetation structure in the Yellow River Delta (China) remain largely unclear. In this study, we examined soil samples from two sites featuring a single vegetation type (Suaeda salsa) in the Yellow River Delta. Specifically, we investigated the impacts of PAHs on the diversity and composition of soil bacteria communities through high-throughput 16 S rRNA sequencing. PAHs significantly increased the soil organic carbon content but decreased the total phosphorus content (p = 0.02). PAH contamination notably reduced soil bacterial community α diversity (Shannon index) and β diversity. Furthermore, PAHs significantly altered the relative abundance of bacterial phyla, classes, and genera (p < 0.05). Specifically, PAHs increased the relative abundance of the bacterial phyla Acidobacteriota and Gemmatimonadota (p < 0.05), while decreasing the relative abundance of Bacteroidota, Desulfobacterota, and Firmicutes compared to the control wetland (p < 0.05). Moreover, PAHs and certain soil properties [total nitrogen (TN), soil organic carbon (SOC), total phosphorus (TP), and total salt (TS)] were identified as key parameters affecting the community of soil bacteria, with the abundance of specific bacteria being both negatively and positively affected by PAHs, SOC, and TN. In summary, our findings could facilitate the identification of existing environmental problems and offer insights for improving the protection and management of tidal flat wetland ecosystems in the Yellow River Delta of China.

Polycyclic aromatic hydrocarbons in dust from rural communities around gas flaring points in the Niger Delta of Nigeria: an exploration of spatial patterns, sources and possible risk.

Indoor and outdoor dust from three rural communities (Emu-Ebendo, EME, Otu-Jeremi, OTJ, and Ebedei, EBD) around gas flaring points, and a rural community (Ugono Abraka, UGA) without gas flare points, in the Niger Delta of Nigeria, was analysed for the concentrations and distribution of polycyclic aromatic hydrocarbons (PAHs), their sources, and possible health risk resulting from human exposure to PAHs in dust from these rural communities. The PAHs were extracted from the dust with a mixture of dichloromethane/n-hexane by ultrasonication, and purified on a silica gel/alumina packed column. Gas chromatography-mass spectrometry was employed to determine the identity and concentrations of PAHs in the cleaned extracts. The Σ16PAH concentrations in the indoor dust ranged from 558 to 167 000, 6580 to 413 000, and 2350-37 500 μg kg-1 for EME, OTJ and EBD respectively, while those of their outdoor counterparts varied from 347 to 19 700, 15 000 to 130 000, and 1780 to 46 300 μg kg-1 for EME, OTJ and EBD respectively. On the other hand, the UGA community without gas flare points had Σ16PAH concentrations in the range of 444-5260 μg kg-1 for indoor dust, and 154-7000 μg kg-1 for outdoor dust. The lifetime cancer risk values for PAHs in these matrices surpassed the acceptable limit of 10-6 suggesting a potential carcinogenic risk resulting from human exposure to PAHs in indoor and outdoor dust from these rural communities. Principal component analysis suggested that PAH contamination of dust from these communities arises principally from gas flaring, combustion of wood/biomass, and vehicular emissions.

Monitoring of polycyclic aromatic hydrocarbons in wastewater of industrial city, Riyadh region, Saudi Arabia

Polycyclic aromatic hydrocarbons (PAHs) are hydrocarbons with more than two benzene rings in their molecules and are a class of harmful organic pollutants widely distributed in nature. This research aims to determine the Polycyclic Aromatic Hydrocarbons (PAHs (Naphthalene, Anthracene, and Chrysene (2, 3, and 4 Rings respectively) in different sources of treated and untreated wastewater collected from different sources during the years of 2021 and 2022. Eleven wastewater sources were collected from different industrial treated wastewater, farms, main treatment plants, tanning factory treated wastewater, tanning factory non-treated wastewater, Carton factories, Factories Lake, and Grease refining plants. PAHs were extracted by QuEChERS methodology and Analyzed by GCMSMS/TQD. The results of PAHs concertation in wastewater ranged from 19.55 -278.29 µg/l for Naphthalene, 21.09 -223.69 µg/l for Anthracene, and 14.05-123.11 for Chrysene. Tanning factory non-treated wastewater had the highest concentration of examined 3 PAHs. Results showed also the highest PAHs concentrations was in tanning factory non-treated wastewater, followed by carton factories, tanning factory treated wastewater, Grease refining plants, Factories Lake, and then the main treatment plant. These outcomes of this study can be used to deliver significant guidelines concerning habitants of the area for possible measures for controlling PAHs contamination in Riyadh industrial city to protect human health and ensure environmental and wastewater sustainability.

Enhancing Anaerobic Biodegradation of Phenanthrene in Polluted Soil by Bioaugmentation and Biostimulation: Focus on the Distribution of Phenanthrene and Microbial Community Analysis

The remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soils has received much attention in recent years, and most of the contaminated sites are in anaerobic environments, such as deep soils and flooded soils. We simulated the natural flooded soil environment, selected phenanthrene (PHE) as a model PAH contaminant, and designed batch experiments run for 63 days to comprehensively investigate the effects of the combined addition of anaerobic sludge and granular biochar on microbial community and function and the anaerobic biodegradation of PHE. Firstly, the residue, distribution, and removal of PHE in the flooded soil environment were quantified for each group. Secondly, the effects of bioaugmentation of soil indigenous microorganisms by the addition of anaerobic activated sludge and biostimulation of biochar on the removal of PHE from the soil were analyzed against each other. Lastly, the changes in the structure of the microbial community under the effect of bioaugmentation and biostimulation were illustrated by sequencing analyses. The results of this study showed that the removal efficiency of PHE reached 72.0% after the addition of anaerobic activated sludge. The incorporation of anaerobic activated sludge and biochar resulted in a 25.3% increase in PHE removal compared to a single soil, suggesting that the combination of bioaugmentation and biostimulation can have a synergistic effect on the anaerobic biodegradation of PHE in contaminated soils. The results of sequencing analysis further indicated that the introduction of an exogenous microbial community changed the dominant genera associated with PHE degradation and introduced methanogenic archaea, which enriched the metabolic pathways of the carbon cycle in the system. On this basis, the addition of biochar resulted in higher anaerobic microbial community diversity, functional dominant species were enriched, and the direct interspecies electron transfer (DIET) process between electroactive bacteria (Bacteroides, f_Geobacteraceae) and Methanosaeta was facilitated, which accelerated the degradation of PHE by anaerobic microbial communities. The results of this study provide regulatory tools and basic data support for enhanced bioremediation of PAHs in flooded soils.

Polycyclic aromatic hydrocarbon (PAH) source identification and a maternal transfer case study in threatened killer whales (Orcinus orca) of British Columbia, Canada

The northeastern Pacific (NEP) Ocean spans the coast of British Columbia (Canada) and is impacted by anthropogenic activities including oil pipeline developments, maritime fossil fuel tanker traffic, industrial chemical effluents, agricultural and urban emissions in tandem with stormwater and wastewater discharges, and forest wildfires. Such events may expose surrounding marine environments to toxic polycyclic aromatic hydrocarbons (PAHs) and impact critical habitats of threatened killer whales (Orcinus orca). We analyzed skeletal muscle and liver samples from stranded Bigg’s killer whales and endangered Southern Resident killer whales (SRKWs) for PAH contamination using LRMS. C3-phenanthrenes/anthracenes (mean: 632 ng/g lw), C4-dibenzothiophenes (mean: 334 ng/g lw), and C4-phenanthrenes/anthracenes (mean: 248 ng/g lw) presented the highest concentrations across all tissue samples. Diagnostic ratios indicated petrogenic-sourced contamination for SRKWs and pyrogenic-sourced burdens for Bigg’s killer whales; differences between ecotypes may be attributed to habitat range, prey selection, and metabolism. A mother-fetus skeletal muscle pair provided evidence of PAH maternal transfer; low molecular weight compounds C3-fluorenes, dibenzothiophene, and naphthalene showed efficient and preferential exposure to the fetus. This indicates in-utero exposure of PAH-contamination to the fetus. Our results show that hydrocarbon-related anthropogenic activities are negatively impacting these top predators; preliminary data found here can be used to improve oil spill and other PAH pollution management and regulation efforts, and inform policy to conserve killer whale habitats in the NEP.

Fluoranthene biotreatment using prominent freshwater microalgae: physiological responses of microalgae and artificial neural network modeling of the bioremoval process

Due to the intensified industrial activities and other anthropogenic actions, contamination of polycyclic aromatic hydrocarbons (PAHs) has been growing at an alarming rate, turning in to a serious environmental concern. Bioremediation, as an eco-friendly and sustainable removal technology, can be used by organisms to reduce the resulting contaminations. In the present study, the ability of Tetradesmus obliquus to remove of fluoranthene (FLA) was evaluated. It was confirmed that FLA removal efficiency was managed by various environmental parameters and pH was found to be one of the most important influencial factors. The reusability of the algae in long-term repetitive operations confirmed the occurrence of biodegradation along with other natural attenuation and 10 intermediate compounds were identified in the FLA biodegradation pathway by GC-MS. As a result of physiological assays, induced antioxidant enzymes activities and augmentation of phenol and flavonoids contents, after the treatment of the microalgae by a high concentration of FLA, confirmed the ability of the microalgae to upregulate its antioxidant defense system in response to the toxic effects of FLA. An artificial neural network (ANN) model was then developed to predict FLA biodegradation efficiency and the appropriate predictive performance of ANN was confirmed by comparing the experimental FLA removal efficiency with its predicted amounts (R2 = 0.99).

Low levels of flavonoids in Arabidopsis thaliana during phenanthrene exposure suggest new roles for a flavanone 3-hydroxylase

Polycyclic aromatic hydrocarbons (PAHs) contamination impacts the well-being of fauna, flora, and the environment. PAHs are a group of compounds consisting of two or more benzene rings. Due to their structure, PAHs are very stable, generally non-reactive and resistant to biodegradation; yet these compounds are cytotoxic in biological systems. In plants, PAHs induce oxidative stress and cell death, and inhibit growth. Previous PAH exposure studies from our laboratory showed an up-regulation of the Arabidopsis thaliana gene At3g51240. At3g51240 encodes a flavanone 3-hydroxylase (F3H), an enzyme catalyzing the hydroxylation of flavanones, key intermediates in the flavonoid biosynthesis pathway. Considering that flavonoids may act as antioxidants and protect cells against oxidative stress, we hypothesized that F3H was important in alleviating PAH-induced stress symptoms. Analysis of flavonoid content by high performance liquid chromatography showed low levels of flavonoids in phenanthrene-treated plants. Analysis of At3g51240 loss-of-function mutant plant lines growing on phenanthrene-containing growth media showed reduced phenotypic stress responses. Interestingly, low levels of H2O2 were observed in the mutant plants, suggesting that this putative flavanone 3-hydroxylase may be involved in PAH oxidation, with the consequent H2O2 generation. Furthermore, in vitro assays with purified recombinant 6xHis tagged AT3G51240 showed enzyme activity on the PAH when phenanthrene was used as a substrate. Together, these data suggest that F3H is involved in PAH detoxification in planta with the subsequent accumulation of toxic metabolites. This research also indicates the potentiality of using specialized metabolism enzymes such as oxidoreductase in the genetic engineering of plants to remediate PAH-contaminated soils.

Methods of Minimizing Polycyclic Aromatic Hydrocarbon Content in Homogenized Smoked Meat Sausages Using Different Casings and Variants of Meat-Fat Raw Material.

To ensure food safety and protect human health, the levels of polycyclic aromatic hydrocarbon (PAH) contamination in model smoked-pork meat products were examined to select which type of casing and variant of raw material contributes to minimizing the content of PAHs in the final products. The sausages were smoked in a steam smoke chamber with an external smoke generator. The determination of PAHs was performed using the QuEChERS-HPLC-FLD/DAD method. The analyzed products met the requirements of Commission Regulation (EU) No. 835/2011 on the maximum permissible levels of PAHs. Statistically higher sums of 19 PAHs, including 15 heavy and 4 marker PAHs, were stated in smoked sausages in natural and cellulose casings. Synthetic casings like collagen and polyamide exhibited better barriers against PAH contamination than cellulose and natural casings. For each type of casing, significantly higher concentrations of PAHs were found in the external parts of the products. An increase in the fat content of the raw material increased the levels of PAH contamination in the products, regardless of the casing. Therefore, in industrial practice, the selection of an appropriate type of casing and raw material with the lowest possible fat content can be an effective method for reducing PAH levels in the interior of smoked meat products.

The Occurrence of Polycyclic Aromatic Hydrocarbons in Fish Meat and Their Impact on Food Quality

Polycyclic Aromatic Hydrocarbons (PAHs) are organic compounds known to be potentially toxic for human health. Humans are exposed mostly through ingestion, but also through inhalation and skin contact. Thus, their concentrations in foods should be as low as possible. Fish products are appreciated as functional food, with high nutritional properties and organoleptic attributes. Despite these qualities, fish products may also contain PAHs. Humans are exposed to PAHs by eating fish meat, which can be contaminated from environmental sources, from industrial food processing methods, and from some home cooking practices. The main aspects concerning PAHs contamination of fish meat are briefly discussed: analysis and occurrence in some fish products, main factors and sources of contaminations, methodology of the determination of PAHs and current legislation on PAHs. The contamination of fish meat with PAHs has an impact on food quality. Mainly, topical studies from the last 20 years were taken into account, and also some studies that were the basis of the research in PAHs. The following platforms were used in the search: Web of Science and Scopus.