Polycyclic aromatic hydrocarbon (PAHs) geographical distribution in China and their source, risk assessment analysis

Development of human health criteria in China for benzo[a]pyrene: A comparison of deterministic and probabilistic approaches

Human health water quality criteria (HHWQC) for benzo[a]pyrene (BaP) in Chinese rivers and lakes were established using both deterministic and probabilistic approaches. Results showed that the national bioaccumulation factor (BAF) values for BaP at trophic levels 2, 3, and 4 were 342 L/kg, 199 L/kg, and 196 L/kg, respectively. The probabilistic HHWQC for BaP was 0.00407 μg/L for both water and organisms consumption and 0.00488 μg/L for organisms consumption only, which provide a more adequate protection than the deterministic HHWQC. Approximately 32.1% of the studied waters in China exceeded the derived HHWQC, which is likely to have adverse health effects and need be considered more attention. The derived HHWQC for BaP is soly based on Chinese exposure-related activity patterns and field-measured BAFs in surface freshwaters in China, which is important to provide a scientific basis for establishing or revising water quality standards (WQS) and risk management of BaP in water.

Reduced rural residential emissions in the Northern China Plain from 2015 to 2021

China's rapid economic growth over the past few decades has been fueled by the fossil-fuel dominated energy system. In Northern China, coal and biomass are important fuel types for household cooking and heating. The use of coal and biomass not only contributes to CO₂ emissions, but also worsens the ambient air quality and further causes adverse health outcomes. Since 2016, action plans have been implemented annually to promote the substitution of solid fuel use in the rural households of the Beijing-Tianjin-Hebei and surrounding region ("2 + 26" region). However, a comprehensive evaluation of the emission reductions by the control policies is still lacking. In this study, we built a rural residential emission inventory in the "2 + 26" region based on two-phase national household surveys in 2010 and 2015. We evaluated the air pollutant and CO₂ reduction benefits of various control measures from 2015 to 2021 and discussed the opportunities for the synergistical control of air pollutant and CO₂ emissions. We estimated that, in 2015, the coal and biomass fuel consumption from rural households in the "2 + 26" region was 28.7 Mt. and 30.6 Mt., respectively, which resulted in 93.8 Mt., 416.5kt, 402.5kt, 80.1kt, 268.0kt, and 6122.2kt of CO₂, PM_2.5, SO₂, NO_x, VOCs, and CO emissions. With the implementation of household solid fuel substitution policies, air pollutant emissions were estimated to decrease by 53- 74 % from 2015 to 2021, while the percentage reduction of CO₂ was only 39 % due to additional emissions from the alternative clean energy sources. If biomass was treated as carbon-neutral fuel, the CO₂ reducing potential was even lower. Building a clean and sustainable rural energy system is a multi-win option for China to achieve the "Beautiful China", "Healthy China" and carbon-neutrality goals.

The distribution, sources and health risk of polycyclic aromatic hydrocarbons (PAHs) in sediments of Liujiang River Basin: A field study in typical karstic river

The accumulation of PAHs in sediments of Liujiang River Basin were investigated to disclose the sources, input processes and toxicity risk of PAHs in a typical karstic river. The results revealed the concentrations of ∑₁₅PAHs are ranging from 111.97 to 593.39 ng/g, most of which are centralized in upstream and midstream of Liujiang River. Positive Matrix Factorization identified PAHs are mainly from the mixed combustion of oil and coal, biomass combustion and oil products leaking. Redundancy analysis manifested mixed accumulation should be the main approach of PAHs that inputting sediment. The values of RQ_NCs and RQ_MPCs suggested the moderate contamination of PAHs. The higher HQ and ILCR indicated the ingestion of PAHs are the main way to impact public health, while children should be more susceptible to PAHs. The values of HQ and ILCR indicated the overall low non-carcinogenic risk of PAHs, but relatively high carcinogenic risk of PAHs.

Association of human cohorts exposed to blood and urinary biomarkers of PAHs with adult asthma in a South Asian metropolitan city

Semi-volatile organic compounds (SVOCs) are a major global problem that causes the greatest impact on urban settings and have been linked to bronchial asthma in both children and adults in Pakistan. The association between exposure of polycyclic aromatic hydrocarbons (PAHs) and asthma in the adult population is less clear. The current study aimed to assess the clinico-chemical parameters and blood levels of naphthalene phenanthrene, pyrene, and 1,2-benzanthracene and urinary levels of 1-OH pyrene and 1-OH phenanthrene as well as asthma-related biomarkers immunoglobulin E (IgE), resistin, and superoxide dismutase (SOD) of oxidative stress and other hematologic parameters in adults and their relationship with bronchial asthma. The GC/MS analysis showed higher mean concentrations of blood PAHs in asthma respondents (4.48 ± 1.34, 3.46 ± 1.04, 0.10 ± 0.03, and 0.29 ± 0.09) (ng/mL) as compared to controls (3.07 ± 0.92, 1.71 ± 0.51, 0.06 ± 0.02, and 0.11 ± 0.03) (ng/mL), with p = .006, p = .001, p = .050, and p = .001. Similarly, urinary levels of 1-OHpyr and 1-OHphe were significantly increased in adults with bronchial asthma (0.54 ± 0.16; 0.13 ± 0.04) (μmol/mol-Cr) than in controls (0.30 ± 0.09; 0.05 ± 0.02) (μmol/mol-Cr), with p = .002 and p = .0001, respectively, with a significant positive correlation to asthma severity. The asthma-related biomarkers IgE, resistin, and SOD were significantly higher (p 0.0001, 0.0001, and 0.0001) in people with asthma than in control persons. The findings showed that higher blood and urine PAHs levels were linked to higher asthma risk in adults and significant interaction with participants who smoked, had allergies, had a family history of asthma, and were exposed to dust. The current study's findings will be useful to local regulatory agencies in Lahore in terms of managing exposure and advocating efforts to minimize PAH pollution and manage health.

Determination of polycyclic aromatic hydrocarbons in Chinese herbal medicines by gas chromatography-mass spectrometry with graphene-functionalized nickel foam

Graphene-functionalized nickel foam (NF) sorbent materials were prepared and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Thermogravimetric analysis. For the separation and detection of polycyclic aromatic hydrocarbons (PAHs) in five Chinese medicine samples, namely dandelion, fructus aurantii, peppermint, mulberry leaf and embryo chrysanthemum, a method combining dispersive micro-solid phase extraction and gas chromatography-mass spectrometry (GC-MS) was developed. Four conditions affecting the extraction efficiency, such as the type of desorption solvent, the amount of sorbent, the extraction time and the volume of water sample, were optimized. The results of the methodological validation showed that NF@SiO₂@G was able to adsorb PAHs well and with good reproducibility. All analytes showed good linearity in the concentration range of 20-2000 ng/mL with coefficient of determination R²≥0.9956. The limit of detection was 0.98-13.34 ng/mL, and the limit of quantification ranged from 3.25 to 44.47 ng/mL. Both the intra-day and inter-day precision were lower than 15.46%, and the spiked recoveries were in the range of 75.5-118.4%. The total contents of the 16 PAHs contained in these five Chinese herbal medicines (CHMs) were varied from 450 to 1557 µg/kg. The results indicated that the graphene-functionalized NF sorbent combined with GC-MS can effectively detect PAHs in CHMs.

Spatial distribution, source identification, and human health risk assessment of PAHs and their derivatives in soils nearby the coke plants

The coking industry can generate large amounts of polycyclic aromatic hydrocarbons (PAHs) and their derivatives, which may negatively impact the environment and human health. In this study, soils nearby a typical coking plant were sampled to assess the impact of coke production on the surrounding residential areas and human health. The mean concentration of PAHs and their derivatives in residential area soils nearby the coke plant was 4270 ng/g dw, which was 1 order of magnitude higher than that observed in areas far from the coke plant and approximately 4 times lower than that revealed the coke plant. In addition, the results showed that coking processing area was the most contaminant area of the coke plant (mean: 74.4 μg/g dw), where was also the main source of pollutants in residential areas. In terms of vertical soils in coking plant, the maximum levels of chemicals (mean: 205 μg/g dw) were presented at the leakage of underground pipelines, where were much higher than those in surface soils, and decreased with the increase of depth. The analysis of variance (ANOVA) results showed obvious differences in the concentrations of 6-nitrochrysene between the plant, residential areas and control areas. Meanwhile, 6-nitrochrysene had potential cancer risk (CR) for human in the coking site. Thus, 6-nitrochrysene was the most noteworthy PAH derivatives. Furthermore, the CR (mean: 5.94 × 10^-5) and toxic equivalent quantities (TEQs) (mean: 14.8 μg·TEQ/g) of PAHs and their derivatives was assessed in this study. This finding suggested that PAHs and their derivatives especially those extremely toxic chemicals (Nitro-PAHs (NPAHs) and Br/Cl-PAHs (XPAHs)) might pose a potential health risk to residents nearby the coke plant. The current study provides further insights into the pollution characteristics of PAHs and their derivatives in coke plants and potential risks to the workers and surrounding residents.

Distribution, sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in surface water in the coal mining area of northern Shaanxi, China

This study investigated the spatial distribution, pollution source, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in the Kuye River, which is a typical river in the mining area of China, 16 priority PAHs were quantitatively detected at 59 sampling sites by high-performance liquid chromatography-diode array detector-fluorescence detector. The results showed that the ∑PAHs concentrations in the Kuye River were in the range of 50.06-278.16 ng/L. The PAHs monomer concentrations were in the range 0-121.22 ng/L, of which chrysene had the highest average concentration (36.58 ng/L), followed by benzo[a]anthracene and phenanthrene. In addition, the 4-ring PAHs showed the highest relative abundance in the 59 samples, ranging from 38.59 to 70.85%. Moreover, the highest concentrations of PAHs were mainly observed in coal mining, industrial, and densely populated areas. On the other hand, according to the diagnostic ratios and positive matrix factorization (PMF) analysis, it can be concluded that coking/petroleum sources, coal combustion, vehicle emission, and fuel-wood combustion contributed to the PAHs concentrations in the Kuye River by 37.91%, 36.31%, 13.93%, and 11.85%, respectively. In addition, the results of the ecological risk assessment indicated that benzo[a]anthracene had a high ecological risk. Among the 59 sampling sites, only 12 belong to low ecological risk areas, and others were at medium to high ecological risks. The current study provides data support and a theoretical basis to effectively manage pollution sources and ecological environment treatment in mining areas.

Health Risk Assessment of PAHs from Estuarine Sediments in the South of Italy

Increased concerns about the toxicities of Polycyclic Aromatic Hydrocarbons (PAHs), ubiquitous and persistent compounds, as well as the associated ecotoxicology issue in estuarine sediments, have drawn attention worldwide in the last few years. The levels of PAHs in the Sele, Sarno, and Volturno Rivers sediments were evaluated. Moreover, the cancerogenic risk resulting from dermal and ingestion exposure to PAHs was estimated using the incremental lifetime cancer risk (ILCR) assessment and the toxic equivalent concentration (TEQ_BaP). For Sele River, the results showed that the total PAH concentration ranged from 632.42 to 844.93 ng g^-1 dw, with an average value of 738.68 ng g^-1 dw. ∑PAHs were in the range of 5.2-678.6 ng g^-1 dw and 434.8-872.1 ng g^-1 dw for the Sarno and Volturno River sediments, respectively. The cancerogenic risk from the accidental ingestion of PAHs in estuarine sediments was low at all sampling sites. However, based on the ILCR_dermal values obtained, the risk of cancer associated with exposure by dermal contact with the PAHs present in the sediments was moderate, with a mean ILCR_dermal value of 2.77 × 10^-6. This study revealed the pollution levels of PAHs across the South of Italy and provided a scientific basis for PAH pollution control and environmental protection.

Sex-specific effect of urinary metabolites of polycyclic aromatic hydrocarbons on thyroid profiles: results from NHANES 2011-2012

The current study aims to evaluate the associations between 10 urinary polycyclic aromatic hydrocarbon (PAH) metabolites and thyroid profiles. The levels of 10 PAH metabolites and thyroid profiles were obtained from National Health and Nutrition Examination Survey (NHANES) 2011-2012. Spearman analysis was utilized to evaluate the correlation coefficients among these 10 PAH metabolites. Multivariate linear and logistic regression models assessed the relationship between urinary PAH metabolite levels, thyroid hormones, and thyroid autoantibodies after adjusting potential confounders. Stratified analysis by gender was performed to evaluate sex-specific effect of urinary metabolites of PAH on thyroid profiles. One thousand six hundred forty-five eligible adult participants with complete research data were enrolled. Of note, the concentrations of the majority of urinary PAH metabolites were remarkedly higher in females compared with males. 2-hydroxyfluorene (2-FLU) was associated with higher total triiodothyronine (T3) levels in whole population (β = 2.113, 95% CI 0.339-3.888). In males, positive associations were observed in 1-hydroxynaphthalene (1-NAP) and free thyroxine (T4) (β = 0.0002, 95% CI 0.0000-0.0004). 2-FLU was also found positively associated with total T3 (β = 2.528, 95% CI 0.115-4.940) in male subjects. While in female participants, 2-hydroxynaphthalene (2-NAP) was associated with free T3 (β = 0.002, 95% CI 0.000-0.005). 2-FLU was associated with total T3 (β = 2.683, 95% CI 0.038-5.328), free T3 (β = 0.050, 95% CI 0.012-0.087), and total T4 (β = 0.195, 95% CI 0.008-0.382). 2-Hydroxyphenanthrene (2-OHP), 1-hydroxypyrene (1-HP), and 9-hydroxyfluorene (9-FLU) were all positively related to total T3 levels, and the corresponding coefficients were 16.504, 6.587, and 3.010. 9-FLU was also associated with free T3 (β = 0.049, 95% CI 0.008-0.090). No statistical significances were found between PAH metabolite levels and increased prevalence of increased thyroglobulin antibody (TgAb)/thyroid peroxidase antibody (TPOAb) when PAH metabolites were treated as continuous variables. Meanwhile, in the quartile analyses, increased prevalence of elevated TgAb was observed in participants with quartile 2 2-NAP compared with lowest quartile (OR = 1.753, 95% CI 1.021-3.008). Male subgroup analyses indicated that increased prevalence of elevated TgAb was observed in higher quartile of 1-NAP, 2-NAP, and 3-hydroxyfluorene (3-FLU). Increased prevalence of elevated TPOAb was associated with higher 2-NAP quartile. However, in subgroup analysis of females, no statistical significances were found between PAH quartiles and increased TgAb/TPOAb. Significant correlations were found among these 10 PAH metabolites. In conclusion, the cross-sectional study indicated that exposure to PAH might disturb the concentrations of thyroid hormones and thyroid autoantibodies. It is noteworthy that significant differences existed in males and females. Further prospective research is warranted to explore the causal relationship and underlying mechanism of PAH exposure on thyroid dysfunction.

Assessment of seasonal variation in distribution, source identification, and risk of polycyclic aromatic hydrocarbon (PAH)-contaminated sediment of Ikpoba River, South-South Nigeria

The study aims to assess the seasonal variation in distribution, source identification, and risk of 20 polycyclic aromatic hydrocarbons (20 PAHs) in the sediment of the Ikpoba River, south-south Nigeria. The PAHs were extracted in an ultrasonic bath with a mixture of n-hexane and dichloromethane (1:1 v/v). The extract was cleaned by silica-alumina gel mixed with anhydrous Na₂SO₄ in a chromatography column, eluted by n-hexane, and analysed by gas chromatography-mass spectrometry. The range of the average PAHs in mg.kg-dw was 0.15 (Nap)-0.54 (Acy) and 0.13 (D.al.P)-0.99 (Acy) in wet and dry periods correspondingly, indicating an increase in concentration from wet to dry period. However, the rings of the average concentration of the PAHs show 6 and 3 rings to be the highest values during the wet and dry seasons, respectively. Based on the human health risk analysis, the hazard quotient (HQ) and hazard index (HI), and carcinogenic risk indices showed low non-carcinogenic and carcinogenic risk for both seasons. The ecological risk analysis showed the mean effect range median quotient (mERMQ) recorded a medium-low effect on the biota of the locations, except in AS3 during the wet season and also in WS8 and WS9 during the dry season. The minimum value of the toxic equivalent quotient (TEQ) was > 0.2 mg/kg, which indicated a recommendation for the clean-up of the Ikpoba River. The isomer ratio and the principal component analysis (PCA) revealed the sources of the PAHs to be majorly combustion, followed by pyrolytic and petrogenic sources for both seasons.

Exploration of bacterial community-induced polycyclic aromatic hydrocarbons degradation and humus formation during co-composting of cow manure waste combined with contaminated soil

To solve polycyclic aromatic hydrocarbons (PAHs) pollution, composting was chosen as a remediation method. During composting, the dissipation of PAHs was carried out by resource utilization of organic solid waste and its degradation by bacteria. This study was conducted by co-composting with contaminated soil and cow manure. The results showed that the degradation rates of naphthalene (Nap), phenanthrene (Phe), and benzo[α]pyrene (BaP) could reach 82.2%, 79.4%, and 59.6% respectively during composting. Cluster analysis indicated that polyphenol oxidase (PPO), laccase, and protease were important drivers of PAHs transformation. The content of humic substances (HS) was 106.67 g/kg in PAH treatment, which was significantly higher than that in the control group at 65 days. The phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) and network analysis was used to infer the degradation mechanism of PAHs by microorganisms. The degradation of PAHs by PPO was found to have a significant contribution to the formation of HS. It was shown that PAHs and metabolic intermediates were more inclined to be oxidized and decomposed by PPO to form quinone, which in turn condensed with amino acids to form HS. Composting could promote the degradation of PAHs while improving the quality of compost, achieving a win-win situation.

The association between urinary polycyclic aromatic hydrocarbon metabolites and liver function among US population: a cross-sectional study

Most studies have focused on the pulmonary toxicity of inhaled PAHs to date; therefore, their hepatotoxic consequences are yet unknown. The main aim of this study is to examine the association between urinary polycyclic aromatic hydrocarbons (PAHs) and liver function parameters among the US population. The data included in this study were from the National Health and Nutritional Examination Survey (NHANES) 2003-2016. Finally, we included 2515 participants from seven cycles of the NHANES. Logistic regression was performed to calculate the association between each PAH and liver function parameters (elevated vs. normal) with odds ratio (OR) and 95% confidence intervals (CIs), along with adjustment for confounding variables. P < 0.05 was considered to indicate a statistically significant difference. All analyses were performed using R software 4.0.1. In the present study, all 2515 individuals were aged ≥ 18 years, 1211 males, and 1304 females. The average age normal was 45.56 ± 20.20, and the elevated was 46.04 ± 19.73 years, respectively. The results of logistic regression indicated that increased 9-hydroxyfluorene (OR  = 2.11, 95% CI = [1.52, 2.95], P < 0.001), 2-hydroxyfluorene (OR  = 1.61, 95% CI = [1.23, 2.11], P < 0.001), and 3-hydroxyfluorene (OR  = 1.54, 95% CI = [1.21, 1.95], P < 0.001) were associated with elevated GGT. In conclusion, 9-hydroxyfluorene is associated with elevated GGT level, and the effect of 9-hydroxyfluorene on GGT is modified by other PAHs, which means that 9-hydroxyfluorene has a greater influence on GGT when other PAHs are increased.

Assessment of biological community in riparian zone contaminated by PAHs: Linking source apportionment to biodiversity

Riparian zone, an important land-water interface, plays an essential role in maintaining the ecological health of rivers, whereas the effects of Polycyclic aromatic hydrocarbons (PAHs) on the health of biological communities in riparian groundwater remain undetermined. To understand the responses of multiple communities to environmental variables, the distribution and ecosystem risk of 16 PAHs have been investigated in the Beiluo River, China. The distribution of multiple communities in riparian groundwater was investigated by environmental DNA metabarcoding, including 16S rRNA, 18S rRNA, and COI gene sequencing for bacteria, microbial eukaryotes (including algae, fungi, and protozoa), and metazoan, respectively, followed by correlation analysis between multiple communities and PAH contamination levels. The concentration of PAHs in the Beiluo River ranged largely from 35.32 to 728.59 ng/L. Here, the Shannon's diversity index of bacteria (Firmicutes) decreased possibly due to the occurrence of Pyrene, which mainly derives from coal and biomass combustion. Furthermore, the reduced richness of fungi (Ascomycota, Basidiomycota) and algae (Chlorophyta, Chrysophyceae) can be attributed to the presence of medium molecular weight (MMW) PAHs (Pyrene, Benz(a)anthracene, Chrysene), and low molecular weight (LMW) PAHs (Naphthalene, Fluorene, Phenanthrene). The richness and Shannon's diversity index of metazoan (Arthropoda) were promoted owing to MMW PAHs (Chrysene, Fluoranthene) generated from coal and biomass combustion and traffic emission. The ecological risk of PAHs in the groundwater environment of the Beiluo River was characterized as low to medium, where LMW and MMW PAHs posed higher risk than the high molecular weight (HMW) compounds. Overall, this study provides insights into the structures of riparian multi-biological communities altered by PAHs.

Source apportionment of polycyclic aromatic hydrocarbons (PAHs) in a sediment core from Lake Dagze Co, Tibetan Plateau, China: Comparison of three receptor models

Receptor models are a useful tool for identifying sources of polycyclic aromatic hydrocarbons (PAHs) in multiple environmental media. In this study, three different receptor models (including the principal component analysis-multiple linear regression (PCA-MLR), positive matrix factorization (PMF), and Unmix models) were used to apportion the sources of 16 priority PAHs in a sediment core of Lake Dagze Co. The ∑PAHs (sum of all 16 measured PAHs) concentrations ranged from 51.89 to 132.82 ng/g with an average of 80.39 ng/g. The ∑PAHs were dominated by 2-3 ring PAHs, accounting for 80.12% on average, thereby indicating that they mainly originated from biomass and coal combustion and/or from long-range atmospheric transportation. The three models produced consistent source apportionment results. The greatest contributor to ∑PAHs was biomass combustion, followed by coal combustion, vehicle emissions, and petrogenic sources. Moreover, the temporal variation of the common sources was well-correlated among models. The multi-method comparison and evaluation results showed that all three models were useful tools for source apportionment of PAHs, with the PMF model providing better results than the PCA-MLR and Unmix models. The temporal trends of factor contributions were verified by PAHs with different ring numbers. Significant correlations were found between the simulated concentrations of each source factor and the PAHs with different ring numbers (P<0.01), except for the petrogenic source identified by the Unmix model (P>0.05). This study can provide useful information for further investigation of source apportionment of PAHs in the sediment cores.

Adsorption of acetone, ethyl acetate and toluene by beta zeolite/diatomite composites: preparation, characterization and adsorbability

The hierarchical porous composites (Beta/Dt) were prepared by secondary growth method using natural diatomite and beta zeolite. Moreover, XRD, SEM, and BET characterize the composite's composition, surface structure, and pore structure. The adsorbability of Beta/Dt was evaluated by adsorption of three common volatile organic compounds (VOCs) of the printing industry: acetone, ethyl acetate, and toluene. The results show that under the optimum preparation condition, the adsorption capacities of the three VOCs on Beta/Dt were about 3.5 times those of pure beta zeolite and 4.7-35.3 times those of diatomite, respectively. It indicates the synergistic adsorption effect between beta zeolite and diatomite. The superior adsorption capacity of Beta/Dt can be attributed to the suitable micropore size, the increase of the diffusion channels, and the chemical adsorption on modification diatomite. The adsorption of acetone, ethyl acetate, and toluene on Beta/Dt conformed to the pseudo-second-order kinetic model. In contrast, adsorption isotherms conformed to the Langmuir model, meaning that both physical and chemical adsorption occurred simultaneously during the adsorption process, and the adsorption belonged to the monolayer adsorption. The chemical adsorption mechanism can be ascribed to the nucleophilic reaction between the three VOCs (acetone, ethyl acetate, and toluene) and Beta/Dt with positive charges resulting from the modification diatomite. Furthermore, the composite could still keep more than 90% of the adsorption capacity of the original adsorbent after five regeneration cycles.

Al-Dalain S, Al-Dmour R, Alahmad A, Batarseh MI. Accumulation, Source Identification, and Cancer Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Different Jordanian Vegetables

The accumulation of polyaromatic hydrocarbons in plants is considered one of the most serious threats faced by mankind because of their persistence in the environment and their carcinogenic and teratogenic effect on human health. The concentrations of sixteen priority polycyclic aromatic hydrocarbons (16 PAHs) were determined in four types of edible vegetables (tomatoes, zucchini, eggplants, and cucumbers), irrigation water, and agriculture soil, where samples were collected from the Jordan Valley, Jordan. The mean total concentration of 16 PAHs (∑16PAHs) ranged from 10.649 to 21.774 µg kg−1 in vegetables, 28.72 µg kg−1 in soil, and 0.218 µg L−1 in the water samples. The tomato samples posed the highest ∑16PAH concentration level in the vegetables, whereas the zucchini samples had the lowest. Generally, the PAHs with a high molecular weight and four or more benzene rings prevailed among the studied samples. The diagnostic ratios and the principal component analysis (PCA) revealed that the PAH contamination sources in soil and vegetables mainly originated from a pyrogenic origin, traffic emission sources, and biomass combustion. The bioconcentration factors (BCF) for ∑16PAHs have been observed in the order of tomatoes > cucumbers and eggplants > zucchini. A potential cancer risk related to lifetime consumption was revealed based on calculating the incremental lifetime cancer risk of PAHs (ILCR). Therefore, sustainable agricultural practices and avoiding biomass combusting would greatly help in minimizing the potential health risk from dietary exposure to PAHs.

Effect of photooxidation on size distribution, light absorption, and molecular compositions of smoke particles from rice straw combustion

Organic aerosol (OA) emitted from biomass burning (BB) impacts air quality and global radiation balance. However, the comprehensive characterization of OA remains poorly understood because of the complex evolutionary behavior of OA in atmospheric processes. In this work, smoke particles were generated from rice straw combustion. The effect of OH radicals photooxidation on size distribution, light absorption, and molecular compositions of smoke particles was systematically investigated. The results showed that the median diameters of smoke particles increased by a factor of approximately 1.2 after photooxidation. In the particle compositions, although both non-polar fractions (n-hexane-soluble organic carbon, HSOC) and polar fractions (water-soluble organic carbon, WSOC) underwent photobleaching after aging, the photobleaching properties of HSOC (1.87-2.19) was always higher than that of WSOC (1.52-1.33). Besides, the light-absorbing properties of HSOC were higher than that of WSOC, showing a factor of approximately 1.75 times for mass absorption efficiency at 365 nm (MAE₃₆₅). Consequently, the simple forcing efficiency (SFE) caused by absorption showed that HSOC has higher radiation effects than WSOC. After photooxidation, the concentration of 16 PAHs in HSOC fractions significantly decreased by 15.3%-72.5%. In WSOC fractions, the content of CHO, CHONS, and CHOS compounds decreased slightly, while the content of CHON compounds increased. Meantime, the variations in molecular properties supported the decrease in light absorption of WSOC fractions. These results reveal the aging behavior of smoke particles, then stress the importance of non-polar organic fractions in particles, providing new insights into understanding the atmospheric pollution caused by BB smoke particles.

Relationship between miRNAs polymorphisms and peripheral blood leukocyte DNA telomere length in coke oven workers: A cross-sectional study

OBJECTIVE

The purpose of this study was to investigate the factors affecting telomere length (TL) in coke oven workers by analyzing the interaction between miRNAs polymorphisms and coke oven emissions (COEs) exposure.

METHODS

A total of 544 coke oven workers and 238 healthy controls were recruited. Peripheral blood was collected from the subjects, genomic DNA was extracted, leukocyte TL was detected by real-time quantitative polymerase chain reaction, and fifteen polymorphisms of eight miRNAs were genotyped by flight mass spectrometry.

RESULTS

Statistical analysis showed that the peripheral blood DNA TL in the exposure group was shorter than that in the control group (P < 0.001). Generalized linear model found that COEs-exposure [β (95%CI) = -0.427 (-0.556, -0.299), P < 0.001], genotype CC+CT for miR-612 rs1144925 [β (95%CI) = -0.367 (-0.630, -0.104), P = 0.006], and the interaction of miR-181B1 rs12039395 TT genotype and COEs-exposure [β (95% CI) = 0.564 (0.108, 1.020), P = 0.015] were associated with the shortened TL.

CONCLUSION

COEs-exposure and miR-612 rs1144925 TT could promote telomere shortening in coke oven workers. The interaction of miR-181B1 rs12039395 TT genotype and COEs-exposure could protect telomere. This provides clues for further mechanistic studies between miRNA and telomere damage.

Spatial Distribution, Potential Sources, and Health Risk of Polycyclic Aromatic Hydrocarbons (PAHs) in the Surface Soils under Different Land-Use Covers of Shanxi Province, North China

Polycyclic aromatic hydrocarbons (PAHs) are widespread in the environment and pose a serious threat to the soil ecosystem. In order to better understand the health risks for residents exposed to PAH-contaminated soil, 173 surface soil samples were collected in Shanxi Province, China, to detect the levels of 16 priority PAHs. The spatial distribution patterns of PAHs were explored using interpolation and spatial clustering analysis, and the probable sources of soil PAHs were identified for different land-use covers. The results indicate that the soil Σ16 PAH concentration ranged from 22.12 to 1337.82 ng g^-1, with a mean of 224.21 ng g^-1. The soils were weakly to moderately contaminated by high molecular weight PAHs (3-5 ring) and the Taiyuan-Linfen Basin was the most polluted areas. In addition, the concentration of soil PAHs on construction land was higher than that on other land-use covers. Key sources of soil PAHs were related to industrial activities dominated by coal burning, coking, and heavy traffic. Based on the exposure risk assessment of PAHs, more than 10% of the area was revealed to be likely to suffer from high carcinogenic risks for children. The study maps the high-risk distribution of soil PAHs in Shanxi Province and provides PAH pollution reduction strategies for policy makers to prevent adverse health risks to residents.

Chemical characterization of PM2.5 in heavy polluted industrial zones in the Guanzhong Plain, northwest China: Determination of fingerprint source profiles

Industrial emission has been proved to be an important source of atmospheric PM_2.5, which causes serious air pollution and health impacts. The air quality of the industrial zones, which are the intermediate stationary areas between the direct emissions and diffusion to the atmosphere, is always overlooked. In this study, the PM_2.5 filter samples were collected in the six representative types of industrial zones in four cities of the Guanzhong Plain in 2020. The chemical characteristics of fine particulate matter (PM_2.5) in the zones were investigated. The mass concentrations of 13 elements and 39 polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 were quantified. Cement and concrete (CC) and brick production (BP) exhibited a similar chemical composition profile characterized by high proportions of calcium (Ca), aluminum (Al), benzo[k]fluoranthene (BkF), 1-nitronaphthalene (1N-NAP), and 3-nitrofluoranthene (3N-FLA). Glassware and ceramics (GC) showed a distinguishable profile with a relatively low ratio of copper/cadmium (Cu/Cd) and lead (Pb)/Cd. The profile for metal forging (MF) was abundant in vanadium (V), Pb, indeno[1,2,3-cd]pyrene (IcdP) and also recognized by particular diagnostic ratios of nitrated-PAHs (n-PAHs). The highest proportions of several metals such as chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), zinc (Zn), Cd, and fluoranthene (FLA) were found in the thermoelectric industry (TI) due to a large amount of coal consumption in the manufacture processing. Chemical production (CP) was the only industrial type using natural gas as the main fuel in this study, which shows the distinguishing feature of relatively high proportions of low molecular weight parent-PAHs (p-PAHs) and 2-ring oxygenated-PAHs (o-PAHs). This study not only attains the detailed chemical fingerprints, but also the potential tracers and ratios, which are of great significance for refining source apportionment and relieving PM_2.5 pollution contributed by the industrial sources.

The association between phenanthrene and nutrients uptake in lotus cultivar 'Zhongguo Hong Beijing'

It has been well documented that polycyclic aromatic hydrocarbon (PAHs) can be taken up from the environment by the plants and translocated into the shoots. However, the mechanisms underlying this process are poorly understood. Nelumbo nucifera L. (lotus) is a highly ornamental aquatic plant known to possess strong phytoremediation capability. In the present study, the association between phenanthrene (Phe) and nutrients, including nitrogen (N) and phosphorus (P), in lotus was investigated. Over 2 years, all eight lotus cultivars tested accumulated Phe to various degrees when grown in PAH-polluted sediment (0.46 mg/kg Phe). Cluster analysis showed N. nucifera 'Zhongguo Hong Beijing (ZHB)' was the one with the highest Phe levels in the leaves and petals in 2 years. The Phe concentrations in the tissues of 'ZHB' were 3.14 mg/kg and 1.63 mg/kg on average in the first and second year, respectively. Interestingly, 'ZHB' was also the cultivar with the lowest N and P levels considering 2 years and tissues. Hydroponic studies further revealed a negative association between the concentrations of Phe and those of N and P in the aerial tissues under 0.5 and 1.0 mg/L Phe treatments in 'ZHB'. Furthermore, the significant reductions of the roots number (72.6%), longest root length (75.8%), and petiolar height (34.6%) in 'ZHB' seedlings exposed to 1.0 mg/L Phe were observed, indicating that Phe retarded the growth of lotus. These results provide a new understanding of the accumulation of Phe in plants and the association with nutrients and enrich the basis of phytoremediation to the contaminated environment.

Influence of bacterial community diversity, functionality, and soil factors on polycyclic aromatic hydrocarbons under various vegetation types in mangrove wetlands

Polycyclic aromatic hydrocarbons (PAHs) are prevalent organic pollutants in coastal ecosystems, particularly in mangrove wetlands. However, it is still largely unclear how PAHs affect the soil bacterial community under various vegetation types in the Greater Bay Area. Here, we selected soil samples from four sites with different vegetation types (native mangrove forest dominated by Kandelia candel, invasive mangrove forest dominated by Sonneratia apetala, unvegetated mudflat, and riverine runoff outlet) in the Qi'ao and Futian Nature Reserves. We investigated the effects of PAHs on soil bacterial community composition and diversity, function, and co-occurrence via 16S rRNA high-throughput sequencing. PAHs obviously reduced soil bacterial community diversity and richness. Based on PICRUSt 2, PAHs demonstrated positive influences on PAHs degradation metabolism related bacterial genes. Meanwhile, we predicted that riverine runoff outlets can potentially degrade PAHs, may donate to sustain healthy mangrove ecosystem. Also, PAHs and total nitrogen (TN) were crucial factors driving the soil bacterial community in Qi'ao sites, whereas in the Futian sites, PAHs and SOC were more important. PAHs, SOC and TN showed negative effects on specific bacteria abundance. Subsequently, environmental factors and PAHs levels influenced the soil bacterial ecological functions community. Co-occurrence network analysis revealed non-random assembly patterns of the bacterial communities. SBR1031 and A4b were the keystone genera and played a crucial role whgich played an irreplaceable role in PAHs degradation in Qi'ao and Futian sites. PAHs inhibited specific microbial activity and metabolism in native mangrove forest, while affects positively to bacterial community in riverine runoff outlet which might profoundly affect the whole soil quality under various vegetation types. Overall, this study might identify existing health problems and provide insights for enhancing protection and utilization management for mangrove ecosystem in the Greater Bay Area.

The association of co-exposure to polycyclic aromatic hydrocarbon and phthalates with blood cell-based inflammatory biomarkers in children: A panel study

The association of co-exposure to polycyclic aromatic hydrocarbons (PAHs) and phthalates (PAEs) with blood cell-based inflammatory biomarkers is largely unknown. We conducted a panel study of 144 children aged 4-12 years, with up to 3 repeated visits across 3 seasons. For each visit, we collected the first-morning urine for 4 consecutive days and fasting blood on the day of physical examination. We developed a gas chromatography/tandem mass spectrometry method to detect the metabolites of 10 PAHs (OH-PAHs) and 10 PAEs (mPAEs) in urine samples. We employed linear mixed-effects models to evaluate the individual associations of each OH-PAH and mPAE with blood cell-based inflammatory biomarkers over different lag times. Bayesian kernel machine regression (BKMR) and quantile g-computation were used to evaluate the overall associations of OH-PAHs and mPAEs mixtures with blood cell-based inflammatory biomarkers. After multiple adjustments, we found positive associations of summed hydroxylphenanthrene (∑OHPHE), summed OH-PAHs, and mono-n-butyl phthalate with inflammatory biomarkers such as neutrophil count, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and the systemic immune-inflammation index (SII) at lag 0 (the day of physical examination). Each 1% increase in ∑OHPHE was related to a 0.18% (95% confidence interval: 0.10%, 0.25%) increase in SII, which was the strongest among the above associations. The results of BKMR and quantile g-computation suggested that co-exposure to PAHs and PAEs mixture was associated with an elevated white blood cell count, neutrophil count, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and SII, to which ∑OHPHE and 1-hydroxypyrene (1-OHPYR) might be the major contributors. In addition, gender and age modified the associations of ∑OHPHE and 1-OHPYR with inflammatory biomarkers, where girls and younger children were more susceptible. In conclusion, co-exposure to PAHs and PAEs was associated with elevated inflammation in children, in which ∑OHPHE and 1-OHPYR might play important roles.

Source risk, ecological risk, and bioeffect assessment for polycyclic aromatic hydrocarbons (PAHs) in Laizhou Bay and Jiaozhou Bay of Shandong Peninsula, China

In order to incorporate the contribution of pollution sources to ecological risks into environmental monitoring, positive matrix factorization-risk quotient (PMF-RQ) was used to quantify the contribution of different PAH sources to ecological risks, which indicated that the unburned petroleum, vehicular emissions, and diesel combustion were the main sources of PAHs in Laizhou Bay and Jiaozhou Bay, and they were caused by petrochemical industry, maritime shipping, and urban traffic exhaust as the major sources of PAHs for ecological risk. Meanwhile, integrated biomarker response (IBR) and multi-biomarker pollution index (MPI) suggested that September was the most polluted month for PAHs in Laizhou Bay and Jiaozhou Bay and the pollution in Laizhou Bay was significantly higher than that in Jiaozhou Bay. This research was dedicated to explore the monitoring pattern for PAH pollution from the source to bioeffects, and it may have contributed a scientific support to monitoring and governance of marine PAH pollution.

Distribution, sources and transport of polycyclic aromatic hydrocarbons (PAHs) in karst spring systems from Western Hubei, Central China

Karst groundwater is an important water resource but it is vulnerable to contaminants, due to the distinctive geological features of abundant transmissive fractures and conduits in the karst area which connect the surface to the underground systems. Anthropogenic activity-derived polycyclic aromatic hydrocarbons (PAHs) on the surface environment could enter groundwater easily and rapidly and threaten water security in karst areas. Samples in the multimedia environment from 10 specific karst spring systems from Western Hubei of Central China were collected to analyze 16 priority PAHs and to investigate their transport in these karst spring systems. The total concentrations of PAHs in the soil, river water, river sediments, spring water, and spring sediments ranged between 6.04 and 67.7 ng g^-1, 4.56 and 11.4 ng L^-1, 29.9 and 1041 ng g^-1, 4.09 and 222 ng L^-1, and 5.88 and 83.0 ng g^-1, respectively. Levels of PAHs in this area were relatively low when compared to other karst areas. Proportions of low-molecular-weight (LMW)-PAHs in the water, sediments and soil (average 58.2-78.8%) were much higher than those of high-molecular-weight (HMW)-PAHs. The proportion of LMW-PAHs in the sediments (especially in river sediments) was higher than that in the soil. Characteristic ratio analysis and principal component analysis showed that PAHs were from high-temperature combustion of the mixture of coal and biomass, and vehicle emission, where coal and biomass combustion were the dominant sources. Significant correlations of PAH compositions in different media of karst spring systems were observed, especially in the Yuquangdong (YQD)-Migongquan (MGQ), Jiuzhenziquan (JZZQ), Xianyudong (XYD) and Fengdong (FD) karst spring systems, indicating the rapid PAH transport from the recharge area soil to the discharge area of spring water and sediments.

Elucidating the effect of different desorbents on naphthalene desorption and degradation: Performance and kinetics investigation

In this work, the effect of different desorbents (low molecular weight organic acids (LMWOAs), surfactants, and inorganic salts) on naphthalene (NAP) desorption in soil was investigated, and the results showed that NAP desorption pattern fitted the pseudo-second-order kinetics. The addition of LMWOAs, especially citric acid (CA), could stimulate the reactive oxygen species (ROS) generation and NAP degradation in Fe(II) activated persulfate (PS) system, while the presence of surfactants and CaCl₂ could inhibit the NAP removal due to the competitive consumption of ROS. The maximum removal of NAP was 97.5% within 120 min at the PS/Fe(II)/CA/NAP molar ratio of 15/5/1/1, and the pseudo-first-order kinetic constant of NAP removal increased from 0.0110 min^-1 to 0.0783 min^-1 with the addition of CA. Compared with surfactants and inorganic salts, LMWOAs, especially CA, were more suitable as desorbent in soil washing coupled with in situ chemical oxidation technique. Moreover, 1.86 mg L^-1 desorbed amount and 36.1% removal of NAP from soil could be obtained with the presence of 1 mM CA. Finally, the significant removal of NAP and other contaminants (phenanthrene, fluoranthene, and benzene series) in actual groundwater could provide theoretical basis and technical support for the remediation of organic contaminated sites with desorbents.

Experimental analysis on products distribution and characterization of medical waste pyrolysis with a focus on liquid yield quantity and quality

The massive generation of medical waste (MW) poses a serious risk to the natural environment and human health. The pyrolysis technique is proposed as a potential treatment for MW to tackle the associated environmental issues and produce value-added products. In this work, medical waste pyrolysis has been conducted at various temperatures using a fixed bed reactor with a 20 °C·min^-1 heating rate and nitrogen was used as a career gas with a flow rate of 100 ml·min^-1. In addition, the effect of temperature on products yield and chemical composition of MW pyrolysis have been investigated. The maximum yield of 57.1% for liquid oil was observed from the mixed MW pyrolysis at 500 °C. The gas and char yield were found between 26.5-37.3% and 24.2-12.4%, respectively, for the pyrolysis temperature of 450 °C to 600 °C. According to GC analysis, the concentration of the main gaseous products such as CH₄, H₂, and C₂H₄ was increased with increasing temperature, while CO and CO₂ experienced a decreasing trend. The results of GC-MS analysis revealed that the main components of MW pyrolysis oil were aromatic hydrocarbons, cyclic hydrocarbons, aliphatic hydrocarbons, alcohol, carboxylic acids, and their derivatives. The aromatic and cyclic hydrocarbons content increased up to 38.2% at a pyrolysis temperature of 600 °C. As pyrolysis oil tends to have more long-chain hydrocarbons therefore carbon distributions from C₇ to C₃₅ were observed. The ultimate analysis of oil and char revealed that the increased temperature enhanced the carbon content up to 78.6% and 68.0%, respectively. Furthermore, the higher heat values of 41.8, 24.4, and 52.7 MJ·kg^-1 were reported for oil, char, and gas, respectively.

Uptake and accumulation of naphthalene, phenanthrene, and benzo(b)fluoranthene in winter wheat affected by foliar exposure at different growth stages

Foliar uptake, as an important pathway of polycyclic aromatic hydrocarbons (PAHs) accumulation in winter wheat, has a great contribution to wheat PAHs, which mainly depends on atmospheric PAHs level. An indoor simulation experiment was conducted to explore the effects of foliar exposure to PAHs at different growth stages on PAHs uptake in wheat. Three levels (0, 0.75, 4.5 mg L^-1) of mixed solution of three PAHs (Σ₃PAHs) including naphthalene (NAP), phenanthrene (PHE), and benzo(b)fluoranthene (BbF) were sprayed on leaves of two varieties (Yunong, YN; Xiaoyan, XY) of winter wheat (Triticum aestivum L.) during the booting, heading, pre-filling, and post-filling stage. The results showed that the sprayed PAHs exhibited little effects on the growth of the two varieties except the stem biomass of YN was significantly (p < 0.05) reduced when high concentration of PAHs was applied at the post-filling stage. PAHs concentration in winter wheat grain was highest under foliar exposure at the pre-filling stage, while the lowest was found under foliar exposure at the post-filling stage. Transfer factor of PAHs from stem to root (TF_root/stem) of three PAHs when foliar exposure to PAHs at the booting and heading stage was significantly (p < 0.001) higher than that at the pre-filling and post-filling stage, while TF_grain/glume of three PAHs when foliar exposure to PAHs at pre-filling stage was significantly (p < 0.01) higher than that at the other three stages. These results indicated that foliar exposure to PAHs during the vegetative growth stage was transferred and distributed to the root, while PAHs are mainly transferred and accumulated to the grain during the grain filling stage. Additionally, the higher lipophilic PAHs showed a lower ability to transfer from the glume to grain, and larger flag leaf area had the potential to promote the enrichment of PAHs in grain. This study indicated that the health risk of PAHs in winter wheat could be effectively reduced by controlling atmospheric PAHs level during pre-filling stage.

Characteristics of polycyclic aromatic hydrocarbons in ambient air of a tropical mega-area, Ho Chi Minh City, Vietnam: concentration, distribution, gas/particle partitioning, potential sources and cancer risk assessment

This is the first investigation on overall characteristics of 25 polycyclic aromatic hydrocarbons (PAHs) (15 PAHs regulated by US-EPA (excluding naphthalene) and 16 PAHs recommended by the European Union) in ambient air of Ho Chi Minh City, Vietnam. Their levels, congener profiles, gas/particle partitioning, potential sources of atmospheric PAHs (gas and particulate phases), and lung cancer risks in the dry and rainy seasons were examined. The ∑25 PAH concentration in the dry and rainy seasons ranged from 8.79 to 33.2 ng m^-3 and 26.0 to 60.0 ng m^-3, respectively. Phenanthrene and Indeno[123-cd]pyrene were major contributors to gaseous and particulate PAHs, respectively, while benzo[c]fluorene was dominant component of the total BaP-TEQ. The ∑16 EU-PAH concentration contributed to 13 ± 2.7% of the total ∑ 25 PAH concentration; however, they composed over 99% of the total ∑ 25 PAH toxic concentration. Adsorption mainly governed the phase partitioning of PAHs because the slope of correlation between logK_p and logP⁰_L was steeper than - 1. Vehicular emission was the primary source of PAHs in two seasons; however, PAHs in the dry season were also originated from biomass burning. Assessment of lung cancer risk showed that children possibly exposed to potential lung cancer risk via inhalation.

One-century sedimentary record, sources, and ecological risk of polycyclic aromatic hydrocarbons in Dianchi Lake, China

In this study, the sedimentary records, sources, and ecological risks of polycyclic aromatic hydrocarbons (PAHs) in Dianchi Lake were analyzed. The concentrations of ΣPAH₁₆ in the sediments of Dianchi Lake ranged from 368 to 990 ng/g, with an average value of 572 ng/g, peaking in 1988. Economic development, rapid population growth, and rapid growth of coal consumption have a greater impact on the HMW (high molecular weight) PAHs than on the LMW (low molecular weight) PAHs in the sedimentary environment. The results of the diagnostic ratios and PCA (principal component analysis) model show that the main sources of PAHs were coal and biomass combustion, as well as the fossil fuel combustion in individual years. The risk assessment results showed that the PAH concentrations in the sediment were within a safe range. In the past 100 years of sediment pore water, other 2-3 ring LMW PAHs were within a safe range (except for Phe, which reached chronic toxic pollution levels in some years). With an increase in industrialization and urbanization, the burning of fossil fuels such as coal and petroleum has increased, and some of the 4-6 ring HMW PAHs have reached chronic toxicity or even acute toxicity in the sediment pore water.

A comprehensive study on simultaneous enhancement of sludge dewaterability and elimination of polycyclic aromatic hydrocarbons by Fe2+ catalyzing O3 process

Simultaneous removal of polycyclic aromatic hydrocarbons (PAHs) in the process of enhancement of sludge dewaterability via oxidation of hydroxyl radicals (•OH) and flocculation of Fe³⁺ by Fe²⁺-catalyzing O₃ were investigated as a novel research focus. The results showed that capillary suction time (CST) and water content of dewatered sludge cake (Wc) were reduced from 57.9 s and 85.1% to 13.6 s and 69.65% under the optimum usage of 60 mg/g dry solids (DS) O₃ and 80 mg/g DS FeSO₄, respectively. The relevant dewatering mechanism of Fe²⁺-catalyzing O₃ treatment was elucidated. It was found that extracellular polymeric substances-bound (EPS-bound) and intracellular water was dramatically released through destroying sludge cells and EPS gel-like structure by produced •OH. In addition, the results of X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and ¹³C NMR spectroscopy revealed that •OH oxidized and mineralized hydrophilic organic matters intensifying hydrophobicity of sludge surface. Moreover, Fe³⁺ generated by oxidation of Fe²⁺ agglomerated fragmented fine particles into large aggregates and decreased exposure of hydrophilic sites by neutralizing negative charge, which promoted water-solids separation. Meanwhile, sludge surface roughness was decreased which was determined by material type upright confocal laser microscope (CLM). As a consequence, •OH and Fe³⁺ were mainly responsible for enhancement of sludge dewaterability. Moreover, more than 40% of removal rate of PAHs was accomplished by Fe²⁺-catalyzed O₃ treatment mitigating the environmental risks of PAHs spread.

PM2.5 causes vascular hyperreactivity through the upregulation of the thromboxane A2 receptor and activation of MAPK pathways

Airborne fine particulate matter (PM_2.5) is a major cardiovascular disease environmental risk factor. However, the underlying mechanism of action is not fully understood. Thromboxane is widely known as an important vasoconstrictor substance that binds to G-protein-coupled receptors (GPCR) in arteries and is involved in various cardiovascular diseases. This study examined the effect of PM_2.5 on thromboxane A₂ receptor (TP) in the mesenteric arteries and the underlying intracellular signal mechanisms (by focusing on the mitogen-activated protein kinase (MAPK) pathway). Rat mesenteric artery segments were exposed to PM_2.5 in the presence of MAPK pathway inhibitors. The contractile reactivity of mesenteric arteries was analyzed using wire myography. The mRNA and protein expression of TP receptor and MAPK pathway molecules were detected by real-time PCR and Western blot. Mesenteric artery receptor localization was assessed by immunohistochemistry. The results showed that TP receptor-mediated maximum contraction response was achieved after exposing arteries to 1.0 μg/mL PM_2.5 for 16 h (Emax: 228 ± 16% of K⁺). Moreover, inhibitor U0126 (ERK1/2 inhibitor), SB203580 (p38 inhibitor), and SP600125 (JNK inhibitor) depressed the increased TP receptor-mediated contractile responses (reduced rage were 17.9 ~ 59.6%). These inhibitors also decreased the increased mRNA expression and protein of the TP receptor induced by PM_2.5 (reduced by more than 50% and 46%, respectively). The immunoreactivity of increased TP receptor expression was primarily localized in the cytoplasm. In addition, phosphorylation quantitative analysis showed that in the presence of MAPK inhibitors, the PM_2.5-induced phosphorylation of ERK1/2, p38, and JNK protein increased by more than 30.0 ~ 130.3%. These results suggest that PM_2.5 upregulates the TP receptor of rat mesenteric arteries through activation of the ERK1/2, p38, and JNK MAPK pathways.

Risk of Lung Cancer and Occupational Exposure to Polycyclic Aromatic Hydrocarbons Among Workers Cohorts - Worldwide, 1969-2022

What is already known about this topic?

Lung cancer has a high mortality, resulting in a severe disease burden. Polycyclic aromatic hydrocarbons (PAHs) are definitive carcinogen to human, and occupational exposure to PAHs is associated with lung cancer.

What is added by this report?

We analyzed the cancer cases from cohort studies on various PAHs exposed workers in China and other countries, calculated the quantitative risk of lung cancer based on meta-analyses, and confirmed the increased risk from lung cancer in selected PAHs exposed occupations.

What are the implications for public health practices?

There is a clear need to prevent lung cancer on a wide range of PAHs-related occupations in China and around the world. It is crucial to establish guidelines for improving the monitoring on exposure and health promotion in related working environments.

Temporal profiles, source analysis, and health risk assessments of parent polycyclic aromatic hydrocarbons (PPAHs) and their derivatives (NPAHs, OPAHs, ClPAHs, and BrPAHs) in PM2.5 and PM1.0 from the eastern coastal region of China: Urban coastal area versus coastal background area

The eastern coastal region of China is the area with the highest emission of PAHs in China. Therefore, understanding the sources and health risk of parent polycyclic aromatic hydrocarbons (PPAHs) and their derivatives in eastern coastal cities of China is the main basis for air pollution control. In this study, we measured the concentrations of 18 parent PAHs, 17 nitrated PAHs, 7 oxygenated PAHs, 8 chlorinated PAHs, and 13 brominated PAHs in PM_1.0 and PM_2.5 samples collected at an urban coastal city site and a coastal background site in 2019. We analyzed the temporal distribution, molecular composition, and sources and performed health risk assessments for both winter and summer samples. The average concentration of the PPAHs and their derivatives (all 63 compounds combined) in the PM_1.0 samples accounted for 75.57% of the PAHs concentration in PM_2.5 samples. The average concentration of PM_2.5- and PM_1.0- bound PPAHs in winter was 114.70 times higher than in summer, and their derivatives was 27.51 times. Both the combined concentrations of the 18 PPAHs and the combined concentrations of the 45 derivatives were higher in the coastal city compared to the background site during the winter (1.90 and 1.48 times, respectively), but they were comparable during the summer. The positive matrix factorization analysis indicated that the compounds mainly originated from coal/biomass combustion, industrial sources, vehicle emissions, and secondary formation. In addition, the concentration-weighted trajectories model revealed that the PAHs were mainly emitted locally in Shandong Province and surrounding areas, such as Hebei Province, Henan Province, and Bohai Sea. The compounds 1-NPYR, 2+9-BrPHE, 9,10-Cl2PHE, and 1-ClPYR dominantly contributed to the derivatives of TEQ during the winter due to their high concentrations or the high TEFs of these compounds.

Phytoremediation potential of Bermuda grass (Cynodon dactylon (L.) pers.) in soils co-contaminated with polycyclic aromatic hydrocarbons and cadmium

Soils co-contaminated with polycyclic aromatic hydrocarbons (PAHs) and cadmium (Cd) have serious environmental impacts and are highly toxic to humans and ecosystems. Phytoremediation is an effective biotechnology for the remediation and restoration of PAH- and Cd-polluted soils. Pot experiments were conducted to investigate the individual and combined effects of PAHs (1238.62 mg kg-1) and Cd (23.1 mg kg-1) on the phytoremediation potential of Bermuda grass grown in contaminated soils. Bermuda grass exhibited a significant decrease in plant growth rate, leaf pigment content, root activity, plant height and biomass and a remarkable increase in malondialdehyde content and electrolyte leakage when grown in PAH- and Cd-contaminated soils compared with grass grown in uncontaminated soils. The activity of soil enzymes, including urease, alkaline phosphatase, sucrose, and fluorescein diacetate hydrolysis, were reduced in soil with PAH and Cd stress. Furthermore, the toxicity of combined PAHs and Cd on Bermuda grass growth and soil enzyme activity was much higher than that of PAH or Cd stress alone, suggesting a synergistic effect of PAHs and Cd on cytotoxicity. To scavenge redundant reactive oxygen species and avoid oxidative damage, Bermuda grass increased plant catalase, superoxide dismutase, and peroxidase activity and soluble sugar and proline content. The bioconcentration factor of Cd in Bermuda grass grown under Cd alone and combined PAH and Cd exposure was greater than 1 for both, suggesting that Bermuda grass has a high Cd accumulation ability. Under PAH alone and combined PAH and Cd exposure conditions, a higher PAH removal rate (41.5-56.8%) was observed in soils planted with Bermuda grass than in unplanted soils (24.8-29.8%), indicating that Bermuda grass has a great ability to degrade PAHs. Bermuda grass showed great phytoremediation potential for the degradation of PAHs and phytoextraction of Cd in co-contaminated soils.

Spatial distribution and source apportionment of polycyclic aromatic hydrocarbons in typical oasis soil of north-western China and the bacterial community response

Oases environments in oases to be sensitive to anthropogenic activity because of ecological fragility. Polycyclic aromatic hydrocarbon (PAH) pollution resulting from anthropogenic activity leads to ecological degradation in oases. To examine the impact of anthropogenic activity on the oasis ecological environment, the present study focused on the spatial distribution and source apportionment of soil PAHs and bacterial community responses in typical oases in Xinjiang, China. The results showed that the soil PAH level were higher in the city centres of Urumqi (9-6340 μg kg^-1), Aksu (8-957 μg kg^-1) and Korla (8-1103 μg kg^-1) and lower in the centres of Hotan city (11-268 μg kg^-1) and Qira county (7-163 μg kg^-1). Source apportionment suggested that gasoline emissions, diesel emissions, vehicle emissions, coal combustion, coke processing and biomass burning were the sources of soil PAHs. The integrated lifetime cancer risks of soil PAH exceeding the guideline safety values (10^-6) recommended by United States Environmental Protection Agency. The ingestion and dermal exposure pathways caused the greatest health risk (contribution ≤82%). Additionally, in the soil with low PAH concentrations, the richness and evenness of the soil bacterial community were great, and the molecular ecological network (MEN) structure was complex. Among populations, Proteobacteria and Actinobacteria (relative abundance ≥17%) are the main dominant species in the bacterial communities and the keystone species in the MEN.

Synergistic leaching of heavy metal-polycyclic aromatic hydrocarbon in co-contaminated soil by hydroxamate siderophore: Role of cation-π and chelation

Exploring a novel green efficient bioeluant is a golden key to unlock the ex-situ scale remediation of soil contaminated with heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs). Hydroxamate siderophore (HDS) produced by Pseudomonas fluorescens HMP01, with certain hydrophobicity and strong coordination because of its special chemical structure (e.g., hydroxamic acid and dihydroxy quinoline chromophore), was used to investigate the bioleaching efficiency of HMs and PAHs from actual contaminated soils and underlying mechanisms. Results showed that leaching efficiency for HMs and PAHs from the co-contaminated soil was higher than that of single contaminated soil due to the cation-π interaction and coordination, which was closely related to the spacial configuration changes of the complex. HDS not only increased the bioleaching efficiency of cationic HMs by chelation (the leaching amount of Cd²⁺, Pb²⁺, Hg²⁺, Cu²⁺, Zn²⁺, and Ni²⁺ achieved 27.5, 110.4, 6.9, 477.7, 10,606.9, and 137.4 mg/kg HDS, respectively) but also enhanced the bioleaching amount of PAHs by solubilization (the leaching amount of phenanthrene reached 90.2 mg/kg HDS. Also, the residual HDS in soils caused no significant ecological risk. As expected, HDS is a desirable bioeluant to promote the scale application of the ex-situ remediation of soil contaminated with HMs and PAHs.

Characterizing the long-term occurrence of polycyclic aromatic hydrocarbons and their driving forces in surface waters

As carcinogenic and ubiquitous pollutants, an in-depth understanding of the long-term environmental behaviors of polycyclic aromatic hydrocarbons (PAHs) and their driving forces is crucial for reducing human health risks. Based on long-term monitoring data from 2001 to 2016, this study systematically investigated the temporal and seasonal trends, periodic oscillation, source apportionment, and human health risks of PAHs in eight rivers in the Free State of Saxony, Germany. The results showed that the annual average ∑₁₆PAHs (sum of 16 PAH concentrations) ranged from 28.2 ng L^-1 to 202 ng L^-1. Using the Mann-Kendall test, a trend of decreasing PAH concentrations was determined (slope range: -0.103 to -0.0159). Wavelet analysis indicated that the most significant periodic oscillation of PAHs was 10-30 months, with more pollution in winter. Source apportionment analysis suggested that vehicular emissions and coal combustion contributed the most to PAH concentrations (20.6-40.3% and 21.7-41.4%, respectively) and related health risks (54.1-80.1% and 5.61-37.9%, respectively). Furthermore, the risks (oral lifetime: 4.24×10^-7-1.34×10^-6; dermal lifetime: 2.86×10^-5-9.05×10^-5) were determined to be low. The data revealed that the substitution of petroleum and coal with cleaner energy would facilitate the mitigation of PAHs.

The PM2.5-bound polycyclic aromatic hydrocarbon behavior in indoor and outdoor environments, part II: Explainable prediction of benzo[a]pyrene levels

Among the polycyclic aromatic hydrocarbons (PAH), benzo[a]pyrene (B[a]P) has been considered more relevant than other species when estimating the potential exposure-related health effects and has been recognized as a marker of carcinogenic potency of air pollutant mixture. The current understanding of the factors which govern non-linear behavior of B[a]P and associated pollutants and environmental processes is insufficient and further research has to rely on the advanced analytical approach which averts the assumptions and avoids simplifications required by linear modeling methods. For the purpose of this study, we employed eXtreme Gradient Boosting (XGBoost), SHapley Additive exPlanations (SHAP) attribution method, and SHAP value fuzzy clustering to investigate the concentrations of inorganic gaseous pollutants, radon, PM_2.5 and particle constituents including trace metals, ions, 16 US EPA priority PM_2.5-bound PAHs and 31 meteorological variables, as key factors which shape indoor and outdoor PM_2.5-bound B[a]P distribution in a university building located in the urban area of Belgrade (Serbia). According to the results, the indoor and outdoor B[a]P levels were shown to be highly correlated and mostly influenced by the concentrations of Chry, B[b]F, CO, B[a]A, I[cd]P, B[k]F, Flt, D[ah]A, Pyr, B[ghi]P, Cr, As, and PM_2.5 in both indoor and outdoor environments. Besides, high B[a]P concentration events were recorded during the periods of low ambient temperature (<12 °C), unstable weather conditions with precipitation and increased soil humidity.

High-efficiency adsorption of phenanthrene by Fe3O4-SiO2-dimethoxydiphenylsilane nanocomposite: Experimental and theoretical study

Phenanthrene (PHE), as one of representative polycyclic aromatic hydrocarbons (PAHs) can cause serious adverse effects on human health, developing effective adsorbents to alleviate PHE contamination is in urgent demand. A novel Fe₃O₄-SiO₂-Dimethoxydiphenylsilane (Fe₃O₄-SiO₂-2DMDPS) nanocomposite was fabricated from encapsulation and grafting process. Magnetic Fe₃O₄ nanoparticles were served as preliminary matrix material, SiO₂ was used to link the magnetic oxide and provide hydroxyl groups for proceeding the silane coupling reaction subsequently, and the aromatic rings in DMDPS could provide active sites for PHE adsorption via π-π interaction. SEM-EDS, TEM, BET, VSM, XRD, FTIR, Raman, Zeta potential, and XPS techniques were used to characterize magnetic nanocomposite. The prepared Fe₃O₄-SiO₂-2DMDPS exhibited an excellent adsorption performance towards PHE, it could maintain 75.97% adsorption capacity after four regeneration cycles. Homogeneous adsorption acted crucial role in the whole adsorption process and film diffusion was the rate-controlling procedure. Theoretical calculations put forward the most favorable bonding modes between Fe₃O₄-SiO₂-2DMDPS and PHE molecules, confirmed the π-π interaction was valid and it usually existed in the form of parallel-displaced. This work might aid us to develop effective modification strategy for Fe₃O₄ nanoparticles and expand its application in the PAHs removing field.

Combined effects of exposure to polycyclic aromatic hydrocarbons and metals on oxidative stress among healthy adults in Caofeidian, China

Exposure to polycyclic aromatic hydrocarbons (PAHs) and metals is associated with many adverse effects on human health, accompanied by oxidative stress. This study aimed to investigate the effects of co-exposure to PAHs and metals on oxidative stress in healthy adults. A preliminary longitudinal panel study was conducted between 2017 and 2018 in 45 healthy college students in Caofeidian, China. Six urinary monohydroxylated-PAHs (OH-PAHs), ten metals, 8-hydroxydeoxyguanosine (8-OHdG), and 8-iso-prostaglandin-F2α (8-iso-PGF2α) were measured. Linear mixed effects (LME) models and Bayesian kernel machine regression (BKMR) models were used to explore the associations of urinary OH-PAHs and metals with 8-OHdG and 8-iso-PGF2α. LME models showed that most urinary OH-PAHs and metals were positively associated with 8-OHdG and 8-iso-PGF2α. For example, a one-unit increase in the ln-transformed level of 1-hydroxypyrene (1-OHPyr) and vanadium (V) was associated with an increase of 143.8% (95% CI: 105.7 - 188.9%) and 105.8% (95% CI: 79.2-136.4%) in 8-OHdG; 8-iso-PGF2α increased by 118.9% (95% CI: 99.2-140.5%) and 83.9% (95% CI: 67.2-102.2%) with a one-unit increase in the ln-transformed level of 3-hydroxyphenanthrene (3-OHPhe) and aluminum (Al). BKMR models indicated the overall positive associations of the mixture of six OH-PAHs, ten metals, or six OH-PAHs and ten metals with 8-OHdG and 8-iso-PGF2α. Urinary 1-OHPyr and V were identified as the major contributors to the increased urinary 8-OHdG levels, while urinary 3-OHPhe and Al were the most vital contributors to the increased urinary 8-iso-PGF2α levels. The results revealed the longitudinal dose-response relationships of urinary OH-PAHs and metals with oxidative stress among healthy adults in Caofeidian; this finding serves as an evidence regarding the early health hazard caused by exposure to PAHs and metals and has implications for the environmental management of PAH and metal emissions in this area.

How humic acid and Tween80 improve the phenanthrene biodegradation efficiency: Insight from cellular characteristics and quantitative proteomics

Polycyclic aromatic hydrocarbons (PAHs) are toxic and recalcitrant pollutants, with an urgent need for bioremediation. Systematic biodegradation studies show that surfactant-mediated bioremediation is still poorly understood. Here, we investigated a comprehensive cellular response pattern of the PAH degrading strain B. subtilis ZL09-26 to (non-)green surfactants at the cellular and proteomic levels. Eight characteristic cellular factor investigations and detailed quantitative proteomics analyses were performed to understand the highly enhanced phenanthrene (PHE) degradation efficiency (2.8- to 3-fold improvement) of ZL09-26 by humic acid (HA) or Tween80. The commonly upregulated pathway and proteins (Arginine generation, LacI-family transcriptional regulator, and Lactate dehydrogenase) and various metabolic pathways (such as phenanthrene degradation upstream pathway and central carbon metabolism) jointly govern the change of cellular behaviors and improvement of PHE transport, emulsification, and degradation in a network manner. The obtained molecular knowledge empowers engineers to expand the application of surfactants in the biodegradation of PAHs and other pollutants.

Seasonal variability in multimedia transport and fate of benzo[a]pyrene (BaP) affected by climatic factors

The impact of meteorological factors on the transport behavior and distribution of volatile and semi-volatile organic pollutants has become an area of increasing concern. Here, we analyzed seasonal variation in climatic variables including wind, temperature, and precipitation to quantitatively assess the impact of these factors on the multimedia transport and fate of BaP in the continental region of China using a Berkeley-Trent (BETR) model. The advective rates of air exhibited an increasing trend of autumn (1.830 mol/h) < summer (1.975 mol/h) < winter (2.053 mol/h) < spring (2.405 mol/h) in association with increasing wind speed, indicating that lower atmospheric BaP concentrations are present in regions with high wind speeds and advective rates. The air-soil transport rates (0.08-45.55 mol/h) in winter were higher than in summer (0.07-32.41 mol/h), while low winter temperatures accelerate BaP accumulation in terrestrial ecosystems due to cold deposition. Cold deposition effects were more evident in northern regions than in southern regions. Further, increasing precipitation enhanced air-soil and soil-freshwater transport rates with the correlation coefficients of r = 0.445 and r = 0.598 respectively, while decreasing the air-vegetation transport rates (r = 0.475), thereby contributing to the accumulation of BaP in soils and freshwaters. In the light of the potential dispersion of BaP pollution at regional and global scales affected by these key climatic factors, this indirectly indicated the impact of future climate change on the BaP transport. Thus, flexible policy interventions should be enacted to slow future climate change.

N-acetylcysteine alleviates pulmonary inflammatory response during benzo[a]pyrene-evoked acute lung injury

Benzo[a]pyrene (BaP), a representative polycyclic aromatic hydrocarbon, exists widely in automobile emissions and polluted atmosphere. The current study aimed to describe pulmonary inflammation during BaP-induced acute lung injury (ALI). All mice except controls were intratracheally instilled with a single dose of BaP (90 μg per mouse). The alveolar structure was damaged, accompanied by numerous inflammatory cell infiltration around pulmonary interstitium and small airway. Airway wall area and mean linear intercept were reduced in BaP-exposed mouse lungs. By contrast, airway wall thickness and destructive index were elevated in BaP-exposed mouse lungs. Several inflammatory genes, such as Tnf-α, Il-1β, Il-6, Mip-2, Kc, and Mcp-1, were upregulated in mouse lungs. Phosphorylated IκBα was elevated in BaP-exposed mouse lungs. Nuclear translocation of NF-κB p65 and p50 was accordingly observed in BaP-exposed mouse lungs. Several molecules of the MAPK pathway, including JNK, ERK1/2, and p38, were activated in mouse lungs. Of interest, pretreatment with N-acetylcysteine (NAC), an antioxidant, alleviated BaP-induced ALI. Moreover, NAC attenuated BaP-induced inflammatory cell infiltration in mouse lungs and inflammatory gene upregulation in A549 cells. In addition, NAC attenuated BaP-induced NF-κB activation in A549 cells and mouse lungs. These results suggest that NAC alleviates pulmonary inflammatory response during BaP-evoked ALI.

Comprehensive insights into the occurrence, source, distribution and risk assessment of polycyclic aromatic hydrocarbons in a large drinking reservoir system

The resource, environment, and ecological value of drinking reservoirs have received widespread concerns due to the pollution of persistent organic pollutants such as polycyclic aromatic hydrocarbons (PAHs). Therefore, we comprehensively studied the occurrence, source, distribution, and risk assessment of representative PAHs in Fengshuba Reservoir (FSBR) (large drinking reservoir, China). The total concentrations of 16 USEPA PAHs in the water phase, porewater phase, sediment phase, and soil phase were in ranges of 109.72-393.19 ng/L, 5.75-35.15 μg/L, 364.4-743.71 μg/kg, and 367.81-639.89 μg/kg, respectively. The naphthalene (Nap) was the dominant PAHs in the water phase, while it was Nap and phenanthrene (Phe) in porewater, sediment, and soil phase. The main sources of PAHs in FSBR were biomass combustion. Redundancy analysis indicated that the NTU, NO₂^-, NH₄⁺, Chl-α, and IC were the dominant factors influencing the PAH distribution in water phase, and the PAHs in sediment phase was affected by T and NO₃^-. Pseudo-partitioning coefficients indicated that the PAHs in the porewater phase were more likely to migrate to the sediment phase. Risk assessment indicated that the PAHs both in the water and sediment phases were generally in a low-risk state, while the PAHs in the soil phase were in a moderate-risk state, and the Nap was in a high-risk state, and exposure to the PAHs in FSBR through drinking and skin exposure had little impact on consumers' health. In summary, Nap could be used as a key indicator to evaluate the existence and potential risk of PAHs in FSBR.

Probability risk assessment of soil PAH contamination premised on industrial brownfield development: a case from China

The harm of polycyclic aromatic hydrocarbons to human health and the natural environment has become an indisputable fact. Compared with other pollutants, PAHs are more toxic at low environmental concentrations, especially in industrialized environments. This study investigated the concentration distribution of soil PAHs at a well-known industrial production site in China and applied the Monte Carlo simulation method to assess the risk of cancer caused by the excessive accidental intake of PAHs in brownfield development environments. The results showed that the PAH content of the soil at the study site exceeded the local soil quality background value to varying degrees, and the excess rate ranged from 0.72 to 22.3%. There are serious health risks of BaP at the site, which has a 95th health risk percentile value of 1.12E-04. Those for BbF, InP, and DBA range from 1.0×10^-6 to 1.0×10^-4, and potential health risks occur. Moreover, the exposure duration and average carcinogenic time were the most influential parameters. The study has revealed that exposure to brownfield soil contaminated with PAHs increases the health risks. This is a representative study on the occurrence and concentration of PAHs in industrial brownfields in China, which can be adopted as a basis and evidence for pollution risk assessment of brownfield development.