Human exposure to polycyclic aromatic hydrocarbons: Metabolomics perspective

Human biomonitoring of serum polycyclic aromatic hydrocarbons and oxygenated derivatives by gas chromatography coupled with tandem mass spectrometry

While polycyclic aromatic hydrocarbons (PAHs) are well-known for their potential carcinogenic and mutagenic effects, the health implications of exposure to oxygenated PAHs (OPAHs), which are significant substitutes with increased persistence and bioaccumulation, are less understood. In this work, we compared the background levels of liquid-liquid, solid-phase, and supported-liquid extraction for the determination of serum PAHs and OPAHs. Liquid-liquid extraction demonstrated minimal background interference and was validated and used for human biomonitoring of PAHs and OPAHs in 240 participants using gas chromatography coupled with tandem mass spectrometry. We observed significant positive correlations between these compounds using Spearman correlation analysis. Furthermore, we investigated the concentration levels and compositions of PAHs and OPAHs among different demographic characteristics, including gender, age, and body mass index. Linear regression analysis demonstrated a weak but significant correlation between total concentrations of PAHs and OPAHs and age and body mass index. A multivariate linear regression analysis was then conducted to examine the association of exposure to individual PAHs and OPAHs with the body mass index. Naphthalene exposure and body mass index showed a statistically significant positive correlation, suggesting that higher levels of naphthalene exposure are associated with higher body mass index values. This study establishes a robust method for biomonitoring PAHs and OPAHs in serum, evaluating the exposure levels of these compounds in healthy adults and highlighting their associations with demographic characteristics.

Benzo[a]pyrene evokes epithelial-mesenchymal transition and pulmonary fibrosis through AhR-mediated Nrf2-p62 signaling

Benzo[a]pyrene (BaP) and its metabolic end product benzo(a)pyren-7,8-dihydrodiol-9,10-epoxide (BPDE), are known toxic environmental pollutants. This study aimed to analyze whether sub-chronic BPDE exposure initiated pulmonary fibrosis and the potential mechanisms. In this work, male C57BL6/J mice were exposed to BPDE by dynamic inhalation exposure for 8 weeks. Our results indicated that sub-chronic BPDE exposure evoked pulmonary fibrosis and epithelial-mesenchymal transition (EMT) in mice. Both in vivo and in vitro, BPDE exposure promoted nuclear translocation of Snail. Further experiments indicated that nuclear factor erythroid 2-related factor 2 (Nrf2) and p62 were upregulated in BPDE-exposed alveolar epithelial cells. Moreover, Nrf2 siRNA transfection evidently attenuated BPDE-induced p62 upregulation. Besides, p62 shRNA inhibited BPDE-incurred Snail nuclear translocation and EMT. Mechanically, BPDE facilitated physical interaction between p62 and Snail in the nucleus, then repressed Snail protein degradation by p62-dependent autophagy-lysosome pathway, and finally upregulated transcriptional activity of Snail. Additionally, aryl hydrocarbon receptor (AhR) was activated in BPDE-treated alveolar epithelial cells. Dual-luciferase assay indicated activating AhR could bind to Nrf2 gene promoter. Moreover, pretreatment with CH223191 or α-naphthoflavone (α-NF), AhR antagonists, inhibited BPDE-activated Nrf2-p62 signaling, and alleviated BPDE-induced EMT and pulmonary fibrosis in mice. Taken together, AhR-mediated Nrf2-p62 signaling contributes to BaP-induced EMT and pulmonary fibrosis.

Systemic oxidative stress levels during the course of pregnancy: Associations with exposure to air pollutants

Increased systemic oxidative stress, implicated in adverse pregnancy outcomes for both mothers and fetuses, has been associated with gestational exposure to air pollutants such as polycyclic aromatic hydrocarbons (PAHs), fine particulate matter (PM2.5), and nitrogen dioxide (NO2). However, it is unclear whether exposure to pollutants at levels below the current air quality standards can increase oxidative stress in pregnant women. In a cohort of 305 pregnant persons residing in western New York, we examined the association between exposure to PM2.5, NO2, and PAHs (measured as urinary 1-hydroxypyrene) and urinary biomarkers of oxidative stress (malondialdehyde [MDA] and 8-hydroxy-2'-deoxyguanosine [8-OHdG]) measured in each trimester. After controlling for gestational stage, maternal age, lifestyles, and socioeconomic factors, each interquartile range (IQR) increase in 1-hydroxypyrene concentration (65.8 pg/ml) was associated with a 7.73% (95%CI: 3.18%,12.3%) higher in MDA levels throughout the pregnancy and in the first and second trimester. An IQR increase in PM2.5 concentration (3.20 μg/m3) was associated with increased MDA levels in the first trimester (8.19%, 95%CI: 0.28%,16.1%), but not the 2nd (-7.99%, 95% CI: 13.8%, -2.23%) or 3rd trimester (-2.81%, 95% CI: 10.0%, 4.38%). The average cumulative PM2.5 exposures in the 3-7 days before urine collection were associated with increased 8-OHdG levels during the second trimester, with the largest difference (22.6%; 95% CI: 3.46%, 41.7%) observed in relation to a one IQR increase in PM2.5 concentration in the previous 7 days. In contrast, neither oxidative stress biomarker was associated with NO2 exposure. Observed in pregnant women exposed to low-level air pollution, these findings expanded previously reported associations between systemic oxidative stress and high-level PM2.5 and PAH concentrations. Further, the first and second trimesters may be a susceptible window during pregnancy for oxidative stress responses to air pollution exposure.

Association between urinary polycyclic aromatic hydrocarbons and risk of metabolic associated fatty liver disease

OBJECTIVE

To investigate the effect of urinary PAHs on MAFLD.

METHODS

The study included 3,136 adults from the National Health and Nutrition Examination Survey (NHANES) conducted between 2009 and 2016. Among them, 1,056 participants were diagnosed with MAFLD and were designated as the case group. The analysis of the relationship between monohydroxy metabolites of seven PAHs in urine and MAFLD was carried out using logistic regression and Bayesian kernel regression (BKMR) models.

RESULTS

In single-pollutant models, the concentration of 2-hydroxynaphthalene (2-OHNAP) was positively correlated with MAFLD (OR = 1.47, 95% CI 1.18, 1.84), whereas 3-hydroxyfluorene (3-OHFLU) and 1-hydroxypyrene (1-OHPYR) demonstrated a negative correlation with MAFLD (OR = 0.59, 95% CI 0.48 0.73; OR = 0.70, 95% CI 0.55, 0.89). Conversely, in multi-pollutant models, 2-OHNAP, 2-hydroxyfluorene (2-OHFLU), 2-hydroxyphenanthrene, and 3-hydroxyphenanthrene (2&3-OHPHE) displayed positive correlations with MAFLD (OR = 6.17, 95% CI 3.15, 12.07; OR = 2.59, 95% CI 1.37, 4.89). However, 3-OHFLU and 1-OHPYR continued to exhibit negative correlations with MAFLD (OR = 0.09, 95% CI 0.05, 0.15; OR = 0.62, 95% CI 0.43, 0.88). Notably, the BKMR analysis mixtures approach did not indicate a significant joint effect of multiple PAHs on MAFLD, but identified interactions between 3-OHFLU and 2-OHFLU, 1-OHPYR and 2-OHFLU, and 1-OHPYR and 3-OHFLU.

CONCLUSION

No significant association was found between mixed PAHs exposure and the risk of MAFLD. However, interactions were observed between 3-OHFLU and 2-OHFLU. Both 2-OHFLU and 2&3-OHPHE exposure are significant risk factors for MAFLD, whereas 3-OHFLU is a key protective factor for the disease.

Machine learning models for predicting thermal desorption remediation of soils contaminated with polycyclic aromatic hydrocarbons

Among various remediation methods for organic-contaminated soil, thermal desorption stands out due to its broad treatment range and high efficiency. Nonetheless, analyzing the contribution of factors in complex soil remediation systems and deducing the results under multiple conditions are challenging, given the complexities arising from diverse soil properties, heating conditions, and contaminant types. Machine learning (ML) methods serve as a powerful analytical tool that can extract meaningful insights from datasets and reveal hidden relationships. Due to insufficient research on soil thermal desorption for remediation of organic sites using ML methods, this study took organic pollutants represented by polycyclic aromatic hydrocarbons (PAHs) as the research object and sorted out a comprehensive data set containing >700 data points on the thermal desorption of soil contaminated with PAHs from published literature. Several ML models, including artificial neural network (ANN), random forest (RF), and support vector regression (SVR), were applied. Model optimization and regression fitting centered on soil remediation efficiency, with feature importance analysis conducted on soil and contaminant properties and heating conditions. This approach enabled the quantitative evaluation and prediction of thermal desorption remediation effects on soil contaminated with PAHs. Results indicated that ML models, particularly the RF model (R2 = 0.90), exhibited high accuracy in predicting remediation efficiency. The hierarchical significance of the features within the RF model is elucidated as follows: heating conditions account for 52 %, contaminant properties for 28 %, and soil properties for 20 % of the model's predictive power. A comprehensive analysis suggests that practical applications should emphasize heating conditions for efficient soil remediation. This research provides a crucial reference for optimizing and implementing thermal desorption in the quest for more efficient and reliable soil remediation strategies.

Association of environmental polycyclic aromatic hydrocarbons exposure with periodontitis in NHANES 2009-2014: A mixtures approach

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) can invade and cause harm to the human body through various pathways, but there is currently little research on the relationship between mixed-PAHs exposure and periodontitis. The purpose of this study was to examine the effects of mixed-urinary PAHs exposure on periodontitis in adults in the United States.

METHODS

The cross-sectional study included 2749 subjects selected from the National Health and Nutrition Examination Survey (NHANES) 2009-2014 cycles. A professional examination of the periodontal status was conducted to distinguish between periodontitis and non-periodontitis based on the Centers for Disease Control and Prevention/American Academy of Periodontology (CDC/AAP) case definition. Laboratory testing of urine samples was performed to obtain the levels of urinary PAHs. Pearson correlation coefficients were utilized to determine the degree of correlation between urinary PAHs, while weighted binary logistic regression and Bayesian kernel machine regression (BKMR) were employed to evaluate the relationship between urinary PAHs and periodontitis.

RESULTS

In a single-exposure model, 3-hydroxyfluorene (OH-3F), 2-hydroxyfluorene (OH-2F), 1-hydroxyphenanthrene (OH-1Ph), and 2-hydroxyphenanthrene and 3-hydroxyphenanthrene (OH-2,3Ph) were positively associated with periodontitis risk. In the mixed-exposure model, BKMR analysis demonstrated that mixed exposure to urinary PAHs was positively associated with periodontitis, with OH-2F being the most critical factor for the overall mixed effects (posterior inclusion probability [PIP] = 0.98). Univariate exposure-response function and univariate effects analysis revealed a positive correlation between urinary OH-2F levels and periodontitis.

CONCLUSIONS

The study reveals a significant positive correlation between exposure to mixed PAHs and periodontitis, with a particular emphasis on the pivotal role of OH-2F. Mitigating PAHs in the environment may serve as a preventive measure against periodontitis and alleviate its global public health burden.

Evidence of economic development revealed in centennial scale sedimentary records of organic pollutants in Huguangyan Marr Lake

Sedimentary records of polycyclic aromatic hydrocarbons (PAHs) and phthalates could reflect energy consumption and industrial production adjustment. However, there is limited knowledge about their effects on variations of PAH and phthalate compositions in the sediment core. The PAH and phthalate sedimentary records in Huguangyan Maar Lake in Guangdong, China were constructed, and random forest models were adopted to quantify the associated impact factors. Sums of sixteen PAH (∑16 PAH) and seven phthalate (∑7 PAE) concentrations in the sediment ranged from 28.8 to 1110 and 246-4290 μg/kg dry weight in 1900-2020. Proportions of 5-6 ring PAHs to the ∑16 PAHs increased from 32.0 %-40.7 % in 1900-2020 with increased coal and petroleum consumption, especially after 1980. However, those of 2-3 ring PAHs decreased from 30.7 % to 23.6 % due to the biomass substitution with natural gas. The proportions of bis (2-ethylhexyl) phthalate to the ∑7 PAEs decreased from 52.3 %-29.1 % in 1900-2020, while those of di-isobutyl phthalate increased (13.7 % to 42.3 %). The shift from traditional plasticizers to non-phthalates drove this transformation, though the primary plastic production is increasing. Our findings underscore the effectiveness of optimizing energy structures and updating chemical products in reducing organic pollution in aquatic environments.

Metabolomics perspectives of the ecotoxicological risks of polycyclic aromatic hydrocarbons: A scoping review

Polycyclic Aromatic Hydrocarbons (PAHs) represent persistent environmental pollutants ubiquitously distributed in the environment. Their presence alongside various other contaminants gives rise to intricate interactions, culminating in profound deleterious consequences. The combination effects of different PAH mixtures on biota remains a relatively unexplored domain. Recent studies have harnessed the exceptional sensitivity of metabolomic techniques to unveil the significant ecotoxicological perils of PAH pollution confronting both human populations and ecosystems. This article furnishes a comprehensive overview of current literature focused on the metabolic repercussions stemming from exposure to complex mixtures of PAHs or PAH-pollution sources using metabolomics approaches. These insights are obtained through a wide range of models, including in vitro assessments, animal studies, investigations on human subjects, botanical specimens, and soil environments. The findings underscore that PAH mixtures induce cellular stress responses and systemic effects, leading to metabolic dysregulations in amino acids, carbohydrates, lipids, and other key metabolites (e.g., organic acids, purines), with specific variations observed based on the organism and PAH compounds involved. Additionally, the ecological consequences of PAH pollutants on plant and soil microbial responses are emphasized, revealing significant changes in stress-related metabolites and nutrient cycling in soil ecosystems. The complex interplay of various PAHs and their metabolic effects on several models, as elucidated through metabolomics, highlight the urgency of further research and the need for comprehensive strategies to mitigate the risks posed by these widespread environmental pollutants.

Spatiotemporal variations in soil pollution by polycyclic aromatic hydrocarbons over a 20-year economic boom in different districts of a heavy industrial city in North China

Urbanization-related human activities, such as population aggregation, rapid industrial expansion, and intensified traffic, are key factors that impact local polycyclic aromatic hydrocarbon emissions and their associated health risks. Consequently, regions with varying degrees of urbanization within a megacity may exhibit diverse spatiotemporal patterns in the presence and distribution of soil polycyclic aromatic hydrocarbons, resulting in different levels of ecological risks for local inhabitants following the same period of development. In this study, we measured the concentrations of 16 polycyclic aromatic hydrocarbons in soil samples collected from industrial district and rural district in Tianjin (China) in 2018, and compared with polycyclic aromatic hydrocarbon data in 2001 from a previous study to characterize these regional variations in occurrence, source, and human risk of polycyclic aromatic hydrocarbons induced by urbanization with time and space. The results indicate the 20-year rapid urbanization and industrialization has differentially affected the composition, distribution and sources of polycyclic aromatic hydrocarbons in soils from different economic functional zones in Tianjin. Additionally, its impact on health risks in rural district appeared to be more significant than that in industrial district.

Effect of polycyclic aromatic compounds (PAH & Polar-PAC) availability on their ecotoxicity towards terrestrial organisms

The exposure of terrestrial organisms to soils freshly contaminated by polycyclic aromatic compounds (PACs, including PAHs and polar-PACs) is known to cause significant toxicity effects. However, historically contaminated soils, such as former coking plant soils, usually induce a limited toxic impact, due to the "aging" phenomenon which is the result of several processes causing a reduction of PAC availability over time. For a better understanding of these behaviors, this study aimed to compare the toxic responses of terrestrial organisms exposed to aged contaminated soils and their counterparts submitted to a moderate heating process applied to increase PAC availability. Two aged "raw" soils (limited PAC availability) were selected for their representativeness of former industrial soils in terms of PAC contamination. These soils were submitted either to moderate heating (expected PAC availability increase) or solvent-extraction (expected PAC removal). Physico-chemical parameters, contamination levels and availability were determined for these three soil modalities. Additionally, standardized limit bioassays on plants and earthworms were performed to assess soil ecotoxicity. The findings demonstrated that historically contaminated soils exposed to moderate heating induced the highest ecotoxic responses from terrestrial organisms. Heating increased PAC (bio)availability, without modifying any other soil physico-chemical properties. These results pointed out the importance of considering the contamination availability parameter in risk evaluation and also provide a possible tool for protective long-term risk assessment.

Dyslexia is associated with urinary polycyclic aromatic hydrocarbon metabolite concentrations of children from China: Data from the READ program

It has been found that exposure to polycyclic aromatic hydrocarbons (PAHs) is associated with the risk of certain childhood neurodevelopmental disorders. However, no research has investigated the relationship between exposure to PAHs and children's dyslexia odds. The objective of this research was to investigate whether urinary mono-hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) are associated with increased dyslexia odds in Chinese children. We recruited 1,089 children (542 dyslexic children and 547 non-dyslexic children) for this case-control study. Ten OH-PAHs were measured in the participants' urine samples, which were collected between November 2017 and March 2023. Odds ratios (ORs) of the associations between the OH-PAHs and dyslexia were calculated using logistic regression models, after adjustment for the potential confounding factors. A significant association was found between urinary concentrations of 2-hydroxynaphthalene (2-OHNap) and the elevated odds of dyslexia. The children in the highest quartile of 2-OHNap had a higher OR of dyslexia (1.87, 95% CI: 1.07-3.27) than those in the lowest quartile (P-trend = 0.02) after adjustment for the covariates. After excluding children with maternal disorders during pregnancy, logistic regression analyses showed similar results. Our results suggested a possible association between PAH exposure and the elevated odds of dyslexia.

Chronic exposure to low levels of phenanthrene induces histological damage and carcinogenic risk in the uterus of female mice

Phenanthrene (Phe), a polycyclic aromatic hydrocarbon with low molecular weight, is detected in the environment at high frequency. To study the toxic effects of Phe on the uterine structure and function, female Kunming mice were exposed to Phe (0.05, 0.5, 5 ng/mL) for 270 days by drinking water. Pathological alterations and their action pathways were analyzed using immunohistochemical and biomolecular technology. Phe significantly increased the percentage of blood vessel area, the number of endometrial neutrophils (indicating the occurrence of inflammation), collagen deposition (indicating fibrosis), and the percentage of Ki-67-positive cells (indicating carcinogenesis) in the uterus. Transcriptome sequencing identified differentially expressed genes that were mainly enriched in some signaling pathways, including inflammation and carcinogenesis, suggesting a carcinogenic risk in the Phe-exposed uterus. Elevated serum estrogen levels and decreased progesterone levels exhibited a disturbance of steroid hormone balance, which might be related to uterine damage. Upregulated protein levels of uterine androgen receptor and estrogen receptor α were linked to the pathological effects. Most of the effects exhibited a nonmonotonic dose response, which might be attributed to the corresponding change in the serum levels of Phe. The results suggest that exposure to low levels of Phe could exert adverse effects on the uterus.

Association of co-exposure to polycyclic aromatic hydrocarbons and phthalates with oxidative stress and inflammation

Exposure to multiple environmental pollutants is ubiquitous and inevitable, but studies investigating their exposure effects on oxidative stress or inflammation have mainly been restricted to single-pollutant models. This study investigated the association of co-exposure to polycyclic aromatic hydrocarbons and phthalates with oxidative stress and inflammation. Using a cross-sectional study in adults, we measured urinary concentrations of metabolites of polycyclic aromatic hydrocarbons (OH-PAHs) and phthalates (mPAEs), urinary oxidative stress biomarker 8-hydroxy-2'-deoxyguanosine, and 9 inflammatory biomarkers in paired blood samples. The associations of urinary OH-PAHs and mPAEs with oxidative stress and inflammation biomarkers were evaluated by different statistical models. The Bayesian kernel machine regression and quantile g-computation was used to examine the joint effects, and increased levels of urinary concentrations of OH-PAHs and mPAEs were associated with elevated 8-hydroxy-2'-deoxyguanosine level and white blood cell counts. Exposure to polycyclic aromatic hydrocarbons contributed more significantly to inflammation, while exposure to phthalates contributed more to oxidative stress. Monoisobutyl phthalate was identified as the most significant metabolite contributing to elevated oxidative stress levels. 1-Hydroxypyrene was negatively associated with platelet, and monomethyl phthalate was significantly positively associated with interleukin 6 in multivariate linear regression. The restricted cubic spline analysis revealed non-linear patterns of 3-hydroxyfluorene with white blood cell, lymphocyte, neutrophil, and C-reactive protein. The results indicated significant associations between increased co-exposure to polycyclic aromatic hydrocarbons and phthalates with elevated oxidative stress and inflammation. Further investigation is needed to elucidate the underlying biological mechanisms and to determine the potential public health implications.

Combined exposure of MAHs and PAHs enhanced amino acid and lipid metabolism disruption in epithelium leading asthma risk

Monoaromatic hydrocarbons (MAHs) and polycyclic aromatic hydrocarbons (PAHs) are ubiquitous air pollutants from industry, with multiple adverse effects on respiratory system. However, the underlying mechanisms of their mixture to induce asthma is still unclear. Here, we examined mixture of 8 MAHs, mixture of 16 PAHs and a total mixture (MIX) on human bronchial epithelial (16-HBE) cells. Exposure to MIX resulted in increased expressions of asthma alarm cytokines (TSLP, IL-25 and IL-33), indicating potential asthma risk. Exposure to MIX led to significant upregulation of transcriptional level of oxidative stress and inflammation biomarkers through aryl hydrocarbon receptor activation, including SOD-2, NQO-1, IL-1β, IL-6 and IL-8 with 3.1, 19.9, 3.5, 23.4, 18.7, 28.1-fold change, indicated asthma related epithelial cell lesions. A total of 25, 49 and 59 differential metabolites were identified in cells response to MAH, PAH and MIX exposure, respectively, and enrichment analysis demonstrated MIX exposure disturbing alanine, aspartate and glutamate metabolism, glutathione metabolism, methionine metabolism and sphingolipid metabolism, involved in antioxidative defense and inflammation response. Combined exposure of MAHs and PAHs may result in increased toxic risks, and provide evidence to asthma onset and deterioration.

Selective cascade activation of polycyclic aromatic hydrocarbons in human cells: Role of enzyme's intrinsic electric field

Polycyclic aromatic hydrocarbons (PAHs) are major environmental organic pollutants. Some metabolites of PAHs show greater toxicity to humans while the others do not. It is highly important to decipher PAHs' regioselective activation mechanism and identify the major metabolites to accurately evaluate their public health risk. Here, we have performed a thorough computational study of benzo[a]anthracene (BA) metabolized by P450 1A1 by employing molecular docking, molecular dynamics simulations, quantum chemical calculation, and quantum mechanics/molecular mechanics calculations. Our findings show that highly-reactive species such as 3,4-epoxide, 8,9-epoxide, 3,4-diol-1,2-epoxide, and 8,9-diol-10,11-epoxide were major metabolites, which can efficiently react with guanine and damage DNA with extremely low energy barrier, therefore, supports the regioselective metabolism of BA. The origin of this selective activation is mainly contributed to both the oxygen‑carbon distance and previously overlooked enzyme's intrinsic electric field. Consequently, based on the resolved activation selectivity of BA. We built a high-throughput strategy to efficiently predict the metabolites of other PAHs. The accuracy of the strategy is validated by studying 16 PAHs on the priority control list. Hopefully this will aid the accurate evaluation of public health risks associated with PAH emissions.

New insight into PAH4 induced hepatotoxicity and the dose-response assessment in rats model

PAH4 (sum of benzo[a]pyrene, chrysene, benz[a]anthracene and benzo[b]fluoranthene) has been proposed as better marker than benzo[a]pyrene to assess total PAHs exposure in foodstuffs. However, the toxicological behaviors of PAH4 combined exposure remain unclear. This study aimed to investigate PAH4 toxicity effects with non-targeted metabolomics approach and evaluate the external and internal dose-response relationships based on benchmark dose (BMD) analysis. Male Sprague-Dawley rats were treated by gavage with vehicle (corn oil) or four doses of PAH4 (10, 50, 250, 1000 μg/kg·bw) for consecutive 30 days. After the final dose, the liver, blood and urine samples of rats were subsequently collected for testing. The concentrations of urinary mono-hydroxylated PAHs metabolites (OH-PAHs) including 3-hydroxybenzo[a]pyrene (3-OHB[a]P), 3-hydroxychrysene (3-OHCHR) and 3-hydroxybenz[a]anthracene (3-OHB[a]A) were determined to reflect internal PAH4 exposure. Our results showed PAH4 exposure increased relative liver weight and serum aspartate aminotransferase (AST) activity and caused hepatocyte swelling and degeneration, implying hepatotoxicity induced by PAH4. Serum metabolomics suggested PAH4 exposure perturbed lipid metabolism through upregulating the expression of glycerolipids metabolites, which was evidenced by markedly increased serum triglyceride (TG) level and hepatic TG content. Additionally, urinary OH-PAHs concentrations presented strong positive correlations with the external dose, indicating they were able to reflect PAH4 exposure. Furthermore, PAH4 exposure led to a dose-response increase of hepatic TG content, based on which the 95% lower confidence value of BMDs for external and internal doses were estimated as 5.45 μg/kg·bw and 0.11 μmol/mol·Cr, respectively. In conclusion, this study suggested PAH4 exposure could induce hepatotoxicity and lipid metabolism disorder, evaluating the involved dose-response relationships and providing a basis for the risk assessment of PAHs.

Joint association of heavy metals and polycyclic aromatic hydrocarbons exposure with depression in adults

BACKGROUND

Heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) represent significant components of environmental pollution, typically occurring as mixtures, raising concerns about their potential impact on human health. However, the combined effect of HMs and PAHs exposure on depression has not been explored.

METHODS

Leveraging National Health and Nutrition Examination Survey (NHANES) data spanning 2005 to 2016, we employ survey-weighted multiple logistic regression models to probe the interrelation between HMs, PAHs, and depression. This exploration is complemented by age and gender-stratified analyses, as well as a determination of the dose-response linkage via restricted cubic spline regression. Furthermore, the combined impact of HMs and PAHs on depression was evaluated through a range of statistical methodologies.

RESULTS

The study encompasses 7732 adults. Our findings unveil notable associations, indicating the significant influence of cadmium (Cd), lead (Pb), and all six PAHs metabolites on depression. Moreover, mixed exposure to HMs and PAHs emerges as a substantial contributor to an augmented depression risk, with Cd, Pb, 1-hydroxynaphthalene (1-NAP), 2-hydroxyfluorene (2-FLU), and 1-hydroxypyrene (1-PYR) likely driving this positive relationship. Intriguingly, subgroup analyses highlight greater prominence of these connections among individuals aged 20-59 and among women. Furthermore, the results tentatively suggest a potential interplay between Cd and 2-NAP in relation to depression.

CONCLUSION

This study posits that exposure to both individual and combined HMs and PAHs may be associated with an elevated risk of depression. Further prospective investigations are warranted to substantiate these findings.

Firefighters' personal exposure to gaseous PAHs during controlled forest fires: A case study with estimation of respiratory health risks and in vitro toxicity

Firefighters are daily exposed to adverse health-hazardous pollutants. Polycyclic aromatic hydrocarbons (PAHs), well known endocrine disruptors with carcinogenic, mutagenic, and teratogenic properties, are among the most relevant pollutants. The characterization of firefighters' occupational exposure to airborne PAHs remains limited; information is scarce for European firefighters. Also, the in vitro assessment of firefighters' respiratory health risks is inexistent. To reply to these scientific gaps, this work characterizes the levels of gaseous PAH in firefighters' personal air during regular working activities at controlled forest fires and at fire stations (control group). Breathable levels were 2.2-26.7 times higher during fire events than in the control group (2.63-32.63 μg/m3versus 1.22 μg/m3, p < 0.001); the available occupational guidelines (100 and 200 μg/m3 defined by the US National Institute for Occupational Safety and Health and the North American Occupational Safety and Health Administration, respectively) were not exceeded. Concentrations of (possible/probable) carcinogenic PAHs were 1.9-15.3 times superior during firefighting (p < 0.001). Increased values of total benzo(a)pyrene equivalents (p = 0.101), dose rates (p < 0.001), and carcinogenic risks (p = 0.063) were estimated in firefighters during controlled fires comparatively with the control group. Firefighters' breathable gaseous phase collected during fire events contributed to induce a significant viability decrease (<70 %; p < 0.05) in A549 and Calu-3 cell lines. The principal component analysis (PCA) allowed the differentiation between firefighters participating in controlled fire events from the control group. PCA analysis demonstrated the potential of PAHs to distinguish different sources of firefighters´ occupational exposure and of combining estimated health risk parameters with in vitro toxicities determined with human-breathable air collected during real-life scenarios. Overall, the participation in controlled fire events contributes to the respiratory health burden of firefighting forces. However, more studies are needed to corroborate these preliminary findings, explore the respiratory toxicological mechanisms, and support the implementation of preventive actions and mitigation strategies to pursue firefighters' health.

Association of chronic cough with exposure to polycyclic aromatic hydrocarbons in the US population

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants formed during the incomplete combustion of organic substances, such as coal and oil. PAHs exposure is known to increase the incidence of respiratory diseases; however, limited research has focused on their impact on chronic cough. In this study, we utilized data from the National Health and Nutritional Examination Surveys (NHANES) from 2003 to 2012. Chronic cough was defined as 'coughing most days for three consecutive months or more'. Employing survey-weighted multivariate logistic regression models, we identified positive associations between all six PAHs metabolites (1-NAP, 2-NAP, 3-FLU, 2-FLU, 1-PHE, and 1-PYR) found in urine and the presence of chronic cough. Furthermore, results from restricted cubic spline modeling revealed a nonlinear relationship between urinary levels of 1-NAP, 2-NAP, 3-FLU, 2-FLU, and 1-PYR and the risk of chronic cough. Co-exposure modeling unveiled the combined effects of multiple exposures and the relative contributions of each PAHs. Notably, co-exposure to PAHs was positively associated with an increased risk of chronic cough, where 2-FLU emerged as the primary contributor to this association. These findings were particularly pronounced in individuals with high cotinine exposure (≥0.05 ng/mL). In conclusion, this study presents epidemiological evidence linking PAHs exposure to an elevated risk of chronic cough. Further prospective investigations are warranted to corroborate these findings.

Association between exposure to polycyclic aromatic hydrocarbons and endometriosis: data from the NHANES 2001-2006

Aim

To evaluate the association between urinary polycyclic aromatic hydrocarbon (PAH) metabolites and the risk of endometriosis.

Methods

This cross-sectional study obtained data on women aged 20-54 years from the National Health and Nutrition Examination Survey (NHANES) 2001-2006. The weighted multivariate logistic regression model was established to assess the association between the eight urinary PAH metabolites and the risk of endometriosis. In this multivariate analysis, the eight urinary PAH metabolites were adjusted with urinary creatinine, and were divided into three groups according to tertiles: Tertile 1, Tertile 2 and Tertile 3. To evaluate the overall association of mixed PAH metabolites with endometriosis, the Bayesian kernel machine regression (BKMR) model was applied.

Results

Totally 1,291 women were included, of which 90 (6.97%) had endometriosis and 1,201 (93.03%) did not have endometriosis. After adjusting for age, race, smoking, age at menarche, hysterectomy, ovary removed, female hormone use, and menopause, compared with the Tertile 1 group, the Tertile 2 and Tertile 3 groups of all PAH metabolites demonstrated no significant risk of endometriosis. A positive tendency was found between mixed PAH metabolites and endometriosis when all the metabolites were at their 60th percentile levels or above compared with their median levels. When all the other metabolites were fixed at their median levels, 1-hydroxynaphthalene was positively correlated with endometriosis. Potential interactions existed between 1-hydroxynaphthalene and 2-hydroxynaphthalene and between 2-hydroxyfluorene and 3-hydroxyfluorene.

Conclusion

No significant association was found between individual PAH metabolites and endometriosis. A positive association existed between mixed PAH metabolites and the risk of endometriosis.

Maternal and newborn metabolomic changes associated with urinary polycyclic aromatic hydrocarbon metabolite concentrations at delivery: an untargeted approach

INTRODUCTION

Prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) has been associated with adverse human health outcomes. To explore the plausible associations between maternal PAH exposure and maternal/newborn metabolomic outcomes, we conducted a cross-sectional study among 75 pregnant people from Cincinnati, Ohio.

METHOD

We quantified 8 monohydroxylated PAH metabolites in maternal urine samples collected at delivery. We then used an untargeted high-resolution mass spectrometry approach to examine alterations in the maternal (n = 72) and newborn (n = 63) serum metabolome associated with PAH metabolites. Associations between individual maternal urinary PAH metabolites and maternal/newborn metabolome were assessed using linear regression adjusted for maternal and newborn factors while accounting for multiple testing with the Benjamini-Hochberg method. We then conducted functional analysis to identify potential biological pathways.

RESULTS

Our results from the metabolome-wide associations (MWAS) indicated that an average of 1% newborn metabolome features and 2% maternal metabolome features were associated with maternal urinary PAH metabolites. Individual PAH metabolite concentrations in maternal urine were associated with maternal/newborn metabolome related to metabolism of vitamins, amino acids, fatty acids, lipids, carbohydrates, nucleotides, energy, xenobiotics, glycan, and organic compounds.

CONCLUSION

In this cross-sectional study, we identified associations between urinary PAH concentrations during late pregnancy and metabolic features associated with several metabolic pathways among pregnant women and newborns. Further studies are needed to explore the mediating role of the metabolome in the relationship between PAHs and adverse pregnancy outcomes.

The role of N6-methyladenosine methylation in PAHs-induced cancers

Polycyclic aromatic hydrocarbons (PAHs), which are a wide range of environmental toxicants, may act on humans through inhalation, ingestion, and skin contact, resulting in a range of toxic reactions. Epidemiological studies showed that long-term exposure to PAHs in the occupational and living environment results in a substantial rise in the incidence rate of many cancers in the population, so the prevention and treatment of these diseases have become a major worldwide public health problem. N6-methyladenosine (m6A) modification greatly affects the metabolism of RNA and is implicated in the etiopathogenesis of many kinds of diseases. In addition, m6A-binding proteins have an important role in disease development. The abnormal expression of these can cause the malignant proliferation, migration, invasion, and metastasis of cancers. Furthermore, a growing number of studies revealed that environmental toxicants are one of the cancer risk factors and are related to m6A modifications. Exposure to environmental toxicants can alter the methylation level of m6A and the expression of the m6A-binding protein, thus promoting the occurrence and development of cancers through diverse mechanisms. m6A may serve as a biomarker for early environmental exposure. Through the study of m6A, we can find the health injury early, thus providing a new sight for preventing and curing environmental health-related diseases.

Association between polycyclic aromatic hydrocarbon exposure and blood lipid levels: the indirect effects of inflammation and oxidative stress

Although previous studies have indicated polycyclic aromatic hydrocarbons (PAHs) as cardiovascular health risk factors, evidence linking exposure to PAHs and blood lipids is still lacking, and the mechanism remains largely unknown. In this study, we evaluated the association between human internal exposure to PAHs and blood lipid levels in adults, as well as the indirect effects of inflammation and oxidative stress. The internal exposure of PAHs was assessed by determining serum PAHs and their hydroxylated metabolites (OH-PAHs) in the paired urine samples. Multivariable linear regression results demonstrated significant positive associations of individual PAHs and OH-PAHs with blood lipid biomarkers. The Bayesian kernel machine regression model revealed positive joint effects of PAH internal exposure on the fasting blood glucose, low-density lipoprotein cholesterol, total cholesterol, and total triglyceride, as well as an increased ratio of apolipoprotein B to apolipoprotein A1. In evaluating individual effects, serum phenanthrene played the most significant role in the association of increased PAH exposure with elevated fasting blood glucose. Quantile g-computation demonstrated the significant change in the levels of apolipoprotein B, ratio of apolipoprotein B to apolipoprotein A1, low-density lipoprotein cholesterol, and total cholesterol per quartile increase in PAH internal exposure. The restricted cubic spline analysis demonstrated the non-linear relationship between individual PAHs and OH-PAHs on blood lipid biomarkers. The mediation analysis indicated that PAH exposure may affect blood lipids not directly, but rather indirectly through intermediate inflammation and oxidative stress. The results demonstrated a significant association between increased PAH exposure levels and elevated blood lipids, highlighting the indirect effects of inflammation and oxidative stress.

Assessment of Phenanthrene Degradation Potential by Plant-Growth-Promoting Endophytic Strain Pseudomonas chlororaphis 23aP Isolated from Chamaecytisus albus (Hacq.) Rothm

Polycyclic aromatic hydrocarbons (PAHs) are common xenobiotics that are detrimental to the environment and human health. Bacterial endophytes, having the capacity to degrade PAHs, and plant growth promotion (PGP) may facilitate their biodegradation. In this study, phenanthrene (PHE) utilization of a newly isolated PGP endophytic strain of Pseudomonas chlororaphis 23aP and factors affecting the process were evaluated. The data obtained showed that strain 23aP utilized PHE in a wide range of concentrations (6-100 ppm). Ethyl-acetate-extractable metabolites obtained from the PHE-enriched cultures were analyzed by gas chromatography-mass spectrometry (GC-MS) and thin-layer chromatography (HPTLC). The analysis identified phthalic acid, 3-(1-naphthyl)allyl alcohol, 2-hydroxybenzalpyruvic acid, α-naphthol, and 2-phenylbenzaldehyde, and allowed us to propose that the PHE degradation pathway of strain 23aP is initiated at the 1,2-, 3,4-carbon positions, while the 9,10-C pathway starts with non-enzymatic oxidation and is continued by the downstream phthalic pathway. Moreover, the production of the biosurfactants, mono- (Rha-C8-C8, Rha-C10-C8:1, Rha-C12:2-C10, and Rha-C12:1-C12:1) and dirhamnolipids (Rha-Rha-C8-C10), was confirmed using direct injection-electrospray ionization-mass spectrometry (DI-ESI-MS) technique. Changes in the bacterial surface cell properties in the presence of PHE of increased hydrophobicity were assessed with the microbial adhesion to hydrocarbons (MATH) assay. Altogether, this suggests the strain 23aP might be used in bioaugmentation-a biological method supporting the removal of pollutants from contaminated environments.

Bioremediation of polycyclic aromatic hydrocarbons contaminated soils: recent progress, perspectives and challenges

The life of all creatures is supported directly or indirectly by soil, which is a significant environmental matrix. The soil has been polluted partly due to increased human activities and population growth, releasing several foreign substances and persistent contaminants. When toxic substances like polycyclic aromatic hydrocarbons (PAHs) are disposed of, the characteristics of the soil are changed, microbial biodiversity is impacted, and items are destroyed. Because of the mutagenicity, carcinogenicity, and toxicity of petroleum hydrocarbons, the restoration and cleanup of PAH-polluted areas represent a severe technological and environmental challenge for long-term growth and development. Although there are several ways to clean up PAH-contaminated soils, much attention is paid to intriguing bacteria, fungus, and their enzymes. Various factors influence PAH breakdown, including pH, temperature, airflow, moisture level, nutrient availability, and degrading microbial populations. This review discusses how PAHs affect soil characteristics and shows that secondary metabolite and carbon dioxide decomposition are produced due to microbial breakdown processes. Furthermore, the advantages of bioremediation strategies were assessed for correct evaluation and considered dependable on each legislative and scientific research level, as analyzed in this review.

Association between exposure to multiple polyaromatic hydrocarbons and periodontitis: findings from a cross-sectional study

The impact of environmental pollutant exposure on periodontitis has raised significant concerns. But the association between exposure to multiple polyaromatic hydrocarbons (PAHs) and periodontitis still remained unclear. Our study investigated the association of exposure to multiple PAHs with periodontitis. A total of 1880 participants from the National Health and Nutrition Examination Survey (NHANES) were included in this study. Urinary samples of the participants exposed to six PAHs, namely, 1-hydroxynaphthalene (1-OHN), 2-hydroxynaphthalene (2-OHN), 3-hydroxyfluorene (3-OHF), 2-hydroxyfluorene (2-OHF), 1-hydroxyphenanthrene (1-OHPhe), and 1-hydroxypyrene (1-OHPyr), were investigated. Multiple logistic regression, restricted cubic spline, and Bayesian kernel machine regression (BKMR) models were employed to identify the association between PAH exposures and periodontitis. The dose-response analysis exhibited a gradual increase in the periodontitis risk with an increase in multiple PAHs. After adjustment for several potential confounders, the odds ratio of the highest quartile (Quartile 4) was 1.648 (95% confidence interval (CI) 1.108-2.456, P = 0.014, P-t = 0.017) for 2-OHN, 2.046 (95%CI 1.352-3.104, P < 0.001, P-t = 0.005) for 3-OHF, 1.996 (95% CI 1.310-3.046, P = 0.001, P-t = 0.003) for 2-OHF, 1.789 (95% CI 1.230-2.604, P = 0.002, P-t = 0.003) for 1-OHPhe, and 1.494 (95% CI 1.025-2.181, P = 0.037, P-t = 0.021) for 1-OHPyr compared with that of the lowest quartile (Quartile 1). BKMR illustrated that the overall effect of the PAH mixture was positively related to periodontitis. Mediation analysis identified blood neutrophils as a partial mediator of 3-OHF and 2-OHF. Exposure to multiple PAHs was positively associated with periodontitis in US adults, and blood neutrophils mediate the effects of 3-OHF and 2-OHF therein.

Association between urinary concentrations of polycyclic aromatic hydrocarbons and risk of endometriosis in the NHANES 2003-2006

To explore the association between exposure to polycyclic aromatic hydrocarbons (PAHs) and endometriosis risk. Data were obtained from the 2003-2006 National Health and Nutrition Examination Survey database. Urinary concentrations of PAHs were divided into quartiles, and weighted multivariate logistic regression, restricted cubic spline, and subgroup analyses were performed. An extreme gradient boosting (XGBoost) algorithm was used to screen the most important PAHs. After multivariable adjustments, 9-fluorene, 1-phenanthrene, 2-phenanthrene, and 4-phenanthrene exposure were significantly associated with a risk of endometriosis. Specifically, compared with the reference group, the odds ratios (ORs) of endometriosis for the fourth quartile were 3.52 (95% confidence interval (CI): 1.15, 10.77), 3.10 (95% CI: 1.37, 6.97), 4.86 (95% CI: 1.93, 12.21), and 2.67 (95% CI: 1.02, 7.01) for 9-fluorene, 1-phenanthrene, 2-phenanthrene, and 4-phenanthrene, respectively. In terms of continuous exposure, each one-standard-deviation increase in the urinary concentration of 9-fluorene, 1-phenanthrene, 2-phenanthrene, and 4-phenanthrene was independently associated with a 66% (OR: 1.66, 95% CI: 1.15, 2.40), 62% (OR:1.62, 95% CI: 1.19, 2.20), 68% (OR: 1.68, 95% CI: 1.24, 2.28), and 56% (OR: 1.56, 95% CI: 1.11, 2.19) increase in the risk of endometriosis, respectively, in the fully adjusted model. A significant association between the urinary concentration of 9-fluorene and the risk of endometriosis was also observed in participants who had a high body-mass index (≥25 kg/m2), with a corresponding OR of 2.61 (95% CI: 1.37, 5.00; P for interaction = 0.006). Our findings show that high urinary concentrations of PAHs were associated with a high risk of endometriosis in participants and that the urinary concentration of 9-fluorene was related with a high susceptibility of endometriosis in participants with overweight.

Effect of electric fields strength on soil factors and microorganisms during electro-bioremediation of benzo[a]pyrene-contaminated soil

Electro-bioremediation is a promising technology for remediating soils contaminated with polycyclic aromatic hydrocarbons (PAHs). However, the resulting electrokinetic effects and electrochemical reactions may inevitably cause changes in soil factors and microorganism, thereby reducing the remediation efficiency. To avoid negative effect of electric field on soil and microbes and maximize microbial degradability, it is necessary to select a suitable electric field. In this study, artificial benzo [a]pyrene (BaP)-contaminated soil was selected as the object of remediation. Changes in soil factors and microorganisms were investigated under the voltage of 1.0, 2.0, and 2.5 V cm-1 using chemical analysis, real-time PCR, and high-throughput sequencing. The results revealed noticeable changes in soil factors (pH, moisture, electrical conductivity [EC], and BaP concentration) and microbes (PAHs ring-hydroxylating dioxygenase [PAHs-RHDα] gene and bacterial community) after the application of electric field. The degree of change was related to the electric field strength, with a suitable strength being more conducive to BaP removal. At 70 d, the highest mean extent of BaP removal and PAHs-RHDα gene copies were observed in EK2.0 + BIO, reaching 3.37 and 109.62 times those in BIO, respectively, indicating that the voltage of 2.0 V cm-1 was the most suitable for soil microbial growth and metabolism. Changes in soil factors caused by electric fields can affect microbial activity and community composition. Redundancy analysis revealed that soil pH and moisture had the most significant effects on microbial community composition (P < 0.05). The purpose of this study was to determine the appropriate electric field that could be used for electro-bioremediation of PAH-contaminated soil by evaluating the effects of electric fields on soil factors and microbial communities. This study also provides a reference for efficiency enhancement and successful application of electro-bioremediation of soil contaminated with PAHs.

Metabolism and elimination kinetics of mono-hydroxylated PAHs metabolites following single exposure to different combinations of PAH4 in rats

The metabolism of polycyclic aromatic hydrocarbons (PAHs) and the elimination kinetics of their mono-hydroxylated metabolites (OH-PAHs) following single exposure to different combinations of four PAHs (PAH4) were studied. Male Sprague-Dawley rats were orally exposed to a single dose of benzo[a]pyrene (B[a]P) or PAH2 (B[a]P + chrysene), PAH3 (B[a]P + chrysene + benz[a]anthracene), and PAH4 (B[a]P + chrysene + B[a]A + benzo[b]fluoranthene) with each combination adjusted to the same dose of individual compound. OH-PAHs including 3-hydroxybenzo[a]pyrene, 3-hydroxychrysene, 3-hydroxybenz[a]anthracene, and 1-hydroxypyrene (1-OHP) were detected in serum and urine samples collected at six intervals over a 72-h period post-dosing. The hepatic mRNA levels of cytochrome P450 (CYPs) were determined to ascertain the expression induction of PAHs metabolic enzymes. Results showed OH-PAHs (except 1-OHP) peaked within 8 h in serum and were excreted from urine within 24-48 h. The serum and urinary concentration of 3-hydroxybenzo[a]pyrene was significantly increased after PAH4 exposure compared with other PAHs combinations. Inversely, urinary concentration of 3-hydroxychrysene was decreased after PAH4 exposure, and the kinetics of 3-hydroxybenz[a]anthracene or 1-OHP were not different depending on the PAHs combinations. Also, CYPs were markedly induced by PAHs. Notably, the induction levels of CYP1A1 and CYP1B1 were significantly higher after PAH4 exposure compared with B[a]P exposure. The results indicated the metabolism of B[a]P was accelerated after PAH4 exposure which might be partly due to the induction of CYPs. These results confirmed PAHs are rapidly metabolized and suggested potential interactions of PAHs may happen among PAH4 mixture.

Persistent organic pollutants (POPs) in marine crustaceans: Bioaccumulation, physiological and cellular responses

Persistent organic pollutants (POPs) are ubiquitous in marine ecosystems. These compounds can be accumulated in water, sediments and organisms, persist in time, and have toxic effects in human and wildlife. POPs can be uptaken and bioaccumulated by crustaceans, affecting different physiological processes, including energy metabolism, immunity, osmoregulation, excretion, growth, and reproduction. Nonetheless, animals have evolved sub-cellular mechanisms for detoxification and protection from chemical stress. POPs induce the activity of enzymes involved in xenobiotic metabolism and antioxidant systems, that in vertebrates are importantly regulated at gene expression (transcriptional) level. However, the activation and control of these enzyme systems upon the exposure to POPs have been scarcely studied in invertebrate species, including crustaceans. Herein, we summarize various aspects of the bioaccumulation of POPs in marine crustaceans and their physiological effects. We specially focus on the regulation of xenobiotics metabolism and antioxidant enzymes as key sub-cellular mechanisms for detoxification and protection from chemical stress.

Single and Joint Associations of Polycyclic Aromatic Hydrocarbon Exposure with Liver Function during Early Pregnancy

The individual and combined associations of polycyclic aromatic hydrocarbons (PAHs) metabolites on liver function during pregnancy are still lacking. We aimed to explore the connection between urinary PAH metabolites and liver function in early pregnant women in southwest China based on the Zunyi birth cohort. Ten urinary PAH metabolites and five liver function parameters during early pregnancy were measured. The associations of single PAHs with parameters of liver function were assessed using multiple linear regression. A Bayesian kernel machine regression (BKMR) model was used to evaluate the joint associations of the PAH mixture with outcomes. We found that each 1% increment of urinary 2-hydroxyphenanthrene (2-OH-PHE) was associated with 3.36% (95% CI: 0.40%, 6.40%) higher alanine aminotransferase (ALT) and 2.22% (95% CI: 0.80%, 3.67%) higher aspartate aminotransferase (AST). Each 1% increment in 1-hydroxy-phenanthrene (1-OH-PHE) was significantly associated with 7.04% (95% CI: 1.61%, 12.75%) increased total bile acid (TBA). Additionally, there was a significant positive linear trend between 2-OH-PHE and AST and 1-OH-PHE and TBA. BKMR also showed a significant positive association of PAH mixture with AST. Our results indicate that PAH metabolites were associated with increased parameters of liver function among early pregnant women. Early pregnant women should pay more attention to the adverse relationships between PAHs and liver function parameters to prevent environment-related adverse perinatal outcomes.

Continent-based systematic review of the short-term health impacts of wildfire emissions

This review systematically gathers and provides an analysis of pollutants levels emitted from wildfire (WF) and their impact on short-term health effects of affected populations. The available literature was searched according to Population, Exposure, Comparator, Outcome, and Study design (PECOS) database defined by the World Health Organization (WHO) and a meta-analysis was conducted whenever possible. Data obtained through PECOS characterized information from the USA, Europe, Australia, and some Asian countries; South American countries were seldom characterized, and no data were available for Africa and Russia. Extremely high levels of pollutants, mostly of fine fraction of particulate matter (PM) and ozone, were associated with intense WF emissions in North America, Oceania, and Asia and reported to exceed several-fold the WHO guidelines. Adverse health outcomes include emergency department visits and hospital admissions for cardiorespiratory diseases as well as mortality. Despite the heterogeneity among exposure and health assessment methods, all-cause mortality, and specific-cause mortality were significantly associated with WF emissions in most of the reports. Globally, a significant association was found for all-cause respiratory outcomes including asthma, but mixed results were noted for cardiovascular-related effects. For the latter, estimates were only significant several days after WF emissions, suggesting a more delayed impact on the heart. Different research gaps are presented, including the need for the application of standardized protocols for assessment of both exposure and adverse health risks. Mitigation actions also need to be strengthened, including dedicated efforts to communicate with the affected populations, to engage them for adoption of protective behaviors and measures.

Occurrence and distribution of polycyclic aromatic hydrocarbons (PAHs) in marine organisms from Shenzhen coastal waters and human health risk assessment

This study investigated the levels and composition of 16 priority polycyclic aromatic hydrocarbons (PAHs) in marine organisms from South China Sea and assessed their potential health risks. The results revealed that the pollution levels of total PAHs ranged from 3.56 to 392.21 ng/g dw. Notably, 4-ring PAHs constituted the predominant fraction (58.02 %) of the total PAHs, with pyrene being the most abundant congener across all species. Intriguingly, our findings suggested that consuming these organisms might pose a low non-cancer hazard. Nonetheless, benzo[a]pyrene was detected in most species, with levels ranging from non-detectable to 11.24 ng/g dw. The individual lifetime cancer risk levels associated with seafood consumption in studied regions ranged from 1.10 × 10-5 to 1.52 × 10-5, highlighting a potential cancer risk that warrants special attention. These findings emphasize the need to prioritize carcinogenic compounds over total PAHs and underscore the importance of continuous monitoring of PAH pollution in seafood.

Human biomonitoring and reference values of urinary 1-hydroxypyrene among Iranian adults population

Polycyclic aromatic hydrocarbons (PAHs) are one of the most important environmental pollutants. Urinary concentrations of 1-hydropyren metabolites of PAHs have been used as biomarkers of these chemicals' exposure in humans. This cross-sectional study was conducted on 468 healthy Iranian adults over 25 years old and non-smokers in six provinces who were selected based on the clustering method. Fasting urine sampling and body composition and demographic measurements were performed. Urine samples were analyzed by GC-MS. The analysis included descriptive statistics and analytical statistics using multiple linear regression by Python software. 1-Hydroxypyrene was found in 100% of samples, and the mean (Reference Value 95%) concentration of 1-hydroxypyrene was 6.12 (RV 95%: 20) μg/L and 5.95 (21) μg/gcrt. There was a direct relationship between the amount of body composition (body fat, visceral fat), BMI, and age with the urinary concentrations of 1-hydropyren metabolites, and this relationship was significant for BMI with urinary concentrations of 1-hydropyren metabolites (P = 0.045). The amount of 1-hydroxypyrene in healthy Iranian adults has been higher than in similar studies in other countries. These results provide helpful information regarding the exposure of Iranian adults to 1-hydroxypyrene, and these data can be used to supplement the national reference values of human biomonitoring for the interpretation of biomonitoring results.

Exploring Single-Cell Exposomics by Mass Spectrometry

Single-cell exposomics, a revolutionary approach that investigates cell-environment interactions at cellular and subcellular levels, stands distinct from conventional bulk exposomics. Leveraging advancements in mass spectrometry, it provides a detailed perspective on cellular dynamics, interactions, and responses to environmental stimuli and their impacts on human health. This work delves into this innovative realm, highlighting the nuanced interplay between environmental stressors and biological responses at cellular and subcellular levels. The application of spatial mass spectrometry in single-cell exposomics is discussed, revealing the intricate spatial organization and molecular composition within individual cells. Cell-type-specific exposomics, shedding light on distinct susceptibilities and adaptive strategies of various cell types to environmental exposures, is also examined. The Perspective further emphasizes the integration with molecular and cellular biology approaches to validate hypotheses derived from single-cell exposomics in a comprehensive biological context. Looking toward the future, we anticipate continued technological advancements and convergence with other -omics approaches and discuss implications for environmental health research, disease progression studies, and precision medicine. The final emphasis is on the need for robust computational tools and interdisciplinary collaboration to fully leverage the potential of single-cell exposomics, acknowledging the complexities inherent to this paradigm.

Polycyclic Aromatic Hydrocarbons in Soil and Vegetation of Niger Delta, Nigeria: Ecological Risk Assessment

The Niger Delta, Nigeria, is noted for crude oil exploration. Whereas there seems to be a handful of data on soil polycyclic aromatic hydrocarbon (PAH) levels in this area, there is a paucity of studies that have evaluated soil and vegetation PAHs simultaneously. The present study has addressed this information gap. Fresh Panicum maximum (Jacq) (guinea grass), Pennisetum purpureum Schumach (elephant grass), Zea mays (L.) (maize), and soil samples were collected in triplicate from Choba, Khana, Trans-Amadi, Eleme, Uyo, and Yenagoa. PAHs determination was carried out using GC-MS. The percentage composition of the molecular weight distribution of PAHs, the molecular ratio of selected PAHs for identification of possible sources, and the isomeric ratio and total index of soil were evaluated. Pennisetum purpureum Schumach (elephant grass) from Uyo has the highest (10.0 mg·kg^-1) PAH while Panicum maximum (Jacq) (guinea grass) has the highest PAH (32.5 mg·kg^-1 from Khana. Zea mays (L.) (maize) from Uyo (46.04%), Pennisetum purpureum Schumach (elephant grass) from Trans-Amadi (47.7%), guinea grass from Eleme (49.2%), and elephant grass from Choba (39.9%) contained the highest percentage of high molecular weight (HMW) PAHs. Soil samples from Yenagoa (53.5%) and Khana (55.3%) showed the highest percentage of HMW PAHs. The total index ranged 0.27-12.4 in Uyo, 0.29-8.69 in Choba, 0.02-10.1 in Khana, 0.01-5.53 in Yenagoa, 0.21-9.52 in Eleme, and 0.13-8.96 in Trans-Amadi. The presence of HMW PAHs and molecular diagnostic ratios suggest PAH pollution from pyrogenic and petrogenic sources. Some soils in the Niger Delta show RQ_(NCs) values higher than 800 and require remediation to forestall ecohealth consequences.

Phenanthrene regulates metabolic pathways for hydrogen accumulation in sludge alkaline dark fermentation

The influence of phenanthrene (PHE), a general polycyclic aromatic hydrocarbon in waste activated sludge, on sludge alkaline dark fermentation for hydrogen accumulation was investigated prospectively. The yield of hydrogen was 16.2 mL/g TSS with 50 mg/kg TSS PHE, which was 1.3-fold greater than that of the control. Mechanism research demonstrated that hydrogen production and the abundance of functional microorganisms were facilitated, whereas those of homoacetogenesis were reduced. The activity of pyruvate ferredoxin oxidoreductase in the conversion of pyruvate to reduced ferredoxin for hydrogen production was promoted by 57.2%, and that of carbon monoxide dehydrogenase and formyltetrahydrofolate synthetase, closely associated with hydrogen consumption, was suppressed by 60.5% and 55.9%, respectively. Moreover, the encoding genes involved in pyruvate metabolism were significantly up-regulated, while genes related to consuming hydrogen to reduce carbon dioxide and produce 5-methyltetrahydrofolate were down-regulated. This study notably illustrates the effect of PHE on hydrogen accumulation from metabolic pathways.

Miniaturized method for the quantification of persistent organic pollutants and their metabolites in HepG2 cells: assessment of their biotransformation

Biotransformation can greatly influence the accumulation and, subsequently, toxicity of substances in living beings. Although traditionally these studies to quantify metabolization of a compound have been carried out with in vivo species, currently, in vitro test methods with very different cell lines are being developed for their evaluation. However, this is still a very limited field due to multiple variables of a very diverse nature. So, an increasing number of analytical chemists are working with cells or other similar biological samples of very small size. This makes it necessary to address the development of analytical methods that allow determining their concentration both inside the cells and in their exposure medium. The aim of this study is to develop a set of analytical methodologies for the quantification of polycyclic aromatic hydrocarbons, PAHs (phenanthrene, PHE), and polybrominated diphenyl ethers, PBDEs (2,2',4,4'-tetrabromodiphenyl ether, BDE-47), and their major metabolites in cells and their exposure medium. Analytical methodologies, based on miniaturized ultrasound probe-assisted extraction, gas chromatography-mass spectrometry-microelectron capture detector (GC-MS-µECD), and liquid chromatography-fluorescence detector (LC-FL) determination techniques, have been optimized and then applied to a biotransformation study in HepG2 at 48 h of exposure. Significant concentrations of the major metabolites of PHE (1-OH, 2-OH, 3-OH, 4-OH-, and 9-OH-PHE) and BDE-47 (5-MeO-, 5-OH-, and 3-OH-BDE-47) were detected and quantified inside the cells and in the exposure medium. These results provide a new method for determination and improve information on the metabolization ratios for a better knowledge of the metabolic pathways and their toxicity.

Association between co-exposure of polycyclic aromatic hydrocarbons and chronic obstructive pulmonary disease among the US adults: results from the 2013-2016 National Health and Nutrition Examination Survey

Although existing epidemiological studies have reported the relationship between single polycyclic aromatic hydrocarbon (PAH) exposure and chronic obstructive pulmonary disease (COPD), little is known about the impact of PAH mixture exposure on COPD. Therefore, we aimed to evaluate the associations of single and mixed exposures to PAHs with COPD in US adults using data from NHANES 2013-2016 by fitting three statistical methods, including multiple logistic regression, Bayesian kernel machine regression (BKMR), and quantile-based g-computation (qgcomp) models. This study included 1836 participants aged 40 and older. Multiple logistic regression showed that 2-FLU, 1-PHE, 1-PYR, and 2&3-PHE increased the risk of COPD after adjusting for all covariates. The BKMR model identified positive trends between PAH mixture and the risk of COPD in all adults and males when all PAHs were at or above their 55th percentile compared to all PAHs at their 50th percentile. The qgcomp model suggested that PAH co-exposure increased the risk of COPD (OR:1.44, 95%CI:1.09, 1.90) when each quartile increased in PAH mixture concentration, with 2-FLU having the highest weight. The combined impact also be observed in men. In conclusion, PAHs co-exposure was associated with a higher risk of COPD, especially in males, with the positive impact of 2-FLU being the most important.

A State-of-the-Science Review on High-Resolution Metabolomics Application in Air Pollution Health Research: Current Progress, Analytical Challenges, and Recommendations for Future Direction

BACKGROUND

Understanding the mechanistic basis of air pollution toxicity is dependent on accurately characterizing both exposure and biological responses. Untargeted metabolomics, an analysis of small-molecule metabolic phenotypes, may offer improved estimation of exposures and corresponding health responses to complex environmental mixtures such as air pollution. The field remains nascent, however, with questions concerning the coherence and generalizability of findings across studies, study designs and analytical platforms.

OBJECTIVES

We aimed to review the state of air pollution research from studies using untargeted high-resolution metabolomics (HRM), highlight the areas of concordance and dissimilarity in methodological approaches and reported findings, and discuss a path forward for future use of this analytical platform in air pollution research.

METHODS

We conducted a state-of-the-science review to a) summarize recent research of air pollution studies using untargeted metabolomics and b) identify gaps in the peer-reviewed literature and opportunities for addressing these gaps in future designs. We screened articles published within Pubmed and Web of Science between 1 January 2005 and 31 March 2022. Two reviewers independently screened 2,065 abstracts, with discrepancies resolved by a third reviewer.

RESULTS

We identified 47 articles that applied untargeted metabolomics on serum, plasma, whole blood, urine, saliva, or other biospecimens to investigate the impact of air pollution exposures on the human metabolome. Eight hundred sixteen unique features confirmed with level-1 or -2 evidence were reported to be associated with at least one or more air pollutants. Hypoxanthine, histidine, serine, aspartate, and glutamate were among the 35 metabolites consistently exhibiting associations with multiple air pollutants in at least 5 independent studies. Oxidative stress and inflammation-related pathways-including glycerophospholipid metabolism, pyrimidine metabolism, methionine and cysteine metabolism, tyrosine metabolism, and tryptophan metabolism-were the most commonly perturbed pathways reported in > 70 % of studies. More than 80% of the reported features were not chemically annotated, limiting the interpretability and generalizability of the findings.

CONCLUSIONS

Numerous investigations have demonstrated the feasibility of using untargeted metabolomics as a platform linking exposure to internal dose and biological response. Our review of the 47 existing untargeted HRM-air pollution studies points to an underlying coherence and consistency across a range of sample analytical quantitation methods, extraction algorithms, and statistical modeling approaches. Future directions should focus on validation of these findings via hypothesis-driven protocols and technical advances in metabolic annotation and quantification. https://doi.org/10.1289/EHP11851.

Biomonitoring of firefighting forces: a review on biomarkers of exposure to health-relevant pollutants released from fires

Occupational exposure as a firefighter has recently been classified as a carcinogen to humans by International Agency for Research on Cancer (IARC). Biomonitoring has been increasingly used to characterize exposure of firefighting forces to contaminants. However, available data are dispersed and information on the most relevant and promising biomarkers in this context of firefighting is missing. This review presents a comprehensive summary and critical appraisal of existing biomarkers of exposure including volatile organic compounds such as polycyclic aromatic hydrocarbons, several other persistent other organic pollutants as well as heavy metals and metalloids detected in biological fluids of firefighters attending different fire scenarios. Urine was the most characterized matrix, followed by blood. Firefighters exhaled breath and saliva were poorly evaluated. Overall, biological levels of compounds were predominantly increased in firefighters after participation in firefighting activities. Biomonitoring studies combining different biomarkers of exposure and of effect are currently limited but exploratory findings are of high interest. However, biomonitoring still has some unresolved major limitations since reference or recommended values are not yet established for most biomarkers. In addition, half-lives values for most of the biomarkers have thus far not been defined, which significantly hampers the design of studies. These limitations need to be tackled urgently to improve risk assessment and support implementation of better more effective preventive strategies.

Changes in metabolic profiles of amphipods Allorchestes compressa after acute exposures to copper, pyrene, and their mixtures

Amphipods are ideal indicators for biomonitoring and ecotoxicological studies of environmental contaminants because they are extensively distributed in aquatic environments, are easy to collect and are important in nutrient cycling. Marine amphipods (Allorchestes compressa) were exposed to two concentrations of copper and pyrene, and their mixtures, for 24 and 48 h. Changes in polar metabolites were assessed using Gas Chromatography Mass Spectrometry (GC-MS)-based untargeted metabolomics. Generally, limited metabolite changes were observed for copper and pyrene single exposures (eight and two significant metabolites, respectively), while 28 metabolites had changed following exposures to mixtures. Furthermore, changes were mainly observed after 24 h but had seemingly returned to control levels after 48 h. Multiple types of metabolites were affected including amino acids, Tricarboxylic acid (TCA) cycle intermediates, sugars, fatty acids, and hormones. This study highlights the sensitivity of metabolomics in assessing the impacts of low concentrations of chemicals compared to traditional ecotoxicological endpoints.

Occurrence and source of PAHs in Miankaleh International Wetland in Iran

We examined the occurrence and sources of 16 priority PAHs in the water and sediment samples of the Miankaleh Wetland (Coastal Biosphere Reserve), famous for harbouring huge flocks of migrating birds. The water and sediment samples collected from various locations were visualized and processed using a self-organizing map, positive matrix factorization and GIS. All the sediment samples, and >90% of the water samples, showed some degree of PAHs contamination. Higher PAH levels occur near the Chopoghi Channel, powerplants, sewage outfalls, and near fishing operations. Compared with previous study in this area, the PAHs concentration in the sediments of aquatic ecosystem of Miankaleh Wetland is increasing. The levels of PAH contamination seem too low to account for the mass deaths of migratory birds, and botulinus contamination seems the likely cause. Fugacity calculations show that the sediments act as a sink for PAHs. According to PMF and SOM analyses, three origins of PAHs were recognized: (i) fossil fuel and vehicular emissions with high-molecular weight PAHs (4-5 ring); (ii) municipal and industrial sewages characterized by low-molecular weight PAHs (2-3 ring) typical of petrogenic sources; and (iii) port activity characterized by prevalence of petrogenic influence and petroleum-related activities (combustion PAHs and low-molecular weight PAHs) consistent with port activity. This wetland needs serious attention because of continuous input of pollutants. The results and the methods used in this study may assist in improving coastal wetlands management.

Association of the urinary polycyclic aromatic hydrocarbons with sex hormones stratified by menopausal status older than 20 years: a mixture analysis

We examined the relationships between exposure to polycyclic aromatic hydrocarbons (PAH) metabolites and sex hormones in pre- and postmenopausal women from the 2013-2016 National Health and Nutrition Examination Survey. The study comprised 648 premenopausal and 370 postmenopausal women (aged 20 years or older) with comprehensive data on PAH metabolites and sex steroid hormones. To evaluate the correlations between individual or mixture of the PAH metabolites and sex hormones stratified by menopausal status, we used linear regression and Bayesian kernel machine regression (BKMR). After controlling for confounders, 1-Hydroxynaphthalene (1-NAP) was inversely associated with total testosterone (TT), and 1-NAP, 3-Hydroxyfluorene (3-FLU), and 2-Hydroxyfluorene (2-FLU) were inversely associated with estradiol (E2). 3-FLU was positively associated with sex hormone-binding globulin (SHBG) and TT/E2, whereas 1-NAP and 2-FLU were inversely associated with free androgen index (FAI). In the BKMR analyses, chemical combination concentrations at or above the 55th percentile were inversely connected to E2, TT, and FAI values but positively correlated with SHBG when compared with the matching 50th percentile. In addition, we only found that mixed exposure to PAHs was positively associated with TT and SHBG in premenopausal women. Exposure to PAH metabolites, either alone or as a mixture, was negatively associated with E2, TT, FAI, and TT/E2 but positively associated with SHBG. These associations were stronger among postmenopausal women.

Distribution, sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in agricultural and dumpsite soils in Sierra Leone

This study investigates the concentration and distribution of polycyclic aromatic hydrocarbons (PAHs) in soils, potential sources, risk assessment, and soil physicochemical properties influencing PAH distribution in developed and remote cities in Sierra Leone. Seventeen topsoil samples (0-20 cm) were collected and analyzed for 16 PAHs. The average concentrations of Σ₁₆PAH in soils in the surveyed areas were 1142 ng g^-1 dw, 265 ng g^-1 dw, 79.7 ng g^-1 dw, 54.3 ng g^-1 dw, 54.2 ng g^-1 dw, 52.3 ng g^-1 dw, and 36.6 ng g^-1 dw in Kingtom, Waterloo, Magburaka, Bonganema, Kabala, Sinikoro, and Makeni, respectively. Based on the European soil quality guidelines, Kingtom and Waterloo soils were categorized as heavily and weakly contaminated soil PAHs respectively. The main PAH compounds of this study were 2-ring, 4-ring, and 5-ring PAHs. High molecular weight PAHs (4-6 rings) made up 62.5% of the total PAHs, while low molecular weight PAHs (2-3 rings) was 37.5%. In general, HMWPAHs were predominant in Kingtom, followed by Waterloo. The appointment of PAH sources using different methods revealed mixed sources, but predominantly pyrogenic sources (petroleum, biomass, coal, and fossil fuel contributions). Soil pH has a significant impact on PAH distribution. The toxicity equivalent quantity (TEQ_BaP) levels in soils pose a potential health risk to residents in developed cities but pose a negligible health risk to residents in remote cities. This study is significant as its findings reveal the status of PAH soil contamination in Sierra Leone. The results have important implications for policymakers and stakeholders to identify high-risk zones and establish proper environmental monitoring programs, pollution control measures, and remediation strategies to prevent future risks.

Organochlorine pesticides and polycyclic aromatic hydrocarbons in serum of Beijing population: Exposure and health risk assessment

Organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants, but large-scale human biomonitoring and health risk assessment data on these contaminants remain limited. In this study, concentrations of 6 OCPs and 5 PAHs were determined by GC-MS/MS in 1268 human serum samples which were collected from the participants in 2017 Beijing Chronic Disease and Risk Factor Surveillance. The detection frequencies of OCPs and PAHs ranged from 64.7 % to 96.5 % and 89.4 % to 99.6 %, respectively. The most abundant contaminants in OCPs and PAHs were pentachlorophenol (PCP) and pyrene (Pyr) with median concentrations reaching up to 3.13 and 8.48 μg/L, respectively. Nonparametric tests were employed to assess the correlations among contaminants levels, demographic characteristics (age, gender, body mass index, residence) and serum biochemical indexes. Significantly higher serum levels of all PAHs were observed in suburb residents than that in urban residents (P < 0.001). Binary logistic regression analysis demonstrated that exposure to benzo(a)pyrene (OR 2.17 [1.29, 3.63]), phenanthrene (OR 1.06 [1.02, 1.11]), fluoranthene (OR 1.04 [1.02, 1.07]) and Pyr (OR 1.02 [1.01, 1.03]) might increase the occurrence of hyperglycemia, and exposure to hexachlorobenzene (HCB) (OR 1.53 [1.05, 2.22]) and pentachlorobenzene (OR 1.14 [1.02, 1.27]) were positively associated with hyperlipidemia. Furthermore, the hazard quotients (HQs) for serum HCB, PCP and p,p'-dichlorodiphenyldichloroethylene were calculated based on health-based guidance values to predict health risks. 0.2 % and 4.3 % of serum samples showed HQ values exceeding 1 for HCB and PCP, respectively, in case of the non-carcinogenic risk, while 23.1 % of HQs for HCB were above 1 in case of the carcinogenic risk for a risk level 10^-5. Our study reveals that the body burden of the Beijing general population relative to OCPs and PAHs was nonnegligible. The past exposure of HCB and PCP might adversely affect the health status of the Beijing population.

Co-exposure health risk of benzo[a]pyrene with aromatic VOCs: Monoaromatic hydrocarbons inhibit the glucuronidation of benzo[a]pyrene

Occupational workers and residents near petrochemical industry facilities are exposed to multiple contaminants on a daily basis. However, little is known about the co-exposure effects of different pollutants based on biotransformation. The study examined benzo[a]pyrene (BaP), a representative polycyclic aromatic hydrocarbon related to the petrochemical industry, to investigate changes in toxicity and co-exposure mechanism associated with different monoaromatic hydrocarbons (MAHs). A central composite design method was used to simulate site co-exposure scenarios to reveal biotransformation of BaP when co-exposed with benzene, toluene, chlorobenzene, or nitrobenzene in microsome systems. BaP metabolism depended on MAH concentration, and association of MAH with microsome concentration/incubation time. Particularly, MAH co-exposure negatively affected BaP glucuronidation, an important phase Ⅱ detoxification process. BaP metabolite intensities decreased to 43%-80% for OH-BaP-G, and 32%-71% for diOH-BaP-G in co-exposure system with MAHs, compared with control group. Furthermore, glucuronidation was affected by competitive and time-dependent inhibition. Co-exposure significantly decreased gene expression of UGT 1A10 and BCRP/ABCG2 in HepG2 cells, which are involved in BaP detoxification through metabolism and transmembrane transportation. Therefore, human co-exposure to multiple contaminants may deteriorate toxic effects of these chemicals by disturbing metabolic pathways. This study provides a reference for assessing toxic effects and co-exposure risks of pollutants.

Distribution, risk assessment, and source apportionment of polycyclic aromatic hydrocarbons (PAHs) using positive matrix factorization (PMF) in urban soils of East India

This study investigated 16 United States environmental protection agency priority PAHs profiles and their sources in 40 urban soils collected from two industrialised cities, Jamshedpur and Bokaro, in east India and assessed their health risk to humans. The results showed the predominance of high molecular weight (HMW) PAHs (4-5 rings). The total PAHs concentration in surface soils ranged from 2223 to 11,266 ng/g and 729 to 5359 ng/g (dw), respectively, for Jamshedpur and Bokaro. Higher concentrations of PAHs were recorded at the selected industrial areas and heavy traffic zones of both cities. In JSR city 4-ring PAHs contributed 43% of total PAHs trailed by 5-ring PAHs 27.2%. Similarly, in BKR city 4-ring PAHs contributed 34% of the total PAHs, followed by 3-ring PAHs 28.9% and 5-ring PAHs 22.9%. Total organic carbon in surface soils exhibited moderate correlation with the low molecular weight (ΣLMW) PAHs (R² = 0.69) and a comparatively strong correlation with the ΣHMW PAHs (R² = 0.89), suggesting strong adsorption of HMW PAHs to urban soils. The Diagnostic and PMF modelling analysis indicated that the major sources of PAHs contamination in soils were petroleum combustion, vehicular emissions, biomass, and coal combustion. The health risk assessment shows that the cumulative probability of carcinogenic risks was under the acceptable limits of 10^-4 to 10^-6. At some sampling areas in both cities, the maximum value of total exposure cancer risk slightly exceeded the acceptable limits indicating some carcinogenic risk for adults.

Impact of Atmospheric Polycyclic Aromatic Hydrocarbons (PAHs) of Falling Dust in Urban Area Settings: Status, Chemical Composition, Sources and Potential Human Health Risks

The present work is considered to investigate the sources, concentration, and composition of polycyclic aromatic hydrocarbons (PAHs) and associated health risk assessment of road dust in Riyadh City, Saudi Arabia. The study region included an urban area, strongly affected by traffic, a bare and an industrial area. A total of 50 locations were selected for sampling and 16 different PAHs were determined. The concentration of PAHs in road dust and their estimated lifetime average daily dose (LADD) for adults (human) ranged from 0.01 to 126 ng g−1 and 1950 to 16,010 mg kg−1 day−1, respectively. The ADDing was calculated separately for children (>6), teenagers (6−12), and adults (>12) for all PAHs with each collected sample. Moreover, the average daily exposure dose by ingestion (ADDing) and average daily exposure dose by dermal absorption (ADDder) were more in children (<6 years) as compared to teenagers (6−12 years) and adults (>12 years). Likewise, total equivalency factor based on BaP (TEQBaP) calculations pointed out that PAHs having more benzene rings or having high molecular weight showed high TEQBaP as compared to low molecular weight PAHs. The data revealed that the children population is at high risk for asthma, respiratory and cardiovascular diseases, and immunity suppression as compared to adults in the particular area of investigated region. These outcomes of this study can be used to deliver significant policy guidelines concerning habitants of the area for possible measures for controlling PAHs contamination in Riyadh City to protect human health and to ensure environmental sustainability.

Polycyclic aromatic hydrocarbons (PAHs): Updated aspects of their determination, kinetics in the human body, and toxicity

Polycyclic aromatic hydrocarbons (PAHs) are legacy pollutants of considerable public health concern. Polycyclic aromatic hydrocarbons arise from natural and anthropogenic sources and are ubiquitously present in the environment. Several PAHs are highly toxic to humans with associated carcinogenic and mutagenic properties. Further, more severe harmful effects on human- and environmental health have been attributed to the presence of high molecular weight (HMW) PAHs, that is PAHs with molecular mass greater than 300 Da. However, more research has been conducted using low molecular weight (LMW) PAHs). In addition, no HMW PAHs are on the priority pollutants list of the United States Environmental Protection Agency (US EPA), which is limited to only 16 PAHs. However, limited analytical methodologies for separating and determining HMW PAHs and their potential isomers and lack of readily available commercial standards make research with these compounds challenging. Since most of the PAH kinetic data originate from animal studies, our understanding of the effects of PAHs on humans is still minimal. In addition, current knowledge of toxic effects after exposure to PAHs may be underrepresented since most investigations focused on exposure to a single PAH. Currently, information on PAH mixtures is limited. Thus, this review aims to critically assess the current knowledge of PAH chemical properties, their kinetic disposition, and toxicity to humans. Further, future research needs to improve and provide the missing information and minimize PAH exposure to humans.