A review of PAH exposure from the combustion of biomass fuel and their less surveyed effect on the blood parameters

Environmental contamination with polycyclic aromatic hydrocarbons and contribution from biomonitoring studies to the surveillance of global health

This work presents an integrated overview of polycyclic aromatic hydrocarbons' (PAHs) ubiquity comprising environmental contamination in the air, aquatic ecosystems, and soils; characterizes the contamination in biota; and identifies main biomonitors and human exposure to PAHs and associated health risks. Urban centers and industrial areas present increased concentrations in the air (1344.4-12,300 versus 0.03-0.60 ng/m3 in industrial/urban and rural zones) and soils (0.14-1.77 × 106 versus 2.00-9.04 × 103 versus 1.59-5.87 × 103 ng/g in urban, forest, and rural soils), respectively. Increased concentrations were found in coastal zones and superficial waters as well as in sediments (7.00 × 104-1.00 × 109 ng/g). Benzo(a)pyrene, a carcinogenic PAH, was found in all environmental media. Mosses, lichens, tree leaves, bivalves, cephalopods, terrestrials' snails, and honeybees are good biomonitors of biota contamination. More studies are needed to improve characterization of PAHs' levels, distribution, and bioaccumulation in the environmental media and assess the associated risks for biota and human health. Actions and strategies to mitigate and prevent the bioaccumulation of PAHs in the environment and trophic chains toward the WHO's One-Health Perspective to promote the health of all ecosystems and human life are urgently needed.

Polycyclic aromatic hydrocarbon skin permeation efficiency in vitro is lower through human than pigskin and decreases with lipophilicity

Polycyclic aromatic hydrocarbons (PAH) are persistent environmental pollutants, which occasionally appear as contaminants in consumer products. Upon dermal contact, transfer of PAH into the stratum corneum (s.c.) and migration through the skin may occur, resulting in this class of highly toxic compounds to become bioavailable. In this study, dermal penetration through human and porcine skin of 24 PAH, comprising broad molar mass (M: 152-302 g/mol) and octanol-water partition coefficient (logP: 3.9-7.3) ranges, was evaluated via Franz diffusion cell in vitro assays. More lipophilic and potentially more toxic PAH had decreased permeation rates through the rather lipophilic s.c. into the more hydrophilic viable (epi-)dermis. Furthermore, human skin was less permeable than pigskin, a commonly used surrogate in skin penetration studies. In particular, the s.c. of human skin retains a greater share of PAH, an effect that is more pronounced for smaller PAH. Additionally, we compared the skin permeation kinetics of different PAH in pigskin. While small PAH (M < 230 g/mol, logP < 6) permeate the skin quickly and are detected in the receptor fluid after 2 h, large PAH (M > 252 g/mol, logP ≥ 6) do not fully permeate the skin up to 48 h. This indicates that highly lipophilic PAH do not become bioavailable as readily as their smaller congeners when transferred to the skin surface. Our data suggest that pigskin could be used as a surrogate for worst case scenario estimates of dermal PAH permeation through human skin.

Percutaneous Absorption of Fireground Contaminants: Naphthalene, Phenanthrene, and Benzo[a]pyrene in Porcine Skin in an Artificial Sweat Vehicle

Firefighters face significant risks of exposure to toxic chemicals, such as polycyclic aromatic hydrocarbons (PAHs), during fire suppression activities. PAHs have been found in the air, on the gear and equipment, and in biological samples such as the skin, breath, urine, and blood of firefighters after fire response. However, the extent to which exposure occurs via inhalation, dermal absorption, or ingestion is unclear. In this study, three PAHs, naphthalene, phenanthrene, and benzo[a]pyrene, were applied to porcine skin in vitro in an artificial sweat solution to better gauge firefighters' dermal exposures while mimicking their sweaty skin conditions using an artificial sweat dosing vehicle. Multiple absorption characteristics were calculated, including cumulative absorption, percent dose absorbed, diffusivity, flux, lag time, and permeability. The absorption of the PAHs was greatly influenced by their molecular weight and solubility in the artificial sweat solution. Naphthalene had the greatest dose absorption efficiency (35.0 ± 4.6% dose), followed by phenanthrene (6.8 ± 3.2% dose), and lastly, benzo[a]pyrene, which had the lowest absorption (0.03 ± 0.04% dose). The lag times followed a similar trend. All chemicals had a lag time of approximately 60 min or longer, suggesting that chemical concentrations on the skin may be reduced by immediate skin cleansing practices after fire exposure.

Characterization of fire investigators' polyaromatic hydrocarbon exposures using silicone wristbands

BACKGROUND

Exposures to polyaromatic hydrocarbons (PAHs) contribute to cancer in the fire service. Fire investigators are involved in evaluations of post-fire scenes. In the US, it is estimated that there are up to 9000 fire investigators, compared to approximately 1.1 million total firefighting personnel. This exploratory study contributes initial evidence of PAH exposures sustained by this understudied group using worn silicone passive samplers.

OBJECTIVES

Evaluate PAH exposures sustained by fire investigators at post-fire scenes using worn silicone passive samplers. Assess explanatory factors and health risks of PAH exposure at post-fire scenes.

METHODS

As part of a cross-sectional study design, silicone wristbands were distributed to 16 North Carolina fire investigators, including eight public, seven private, and one public and private. Wristbands were worn during 46 post-fire scene investigations. Fire investigators completed pre- and post-surveys providing sociodemographic, occupational, and post-fire scene characteristics. Solvent extracts from wristbands were analyzed via gas chromatography-mass spectrometry (GC-MS). Results were used to estimate vapor-phase PAH concentration in the air at post-fire scenes.

RESULTS

Fire investigations lasted an average of 148 minutes, standard deviation ± 93 minutes. A significant positive correlation (r=0.455, p<.001) was found between investigation duration and PAH concentrations on wristbands. Significantly greater time-normalized PAH exposures (p=0.039) were observed for investigations of newer post-fire scenes compared to older post-fire scenes. Regulatory airborne PAH exposure limits were exceeded in six investigations, based on exposure to estimated vapor-phase PAH concentrations in the air at post-fire scenes.

DISCUSSION

Higher levels of off-gassing and suspended particulates at younger post-fire scenes may explain greater PAH exposure. Weaker correlations are found between wristband PAH concentration and investigation duration at older post-fire scenes, suggesting reduction of off-gassing PAHs over time. Exceedances of regulatory PAH limits indicate a need for protection against vapor-phase contaminants, especially at more recent post-fire scenes.

Biomolecular condensates of Chlorocatechol 1,2-Dioxygenase as prototypes of enzymatic microreactors for the degradation of polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are molecules with two or more fused aromatic rings that occur naturally in the environment due to incomplete combustion of organic substances. However, the increased demand for fossil fuels in recent years has increased anthropogenic activity, contributing to the environmental concentration of PAHs. The enzyme chlorocatechol 1,2-dioxygenase from Pseudomonas putida (Pp 1,2-CCD) is responsible for the breakdown of the aromatic ring of catechol, making it a potential player in bioremediation strategies. Pp 1,2-CCD can tolerate a broader range of substrates, including halogenated compounds, than other dioxygenases. Here, we report the construction of a chimera protein able to form biomolecular condensates with potential application in bioremediation. The chimera protein was built by conjugating Pp 1,2-CCD to low complex domains (LCDs) derived from the DEAD-box protein Dhh1. We showed that the chimera could undergo liquid-liquid phase separation (LLPS), forming a protein-rich liquid droplet under different conditions (variable protein and PEG8000 concentrations and pH values), in which the protein maintained its structure and main biophysical properties. The condensates were active against 4-chlorocatechol, showing that the chimera droplets preserved the enzymatic activity of the native protein. Therefore, it constitutes a prototype of a microreactor with potential use in bioremediation.

Atmospheric polycyclic aromatic hydrocarbons in India: geographical distribution, sources and associated health risk-a review

Atmospheric distribution of polycyclic aromatic hydrocarbons and associated human health risks have been studied in India. However, a comprehensive overview is not available in India, this review highlights the possible sources, and associated cancer risks in people living in different zones of India. Different databases were searched for the scientific literature on polycyclic aromatic hydrocarbons in ambient air in India. Database searches have revealed a total of 55 studies conducted at 139 locations in India in the last 14 years between 1996 and 2018. Based on varying climatic conditions in India, the available data was analysed and distributed with four zone including north, east, west/central and south zones. Comparatively higher concentrations were reported for locations in north zone, than east, west/central and south zones. The average concentrations of ∑PAHs is lower in east zone, and concentrations in north, west/central and south zones are higher by 1.67, 1.47, and 1.12 folds respectively than those in east zone. Certain molecular diagnostic ratios and correlation receptor models were used for identification of possible sources, which aided to the conclusion that both pyrogenic and petrogenic activities are the mixed sources of PAH emissions to the Indian environment. Benzo(a)pyrene toxicity equivalency for different zones is estimated and presented. Estimated Chronic daily intake (CDI) due to inhalation of PAHs and subsequently, cancer risk (CR) is found to be ranging from extremely low to low in various geographical zones of India.

A sensitive GC-MS/MS method for the quantification of benzo[a]pyrene tetrol in urine

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants formed during the incomplete combustion of organic matter such as tobacco. Among these, benzo[a]pyrene (BaP) has been classified as a known carcinogen to humans. It unfolds its effect through metabolic activation to BaP-(7R,8S)-diol-(9S,10R)-epoxide (BPDE), the ultimate carcinogen of BaP. In this article, we describe a simple and highly sensitive GC-NICI-MS/MS method for the quantification of urinary BaP-(7R,8S,9R,10S)-tetrol (( +)-BPT I-1), the hydrolysis product of BPDE. The method was validated and showed excellent results in terms of accuracy, precision, and sensitivity (lower limit of quantification (LLOQ): 50 pg/L). In urine samples derived from users of tobacco/nicotine products and non-users, only consumption of combustible cigarettes was associated with a significant increase in BPT I-1 concentrations (0.023 ± 0.016 nmol/mol creatinine, p < 0.001). Levels of users of potentially reduced-risk products as well as non-users were all below the LLOQ. In addition, the urine levels of six occupationally exposed workers were analyzed and showed the highest overall concentrations of BPT I-1 (844.2 ± 336.7 pg/L). Moreover, comparison with concentrations of 3-hydroxybenzo[a]pyrene (3-OH-BaP), the major detoxification product of BaP oxidation, revealed higher levels of 3-OH-BaP than BPT I-1 in almost all study subjects. Despite the lower levels, BPT I-1 can provide more relevant information on an individual's cancers susceptibility since BPDE is generated by the metabolic activation of BaP. In conclusion, BPT I-1 is a suitable biomarker to distinguish not only cigarette smokers from non-smokers but also from users of potentially reduced-risk products.

Baseline data and associations between urinary biomarkers of polycyclic aromatic hydrocarbons, blood pressure, hemogram, and lifestyle among wildland firefighters

Introduction

Available literature has found an association between firefighting and pathologic pathways leading to cardiorespiratory diseases, which have been linked with exposure to polycyclic aromatic hydrocarbons (PAHs). PAHs are highlighted as priority pollutants by the European Human Biomonitoring Initiative in occupational and non-occupational contexts.

Methods

This cross-sectional study is the first to simultaneously characterize six creatinine-adjusted PAHs metabolites (OHPAHs) in urine, blood pressure, cardiac frequency, and hemogram parameters among wildland firefighters without occupational exposure to fire emissions (> 7 days), while exploring several variables retrieved via questionnaires.

Results

Overall, baseline levels for total OHPAHs levels were 2 to 23-times superior to the general population, whereas individual metabolites remained below the general population median range (except for 1-hydroxynaphthalene+1-hydroxyacenaphtene). Exposure to gaseous pollutants and/or particulate matter during work-shift was associated with a 3.5-fold increase in total OHPAHs levels. Firefighters who smoke presented 3-times higher total concentration of OHPAHs than non-smokers (p < 0.001); non-smoker females presented 2-fold lower total OHPAHs (p = 0.049) than males. 1-hydroxypyrene was below the recommended occupational biological exposure value (2.5 μg/L), and the metabolite of carcinogenic PAH (benzo(a)pyrene) was not detected. Blood pressure was above 120/80 mmHg in 71% of subjects. Firefighters from the permanent intervention team presented significantly increased systolic pressure than those who performed other functions (p = 0.034). Tobacco consumption was significantly associated with higher basophils (p = 0.01-0.02) and hematocrit (p = 0.03). No association between OHPAHs and blood pressure was found. OHPAHs concentrations were positively correlated with monocyte, basophils, large immune cells, atypical lymphocytes, and mean corpuscular volume, which were stronger among smokers. Nevertheless, inverse associations were observed between fluorene and pyrene metabolites with neutrophils and eosinophils, respectively, in non-smokers. Hemogram was negatively affected by overworking and lower physical activity.

Conclusion

This study suggests possible associations between urinary PAHs metabolites and health parameters in firefighters, that should be further assessed in larger groups.

Exosomes released by environmental pollutant-stimulated Keratinocytes/PBMCs can trigger psoriatic inflammation in recipient cells via the AhR signaling pathway

Introduction: Exosomes, pivotal in intercellular communication during skin disease pathogenesis, have garnered substantial attention. However, the impact of environmental pollutants, such as benzo[a]pyrene (BaP) and 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD), on exosome release amid inflammatory skin diseases remains unexplored. This study addresses this gap by examining the influence of BaP and TCDD on exosome function, specifically focusing on immune-related pathway alterations in normal recipient keratinocytes and peripheral blood mononuclear cells (PBMCs). Methods: HaCaT cells were treated with exosomes from BaP- or TCDD-treated keratinocytes. Proinflammatory cytokines and chemokines, including TNF-α, IL-1β, IL-6, IL-8, CXCL1, and CXCL5, were assessed. The involvement of the p65NF-κB/p38MAPK/ERK signaling pathway in recipient keratinocytes was investigated. Aryl hydrocarbon receptor (AhR) silencing was employed to elucidate its role in mediating the proinflammatory response induced by exosomes from BaP- or TCDD-treated keratinocytes. Results and discussion: Treatment with exosomes from BaP- or TCDD-treated keratinocytes induced a significant increase in proinflammatory cytokines and chemokines in HaCaT cells. The upregulation implicated the p65NF-κB/p38MAPK/ERK signaling pathway. AhR silencing attenuated this response, suggesting a role for AhR in mediating this response. In PBMCs from healthy controls, exosomes from BaP-stimulated PBMCs of psoriatic patients led to increased expression of proinflammatory cytokines and modulation of Th1/Th17 cell distribution via AhR activation. These findings unveil a novel dimension in the interplay between environmental xenobiotic agents (BaP and TCDD) and exosomal functions. The study establishes their influence on psoriatic inflammatory responses, shedding light on the underlying mechanisms mediated through the AhR signaling pathway in recipient keratinocytes and PBMCs.

Migration of polycyclic aromatic hydrocarbons in the rhizosphere micro-interface of soil-ryegrass (Lolium perenne L.) system

The unclear multi-media and multi-interface processes of polycyclic aromatic hydrocarbons (PAHs) in environments have drawn great concern. Here, 16 controlled PAHs were selected to reveal the differences in the bioavailability and migration of congeners in soil-ryegrass exposure system. The presence of ryegrass in the exposure groups (with newly introduced PAHs) resulted in a decrease in PAHs dissipation (31.3 %) from soil compared to the unplanted groups (43.2 %). The presence of ryegrass inhibited the soil-air exchange process, which has not been widely reported. PAH congeners with less benzene rings (molecular weight < B[a]A) had consistent bioavailability before and after long-term aging, the competition between adsorption/absorption to plants and soil was not strong (RCFs < 3.5), and their migration in the rhizosphere rapidly reached equilibrium. PAH congeners with more benzene rings (molecular weight ≥ B[a]A) adsorbed to soil particles and significantly decreased their bioavailability after long-term aging. Their concentrations in the rhizosphere were stable and lower than bulk soil, revealing their slow equilibrium process in soil. In addition, PAHs with larger molecular weight and KOW showed less migration at the rhizosphere micro-interface. The migration behavior of congeners with close KOW depended on their molecular structure. Congeners with non-symmetric K-region or L-region showed greater migration ability in the rhizosphere. These findings revealed the fate of PAHs, especially different PAH congeners, in the rhizosphere interfaces for the first time, and explored the molecular mechanisms that affect their rhizosphere behaviors, improving the understanding and knowledge of PAHs in the microenvironment, providing new data on evaluating and controlling the environmental risks of PAHs.

Integrative assessment of urban dust polycyclic aromatic hydrocarbons using ground and satellite data in Iran

Recently, for quick urbanization and industrialization, pollutants, especially urban dust, have posed many threats to the human environment. Polycyclic aromatic hydrocarbons (PAHs) are regarded as the main dangerous pollutants that are widespread, persistent, and carcinogenic. The present work aimed to investigate the contamination and sources of PAHs, as well as to assess the risk of cancer for 16 priority PAHs, in urban dust samples in Ahvaz, Isfahan, and Shiraz cities in Iran. We measured PAH concentrations by gas chromatography-mass spectrometry (GC-MS). The average concentrations of the 16 PAHs in Ahvaz, Isfahan, and Shiraz were 6215.11, 7611.03, and 7810.37 μg kg-1, respectively. The domination of low-molecular-weight (LMW) PAHs was observed in Ahvaz, while maximum contribution was observed for high-molecular-weight (HMW) PAHs in Esfahan and Shiraz. For PAHs' source identification, diagnostic ratio, correlation analysis, clustering, and positive matrix factorization (PMF) model were used. PAHs had a combustion (coal and wood, oil, fossil fuels) and gasoline/diesel engine emissions in all cities. Comparative studies suggest that the PAH compounds' level is higher in the research area than in other countries, except for China and India. Also, the pollution of urban dust PAHs has increased over time compared to previous studies in the same cities. The cancer risk from exposure to dust contaminated with PAHs was assessed using the Incremental Lifetime Cancer Risk (ILCR) model. According to the findings, a high risk of exposure to cancer was observed in Ahvaz, Isfahan, and Shiraz. However, compared to adults, children are at higher risk of cancer in their daily lives via dermal contact and unconscious ingestion. Based on the ILCR values, the risk of cancer is in the order of Shiraz > Isfahan > Ahvaz. To assess air pollutants and their effects on urban dust, TROPOMI onboard the Sentinel-5P data were used in the studied cities during 2018-2021. The results show that Ahvaz has different high levels of CO compared to the other 2 cities. Also, Isfahan has different high levels of NO2 compared to the other 2 cities, but Shiraz has different low levels of O3. According to satellite time series data, the trend of the Aerosol Absorbing Index (AAI) has been increasing, while there was a decreasing trend in AAI from the beginning of the COVID-19 pandemic until 12 months later. Therefore, the natural and anthropogenic sources of urban dust PAHs have been increasing in all studied cities. Our findings show that PAH compounds in urban dust pose a significant threat to human health. Therefore, strategic management and planning are vital in reducing urban dust pollution.

Toxicological and Mutagenic Effects of Particulate Matter from Domestic Activities

People spend most of their time indoors, particularly in their houses where daily activities are carried out, enhancing particulate matter (PM) emissions with consequent adverse health impacts. This study intended to appraise the toxicological and mutagenic responses of particulate matter with a diameter less than 10 μm (PM₁₀) released from cooking and ironing activities under different conditions. The cytotoxicity of the PM₁₀ total organic extracts was tested in A549 cells using the WST-8 and the lactate dehydrogenase (LDH) assays, while the interference in cell cycle dynamics and reactive oxygen species (ROS) production was analysed by flow cytometry. The S. typhimurium TA98 and TA100 Ames tester strains with and without metabolic activation were employed to determine the mutagenic potential of the PM₁₀-bound polycyclic aromatic hydrocarbons (PAHs). PM₁₀ organic extracts decreased the metabolic activity of A549 cells; however, no effects in the LDH release were observed. An increase in ROS levels was registered only for cells treated with PM₁₀ at IC₂₀ from steam ironing, in low ventilation conditions, while cell cycle dynamics was only affected by exposure to PM₁₀ at IC₂₀ from frying horse mackerel and grilling boneless pork strips. No mutagenic effects were observed for all the PM₁₀-bound PAHs samples.

Spatial distribution, sources identification, and health risk assessment polycyclic aromatic hydrocarbon compounds and polychlorinated biphenyl compounds in total suspended particulates (TSP) in the air of South Pars Industrial region-Iran

South Pars Industrial Energy Zone, located in the southwest of Iran along the Persian Gulf coast, encompasses many industrial units in the vicinity of urban areas. This research study investigated the effects of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) on human health and the environment. Suspended particulate matters (SPM) in the air sampled, in summer and winter 2019, from ten stations next to industrial units and residential areas. The samples were analyzed by gas chromatography-mass spectrometry (GC-MS). Spatial distribution maps of pollutants in the region were prepared using GIS software. The highest carcinogenic risk due to PAHs and PCBs measured as ([Formula: see text]) and ([Formula: see text], respectively. According to the US Environmental Protection Agency limit ([Formula: see text]), the cancer risks from PAH compounds were significant and need further investigation. The PCB cancer risks were within acceptable ranges. The highest adsorption ratios for PAHs were obtained through skin and PCBs by ingestion. The maximum measured non-carcinogenic hazard indexes (HI) turned out to be 0.037 and 0.023 for PAH and PCB, respectively, and were reported as acceptable risks. The predominant source of PAH in industrial areas was liquid fossil combustion, and in urban areas replaced by coal-wood-sugarcane combustion. Petrochemical complexes, flares, power plants (69%), electric waste disposal sites, and commercial pigments (31%) were reported as PCB sources. Industries activities were the most effective factors in producing the highest level of carcinogenic compounds in the region, and it is necessary to include essential measures in the reform programs.

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.

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.

Porous nanocomposites for sorptive elimination of ibuprofen from synthetic wastewater and its molecular docking studies

Pharmaceuticals are a new developing pollutant that is threatening aquatic ecosystems and impacting numerous species in the ecosystem. The aim of this study is the green synthesis of TiO₂-Fe₂O₃-Chitosan nanocomposites in conjunction with Moringa olifera leaves extract and its applicability for ibuprofen removal. Various characterization studies were performed for the synthesized nanocomposites. Box-Behnken design (BBD) is employed to optimize pH, agitation speed, and composite dosage. Equilibrium results show that adsorption process matches with Langmuir isotherm, demonstrating adsorption on the nanocomposite's homogenous surface and follows pseudo-first-order kinetics. Using the BBD, pH, adsorbent dose, and agitation speed were examined as adsorption parameters. Ibuprofen elimination was demonstrated to be most successful at a pH of 7.3, using 0.05 g of nanocomposites at a rotational speed of 200 rpm. Thermodynamic parameters for ibuprofen sorption were carried out and the ΔH and ΔS was found to be 76.23 & 0.233. Molecular Docking was performed to find the interaction between the pollutant and the nanocomposite. UV-vis spectra confirm the 243 nm absorption band corresponding to the nanocomposite's surface plasmon resonances. Fourier transform infrared spectroscopy spectra relate this band to a group of nanocomposites. The findings of this work emphasize the importance of TiO₂-Fe₂O₃-Chitosan nanocomposites for removing ibuprofen from wastewater.

Removing BaP from soil by biochar prepared with medicago and corn straw using batch and solid-phase extraction method

Low-cost materials with a highly efficient adsorption capability prepared from corn straw and medicago (abbreviated to CB and MB), which can effectively remove benzo(a)pyrene (BaP) from contaminated soil, were prepared at a temperature of 350 °C under limited-oxygen conditions. The appearance traits, contents of C, H, N and functional group types of CB and MB were obtained by SEM, elemental analysis and FT-IR. Through the batch method, it was found that the adsorption of BaP by CB and MB was in accordance with pseudo-secondary kinetics because the correlation coefficients are 0.855 with CB and 0.948 with MB, respectively, and the maximum adsorption capacity in the fitting (CB: 78.2 mg kg^-1, MB: 88.8 mg kg^-1) was consistent with the actual measurement (CB: 79.8 mg kg^-1, MB: 89.3 mg kg^-1). Freundlich and Langmuir equations can well describe the isothermal adsorption data of CB and MB due to the correlation coefficients all being greater than 0.87. Soil samples treated with ASE were separated by solid-phase extraction (SPE) with different biochar contents in packed columns. It was found that the contributions of CB and MB to the removal of BaP increased from 58.5% and 60.4% to 80.6% and 82.1%, respectively, which could effectively reduce BaP in polluted soil.

Long-term exposure to low concentrations of polycyclic aromatic hydrocarbons and alterations in platelet indices: A longitudinal study in China

Long-term exposure to low polycyclic aromatic hydrocarbon (PAH) concentration may ave detrimental effects, including changing platelet indices. Effects of chronic exposure to low PAH concentrations have been evaluated in cross-sectional, but not in longitudinal studies, to date. We aimed to assess the effects of long-term exposure to the low-concentration PAHs on alterations in platelet indices in the Chinese population. During 2014–2017, we enrolled 222 participants who had lived in a village in northern China, 1–2 km downwind from a coal plant, for more than 25 years, but who were not employed by the plant or related businesses. During three follow-ups, annually in June, demographic information and urine and blood samples were collected. Eight PAHs were tested: namely 2-hydroxynaphthalene, 1-hydroxynaphthalene, 2-hydroxyfluorene, 9-hydroxyfluorene (9-OHFlu), 2-hydroxyphenanthrene (2-OHPh), 1-hydroxyphenanthrene (1-OHPh), 1-hydroxypyrene (1-OHP), and 3-hydroxybenzo [a] pyrene. Five platelet indices were measured: platelet count (PLT), platelet distribution width (PDW), mean platelet volume (MPV), platelet crit, and the platelet-large cell ratio. Generalized mixed and generalized linear mixed models were used to estimate correlations between eight urinary PAH metabolites and platelet indices. Model 1 assessed whether these correlations varied over time. Models 2 and 3 adjusted for additional personal information and personal habits. We found the following significant correlations: 2-OHPh (Model1 β₁ = 18.06, Model2 β₂ = 18.54, Model β₃ = 18.54), 1-OHPh (β₁ = 16.43, β₂ = 17.42, β₃ = 17.42), 1-OHP(β₁ = 13.93, β₂ = 14.03, β₃ = 14.03) with PLT, as well as 9-OHFlu with PDW and MPV (odds ratio or Model3 OR_PDW[95%CI] = 1.64[1.3–2.06], OR_MPV[95%CI] = 1.33[1.19–1.48]). Long-term exposure to low concentrations of PAHs, indicated by2-OHPh, 1-OHPh, 1-OHP, and 9-OHFlu, as urinary biomarkers, affects PLT, PDW, and MPV. 9-OHFlu increased both PDW and MPV after elimination of the effects of other PAH exposure modes.

Adsorption/desorption of naphthalene and phenanthrene in a binary competitive system in the riparian zone

Polycyclic aromatic hydrocarbons (PAHs) such as naphthalene (Nap) and phenanthrene (Phe) are organic pollutants that are of concern because of their environmental toxicity. Adsorption is a promising process for the removal of Nap and Phe from water and soil. The riparian zone between a river and a riparian aquifer, which is rich in adsorption medium, may be important for PAH remediation. Nap and Phe may be removed from the surface water through adsorption by the media in the riparian zone. However, there is still a lack of the removal patterns and mechanisms of media in the riparian zone to remediate water contaminated by Nap and Phe simultaneously. In this study, focusing on the typical PAHs (Nap and Phe) as target pollutants, batch static adsorption and desorption experiments of Nap and Phe were carried out to explore the competitive adsorption mechanisms of Nap and Phe in the binary system. Batch dynamic adsorption experiments were conducted to ascertain the adsorption regulation of Nap and Phe in sediments during the recharge of groundwater by river water in a riparian zone. The static adsorption experiment results showed that competitive adsorption of Nap and Phe occurred, and a mutual inhibitory effect of Nap and Phe adsorption was observed in the binary system. Phe had a stronger inhibitory effect on Nap, Phe was preferentially adsorbed on the medium in binary adsorption. The results of batch dynamic experiments showed that, in terms of adsorption, the riparian zone in the study area showed stronger performance for removal of Phe than Nap. The results of this paper could be useful for alleviating Nap and Phe pollution of groundwater and developing treatment protocols for groundwater exposed to Nap and Phe.

Exposure to PAHs during Firefighting Activities: A Review on Skin Levels, In Vitro/In Vivo Bioavailability, and Health Risks

Occupational exposure as a firefighter is a complex activity that continuously exposes subjects to several health hazards including fire emissions during firefighting. Firefighters are exposed to polycyclic aromatic hydrocarbons (PAHs), known as toxic, mutagenic, and carcinogenic compounds, by inhalation, dermal contact, and ingestion. In this work, a literature overview of firefighters' dermal exposure to PAHs after firefighting and data retrieved from skin in vitro/in vivo studies related to their dermal absorption, bioavailability, and associated toxicological and carcinogenic effects are reviewed. The evidence demonstrates the contamination of firefighters' skin with PAHs, mainly on the neck (2.23-62.50 ng/cm²), wrists (0.37-8.30 ng/cm²), face (2.50-4.82 ng/cm²), and hands (1.59-4.69 ng/cm²). Concentrations of possible/probable carcinogens (0.82-33.69 ng/cm²), including benzopyrene isomers, were found on firefighters' skin. PAHs penetrate the skin tissues, even at low concentrations, by absorption and/or diffusion, and are locally metabolized and distributed by the blood route to other tissues/organs. Lighter PAHs presented increased dermal permeabilities and absorption rates than heavier compounds. Topical PAHs activate the aryl hydrocarbon receptor and promote the enzymatic generation of reactive intermediates that may cause protein and/or DNA adducts. Future research should include in vitro/in vivo assays to perform a more realistic health risk assessment and to explore the contribution of dermal exposure to PAHs total internal dose.

Black carbon toxicity dependence on particle coating: Measurements with a novel cell exposure method

Black carbon (BC) is a component of ambient particulate matter which originates from incomplete combustion emissions. BC is regarded as an important short-lived climate forcer, and a significant public health hazard. These two concerns have made BC a focus in aerosol science. Even though, the toxicity of BC particles is well recognized, the mechanism of toxicity for BC as a part of the total gas and particle emission mixture from combustion is still largely unknown and studies concerning it are scarce. In the present study, using a novel thermophoresis-based air-liquid interface (ALI) in vitro exposure system, we studied the toxicity of combustion-generated aerosols containing high levels of BC, diluted to atmospheric levels (1 to 10 μg/m³). Applying multiple different aerosol treatments, we simulated different sources and atmospheric aging processes, and utilizing several toxicological endpoints, we thoroughly examined emission toxicity. Our results revealed that an organic coating on the BC particles increased the toxicity, which was seen as larger genotoxicity and immunosuppression. Furthermore, aging of the aerosol also increased its toxicity. A deeper statistical analysis of the results supported our initial conclusions and additionally revealed that toxicity increased with decreasing particle size. These findings regarding BC toxicity can be applied to support policies and technologies to reduce the most hazardous compositions of BC emissions. Additionally, our study showed that the thermophoretic ALI system is both a suitable and useful tool for toxicological studies of emission aerosols.

The concentration and health risk of potentially toxic elements (PTEs) in the breast milk of mothers: a systematic review and meta-analysis

AIM

Breast milk is the best source of nutrition for a newborn during the first six months of his or her life. However there is a possibility that breast milk may contain pollutants such as metals. The current meta-analytic study assessed the concentration of potentially toxic elements (PTEs), including lead (Pb), cadmium (Cd), arsenic (As), Iron (Fe), Zinc (Zn), copper (Cu), and nickel (Ni), in mothers' milk.

METHOD

The literature studies regarding the concentrations of PTEs in the breast milk of mothers were collected from international databases such as PubMed, Scopus, Web of Science, and Embase. Afterward, the Total Target Hazard Quotient (TTHQ) by Monte Carlo Simulation (MCS) model was used to assess the non-carcinogenic risk.

RESULTS AND DISCUSSION

According to 42 of the 836 retrieved articles, the PTE concentrations in mother's milk were as follows: Cu (1.84 mg/kg) > Zn (1.80 mg/kg) > Fe (1.03 mg/kg) > Ni (0.60 mg/kg) > Pb (0.10 mg/kg) > As (0.15 mg/kg) ≈ Cd (0.15 mg/kg). Based on the containment type, the highest concentrations of As (2.80 mg/kg), Cd (0.07 mg/kg), and Pb (2.68 mg/kg) were related to Western Pacific Region (WPRO), European Region (EURO), and WPRO, respectively. In addition, for trace elements, Eastern Mediterranean Region (EMRO) was the region with the highest concentrations of Cu (3.56 mg/kg), Fe (2.78 mg/kg), Ni (3.13 mg/kg), and Zn (5.58 mg/kg) were related to Lastly, the non-carcinogenic risk assessment of the PTEs in breast milk indicated different risk patterns in various countries, and the calculated TTHQ level in infants was below 1.

CONCLUSION

Overall, human breast milk was generally safe for infants to consume and poses no risks to their health.

The Use of Human Biomonitoring to Assess Occupational Exposure to PAHs in Europe: A Comprehensive Review

Polycyclic aromatic hydrocarbons (PAHs) are among the chemicals with proven impact on workers' health. The use of human biomonitoring (HBM) to assess occupational exposure to PAHs has become more common in recent years, but the data generated need an overall view to make them more usable by regulators and policymakers. This comprehensive review, developed under the Human Biomonitoring for Europe (HBM4EU) Initiative, was based on the literature available from 2008-2022, aiming to present and discuss the information on occupational exposure to PAHs, in order to identify the strengths and limitations of exposure and effect biomarkers and the knowledge needs for regulation in the workplace. The most frequently used exposure biomarker is urinary 1-hydroxypyrene (1-OH-PYR), a metabolite of pyrene. As effect biomarkers, those based on the measurement of oxidative stress (urinary 8-oxo-dG adducts) and genotoxicity (blood DNA strand-breaks) are the most common. Overall, a need to advance new harmonized approaches both in data and sample collection and in the use of appropriate biomarkers in occupational studies to obtain reliable and comparable data on PAH exposure in different industrial sectors, was noted. Moreover, the use of effect biomarkers can assist to identify work environments or activities of high risk, thus enabling preventive risk mitigation and management measures.

Leaching of PAHs from rubber modified asphalt pavements

The present study aimed to, for the first time, quantify the total content of 16 priority EPA PAHs in end-of-life tyre derived crumb rubber granulates and various manufactured rubberised asphalt mix designs. After identifying the availability of 16 EPA PAHs, the leaching behaviour of rubberised asphalt specimens, were evaluated using the Dynamic Surface Leaching Test (DSLT) based on CEN/TS 16637-2:2014 standard. This was prior to modelling the release mechanisms of PAHs by utilizing a mathematical diffusion-controlled leaching model. According to the results, the total content of 16 EPA PAHs in crumb rubber granulates ranged between 0.061 and 8.322 μg/g, which were associated with acenaphthene and pyrene, respectively. The total content of PAHs in rubberised asphalt specimens varied between 0.019 and 4.992 μg/g depending on the volume of crumb rubber granulates in the asphalt concrete mix design, and type of binder. Results of the leaching experiments revealed that the highest leached PAHs were benzo[b]fluoranthene, benzo[k]fluoranthene and naphthalene with a 64-days cumulative release per specimen surface area > 1 μg/m². Acenaphthylene, fluoranthene, fluorene and indeno[1,2,3-c,d]pyrene were released in cumulative concentrations between 0.1 and 1 μg/m². The PAHs with a cumulative release potential below 0.1 μg/m² during DSLT were benzo[a]anthracene, benzo[a]pyrene, benzo[g,h,i]perylene and chrysene. The diffusion coefficients, which were calculated by mathematical modelling of DSLT data, revealed that the leaching process of 16 EPA PAHs from surface of rubberised asphalt concrete mix designs fitted all the criteria set by the NEN 7345 standard for diffusion-controlled leaching during all stages of leaching experiments.

Association between gaseous air pollutants and idiopathic nephrotic syndrome in children: a 12-year population-based cohort study

Background

To date, there is insufficient knowledge about the association of air pollution and childhood nephrotic syndrome in the real world. This study aimed to evaluate the effects of the three common gaseous air pollutants, including sulfur dioxide, total hydrocarbon, and methane, on the risk of idiopathic nephrotic syndrome (INS) in children.

Methods

We collected data from the Taiwan National Health Insurance Research Database and Taiwan Air Quality-Monitoring Database. Children younger than 18 years old, identified from January 1, 2000, were followed up until the first diagnosis of INS was established or until December 31, 2012. We measured the incidence rates and hazard ratios for INS stratified based on the quartiles (Q1–Q4) of air pollutant concentration. Multivariate Cox proportional hazards models were also applied by adjusting age, sex, monthly income, and urbanization.

Results

Compared with participants exposed to Q1 concentrations, the adjusted hazard ratios (aHRs) for INS increased progressively along the four quartiles of sulfur dioxide, total hydrocarbon, and methane, from 1 (Q1) to 1.78 (Q4), 1 (Q1) to 3.49 (Q4), 1 (Q1) to 7.83 (Q4), respectively.

Conclusions

Our study revealed that children with exposure to higher concentrations of sulfur dioxide, total hydrocarbon, and methane was associated with an increased risk of INS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13052-022-01269-8.

Source identification and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in air and dust samples of Lahore City

During two consecutive summer and winter seasons in Lahore, the health risk of air and dust-borne polycyclic aromatic hydrocarbons (PAHs) was evaluated. Gas chromatography/mass spectrometry (GS/MS) was used to determine air and dust samples from various functional areas across the city. The mean ∑₁₆PAHs were higher in air 1035.8 ± 310.7 (pg m^-3) and dust 963.4 ± 289.0 (ng g^-1 d.w.) during winter seasons as compared to summer seasons in air 1010.9 ± 303.3 (pg m^-3) and dust matrices 945.2 ± 283.6 (ng g^-1 d.w.), respectively. PAHs ring profile recognized 3 and 4 rings PAHs as most dominant in air and dust samples. Estimated results of incremental lifetime cancer risk (ILCR) highlighted high carcinogenic risk among the residents of Lahore via ingestion and dermal contact on exposure to atmospheric PAHs. The total ILCR values in air among children (summer: 9.61E - 02, winter: 2.09E - 02) and adults (summer: 1.45E - 01, winter: 3.14E - 02) and in dust, children (summer: 9.16E - 03, winter: 8.80E - 03) and adults (summer: 1.38E - 02, winter: 1.33E - 02) during the study period. The isomeric ratios in the study area revealed mixed PAH sources, including vehicular emission, petroleum, diesel and biomass combustion. As a result, it is advised that atmospheric PAHs should be monitored throughout the year and the ecologically friendly fuels be used to prevent PAHs pollution and health concerns in the city. The findings of this study are beneficial to the local regulating bodies in terms of controlling the exposure and promoting steps to reduce PAHs pollution and manage health in Lahore.

Genotoxic and inflammatory effects of spruce and brown coal briquettes combustion aerosols on lung cells at the air-liquid interface

Solid fuel usage in residential heating and cooking is one of the largest sources of ambient and indoor air particulate matter, which causes adverse effects on the health of millions of peoples worldwide. Emissions from solid fuel combustion, such as biomass or coal, are detrimental to health, but toxicological responses are largely unknown. In the present study, we compared the toxicological responses regarding cytotoxicity, inflammation and genotoxicity of spruce (SPR) and brown coal briquette (BCB) combustion aerosols on human alveolar epithelial cells (A549) as well as a coculture of A549 and differentiated human monocytic cells (THP-1) into macrophages exposed at the air-liquid interface (ALI). We included both the high emissions from the first hour and moderate emissions from the third hour of the batch combustion experiment in one ALI system, whereas, in the second ALI system, we exposed the cells during the whole 4-hour combustion experiment, including all combustion phases. Physico-chemical properties of the combustion aerosol were analysed both online and offline. Both SPR and BCB combustion aerosols caused mild cytotoxic but notable genotoxic effects in co-cultured A549 cells after one-hour exposure. Inflammatory response analysis revealed BCB combustion aerosols to cause a mild increase in CXCL1 and CXCL8 levels, but in the case of SPR combustion aerosol, a decrease compared to control was observed.

Atmospheric particle-bound polycyclic aromatic compounds over two distinct sites in Pakistan: Characteristics, sources and health risk assessment

Much attention is drawn to polycyclic aromatic hydrocarbons (PAHs) as an air pollutant due to their toxic, mutagenic and carcinogenic properties. Therefore, to understand the levels, seasonality, sources and potential health risk of PAHs in two distinct geographical locations at Karachi and Mardan in Pakistan, total suspended particle (TSP) samples were collected for over one year period. The average total PAH concentrations were 31.5 ± 24.4 and 199 ± 229 ng/m³ in Karachi and Mardan, respectively. The significantly lower concentration in Karachi was attributed to diffusion and dilution of the PAHs by the influence of clean air mass from the Arabian sea and high temperature, enhancing the volatilization of the particle phase PAHs to the gas phase. Conversely, the higher concentration (~6 times) in Mardan was due to large influence from local and regional emission sources. A clear seasonality was observed at both the sites, with the higher values in winter and post-monsoon due to higher emissions and less scavenging, and lower values during monsoon season due to the dilution effect. Diagnostic ratios and principal component analysis indicated that PAHs in both sites originated from traffic and mixed combustion sources (fossil fuels and biomass). The average total BaP equivalent concentrations (BaP_eq) in Karachi and Mardan were 3.26 and 34 ng/m³, respectively, which were much higher than the WHO guideline of 1 ng/m³. The average estimates of incremental lifetime cancer risk from exposure to airborne BaP_eq via inhalation indicated a risk to human health from atmospheric PAHs at both sites.

Human Biomonitoring of Selected Hazardous Compounds in Portugal: Part I-Lessons Learned on Polycyclic Aromatic Hydrocarbons, Metals, Metalloids, and Pesticides

Human biomonitoring (HBM) data provide information on total exposure regardless of the route and sources of exposure. HBM studies have been applied to quantify human exposure to contaminants and environmental/occupational pollutants by determining the parent compounds, their metabolites or even their reaction products in biological matrices. HBM studies performed among the Portuguese population are disperse and limited. To overcome this knowledge gap, this review gathers, for the first time, the published Portuguese HBM information concerning polycyclic aromatic hydrocarbons (PAHs), metals, metalloids, and pesticides concentrations detected in the urine, serum, milk, hair, and nails of different groups of the Portuguese population. This integrative insight of available HBM data allows the analysis of the main determinants and patterns of exposure of the Portuguese population to these selected hazardous compounds, as well as assessment of the potential health risks. Identification of the main difficulties and challenges of HBM through analysis of the enrolled studies was also an aim. Ultimately, this study aimed to support national and European policies promoting human health and summarizes the most important outcomes and lessons learned through the HBM studies carried out in Portugal.

The concentration of polycyclic aromatic hydrocarbons (PAHs) in mother milk: A global systematic review, meta-analysis and health risk assessment of infants

Background

Bio-monitoring of polycyclic aromatic hydrocarbons (PAHs) contaminants in mother milk is essential to keep mothers and infants healthy against potential risks. The current study assesses the concentration of PAHs in mother milk through a meta-analytic and systematic review approach.

Methods

All the published studies up to December 2020 regarding the concentrations of various PAHs in mother milk were searched throughout major international databases such as PubMed, Scopus, and Web of Science. Moreover, the possible carcinogenic and mutagenic risks to infants were evaluated based on the BaP (benzo[a]pyrenee) equivalent dose.

Results

According to the results of 13 articles included among 936 retrieved studies, the lowest and highest concentration of PAHs was (0.125 ng/g) and (76.36 ng/g) related to benz(a)anthracenem and 1-methylnaphthalene, respectively. The highest (9.830 ng/g) and lowest (0.009 ng/g) concentration of PAHs was related to Mexico and Japan, respectively. Besides, carcinogenetic and mutagenic risk assessment of the PAHs indicated that risk pattern was different across countries. It can be concluded that the consumption of mother milk is safe and does not pose a risk due to the ingestion of PAHs to the health of infant consumers.

Urinary biohazard markers in firefighters

Firefighters are the professional force at high risk of suffering potential health consequences due to their chronic exposure to numerous hazardous pollutants during firefighting activities. Unfortunately, determination of fire emission exposure is very challenging. As such, the identification and development of appropriate biomarkers is critical in meeting this need. This chapter presents a critical review of current information related with the use of different urinary biomarkers of effect and exposure in occupationally exposed firefighters over the last 25 years. Evidence suggests that urinary isoprostanes and mutagenicity testing are promising biomarkers of early oxidative stress. Data indicate that firefighters participating in firefighting activities present with increased urinary biomarkers of exposure. These include polycyclic aromatic hydrocarbons, heavy metals and metalloids, organo-chlorine and -phosphorus compounds, environmental phenols, phthalates, benzene and toluene. More studies are urgently needed to better evaluate firefighter occupational safety and health and to support the implementation of preventive measures and mitigation strategies to promote the protection of this chronically exposed group of workers.

Occurrence and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in dust of an emerging industrial city in Iran: implications for human health

Polycyclic aromatic hydrocarbons (PAHs) bounded to street dust are a severe environmental and human health danger. This study provides preliminary information on the abundance of PAHs in street dust from Rafsanjan city, Iran, where industrial emissions are high and data are lacking. Seventy street dust samples were collected from streets with different traffic loads. The United States Environmental Protection Agency (USEPA) Standard Methods 8270D and 3550C were used for the measurement of PAHs using GC mass spectroscopy. The total concentration of PAHs was 1443 ng g-1, with a range of 1380-1550 ng g-1. Additionally, the concentration of carcinogenic PAHs (∑carcPAHs) ranged from 729.5 to 889.4 ng g-1, with a mean value of 798.1 ng g-1. Pyrene was the most abundant PAH, with an average concentration of 257 ng g-1. Source identification analyses showed that vehicle emissions along with incomplete combustion and petroleum were the main sources of PAHs. The ecological risk status of the studied area was moderate. Spatial distribution mapping revealed that the streets around the city center and oil company had higher PAH levels than the other sectors of Rafsanjan. The results indicated that dermal contact and ingestion of contaminated particles were the most important pathways compared to inhalation. The mean incremental lifetime cancer risk (ILCR) was 1.4 × 10-3 and 1.3 × 10-3 for children and adults, respectively. This implies potentially adverse health effects in exposed individuals. The mutagenic risk for both subpopulations was approximately 18 times greater than the one recommended by USEPA. Our findings suggest that children are subjected to a higher carcinogenic and mutagenic risk of PAHs, especially dibenzo[a,h]anthracene (DahA), bounded to street dust of Rafsanjan. Our study highlights the need for the development of emission monitoring and control scenarios.

Temporal variability of atmospheric particulate-bound polycyclic aromatic hydrocarbons (PAHs) over central east India: sources and carcinogenic risk assessment

Atmospheric polycyclic aromatic hydrocarbons (PAHs) are of significant interest owing to their high potential health effects, including mutagenicity and carcinogenicity. We report 16 PAHs measured in ambient PM_2.5 from June 2018 to May 2019 over three different sites located in central east India. The annual average PM_2.5 mass concentrations of 97.3 ± 18.1 µg m^-3, 101.9 ± 19.4 µg m^-3, and 93.9 ± 20.3 µg m^-3 were measured at RCI (Ranchi), GHY (Gamharia), and BKR (Bokaro), respectively. The mass concentrations at all sampling sites are relatively higher than the annual average concentration of the National Ambient Air Quality Standard. Total annual PAH concentrations (ng m^-3) are found to be comparable at BKR (797.9 ± 39.1 ng m^-3) and RCI (887.7 ± 38.8 ng m^-3); however, a relatively higher average is observed over GHY (1015.1 ± 42.7 ng m^-3). Using PAH diagnostic ratios and principal component analysis (PCA), their major sources were attributed to coal and wood combustion as well as vehicular emission of diesel and gasoline at all sampling sites. Significant seasonal variability is observed for PAH composition and mainly attributed to change in emission sources. Summer and winter compositions were found to be impacted by the transport from Indo-Gangetic Plains (IGP). However, ambient level PAHs during the post-monsoon season were impacted by mixed sources from Indo-Gangetic Plain and eastern India. These observations are supported by the analysis of back-trajectory and fire count data. The excess life time cancer risk (ELCR) values estimated for the study sites are within acceptable limits suggesting acceptable risk levels at BKR, GHY, and RCI. This study highlights the significance of ambient aerosol concentration for health risks in the pre-COVID-19 scenario.

Recording and response of persistent toxic substances (PTSs) in urban lake sediments to anthropogenic activities

Owing to the intensification of human activities, urban lakes serving as important freshwater resources are becoming seriously deteriorated, especially due to persistent toxic substance (PTS) pollution. Therefore, the spatial distribution and sediment record of PTS in urban lake sediments in the middle Yangtze River Basin were investigated to indicate its response to anthropogenic emission and pollution reduction actions. Spatial distribution of typical PTSs (polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) included) showed that pollutants were concentrated in the southeast and center of the urban lake due to riverine inputs suffering from both petrochemical and municipal wastewaters. The sedimentary record of PAH concentrations indicated an increase from the 1960s to a peak level in the 2000s, which was induced mainly by increased PAH emissions, with PAH levels decreasing subsequently due to craft improvement of wastewater treatment plants (WWTPs). Source apportionment results revealed that historical PAH emissions transferred from petrogenic sources to a mixture of energy combustion and petrochemical industry. Furthermore, OCP and PCB pollutions reached peak levels in 1980s, which is consistent with their historical usage for agricultural and industrial production. From the synthetic sediment quality index (SeQI) analysis, sediment quality in nearly half of sites was poor, while the sediment record suggested that sediment quality had turned better since 2000s maybe due to the WWTP improvement. Furthermore, significant correlations (p < 0.05) between PTS levels and the ratio of PAH emissions to the number of WWTPs documented the PTS levels in response to the surrounding anthropogenic pollution and WWTPs in urban lakes.

A Review on Atmospheric Analysis Focusing on Public Health, Environmental Legislation and Chemical Characterization

Atmospheric pollution has been considered one of the most important topics in environmental science once it can be related to the incidence of respiratory diseases, climate change, and others. Knowing the composition of this complex and variable mixture of gases and particulate matter is crucial to understand the damages it causes, help establish limit levels, reduce emissions, and mitigate risks. In this work, the current scenario of the legislation and guideline values for indoor and outdoor atmospheric parameters will be reviewed, focusing on the inorganic and organic compositions of particulate matter and on biomonitoring. Considering the concentration level of the contaminants in air and the physical aspects (meteorological conditions) involved in the dispersion of these contaminants, different approaches for air sampling and analysis have been developed in recent years. Finally, this review presents the importance of data analysis, whose main objective is to transform analytical results into reliable information about the significance of anthropic activities in air pollution and its possible sources. This information is a useful tool to help the government implement actions against atmospheric air pollution.

Associations between land cover categories, gaseous PAH levels in ambient air and endocrine signaling predicted from gut bacterial metagenome of the elderly

There is evidence that polycyclic aromatic hydrocarbons (PAHs) and human gut microbiota are associated with the modulation of endocrine signaling pathways. Independently, studies have found associations between air pollution, land cover and commensal microbiota. We are the first to estimate the interaction between land cover categories associated with air pollution or purification, PAH levels and endocrine signaling predicted from gut metagenome among urban and rural populations. The study participants were elderly people (65-79 years); 30 lived in rural and 32 in urban areas. Semi-Permeable Membrane devices were utilized to measure air PAH concentrations as they simulate the process of bioconcentration in the fatty tissues. Land cover categories were estimated using CORINE database and geographic information system. Functional orthologues for peroxisome proliferator-activated receptor (PPAR) pathway in endocrine system were analyzed from gut bacterial metagenome with Kyoto Encyclopaedia of Genes and Genomes. High coverage of broad-leaved and mixed forests around the homes were associated with decreased PAH levels in ambient air, while gut functional orthologues for PPAR pathway increased along with these forest types. The difference between urban and rural PAH concentrations was not notable. However, some rural measurements were higher than the urban average, which was due to the use of heavy equipment on active farms. The provision of air purification by forests might be an important determining factor in the context of endocrine disruption potential of PAHs. Particularly broad-leaved forests around homes may reduce PAH levels in ambient air and balance pollution-induced disturbances within commensal gut microbiota.

Background concentration, risk assessment and regulatory threshold development: Polycyclic aromatic hydrocarbons (PAH) in Milwaukee, Wisconsin surface soils

Inputs of polycyclic aromatic hydrocarbons (PAHs) of regulatory interest from diffuse atmospheric sources within urban areas frequently elevate local soil concentrations to levels requiring remediation despite the lack of in-situ contamination. This research sought to determine the distribution and potential health effects of aerially deposited PAHs in soil within the urban core of metropolitan Milwaukee, Wisconsin, U.S.A. as part of a soil regulatory standards reevaluation. Park areas (n = 27) identified as undisturbed for 80+ years, containing no fill material, and receiving only atmospheric deposition were selected for composite surface and 92 cm core soil sample collection (n = 295). Samples were analyzed for the 16 USEPA priority PAHs, 1- and 2- methylnapthalene and ancillary soil properties. Soil core and ancillary data confirm lack of site disturbance. PAH diagnostic ratios and homologue summations indicate that diffuse multiple point source emissions contribute equally to PAH deposition throughout the area. Benzo(a)pyrene (BaP) and dibenz(a,h)anthracene mean concentrations exceed health-based clean up levels. Risk assessment shows only a worst-case exposure scenario (BaP at the 95% upper confidence limit) increasing cancer risk (1.67 × 10^-6) over current regulatory thresholds (1.0 × 10^-6). Health quotients show potential health risks from fluoranthene and pyrene for daily park users and from BaP for all others. Mean soil PAH values are similar to New Orleans, but lower than Chicago, Boston, and London reflecting industrial history and site selection protocols. The soil PAH results presented here for sites selected for non-manipulated soils combined with an almost 100-year uninterrupted atmospheric exposure effectively show the maximum potential PAH values that can be found at any given undisturbed location within the Milwaukee urban core due solely to atmospheric deposition.

Polycyclic aromatic hydrocarbons and their nitro-derivatives in urban road dust across China: Spatial variation, source apportionment, and health risk

As an essential carrier of hazardous substances, fugitive road dust has become a severe issue in China. In this study, 212 road dust samples from 53 cities in China were collected to comprehensively investigate the spatial variations, potential sources, and cancer risk of 16 polycyclic aromatic hydrocarbons (PAHs) and 16 nitro-PAHs. The total PAHs concentrations ranged from 0.07 to 345 μg/g dry weight, which is at a moderate level compared to other regions in the world. The mean concentration of Σ₁₆nitro-PAHs was 111 ± 115 ng/g, which is 2-3 orders of magnitude lower than that of Σ₁₆PAHs. A clear geographical trend of dust PAHs and nitro-PAHs was observed in the northeast, north, and east coastal regions of China at a higher level. Moreover, a significant correlation between latitude and PAHs/nitro-PAHs revealed the influences of outdoor temperature and coal combustion for heating in the different regions on the emission and reaction of PAHs and nitro-PAHs. The secondary formation of most nitro-PAHs increases with a decrease in latitude indicated that solar radiation and temperature are important factors on secondary formation of nitro-PAHs. The average concentration of total PAHs and their derivatives in trunk road samples were statistically higher than those in other road samples (p < 0.05), indicating the influence of traffic load on target compound concentration. Generally, the primary sources of PAHs in the road dust samples were coal combustion (23.9%), vehicles (57.1%), and wood/biomass combustion (19.0%). For nitro-PAHs, the main sources were secondary formation (30.9%), biomass/coal combustion (28.4%), and vehicles (44.9%). Furthermore, a moderate potential carcinogenic risk due to PAHs and nitro-PAHs in the dust samples was found in China.

Evaluation of environmental effects of heavy metals on biochemical profile and oxidative stress among children at brick kiln sites

The present study was designed to study the health risks among children living at brick kiln industries. A survey was conducted, questionnaires were filled out, and demographic data was collected from Punjab, Pakistan. Heavy metals burden and BMI were calculated, hematological and enzyme analysis, comet assay and hormonal ELISA were performed. The results showed decreased BMI, RBC count and hematocrit in the exposed group. Nickel, cadmium, zinc and chromium concentrations in whole blood were detected among exposed children. Antioxidant enzymes and growth hormone concentration decreased, while reactive oxygen species and cortisol level increased in the exposed group. The comet assay findings showed decreased percentage DNA in the head and increased in the tail region among exposed group. It was concluded that children living at brick kiln sites experienced decreased BMI, altered antioxidant enzymes status and hormone levels and cellular DNA damage that pose a major threat on child health.

Elevated exposure to polycyclic aromatic hydrocarbons (PAHs) may trigger cancers in Pakistan: an environmental, occupational, and genetic perspective

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic compounds which are emitted through incomplete combustion of organic materials, fossil fuels, consumption of processed meat, smoked food, and from various industrial activities. High molecular mass and mobility make PAHs widespread and lethal for human health. A cellular system in human detoxifies these toxicants through specialized enzymatic machinery called xenobiotic-metabolizing (CYP450) and phase-II (GSTs) enzymes (XMEs). These metabolizing enzymes include cytochromes P450 family (CYP1, CYP2), glutathione s-transferases, and ALDHs. Gene polymorphisms in XMEs encoding genes can compromise their metabolizing capacity to detoxify ingested carcinogens (PAHs etc.) that may lead to prolong and elevated exposure to ingested toxicants and may consequently lead to cancer. Moreover, PAHs can induce cancer through reprograming XMEs' gene functions by altering their epigenetic markers. This review article discusses possible interplay between individual's gene polymorphism in XMEs' genes, their altered epigenetic markers, and exposure to PAHs in cancer susceptibility in Pakistan.

Comparison of physical and chemical characteristics and oxidative potential of fine particles emitted from rice straw and pine stem burning

Agricultural burning and forest fires are common in Northeast Asia and contribute to the elevation of fine particulate pollution, which greatly affects air quality. In this study, chemical and physical attributes, as well as the oxidative potential of fine particles produced from rice straw and pine stem burning in a laboratory-scale chamber were determined. The burning of rice straw generated notably lower emissions of fine particles and elemental carbon (EC) than did the burning of pine stems. The longer retention of ultrafine particles was observed for rice straw burning likely caused by this material's longer period of initial flaming combustion. Organic carbon (OC), OC/EC, K⁺/OC, K⁺/EC, Zn, and alkanoic acid were higher in the fine particles of rice straw burning, while EC, K⁺/Cl^-, Fe, Cr, Al, Cu, and levoglucosan were higher for pine stem burning particles. Chemical data were consistent with a higher hygroscopic growth factor and cloud formation potential and lower amount of agglomerated soot for rice straw burning particles. Rice straw burning particles displayed an oxidative potential seven times higher than that of pine stems.

Exposure of nursing mothers to polycyclic aromatic hydrocarbons: Levels of un-metabolized and metabolized compounds in breast milk, major sources of exposure and infants' health risks

In this study, biomonitoring of nursing Portuguese mothers to polycyclic aromatic hydrocarbons (PAHs) exposure and assessment of potential health risks of their infants were performed through determination of 18 PAHs and 6 major metabolites (OH-PAHs) in breast milk. Concentrations of total PAHs ranged between 55.2 and 1119 ng/g fat, being naphthalene, dibenz(a,h)anthracene, benzo(g,h,i)perylene, and phenanthrene the most abundant compounds (68.4% of ∑PAHs). Benzo(a)pyrene, known carcinogenic, was not detected. Total levels of OH-PAHs ranged from 6.66 to 455 ng/g fat with 1-hydroxyphenanthrene, 1-hydroxynaphthalene and 1-hydroxyacenaphthene as major compounds (96% of ∑OH-PAHs). Concentrations of ∑PAHs and ∑OH-PAHs were strongly correlated between each other (r = 0.692; p ≤ 0.001) and moderately-to-strongly associated with individual compounds (0.203 < r < 0.841; p ≤ 0.001). The attained data suggest increased levels of PAHs in older nursing mothers (>30 years) and in those whose child had lower weight (up to 3.0 kg). Breast-fed infant presented a median PAHs daily intake of 1.41 μg/kg body weight (total benzo(a)pyrene equivalents of 0.0679 μg/kg) and were exposed to 0.024 μg/kg body weight of ∑PAH4 [benz(a)anthracene, benzo(b)fluoranthene, benzo(j)fluoranthene, and chrysene]. Although breast milk is a secure food for newborns, un-metabolized and metabolized PAHs should be included in biomonitoring surveillance studies during breastfeeding to prevent potential health risks for infants.

Ambient PM2.5 and PM10 bound PAHs in Islamabad, Pakistan: Concentration, source and health risk assessment

Polycyclic aromatic hydrocarbons (PAHs) in ambient particulate matter contribute considerably to human health risk. Simultaneous sampling of ambient PM_2.5/PM₁₀ was done to analyze the Ʃ16PAH across the four seasons of 2017 in Islamabad, Pakistan. The average Ʃ16PAH concentrations in PM_2.5 and PM₁₀ were 25.69 and 40.69 ng m^-3_, respectively. For both PM_2.5 and PM₁₀, the highest PAHs concentration was in winter (45.14, 67.10 ng m^-3), while the lowest was in summer (16.40, 28.18 ng m^-3). Source appointment indicated that vehicular exhaust, i.e., diesel, gasoline and alternatively fuel liquid natural gas (LNG), and compressed natural gas (CNG) combustion was the primary PAHs contributor, whereas biomass burning and fuel combustion (coal, biomass, wood, CNG) from stationary sources were another important sources. Health risk assessment showed that the lifetime cancer risk (LCR) values of PAHs were higher than the acceptable level in all four seasons. LCR values were the highest in winter (9.23 × 10^-4 for PAHs in PM_2.5 and 13.98 × 10^-4 for PAHs in PM₁₀) which were 9 and 13 times higher than tolerable cancer risk level respectively, and they were 2-3 times higher than the acceptable values in other seasons.

Impact of Polycyclic Aromatic Hydrocarbons (PAHs) from an Asphalt Mix Plant in a Suburban Residential Area

Polycyclic aromatic hydrocarbons (PAHs), an important class of hazardous airborne pollutants, are mutagenic and carcinogenic substances known to be released during the paving of asphalt. In this study, PAHs emitted from an asphalt mix plant were analyzed to investigate the effects on a suburban residential area. Black carbon, organic carbon, elemental carbon, and PAHs in fine particulate matter (PM2.5) were analyzed in a village near the asphalt mix plant. The results of wind direction analysis revealed that the village was meteorologically affected by emissions from the asphalt mix plant. PAHs in PM2.5 ranged from 0.51 to 60.73 ng/m3, with an average of 11.54 ng/m3. Seasonal PAHs were highest in winter, followed in order by spring, autumn, and summer. The diagnostic ratios between PAHs indicate that the source of PAHs could be incomplete combustion of petrogenic origin. The maximum black carbon concentration in the intensive periods reaches up to 14.17 μg/m3 during mix plant operation periods. Seasonal ∑BaPTEF values based on Toxic Equivalence Factor were: winter (2.284 ng/m3), spring (0.575 ng/m3), autumn (0.550 ng/m3), and summer (0.176 ng/m3). The values are about 6.5 times higher than the concentration in another background area and more than three times higher than those in the capital city, Seoul, in the Republic of Korea. In conclusion, primary emissions from the point source can be considered the major contributor to pollution in the residential area.

Influence of wood species on toxicity of log-wood stove combustion aerosols: a parallel animal and air-liquid interface cell exposure study on spruce and pine smoke

Background

Wood combustion emissions have been studied previously either by in vitro or in vivo models using collected particles, yet most studies have neglected gaseous compounds. Furthermore, a more accurate and holistic view of the toxicity of aerosols can be gained with parallel in vitro and in vivo studies using direct exposure methods. Moreover, modern exposure techniques such as air-liquid interface (ALI) exposures enable better assessment of the toxicity of the applied aerosols than, for example, the previous state-of-the-art submerged cell exposure techniques.

Methods

We used three different ALI exposure systems in parallel to study the toxicological effects of spruce and pine combustion emissions in human alveolar epithelial (A549) and murine macrophage (RAW264.7) cell lines. A whole-body mouse inhalation system was also used to expose C57BL/6 J mice to aerosol emissions. Moreover, gaseous and particulate fractions were studied separately in one of the cell exposure systems. After exposure, the cells and animals were measured for various parameters of cytotoxicity, inflammation, genotoxicity, transcriptome and proteome.

Results

We found that diluted (1:15) exposure pine combustion emissions (PM₁ mass 7.7 ± 6.5 mg m^− 3, 41 mg MJ^− 1) contained, on average, more PM and polycyclic aromatic hydrocarbons (PAHs) than spruce (PM₁ mass 4.3 ± 5.1 mg m^− 3, 26 mg MJ^− 1) emissions, which instead showed a higher concentration of inorganic metals in the emission aerosol. Both A549 cells and mice exposed to these emissions showed low levels of inflammation but significantly increased genotoxicity. Gaseous emission compounds produced similar genotoxicity and a higher inflammatory response than the corresponding complete combustion emission in A549 cells. Systems biology approaches supported the findings, but we detected differing responses between in vivo and in vitro experiments.

Conclusions

Comprehensive in vitro and in vivo exposure studies with emission characterization and systems biology approaches revealed further information on the effects of combustion aerosol toxicity than could be achieved with either method alone. Interestingly, in vitro and in vivo exposures showed the opposite order of the highest DNA damage. In vitro measurements also indicated that the gaseous fraction of emission aerosols may be more important in causing adverse toxicological effects. Combustion aerosols of different wood species result in mild but aerosol specific in vitro and in vivo effects.

Urinary monohydroxylated polycyclic aromatic hydrocarbons in primiparas from Shenzhen, South China: Levels, risk factors, and oxidative stress

The main objectives of the present study were to investigate urinary monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in 77 primiparas who live in Shenzhen, Guangdong Province, China, and their association with 8-hydroxy-2'-deoxyguanosine (8-OHdG) and human health risks. High detection frequencies of OH-PAHs demonstrated the wide occurrence of chemicals in the human exposure to PAHs. The urinary concentrations of Σ₇OH-PAHs ranged from 1.37 to 45.5 ng/mL, and the median concentrations of 1-hydroxynaphthalene (1-OHN), 2-hydroxynaphthalene (2-OHN), 2-hydoxyfluorene (2-OHF), ΣOHPhe (the sum of 1-, 2+ 3-hydroxyphenanthrene), and 1-hydroxypyrene (1-OHP) were 3.00, 2.58, 0.31, 0.44, and 0.51 ng/mL, respectively. In the sum concentration of seven OH-PAHs, 1-OHN accounted for the largest proportion (43.7% of Σ₇OH-PAHs), followed by 2-OHN (37.1%), 2-OHF (4.94%), 1-OHP (8.01%), 1-OHPhe (4.79%), and 2+3-OHPhe (1.46%). The present results showed that vehicle exhaust and petrochemical emission are the main sources of PAHs in primiparas in Shenzhen, and inhalation is the most important exposure route. The living conditions have a significant influence on human exposure to PAHs. The concentrations of 8-OHdG were positively correlated with OH-PAH concentrations in urine because evidence suggested that urinary 8-OHdG levels can be considered as a biomarker of oxidative DNA damage. Hazard quotient was used to assess the human health risks from exposure to single compound, and hazard index was used to assess the cumulative risks of the compounds, which demonstrated that the exposure risks from PAHs in primiparas were relatively low.

Screening toxicological effects of different contaminants using hepatic homogenates-based ethoxyresorufin-O-deethylase in vitro

In this paper, we demonstrated the potential of an in vitro method of liver homogenate-based ethoxyresorufin-O-deethylase (EROD) to determine the toxicological effects of multiple kinds of contaminants. We evaluated the in vitro impact of nine pharmaceutically active compounds (PhACs), 13 polycyclic aromatic hydrocarbons (PAHs), and three polychlorinated biphenyls (PCBs). There were different responses of EROD to these contaminants. The response of EROD to PhACs was quite complex, exhibiting both induction and inhibition effects. PAHs and PCBs elicited a strong inhibitory response on EROD activity at high concentrations in a dose-dependent manner. PAHs showed more inhibitory effects as the number of benzene rings increased. Our in vitro bioassay seems to be a potential method for toxicological screening of multiple types of contaminants.

Firefighters exposure to fire emissions: Impact on levels of biomarkers of exposure to polycyclic aromatic hydrocarbons and genotoxic/oxidative-effects

Firefighters represent one of the riskiest occupations, yet due to the logistic reasons, the respective exposure assessment is one of the most challenging. Thus, this work assessed the impact of firefighting activities on levels of urinary monohydroxyl-polycyclic aromatic hydrocarbons (OHPAHs; 1-hydroxynaphthalene, 1-hydroxyacenaphthene, 2-hydroxyfluorene, 1-hydroxyphenanthrene, 1-hydroxypyrene, 3-hydroxybenzo(a)pyrene) and genotoxic/oxidative-effect biomarkers (basal DNA and oxidative DNA damage) of firefighters from eight firehouses. Cardiac frequency, blood pressure and arterial oxygen saturation were also monitored. OHPAHs were determined by liquid-chromatography with fluorescence detection, while genotoxic/oxidative-effect biomarkers were assessed by the comet assay. Concentrations of total OHPAHs were up to 340% higher (p ≤ 0.05) in (non-smoking and smoking) exposed workers than in control subjects (non-smoking and non-exposed to combat activities); the highest increments were observed for 1-hydroxynaphthalene and 1-hydroxyacenaphthene (82-88% of ∑OHPAHs), and for 2-hydroxyfluorene (5-15%). Levels of biomarker for oxidative stress were increased in non-smoking exposed workers than in control group (316%; p ≤ 0.001); inconclusive results were found for DNA damage. Positive correlations were found between the cardiac frequency, ∑OHPAHs and the oxidative DNA damage of non-smoking (non-exposed and exposed) firefighters. Evidences were raised regarding the simultaneous use of these biomarkers for the surveillance of firefighters' health and to better estimate the potential short-term health risks.

Contamination and cancer risk assessment of polycyclic aromatic hydrocarbons (PAHs) in urban dust from different land-uses in the most populated city of Iran

Due to population growth and the considerable increase in usage of the resources, Human environment quality has been highly threatened by pollutants in recent decades. Polycyclic aromatic hydrocarbons (PAHs) are widespread, persistent organic pollutants which are of great concern due to their carcinogenicity. The present study is the first investigation that assesses contamination, sources and cancer risk of 16 priority PAHs proposed by US EPA in urban dust samples (n = 80) taken in different land-uses of Tehran metropolis, the capital of Iran. Gas chromatography-mass spectrometry (GC-MS) is used to measure PAHs concentrations. The results showed that the average concentration of the total 16 PAHs and the average Benzo[a]pyrene total potency equivalency were 566 μg kg^-1 dry weight and 36.4 μg kg^-1, respectively. In the commercial and residential land-uses high molecular weight (HMW) PAHs were dominated, whereas in green lands, light molecular weight (LMW) PAHs showed maximum contribution. The highest concentration of total PAHs were observed in the commercial areas due to limited air circulation and heavy traffic loads. Incremental Lifetime Cancer Risk (ILCR) model was applied to evaluate the cancer risk of exposure to PAHs contaminated dust. Based on the results, Tehran's residents (children and adults) in various land-uses except for green lands, are in high potential cancer risk of PAHs via ingestion and dermal contact exposure routs. Ace, Chr, Pyr, and BghiP which are indicators of traffic emissions, were found to be predominant PAH contributors in urban dust of commercial areas. Also, Ace, Fl, Phe, and BghiP which are derived from fossil fuel combustion, were mainly observed in the industrial land-use. Based on the results of factor analysis and diagnostic ratios, Diesel/gasoline engine vehicular emissions and combustion were found to be the main sources of PAHs in urban dust of Tehran.