Aryl hydrocarbon receptor mediated activities in road dust from a metropolitan area, Hanoi-Vietnam: contribution of polycyclic aromatic hydrocarbons (PAHs) and human risk assessment

In vitro endocrine and cardiometabolic toxicity associated with artificial turf materials

Artificial turf, a consumer product growing in usage in the United States, contains diverse chemicals, some of which are endocrine disruptive. Endocrine effects from turf material extracts have been primarily limited to one component, crumb rubber, of these multi-material products. We present in vitro bioactivities from non-weathered and weathered turf sample extracts, including multiple turf components. All weathered samples were collected from real-world turf fields. Non-weathered versus weathered differentially affected the androgen (AR), estrogen (ER), glucocorticoid (GR), and thyroid receptors (TR) in reporter bioassays. While weathered extracts more efficaciously activated peroxisome proliferator activated receptor γ (PPARγ), this did not translate to greater in vitro adipogenic potential. All turf extracts activated the aryl hydrocarbon receptor (AhR). High AhR-efficacy extracts induced modest rat cardiomyoblast toxicity in an AhR-dependent manner. Our data demonstrate potential endocrine and cardiometabolic effects from artificial turf material extracts, warranting further investigation into potential exposures and human health effects.

Study of polycyclic aromatic hydrocarbons accumulation in bioretention facilities and its influence on microbial community structure

Bioretention facilities are one of the most widely used measures for urban stormwater control and utilization. In this study, the accumulation characteristics of polycyclic aromatic hydrocarbons (PAHs) in bioretention facilities and the effects of PAHs on the structure of microbial communities were explored by combining on-site monitoring and water distribution simulation experiments. The correlation between pollutant accumulation and dominant microorganisms in the bioretention systems was also clarified. The results showed that all 16 priority PAHs were detected in the bioretention facilities in the sponge city pilot area. The PAH concentrations in the soil during the non-rainy season were higher than those in the rainy season and medium- and high-ring PAHs dominated. PAHs in the study area were mainly derived from coal and biomass combustion. The potential carcinogenic risk of PAHs accumulated in the bioretention facilities in the study area was low. The microbial diversity during the non-rainy season was greater than that during the rainy season. Firmicutes, Bacteroidetes, Bacteroides, and Massilia were strongly correlated with naphthalene (NAP), pyrene (PYR), fluoranthene (FLT), and benzo[a]pyrene (BaP). According to the results of the small-scale water distribution test, the addition of PAHs had little effect on the decline in water quantity, and there was no significant regularity in the reduction of water quality including TP, NH4+-N, NO3-N, and TN. The addition of PAHs had a significant effect on the microbial community structure and an inhibitory effect on enzyme activity.

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.

Emission and distribution profiles of polycyclic aromatic hydrocarbons in solid residues of municipal and industrial waste incinerators, Northern Vietnam

The concentrations and profiles of 18 polycyclic aromatic hydrocarbons (PAHs) in particulate matter (PM₁₀), fly ash (FA), and bottom ash (BA) were examined in three incineration residues. Samples were collected from different municipal and industrial solid waste incinerators in Northern Vietnam. The average concentrations of total PAHs in PM₁₀, fly ash, and bottom ash were 9.55 × 10³ ng/Nm³, 215 × 10³ ng/g, and 2.38 ng/g, respectively. Low-molecular-weight PAHs (2 to 3 rings) were predominant in most samples. The emission factor of total PAHs decreased in the order of FA > BA > PM₁₀. A higher concentration of total PAHs was found in industrial facilities than that in municipal ones. The high carcinogenic proportion of PAHs together with significantly high annual emissions reflect the high pollution risk to the ecosystem by PAHs in the case of reuse of incineration ashes (e.g., brick production). Regarding the carcinogenic risk of PAH-bounded ashes or particles, calculations from this study imply the significant threat for workers who have been manipulated in the incineration facilities, directly exposed to fly and bottom ashes. Meanwhile, the risk from PAH-bound particulate was not considered a significant threat for both normal adults and children. Further study on PAHs contained in incinerator waste dumps should be conducted in Vietnam to assess the potential contamination risk of these incineration by-products.

Statistical analysis, source apportionment, and toxicity of particulate- and gaseous-phase PAHs in the urban atmosphere

Introduction

The concentrations of particulate and gaseous Polycyclic Hydrocarbons Carbon (PAHs) were determined in the urban atmosphere of Delhi in different seasons (winter, summer, and monsoon).

Methodology

The samples were collected using instrument air metric (particulate phase) and charcoal tube (gaseous phase) and analyzed through Gas chromatography. The principal component and correlation were used to identify the sources of particulate and gaseous PAHs during different seasons.

Results and discussion

The mean concentration of the sum of total PAHs (TPAHs) for particulate and gaseous phases at all the sites were found to be higher in the winter season (165.14 ± 50.44 ng/m3 and 65.73 ± 16.84 ng/m3) than in the summer season (134.08 ± 35.0 ng/m3 and 43.43 ± 9.59 ng/m3), whereas in the monsoon season the concentration was least (68.15 ± 18.25 ng/m3 and 37.63 1 13.62 ng/m3). The principal component analysis (PCA) results revealed that seasonal variations of PAHs accounted for over 86.9%, 84.5%, and 94.5% for the summer, monsoon, and winter seasons, respectively. The strong and positive correlation coefficients were observed between B(ghi)P and DahA (0.922), B(a)P and IcdP (0.857), and B(a)P and DahA (0.821), which indicated the common source emissions of PAHs. In addition to this, the correlation between Nap and Flu, Flu and Flt, B(a)P, and IcdP showed moderate to high correlation ranging from 0.68 to 0.75 for the particulate phase PAHs. The carcinogenic health risk values for gaseous and particulate phase PAHs at all sites were calculated to be 4.53 × 10-6, 2.36 × 10-5 for children, and 1.22 × 10-5, 6.35 × 10-5 for adults, respectively. The carcinogenic health risk for current results was found to be relatively higher than the prescribed standard of the Central Pollution Control Board, India (1.0 × 10-6).

Antiandrogenic and Estrogenic Activity Evaluation of Oxygenated and Nitrated Polycyclic Aromatic Hydrocarbons Using Chemically Activated Luciferase Expression Assays

To establish the risk of the endocrine disrupting activity of polycyclic aromatic compounds, especially oxygenated and nitrated polycyclic aromatic hydrocarbons (oxy-PAHs and nitro-PAHs, respectively), antiandrogenic and estrogenic activities were determined using chemically activated luciferase expression (CALUX) assays with human osteoblast sarcoma cells. A total of 27 compounds including 9 oxy-PAHs (polycyclic aromatic ketones and quinones) and 8 nitro-PAHs was studied. The oxy-PAHs of 7H-benz[de]anthracen-7-one (BAO), 11H-benzo[a]fluoren-11-one (B[a]FO), 11H-benzo[b]fluoren-11-one (B[b]FO), and phenanthrenequinone (PhQ) exhibited significantly the potent inhibition of AR activation. All nitro-PAHs exhibited high antiandrogenic activities (especially high for 3-nitrofluoranthene (3-NFA) and 3-nitro-7H-benz[de]anthracen-7-one (3-NBAO)), and the AR inhibition was confirmed as noncompetitive for 3-NFA, 3-NBAO, and 1,3-dinitropyrene (1,3-DNPy). Antiandrogenic activity of 3-NFA demonstrated characteristically a U-shaped dose-response curve; however, the absence of fluorescence effect on the activity was confirmed. The prominent estrogenic activity dependent on dose-response curve was confirmed for 2 oxy-PAHs (i.e., B[a]FO and B[b]FO). Elucidating the role of AR and ER on the effects of polycyclic aromatic compounds (e.g., oxy- and nitro-PAHs) to endocrine dysfunctions in mammals and aquatic organisms remains a challenge.

Long-term ambient hydrocarbon exposure and incidence of urinary bladder cancer

Particulate matter and volatile organic compounds, including total hydrocarbons (THCs), are major ambient air pollutants. Primary nonmethane hydrocarbons (NMHCs) originate from vehicle emissions. The association between air pollution and urinary bladder cancer (UBC) is debatable. We investigated whether long-term exposure to ambient hydrocarbons increases UBC risk among people aged ≥ 20 years in Taiwan. Linkage dataset research with longitudinal design was conducted among 589,135 initially cancer-free individuals during 2000-2013; 12 airborne pollutants were identified. Several Cox models considering potential confounders were employed. The study outcomes were invasive or in situ UBC incidence over time. The targeted pollutant concentration was divided into three tertiles: T1/T2/T3. The mean age of individuals at risk was 42.5 (SD 15.7), and 50.5% of the individuals were men. The mean daily average over 10 years of airborne THC concentration was 2.25 ppm (SD 0.13), and NMHC was 0.29 ppm (SD 0.09). Both pollutants show long-term monotonic downward trend over time using the Mann-Kendall test. There was a dose-dependent increase in UBC at follow-up. UBC incidence per 100,000 enrollees according to T1/T2/T3 exposure to THC was 60.9, 221.2, and 651.8, respectively; it was 170.0/349.5/426.7 per 100,000 enrollees, corresponding to T1/T2/T3 exposure to NMHC, respectively. Without controlling for confounding air pollutants, the adjusted hazard ratio (adj.HR) was 1.83 (95% CI 1.75-1.91) per 0.13-ppm increase in THC; after controlling for PM_2.5, adj.HR was even higher at 2.09 (95% CI 1.99-2.19). The adj.HR was 1.37 (95% CI 1.32-1.43) per 0.09-ppm increase in ambient NMHC concentration. After controlling for SO₂ and CH₄, the adj.HR was 1.10 (95% CI 1.06-1.15). Sensitivity analyses showed that UBC development risk was not sex-specific or influenced by diabetes status. Long-term exposure to THC and NMHC may be a risk factor for UBC development. Acknowledging pollutant sources can inform risk management strategies.

Examination of aryl hydrocarbon receptor (AhR), estrogenic and anti-androgenic activities, and levels of polyaromatic compounds (PACs) in tire granulates using in vitro bioassays and chemical analysis

Tire granulates recovered from end-of-life tires contain a complex mixture of chemicals, amongst them polyaromatic compounds (PACs), of which many are recognized to be toxic and persistent in the environment. Only a few of these PACs are regularly monitored. In this study a combined approach of chemical analysis and a battery of CALUX® in vitro bioassays was used to determine PAC concentrations and estrogenic, (anti)-androgenic and aryl hydrocarbon receptor (AhR) activities in tire granulates. Tire granulates from a recycling company was analyzed for PAHs, alkyl-PAHs, oxy-PAHs and heterocyclic PACs (NSO-PACs), in total 85 PACs. The concentrations of PACs were between 42 and 144 mg/kg, with major contribution from PAHs (74-88%) followed by alkyl-PAHs (6.6-20%) and NSO-PACs (1.8-7.0%). The sum of eight priority PAHs were between 2.3 and 8.6 mg/kg, contributing with 4.7-8.2% of ∑PACs. Bioassay analysis showed presence of AhR agonists, estrogen receptor (ERα) agonists, and androgen receptor (AR) antagonists in the tire granulate samples. Only 0.8-2.4% of AhR-mediated activities could be explained by the chemical analysis. Benzo[k+j]fluoranthenes, benzo[b]fluoranthene, indeno[1,2,3-cd]pyrene, 2-methylchrysene, and 3-methylchrysene were the major contributors to the AhR-mediated activities. The high contribution (98-99%) of unknown bioactive compounds to the bioassay effects in this study raises concerns and urges for further investigations of toxicants identification and source apportionment.

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

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

Polycyclic aromatic hydrocarbons in airborne particulate matter samples from Hanoi, Vietnam: Particle size distribution, aryl hydrocarbon ligand receptor activity, and implication for cancer risk assessment

Concentrations and profiles of unsubstituted and methylated polycyclic aromatic hydrocarbons (PAHs and Me-PAHs) were analyzed in airborne particulate matter (PM) samples collected from high-traffic roads in Hanoi urban area. Levels of PAHs and Me-PAHs ranged from 210 to 660 (average 420) ng/m³ in total PM, and these pollutants were mainly associated with fine particles (PM_2.5) rather than coarser ones (PM _> 10 and PM₁₀). Proportions of high-molecular-weight compounds (i.e., 5- and 6-ring) increased with decreasing particle size. Benzo[b+k]fluoranthene, indeno[1,2,3-cd]pyrene, and benzo[ghi]perylene were the most predominant compounds in the PM_2.5 samples. In all the samples, Me-PAHs were less abundant than unsubstituted PAHs. The PAH-CALUX assays were applied to evaluate aryl hydrocarbon receptor (AhR) ligand activities in crude extracts and different fractions from the PM samples. Benzo[a]pyrene equivalents (BaP-EQs) derived by the PAH-CALUX assays for low polar fractions (mainly PAHs and Me-PAHs) ranged from 300 to 840 ng/m³, which were more consistent with theoretical values derived by using PAH-CALUX relative potencies (270-710 ng/m³) rather than conventional toxic equivalency factor-based values (22-69 ng/m³). Concentrations of PAHs and Me-PAHs highly correlated with bioassay-derived BaP-EQs. AhR-mediated activities of more polar compounds and interaction effects between PAH-related compounds were observed. By using PAH-CALUX BaP-EQs, the ILCR values ranged from 1.0 × 10^-4 to 2.8 × 10^-4 for adults and from 6.4 × 10^-5 to 1.8 × 10^-4 for children. Underestimation of cancer risk can be eliminated by using effect-directed method (e.g., PAH-CALUX) rather than chemical-specific approach.

Characterization of unsubstituted and methylated polycyclic aromatic hydrocarbons in settled dust: Combination of instrumental analysis and in vitro reporter gene assays and implications for cancer risk assessment

Concentrations of 34 unsubstituted and methylated polycyclic aromatic hydrocarbons (PAHs and Me-PAHs) and AhR-mediated activities in settled dust samples were determined by a combination of gas chromatography-mass spectrometry and an in vitro reporter gene assay (PAH-CALUX). The levels of Σ34PAHs and bioassay-derived benzo[a]pyrene equivalents (CALUX BaP-EQs) were significantly higher in workplace dust from informal end-of-life vehicle dismantling workshops than in common house dust and road dust. In all the samples, the theoretical BaP-EQs of PAHs (calculated using PAH-CALUX relative potencies) accounted for 28 ± 19% of the CALUX BaP-EQs, suggesting significant contribution of aryl hydrocarbon receptor (AhR) agonists and/or mixture effects. Interestingly, the bioassay-derived BaP-EQs in these samples were significantly correlated with not only unsubstituted PAHs with known carcinogenic potencies but also many Me-PAHs, which should be included in future monitoring and toxicity tests. The bioassay responses of many sample extracts were substantially reduced but not suppressed with sulfuric acid treatment, indicating contribution of persistent AhR agonists. Cancer risk assessment based on the CALUX BaP-EQs has revealed unacceptable level of risk in many cases. The application of bioassay-derived BaP-EQs may reduce underestimation in environmental management and risk evaluation regarding PAHs and their derivatives (notably Me-PAHs), suggesting a consideration of using in vitro toxic activity instead of conventional chemical-specific approach in such assessment practices.

Occurrence and risk assessment of herbicides and fungicides in atmospheric particulate matter in Hanoi, Vietnam

Vietnam is a Southeast Asian developing country with rapidly increasing air pollution, especially in large cities. Over 350,000 chemicals and chemical mixtures are produced and used in Vietnam; however, the country has only implemented air quality standards for 44 substances, which are primarily focused on inorganic and volatile organic compounds. Although numerous pesticides are frequently applied across large cities in Vietnam, information on their concentrations in atmospheric particulate matter (APM) is limited. Therefore, to investigate their occurrence and health effects, 187 pesticides in APM were screened using the liquid chromatography-mass spectrometry-quadrupole time of flight- Sequential Window Acquisition of All Theoretical Fragment Ion Spectra method (LC-QTOF-MS-SWATH). A total of 22 pesticides (16 fungicides and 6 herbicides) were quantified in the dry and rainy seasons. Among them, 19 substances were quantified in APM for the first time in Vietnam. Their median total concentrations in the dry season were higher than those in the rainy season, and the concentrations in the daytime were one-third of the night-time concentrations in both seasons. Their total levels ranged from 0.82 to 21.1 ng m^-3 (median, 3.63 ng m^-3), the detection frequencies of 9 pesticides were higher than 70%, and 7-14 pesticides were detected per sample (median, 10). Some of the detected pesticides were likely sourced from their prevalent use in amenity turf protection (e.g., in parks and public roads) and weed control (e.g., in gardens, floriculture, and agriculture). The total daily intake (DI_air) values for adults, children, and infants were 8.17E-06, 2.06E-05, and 2.45E-05 mg kg^-1 d^-1, respectively, and the highest Hazard Quotients (HQs) were 4.81E-04, 1.22E-03, and 1.44E-03, respectively. All HQs and HIs of the pesticides were < 1 for all population groups (adults, children, and infants), indicating negligible exposure risks.

Direct Analysis of Soil Composition for Source Apportionment by Laser Ablation Single-Particle Aerosol Mass Spectrometry

Soil has always been the most complex biomaterial on the planet. The rapid determination of the components in the soil and their original source is a prerequisite for soil quality, environmental, and human health risk assessments. In this study, the chemical compositions and source apportionment of surface soil samples collected from five sites in Shanghai, China, were successfully investigated using a laboratory-developed laser ablation single-particle aerosol mass spectrometry (LA-SPAMS) instrument combined with an adaptive resonance theory-based neural network algorithm (ART-2a) data-processing method for the first time. In total, more than 35,000 particles, ranging from 200 to 2000 nm, were sized, and around 15-20% of the particles were chemically analyzed by LA-SPAMS to generate both positive and negative mass spectra. The results show that there are significant differences in particle size distribution among the five samples, with peaks of various sizes and different profiles, while all five soil samples contain crustal elements, heavy metals, organic and inorganic components, and so forth. The chemical composition of each sample varied considerably, so different classes of SPAMS particle classes were identified, which were later grouped into seven general categories: EC-rich (containing elemental carbon), secondary components, organic nitrogen, crust, HM (containing heavy metal), PAH (containing polycyclic aromatic hydrocarbons), and NaK-rich particles, based on the dominant marked ions. The composition analysis and source apportionment showed that soil components in different areas have been affected by the local environment, such as local industrial emissions and automobile exhaust, which are usually characterized by varying degrees of mixing between the crust and environmental aerosols. In combination with the ART-2a method, LA-SPAMS enables rapid and direct analysis of soil samples based on real-time single-particle measurements, which will help in understanding the distribution, transport, and fate of the soil components, thus providing new insights into soil-quality assessment. Moreover, the established LA-SPAMS can also be practically applied to other daily inspection tasks, such as rocks, minerals, metals, ceramics, polymers, and other solid materials for ingredient analysis and quality evaluation.

Assessment of incremental lifetime cancer risks of ambient air PM10-bound PAHs in oil-rich cities of Iran

This study investigates the concentrations of PM₁₀-bound PAHs and their seasonal variations in three cities of Ahvaz, Abadan, and Asaluyeh in Iran. The mean concentrations of PM₁₀ in two warm and cold seasons in Ahvaz were higher and in Abadan and Assaluyeh were lower than the national standard of Iran and the guidelines of the World Health Organization. The Σ16 PAHs concentration in ambient air PM₁₀ during the cold season in Ahvaz, Abadan and Asaluyeh was 244.6, 633, and 909 ng m^- 3, respectively, and during the warm season in Ahvaz, Abadan, and Asaluyeh was 242.1, 1570 and 251 ng m^- 3, respectively. The high molecular weight PAHs were the most predominant components. The most abundant PAHs species were Pyr, Chr, B [ghi] P, and Flt. The results showed that the total PAHs concentration in the cold and warm seasons was dependent on industrial activities, particularly the neighboring petrochemical units of the city, vehicular exhausts, traffic and use of oil, gas, and coal in energy production. The total cancer risk values as a result of exposure to PAHs in ambient air PM₁₀ in all three cities for children and adults and in both cold and warm seasons were between 1 × 10^- 6 and 1 × 10^- 4, and this indicates a potential carcinogenic risk. Therefore, considering the various sources of air pollutants and its role on people's health, decision makers should adopt appropriate policies on air quality to reduce the ambient air PAHs and to mitigate human exposure.

Assessment of Pollution and Health Risks of Heavy Metals in Particulate Matter and Road Dust Along the Road Network of Dhanbad, India

BACKGROUND

The rise in particulate matter (PM) concentrations is a serious problem for the environment. Heavy metals associated with PM₁₀, PM_2.5, and road dust adversely affect human health. Different methods have been used to assess heavy metal contamination in PM₁₀, PM_2.5, and road dust and source apportionment of these heavy metals. These assessment tools utilize pollution indices and health risk assessment models.

OBJECTIVES

The present study evaluates the total mass and average concentrations of heavy metals in PM₁₀, PM_2.5, and road dust along selected road networks in Dhanbad, India, analyzes the source apportionment of heavy metals, and assesses associated human health risks.

METHODS

A total of 112 PM samples and 21 road dust samples were collected from six stations and one background site in Dhanbad, India from December 2015 to February 2016, and were analyzed for heavy metals (iron (Fe), lead (Pb), cadmium (Cd), nickel (Ni), copper (Cu), chromium (Cr), and zinc (Zn)) using atomic absorption spectrophotometry. Source apportionment was determined using principal component analysis. A health risk assessment of heavy metal concentrations in PM₁₀, PM_2.5, and road dust was also performed.

RESULTS

The average mass concentration was found to be 229.54±118.40 μg m^-3 for PM₁₀ and 129.73 ±61.74 μg m^-3 for PM_2.5. The average concentration of heavy metals was found to be higher in PM_2.5 than PM₁₀. The pollution load index value of PM₁₀ and PM_2.5 road dust was found to be in the deteriorating category. Vehicles were the major source of pollution. The non-carcinogenic effects on children and adults were found to be within acceptable limits. The heavy metals present in PM and road dust posed a health risk in the order of road dust> PM₁₀> and PM_2.5. Particulate matter posed higher health risks than road dust due to particle size.

CONCLUSIONS

The mass concentration analysis indicates serious PM₁₀ and PM_2.5 contamination in the study area. Vehicle traffic was the major source of heavy metals in PM₁₀, PM_2.5, and road dust. In terms of non-carcinogenic risks posed by heavy metals in the present study, children were more affected than adults. The carcinogenic risk posed by the heavy metals was negligible.

COMPETING INTERESTS

The authors declare no competing financial interests.

Comprehensive study of insecticides in atmospheric particulate matter in Hanoi, Vietnam: Occurrences and human risk assessment

Air pollution is the most serious environmental issue in Vietnam, particularly in big cities. Air pollutants that are set as environmental standards are regularly monitored by the public institutions. Whereas, environmental data on organic micro-pollutants in atmospheric particulate matters (APMs) is limited, including PAHs and POPs. Although massive pesticides are used in big cities, their data in APMs in Vietnam is very scarce. In order to elucidate their occurrence in the ambient air in Hanoi and their health effects, we surveyed 107 insecticides in APMs by a novel target screening method using LC-QTOF-MS-SWATH. A total of 19 insecticides were detected in the dry and the rainy seasons. Among them, 16 substances are, to our knowledge, reported for the first time in the literature. Their total concentrations varied from 0.47 to 27.0 ng m^-3 (median, 3.6 ng m^-3), detection frequencies of 12 compounds are higher than 42%, and the number of insecticides detected per each sample ranging from 5 to 13 (median, 9). Total concentrations in the dry season were generally higher than in the rainy season, and concentrations at night were higher than daytime in both seasons. The level of insecticides depends not only on the season, but also on its physicochemical properties, its application conditions, and the meteorological conditions. Their emission sources could be related to agricultural usage, floricultural activities, and pest control in houses. The total maximum daily intake (DI_air) through inhalation for adults and children were 2.39E-05 mg kg^-1 d^-1 and 2.98E-05 mg kg^-1 d^-1, respectively. The highest Hazard Quotients (HQs) were 1.34E-03 and 3.37E-03, and the highest Hazard Indices (HIs) were 2.71E-03 and 6.33E-03 for adults and children, respectively. All values of HQs, and HIs of insecticides were less than 1, indicating that health risk would be negligible.

Assessment of cancer risk of microplastics enriched with polycyclic aromatic hydrocarbons

Abundance of microplastics in aquatic and marine ecosystems is contaminating the seafood and it is leading to transfer of toxic pollutants to human beings. In this article, we report the hazardous nature and cancer risk of microplastics which originate from e-waste. Capture of carcinogenic polycyclic aromatic hydrocarbons (PAHs) onto microplastics by adsorption phenomena and an assessment of probable cancer risk of ingested PAHs enriched microplastics by human beings have been investigated. The adsorption equilibrium was well fit for the Freundlich isotherm model. The adsorption capacity of carcinogenic PAHs on microplastics was ranged from 46 to 236 μg g^-1 and the maximum binding was achieved within 45 min in water. The leachate derived from microplastics of e-waste were highly hazardous in nature, for example, the sum of PAHs was 3.17 mg L^-1 which is about 1000 times higher than the standard for benzo[a]pyrene, a congener of PAHs. The calculated cancer risk in terms of lifetime of microplastic ingestion would be 1.13 × 10^-5 for children and 1.28 × 10^-5 for adults and these values are higher than the recommended value of 10⁶. The abundance of microplastics could transfer hazardous pollutants to seafood (e.g., fishes and prawns) leading to cancer risk in human beings.

Polycyclic aromatic hydrocarbons (PAHs) in dry tea leaves and tea infusions in Vietnam: contamination levels and dietary risk assessment

The total mean ∑[Formula: see text] in samples were from 75.3 to 387.0 ng/g dry weight (d.w) and showed high value in black dry tea, followed by herbal, oolong, and green tea. The mean ∑[Formula: see text] (a combination of benz[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene) values were 54.3 ng/g, 16.4 ng/g, 14.2 ng/g, and 6.6 ng/g for black, herbal, green, and oolong teas, respectively. Concentration for benzo[a]pyrene (BaP) was from 0.4 to 35.8 ng/g, and the BaP equivalent concentration values ranged from 0.3 to 48.1 ng/g. There was only 1 black tea sample that BaP concentration exceeded the maximum level according to European Union (EU) standards. Tea samples marketed in Vietnam showed insignificant difference with the samples from other origins by same analytical method. Black teas showed high PAHs contents in dry tea samples but the released percentage of sum of PAHs from tea-to-tea infusion was lower than that in other tea type samples. The released percentages of PAH4 from tea-to-tea infusion were 40.7, 15.4, and 1.9 for green, herbal, and black tea. High temperature in black tea manufacturing processes might reduce essential oil content in tea that might effect on the PAHs partially release into the infusion. Indeed, based on EU regulations, we may conclude that tea consumers are safe in risk of exposure to PAHs obtained from teas.

Nationwide health risk assessment of juvenile exposure to polycyclic aromatic hydrocarbons (PAHs) in the water body of Chinese lakes

The high emissions of polycyclic aromatic hydrocarbons (PAHs) pose a serious threat to the lake ecosystem and human health, and the human health risk assessment of PAH exposure is expected as an urgent project in China. This paper focused on 44 Chinese lakes in 6 lake zones to investigate the occurrence, composition and source of 19 PAHs in water body and estimate the human health risk under PAH exposure. The "List of PAH Priority Lakes" in China was generated based on the combination of incremental lifetime cancer risk (ILCR) model and Monte Carlo simulation. Our results showed that the Σ₁₇ PAHs ranged from 3.75 ng·L^-1 to 368.68 ng·L^-1 with a median of 55.88 ng·L^-1. Low-ring PAHs were the predominant compounds. PAH profiles varied significantly at lake zone level. Diagnostic ratios showed that PAHs might derive from petroleum and coal or biomass combustion. Benzo[a]pyrene-equivalent toxic concentrations (BaPeq) of the Σ₁₇ PAHs ranged from 0.07 ng·L^-1 to 2.26 ng·L^-1 (0.62 ± 0.52 ng·L^-1, mean ± standard deviation) with a median of 0.47 ng·L^-1. Benzo[a]anthracene (BaA), benzo[a]pyrene (BaP) and benzo[e]pyrene (BeP) were the main toxic isomers. Juvenile exposure to PAHs via oral ingestion (drinking) and dermal contact (showering) had negligible and potential health risks, respectively. Juveniles were the sensitive population for PAH exposure. 15 lakes were screened into the "List of PAH Priority Lakes" in three priority levels: first priority (Level A), moderate priority (Level B) and general priority (Level C). Lake Taihu, Lake Chaohu and Lake Hongze were the extreme priority lakes. Optimizing the economic structures and reducing the combustion emissions in these areas should be implemented to reduce the population under potential health risk of PAHs.

Soil and sediment contamination by unsubstituted and methylated polycyclic aromatic hydrocarbons in an informal e-waste recycling area, northern Vietnam: Occurrence, source apportionment, and risk assessment

Improper processing activities of e-waste are potential sources of polycylic aromatic hydrocarbons (PAHs) and their derivatives, however, information about the environmental occurrence and adverse impacts of these toxic substances is still limited for informal e-waste recycling areas in Vietnam and Southeast Asia. In this study, unsubstituted and methylated PAHs were determined in surface soil and river sediment samples collected from a rural village with informal e-waste recycling activities in northern Vietnam. Total levels of PAHs and MePAHs decreased in the order: workshop soil (median 2900; range 870-42,000 ng g^-1) > open burning soil (2400; 840-4200 ng g^-1) > paddy field soil (1200; range 530-6700 ng g^-1) > river sediment samples (750; 370-2500 ng g^-1). About 60% of the soil samples examined in this study were heavily contaminated with PAHs. Fingerprint profiles of PAHs and MePAHs in the soil and sediment samples indicated that these pollutants were mainly released from pyrogenic sources rather than petrogenic sources. The emissions of PAHs and MePAHs in this area were probably attributed to uncontrolled burning of e-waste and agricultural by-products, domestic coal and biomass combustion, and traffic activities. Carcinogenicity and mutagenicity of PAHs in the e-waste workshop soils were significantly higher than those of the field soils; however, the incremental lifetime cancer risk of PAH-contaminated soils in this study ranged from 5.5 × 10^-9 to 4.6 × 10^-6, implying acceptable levels of human health risk. Meanwhile, concentrations of some compounds such as phenanthrene, anthracene, fluoranthene, benz[a]anthracene, and benzo[a]pyrene in several soil samples exceeded the maximum permissible concentrations, indicating the risk of ecotoxicological effects.

Assessment of the toxicity of firefighter exposures using the PAH CALUX bioassay

Firefighters can be exposed to a complex set of contaminants while at a fire scene. Identifying new ways to monitor and assess exposure, particularly relating to toxicity is essential to determine the effectiveness of intervention techniques to reduce exposure. This study investigated the use of the polycyclic aromatic hydrocarbon (PAH) CALUX® bioassay for the assessment of exposure and associated toxicity firefighters might encounter. This was done through analysis of extracts of dermal wipes and urine samples collected from firefighters before and after a controlled fire. An increased bioassay response was observed from post-fire neck and calf samples, indicating a greater concentration of PAH-like compounds on the skin. The use of a baby wipe to clean the face and neck during rehab resulted in the attenuation of the observed bioassay response from the neck post-fire. Though a correlation was observed between the bioassay response and hydroxylated PAH concentrations found in the urine, the increased bioassay response from the post-fire urine samples was likely due to unknown compounds other than the hydroxylated PAHs tested. Our results suggest that this bioassay provides a useful measure of firefighter exposure, particularly relating to the potential toxicity of contaminants.

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.

Polycyclic Aromatic Hydrocarbons (PAHs) in Road Dust Collected from Myanmar, Japan, Taiwan, and Vietnam

In this study, we determined the concentrations of polycyclic aromatic hydrocarbons (PAHs) in road dust from Myanmar, Japan, Taiwan, and Vietnam. PAHs were detected in urban and rural areas of Myanmar at mean concentrations of 630 ng/g dry weight and 200 ng/g dry weight, respectively. PAHs were also detected in road dust from Vietnam (mean 1700 ng/g) and Taiwan (2400 ng/g). PAH diagnostic ratios suggested that fossil fuel vehicular exhaust and biomass combustion are major sources of PAHs in road dust in Myanmar. Road dust samples from Japan, Taiwan, and Vietnam had similar PAH diagnostic ratios, implying that PAH sources are similar. We assessed the human health risks posed by PAHs in road dust using carcinogenic equivalents (CEQs) and incremental lifetime cancer risk (ILCR). Mean CEQs were decreased in the order Taiwan (173 ng/g) > Vietnam (162 ng/g for Hanoi) > Myanmar (42 and 31 ng/g for Yangon and Pathein, respectively) > Japan (30 ng/g for Kumamoto). Benz[a]pyrene, fluoranthene, and benzo[b]fluoranthene, the predominant PAHs, contributed > 70% of total CEQs. High ILCR values were found for Taiwan (5.9 × 10^-4 and 9.9 × 10^-4 for children and adults, respectively) and Vietnam (6.5 × 10^-4 and 9.2 × 10^-4 for children and adults, respectively, in Hanoi), indicating that PAHs in road dust pose cancer risks to the inhabitants of Taiwan and Hanoi. To our knowledge, this is the first report to identify PAH pollution in the environment and to evaluate the human health risks of these PAHs in Myanmar.

Road dust contamination by polycyclic aromatic hydrocarbons and their methylated derivatives in northern Vietnam: Concentrations, profiles, emission sources, and risk assessment

Concentrations of unsubstituted and methylated polycyclic aromatic hydrocarbons (PAHs and Me-PAHs) were examined in road dusts from some representative areas with different land-use types in northern Vietnam, providing updated information about the occurrence, sources, and risks of these pollutants in Southeast Asian region. The Vietnamese road dusts were contaminated with low to moderate levels of PAHs and Me-PAHs as compared to those from other countries in the world. Concentrations of PAHs and Me-PAHs (Σ34PAHs) decreased in the order: urban (median 1800; range 1100-5500) ≈ industrial (1300; 550-10,000) > suburban (450; 310-1300) ≈ rural road dust (330; 210-2300 ng g^-1), suggesting an urban-rural declining trend and effects of urbanization-industrialization processes in PAH emission extent in Vietnam. The profiles and diagnostic ratios of PAHs and Me-PAHs in our samples revealed that these compounds were mainly derived from pyrogenic sources rather than petrogenic sources. Traffic emissions (e.g., vehicle exhaust, tire debris, and possible leaks of fuels, oils, and lubricants) were estimated as principal sources of PAHs and Me-PAHs, especially in the urban and industrial areas. Other pyrogenic sources (e.g., coal, wood, and biomass combustion) were also existed in the industrial, suburban, and rural areas, reflecting PAH origins from thermal industrial processes, open burning of agricultural by-products, and domestic energy utilization. Persons working outdoors and children in the urban and industrial areas were estimated to receive higher intake doses of PAHs and Me-PAHs, which were one to two orders of magnitude higher than those estimated for other groups. Except for potential cancer risk estimated for the occupational groups in the industrial area under the worst exposure scenarios, the non-cancer and cancer risk levels were generally acceptable; however, more comprehensive risk assessment considering other exposure pathways (e.g., inhalation and diet) is needed.

Polycyclic aromatic hydrocarbons and their methylated derivatives in settled dusts from end-of-life vehicle processing, urban, and rural areas, northern Vietnam: Occurrence, source apportionment, and risk assessment

The occurrence and profiles of 19 polycyclic aromatic hydrocarbons (PAHs) and 15 methylated derivatives (Me-PAHs) were examined in settled dust samples collected from workplaces and living areas of an informal end-of-life vehicle (ELV) processing village, and house dusts from urban and rural areas in northern Vietnam. Concentrations of total PAHs and Me-PAHs decreased in the order: ELV workplace (median 5700, range 900-18,000 ng g^-1) > rural house (3700, 1800-6200 ng g^-1) > urban house (1800, 620-3100 ng g^-1) ≈ ELV living dusts (1000, 600-3900 ng g^-1). PAHs with 4 rings or more dominated in almost all the samples, indicating the abundance of pyrogenic sources (e.g., vehicular emissions and domestic thermal processes). Levels of Me-PAHs were exceeded those of PAHs in several ELV samples, revealing specific petrogenic sources derived from vehicle processing activities. Results from source apportionment analysis have partially identified traffic emission, biomass and coal combustion, and mixed petrogenic-pyrogenic sources related to ELV waste as the major sources of PAHs and Me-PAHs in the urban, rural, and ELV areas, respectively. Daily intake doses and health risk related to PAHs and Me-PAHs in settled dusts were estimated for ELV workers and residents living in the study areas. The worst exposure scenario of dust-bound PAHs showed a potential cancer risk for the ELV workers, meanwhile, no significant non-cancer and cancer risk was expected for other exposed groups. A more comprehensive and accurate risk assessment of PAHs and related compounds should be conducted in Vietnam.

Screening analysis of organic micro-pollutants in road dusts from some areas in northern Vietnam: A preliminary investigation on contamination status, potential sources, human exposure, and ecological risk

Road dust samples collected from some representative areas in northern Vietnam were examined to determine the occurrence of multiple classes of organic micro-pollutants. Of 942 target compounds screened, 105 organic pollutants originating from different sources such as traffic, household, agricultural, and industrial activities, were detected at least once in our samples. Concentrations of total organic pollutants in the road dusts ranged from 7.8 to 170 μg g^-1, with a median value of 28 μg g^-1. Overall contamination levels were the highest in samples from an urban area, followed by those from an industrial park, a suburban area, and a rural commune, suggesting environmental impacts of urbanization and industrialization. The most predominant pollutants found in the road dusts were n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and current-use chemicals such as phthalate plasticizers and pharmaceutical and personal care products (PPCPs), whereas, industrial chemicals and pesticides were detected at relatively low levels. Persons occupationally exposed to road dusts (e.g., street sweepers, vendors, and traffic policemen) were estimated to receive the highest daily intake doses of dust-bound organic pollutants that were one to two orders of magnitude greater than those received by general population. No serious human health risk associated with ingestion of contaminated road dusts was observed in this study. However, levels of some phthalates were higher than related environmental quality guidelines in terms of ecological risk. More comprehensive and detailed risk assessment of organic pollutants in road dusts should be conducted, especially for highly urbanized and industrialized areas in developing countries.

Target screening analysis of 970 semi-volatile organic compounds adsorbed on atmospheric particulate matter in Hanoi, Vietnam

Vietnam's rapid economic development has resulted in dramatic increases in construction and the number of transportation vehicles. There is now growing public concern regarding increasing air pollution, especially in big cities; however, little information is available on air quality, particularly regarding semi-volatile organic compounds (SVOCs) adsorbed on atmospheric particulate matter. Here, we determined the frequency and concentrations of 970 SVOCs in 48 air particle samples collected by means of high-volume air sampling in Hanoi, Vietnam, by using a target screening method and a gas chromatography-mass spectrometry database. A total of 118 compounds (12.2% of the target compounds) were detected at least once in the samples, and the number of chemicals detected in each sample ranged from 85 to 103 (median, 92). For samples collected near a heavily trafficked road, the concentrations of target compounds in the samples were higher in samples collected during the day than in those collected at night, whereas the opposite was true for samples collected in a highly populated residential area with industrial activities related to the production of fresh noodles. Sixteen PAHs were detected at high concentrations in nearly 100% of the samples. Eighteen pesticides were detected, with permethrin being detected the most frequently (>70% samples), which can be explained by the use of permethrin-based Permecide 50 EC for dengue fever control during the sampling period. Endocrine-disrupting chemicals (i.e., bisphenol A, 4-nitrophenol) and pharmaceuticals and personal care products (diethyltoluamide, caffeine) were detected in over 90% of the samples. Seven sterols, five phthalate compounds and five organophosphorus flame retardants were detected in the samples. This is the first comprehensive survey of SVOCs adsorbed on atmospheric particulate matter in Vietnam, and as such, this study provides important new information about the frequency and concentrations of atmospheric SVOC contamination. The variety of chemicals detected in this study implies an abundance of pollution sources; further investigations to determine these pollution sources and the risks posed by the detected SVOCs to human health are warranted.

Characterization of 209 polychlorinated biphenyls in street dust from northern Vietnam: Contamination status, potential sources, and risk assessment

A full congener-specific determination of polychlorinated biphenyls (PCBs) was conducted for street dusts in some areas in northern Vietnam. Total 209 PCB concentrations (median and range) of 14 (2.2-120), 11 (6.6-32), and 0.25 (0.10-0.97) ng g^-1 were measured in the street dusts from an industrial park, an urban area, and a rural commune, respectively, suggesting environmental loads of PCBs related to industrialization and urbanization in northern Vietnam. PCB patterns of street dusts from the industrial park were dominated by lightly chlorinated homologs (tri- and tetra-CBs), while more highly chlorinated homologs (penta- and hexa-CBs) were the major contributors to total PCBs in the urban samples, indicating different emission sources. Linear correlations of log-transformed sum of 7 indicator congeners with total PCBs and sum of dioxin-like PCBs were observed. PCB-11, an inadvertently produced congener of pigment manufacturing processes, was detected in all the samples with more elevated proportions in the urban and rural areas than industrial park. Our results have revealed complex emission sources of PCBs in the study areas, including both historical (e.g., the past usage of imported PCB-containing oils and old electric equipment) and current sources such as releases from industrial activities and increasing use of new consumer products. Occupationally exposed persons (e.g., street sweepers, street vendors, and traffic policemen) and children in the urban and industrial areas were estimated to receive much higher doses of dust-bound PCBs than general population, suggesting the need for appropriate protection conditions.

A preliminary investigation of 942 organic micro-pollutants in the atmosphere in waste processing and urban areas, northern Vietnam: Levels, potential sources, and risk assessment

Of 942 organic micro-pollutants screened, 167 compounds were detected at least once in the atmosphere in some primitive waste processing sites and an urban area in northern Vietnam by using a polyurethane foam-based passive air sampling (PUF-PAS) method and an Automated Identification and Quantification System with a Database (AIQS-DB) for GC-MS. Total concentrations of organic pollutants were higher in samples collected from an urban area of Hanoi city (2300-2600 ng m^-3) as compared with those from an end-of-life vehicle (ELV) dismantling area in Bac Giang (900-1700 ng m^-3) and a waste recycling cooperative in Thai Nguyen (870-1300 ng m^-3). Domestic chemicals (e.g., n-alkanes, phthalate ester plasticizers, and synthetic phenolic antioxidants) dominated the organic pollutant patterns in all the samples, especially in the urban area. Pesticides (e.g., permethrins, chlorpyrifos, and propiconazole) were found in the atmosphere around the ELV sites at more elevated concentrations than the other areas. Levels of polycyclic aromatic hydrocarbons and their derivatives in the Bac Giang and Thai Nguyen facilities were significantly higher than those measured in Hanoi urban houses, probably due to the waste processing activities. Daily intake doses of organic pollutants via inhalation were estimated for waste processing workers and urban residents. This study shall provide preliminary data on the environmental occurrence, potential emission sources, and effects of multiple classes of organic pollutants in urban and waste processing areas in northern Vietnam.

Biological toxicity estimates show involvement of a wider range of toxic compounds in sediments from Durban, South Africa than indicated from instrumental analyses

The toxic equivalences (TEQs) of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) from sediment of aquatic systems in Durban, South Africa were determined in two ways: 1) TEQs of PAHs and PCBs were determined by instrumental analyses and converted to 2,3,7,8‑tetrachlorodibenzo‑para‑dioxin equivalence (TCDDeq). 2) Bioassay equivalences (BEQs) of aryl hydrocarbon receptor (AhR) ligands were analysed using the H4IIE-luc bioassay. TEQs of PCBs ranged from below limit of detection (<LOD) to 57 pg TCDDeq·g^-1 while PAHs ranged from <LOD to 790 pg TCDDeq·g^-1. BEQs were 100- to 1000-fold greater than TEQs. Potency-balance revealed <10% of the BEQs were explained by instrumentally analysed compounds. Sediment quality guidelines indicated di minimis risk relating to TEQs, however had potential risk due to BEQs. The results reveal that far more AhR ligands were present in the sediments than what was instrumentally analysed and capable of causing AhR-mediated toxicity.

An overview of research and development themes in the measurement and occurrences of polyaromatic hydrocarbons in dusts and particulates

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds consisting of two or more fused aromatic rings and are probably one of the most studied groups of organic chemicals in environmental research. PAHs originate mainly from anthropogenic processes, particularly from incomplete combustion of organic fuels. PAHs are distributed widely in particulate matter. Due to widespread sources and persistent characteristics, PAHs disperse through atmospheric transport and exist almost everywhere. Human beings are exposed to PAH mixtures in gaseous or particulate phases in ambient air. Long-term exposure to high concentrations of PAHs is associated with adverse health problems. This review identifies the main research and development themes in the measurement and occurrences of PAHs in dusts and particulates using a new approach to carrying out a literature review where many peer-review publications have been produced. The review extracts the most important research themes from a literature search using a combination of text mining and a more detailed review of selected papers from within the identified themes.

Polycyclic Aromatic Hydrocarbons in Urban Soil in the Semi-arid City of Xi'an, Northwest China: Composition, Distribution, Sources, and Relationships with Soil Properties

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment. This study collected a total of 62 urban soil samples from the typical semi-arid city of Xi'an in Northwest. They were analyzed for the composition, distribution, and sources of PAHs as well as the relationships with soil properties. The sum of 16 individual PAHs (∑16PAHs) ranged from 390.6 to 10,652.8 μg/kg with a mean of 2052.6 μg/kg. The average ∑16PAHs decreased in the order of the third ring road (2321.1 μg/kg) > the first ring road (1893.7 μg/kg) > the second ring road (1610.0 μg/kg), and in the order of industrial areas (3125.6 μg/kg) > traffic areas (2551.6 μg/kg) > educational areas (2414.4 μg/kg) > parks (1649.5 μg/kg) > mixed commercial and traffic areas (1332.8 μg/kg) > residential areas (1031.0 μg/kg). The most abundant PAHs in the urban soil were 3- to 5-ring PAHs. Elevated levels of PAHs were found in industrial and traffic areas from the east and west suburbs and the northwest corner of Xi'an as well as the northeast corner in the urban district of Xi'an. PAHs in the urban soil were mainly related to the combustion of fossil fuel (i.e., coal, gasoline, diesel, and natural gas) and biomass (i.e., grass and wood) (variance contribution 57.2%) as well as the emissions of petroleum and its products (variance contribution 29.9%). Soil texture and magnetic susceptibility were the main factors affecting the concentration of PAHs in urban soil. Meanwhile, this study suggested that the single, rapid, and nondeductive magnetic measurements can be an indicator of soil pollution by PAHs.

Concentration and Risk Evaluation of Polycyclic Aromatic Hydrocarbons in Urban Soil in the Typical Semi-Arid City of Xi'an in Northwest China

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants, presenting potential threats to the ecological environment and human health. Sixty-two urban soil samples were collected in the typical semi-arid city of Xi’an in Northwest China. They were analyzed for concentration, pollution, and ecological and health risk of sixteen U.S. Environmental Protection Agency priority PAHs. The total concentrations of the sixteen PAHs (Σ16PAHs) in the urban soil ranged from 390.6 to 10,652.8 µg/kg with an average of 2052.6 µg/kg. The concentrations of some individual PAHs in the urban soil exceeded Dutch Target Values of Soil Quality and the Σ16PAHs represented heavy pollution. Pyrene and dibenz[a,h]anthracene had high ecological risk to aquatic/soil organisms, while other individual PAHs showed low ecological risk. The total ecological risk of PAHs to aquatic/soil organisms is classified as moderate. Toxic equivalency quantities (TEQs) of the sixteen PAHs varied between 21.16 and 1625.78 µg/kg, with an average of 423.86 µg/kg, indicating a relatively high toxicity potential. Ingestion and dermal adsorption of soil dust were major pathways of human exposure to PAHs from urban soil. Incremental lifetime cancer risks (ILCRs) of human exposure to PAHs were 2.86 × 10⁻⁵ for children and 2.53 × 10⁻⁵ for adults, suggesting that the cancer risk of human exposure to PAHs from urban soil is acceptable.

Elemental Concentrations in Roadside Dust Along Two National Highways in Northern Vietnam and the Health-Risk Implication

There is a need to assess the risk of exposure to metals via roadside dust in Vietnam where many people live along the road/highways and are constantly exposed to roadside dust. In this study, we collected dust samples at 55 locations along two major Highways in north-east Vietnam, which passed through different land use areas. Samples were sieved into three different particle sizes and analyzed for concentrations of eight metals using a X-ray fluorescence instrument. The concentrations and environmental indices (EF, I _geo) of metals were used to evaluate the degree of pollution in the samples. Among different land uses, industrial areas could be highly polluted with heavy metals in roadside dust, followed by commerce and power plants. Additionally, the traffic density probably played an important role; higher concentrations were observed in samples from Highway No. 5 where traffic is several times higher than Highway No. 18. According to the risk assessment, Cr poses the highest noncarcinogenic risk even though the health hazard index values of assessed heavy metals in this study were within the acceptable range. Our assessment also found that the risk of exposure to heavy metals through roadside dust is much higher for children than for adults.

Mechanistic link between diesel exhaust particles and respiratory reflexes

Background

Diesel exhaust particles (DEPs) are a major component of particulate matter in Europe's largest cities, and epidemiologic evidence links exposure with respiratory symptoms and asthma exacerbations. Respiratory reflexes are responsible for symptoms and are regulated by vagal afferent nerves, which innervate the airway. It is not known how DEP exposure activates airway afferents to elicit symptoms, such as cough and bronchospasm.

Objective

We sought to identify the mechanisms involved in activation of airway sensory afferents by DEPs.

Methods

In this study we use in vitro and in vivo electrophysiologic techniques, including a unique model that assesses depolarization (a marker of sensory nerve activation) of human vagus.

Results

We demonstrate a direct interaction between DEP and airway C-fiber afferents. In anesthetized guinea pigs intratracheal administration of DEPs activated airway C-fibers. The organic extract (DEP-OE) and not the cleaned particles evoked depolarization of guinea pig and human vagus, and this was inhibited by a transient receptor potential ankyrin-1 antagonist and the antioxidant N-acetyl cysteine. Polycyclic aromatic hydrocarbons, major constituents of DEPs, were implicated in this process through activation of the aryl hydrocarbon receptor and subsequent mitochondrial reactive oxygen species production, which is known to activate transient receptor potential ankyrin-1 on nociceptive C-fibers.

Conclusions

This study provides the first mechanistic insights into how exposure to urban air pollution leads to activation of guinea pig and human sensory nerves, which are responsible for respiratory symptoms. Mechanistic information will enable the development of appropriate therapeutic interventions and mitigation strategies for those susceptible subjects who are most at risk.

Spatial Distribution of Elemental Concentrations in Street Dust of Hanoi, Vietnam

Street dust samples were collected at 163 locations across four different zones of Hanoi, Vietnam, covering different traffic and population densities. Samples were sieved into three fractions of different particle sizes and analyzed for elemental concentrations (K, Ca, Mn, Fe, Zn, Pb) using an X-ray fluorescence (XRF) instrument. The metal concentrations in street dust were compared among different sampling zones and with samples from background to evaluate the degree of pollution. The smallest size particle fraction (diameter <75 μm) contained higher concentrations of metals than the coarser ones (diameters = 75-180 and >180 μm). While concentrations of metals like Ca and Fe are spatially similar, concentrations of Pb and Zn in street dust varied between different zones, with the highest concentrations observed in dust from the downtown area, and lowest levels in the new suburb areas. Overall, compared to studies from cities in other countries, the mean concentration of Pb in street dust in Hanoi was relatively low, suggesting a lower risk to human health due to inhalation or ingestion of Pb-containing dust particles than in cities where Pb concentrations were several times higher.

Procarcinogens - Determination and Evaluation by Yeast-Based Biosensor Transformed with Plasmids Incorporating RAD54 Reporter Construct and Cytochrome P450 Genes

In Vietnam, a great number of toxic substances, including carcinogens and procarcinogens, from industrial and agricultural activities, food production, and healthcare services are daily released into the environment. In the present study, we report the development of novel yeast-based biosensor systems to determine both genotoxic carcinogens and procarcinogens by cotransformation with two plasmids. One plasmid is carrying human CPR and CYP (CYP3A4, CYP2B6, or CYP2D6) genes, while the other contains the RAD54-GFP reporter construct. The three resulting coexpression systems bearing both CPR-CYP and RAD54-GFP expression cassettes were designated as CYP3A4/CYP2B6/CYP2D6 + RAD54 systems, respectively and used to detect and evaluate the genotoxic potential of carcinogens and procarcinogens by selective activation and induction of both CPR-CYP and RAD54-GFP expression cassettes in response to DNA damage. Procarcinogens were shown to be predominantly, moderately or not bioactivated by one of the CYP enzymes and thus selectively detected by the specific coexpression system. Aflatoxin B₁ and benzo(a)pyrene were predominantly detected by the CYP3A4 + RAD54 system, while N-nitrosodimethylamine only moderately activated the CYP2B6 + RAD54 reporter system and none of them was identified by the CYP2D6 + RAD54 system. In contrast, the genotoxic carcinogen, methyl methanesulfonate, was detected by all systems.

Our yeast-reporter system can be performed in 384-well microplates to provide efficient genotoxicity testing to identify various carcinogenic compounds and reduce chemical consumption to about 53% as compared with existing 96-well genotoxicity bioassays. In association with a liquid handling robot, this platform enables rapid, cost-effective, and high-throughput screening of numerous analytes in a fully automated and continuous manner without the need for user interaction.

Polycyclic aromatic hydrocarbons associated with road deposited solid and their ecological risk: Implications for road stormwater reuse

Reusing stormwater is becoming popular worldwide. However, urban road stormwater commonly contains toxic pollutants, such as polycyclic aromatic hydrocarbons (PAHs), which could undermine reuse safety. This study investigated pollution level of PAHs and their composition build-up on urban roads in a typical megacity in South China. The potential ecological risk posed by PAHs associated with road deposited solid (RDS) was also assessed. Results showed that ecological risk levels varied based on different land use types, which could be significantly influenced by the composition of PAHs and characteristics of RDS. A higher percentage of high-ring PAHs, such as more than four rings, could pose higher ecological risk and are more likely to undermine stormwater reuse safety. Additionally, the degree of traffic congestion rather than traffic volume was found to exert a more significant influence on the generation of high-ring PAH generation. Therefore, stormwater from more congested roads might need proper treatment (particularly for removing high-ring PAHs) before reuse or could be suitable for purposes requiring low-water-quality. The findings of this study are expected to contribute to adequate stormwater reuse strategy development and to enhance the safety of urban road stormwater reuse.

Characteristics, sources, and health risk of polycyclic aromatic hydrocarbons in urban surface dust: a case study of the city of Xi'an in Northwest China

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants. Urban surface dust is an important carrier of PAHs. To investigate the characteristics, sources, and health risk of PAHs in urban surface dust, this study collected urban surface dust samples from Xi'an, the largest city in Northwest China and one of the cities with severe smog occurrences in China. The total concentration of 16 US EPA priority PAHs (∑16PAHs) ranged from 5.0 to 48 mg/kg, with an average of 14 mg/kg. The seven carcinogenic PAHs accounted for 21 to 65 % of the ∑16PAHs. Higher levels of PAHs were found in its industrial, traffic, and mixed commercial and traffic districts. The PAHs were dominated by four-ring PAHs, and the predominant components were Fla, Phe, Chy, and Pyr. Multivariate statistical analyses showed that the PAHs originated mainly from the combustion of fossil fuel as well as coal and wood, and petroleum emission. The toxic equivalency quantities (TEQs) of urban surface dustborne PAHs ranged from 0.25 to 8.3 mg/kg, with a mean of 1.8 mg/kg. The 95 % upper confidence limit of incremental lifetime cancer risk (ILCR) due to human exposure to urban surface dustborne PAHs was 8.2 × 10(-5) for children and 7.3 × 10(-5) for adults.

Ecological and human health hazards of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in road dust of Isfahan metropolis, Iran

This study investigates trace elements and PAHs content in road dust of Isfahan metropolis, central Iran. The mean concentrations of As, Cd, Cu, Ni, Pb, Sb and Zn are 22.15, 2.14, 182.26, 66.63, 393.33, 6.95 and 707.19 mg kg(-1), respectively. When compared with upper continental crust, the samples generally display elevated trace element concentrations, except for Co and Cr. The decreasing trend of calculated enrichment factors (EFs) is Cd>Pb>Sb>Zn>Cu>As>Ni>Cr>Co. Calculated potential ecological risk reveals that among the analyzed metals, Cd and Pb, have a higher potential ecological risk. Statistically, two identified main sources of trace elements include road traffic emissions and resuspension of soil particles. As, Cd, Cu, Pb, Sb and Zn in Isfahan road dust are strongly influenced by anthropogenic activity, mainly traffic emissions, while Co, Cr and Ni originate from resuspension of soil natural parent particles. The sum of 13 major PAHs (∑13PAHs) mass concentration ranges from 184.64 to 3221.72 μg kg(-1) with the mean being 1074.58 μg kg(-1). PAHs sources are identified using PCA analysis. It is demonstrated that the PAHs in Isfahan road dust are mainly derived from traffic emission, coal combustion and petroleum. Toxic equivalent concentrations (TEQs) of PAHs in the road dust ranges between 25.021 μg kg(-1) and 230.893 μg kg(-1). High correlation coefficients (r(2)=0.909 and 0.822, p<0.01) between Benzo[a]pyrene, Benzo[b+k]fluoranthene and toxicity equivalent concentrations of road dust indicate that Benzo[a]pyrene and Benzo[b+k]fluoranthenes are major TEQ contributors. The total incremental life time cancer risk (ILCR) of exposure to PAHs from Isfahan metropolis urban dust is 4.85 × 10(-4) for adult and 5.02 × 10(-4) for children. Estimated results of ILCR indicate that Isfahan residents are potentially exposed to high cancer risk via both dust ingestion and dermal contact.