Characteristics and unique sources of polycyclic aromatic hydrocarbons and nitro-polycyclic aromatic hydrocarbons in PM2.5 at a highland background site in northwestern China☆

Exposure to 1-nitropyrene after weaning induces anxiety-like behavior partially by inhibiting steroid hormone synthesis in prefrontal cortex

1-Nitropyrene (1-NP) is a neurodevelopmental toxicant. This study was to evaluate the impact of exposure to 1-NP after weaning on anxiety-like behavior. Five-week-old mice were administered with 1-NP (0.1 or 1 mg/kg) daily for 4 weeks. Anxiety-like behaviour was measured using elevated-plus maze (EPM) and open field test (OFT). In EPM test, time spending in open arm and times entering open arm were reduced in 1-NP-treated mice. In OFT test, time spent in the center region and times entering the center region were diminished in 1-NP-treated mice. Prefrontal dendritic length and number of dendrite branches were decreased in 1-NP-treated mice. Prefrontal PSD95, an excitatory postsynaptic membrane protein, and gephyrin, an inhibitory postsynaptic membrane protein, were downregulated in 1-NP-treated mice. Further analysis showed that peripheral steroid hormones, including serum testosterone (T) and estradiol (E2), testicular T, and ovarian E2, were decreased in 1-NP-treated mice. Interestingly, T and E2 were diminished in 1-NP-treated prefrontal cortex. Prefrontal T and E2 synthases were diminished in 1-NP-treated mice. Mechanistically, GCN2-eIF2α, a critical pathway that regulates ribosomal protein translation, was activated in 1-NP-treated prefrontal cortex. These results indicate that exposure to 1-NP after weaning induces anxiety-like behaviour partially by inhibiting steroid hormone synthesis in prefrontal cortex.

Promotive effects of marine-derived dimethyl sulfoxide on the photodegradation of phenanthrene in the atmosphere

Dimethyl sulfoxide (DMSO), a versatile medium, is a particular component in the marine atmosphere that possibly causes polycyclic aromatic hydrocarbons (PAHs) to degrade differently than they do in the continental atmosphere. In this study, phenanthrene (Phe) was used as a model PAH in batch photochemical experiments to investigate the chemical actions of DMSO and the underlying mechanisms. The photodegradation of Phe in aqueous solutions with DMSO volume fractions from 0 % to 100 % was initiated by ultraviolet (UV) radiation and promoted by singlet oxygen, which was consistent with pseudo-first-order kinetics. Phe photodegraded faster in a mixture of DMSO and water than in water or DMSO alone, and the rate constant showed a unimodal distribution over the DMSO fraction range, peaking at 33 % DMSO (0.0333 ± 0.0009 min-1) and 40 % DMSO (0.0199 ± 0.0005 min-1) under 254 nm and 302 nm UV radiation, respectively. This interesting phenomenon was attributed to the competition of DMSO for UV radiation and singlet oxygen and changes in dissolved oxygen and free water contents caused by the interaction between DMSO and water molecules. In addition, 9,10-phenanthrenequinone (9,10-PhQ) with high cytotoxicity was the main photodegradation product of Phe under various conditions. The photodegradation rate of Phe in the mixtures of DMSO and water was comparable to its reaction rate with OH radicals, suggesting that 9,10-PhQ can be rapidly generated in the marine atmosphere, driven by a mechanism different from that in the continental or urban atmosphere. Under the presented experimental conditions, UV intensity and DMSO fraction were the primary factors that affected the photodegradation rate of Phe and 9,10-PhQ and altered their integrated toxicity. The findings of this study support the conclusion that the marine atmosphere is an essential field in the atmospheric transport of PAHs, in which DMSO is an important component that affects their photodegradation.

Contributions of long-range transport from the Asian continent and local emissions on atmospheric PM2.5, polycyclic aromatic hydrocarbons, and their nitro-derivatives in Kanazawa and Noto Peninsula, Japan

This study collected samples of particulate matter that are 2.5 μm or less in diameter (PM2.5) in Kanazawa, Japan, and Noto Peninsula located 100 km north on the windward side of the westerlies from the Asian continent and characterized the extent of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs (NPAHs) pollution in Kanazawa. Emission areas and specific sources of PM2.5 and of PAHs and NPAHs were clarified via back-trajectory analysis and the NP-method, respectively. The results indicate that during 2020 and 2021, most PAHs (93%) in Kanazawa were transported from the Asian continent by westerlies and that the main source was coal and biomass combustion. The presence of NPAHs in Kanazawa was caused by a mixture of transport from the Asian continent (53%) and local emissions (47%), with the main source of the latter being from vehicles. Although the content of combustion-derived particulates (Pc) was <2.4% of PM2.5 in Kanazawa, this showed a similar seasonal variation (winter > summer) to that of PAHs. The contribution of Pc transported from the Asian continent exceeded that of locally emitted Pc. The current situation of Kanazawa is considerably different from that of 1997, when local vehicles were the main source of pollution.

The occurrence and sources of PAHs, oxygenated PAHs (OPAHs), and nitrated PAHs (NPAHs) in soil and vegetation from the Antarctic, Arctic, and Tibetan Plateau

Although the fate of PAHs in the three polar regions (Antarctic, Arctic, and Tibetan Plateau) has been investigated, the occurrence and contamination profiles of PAH derivatives such as oxygenated PAHs (OPAHs) and nitrated PAHs (NPAHs) remain unclear. Some of them are more toxic and can be transformed from PAHs in environment. This study explored and compared the concentrations composition profiles and potential sources of PAHs, OPAHs, and NPAHs in soil and vegetation samples from the three polar regions. The total PAH, OPAH, and NPAH concentrations were 3.55-519, n.d.-101, and n.d.-1.10 ng/g dry weight (dw), respectively. The compounds were dominated by three-ring PAHs, and the most abundant individual PAH and OPAH were phenanthrene (PHE) and 9-fluorenone (9-FO), respectively. The sources of PAHs and their derivatives were qualitatively analyzed by the diagnostic ratios and quantified using the positive matrix factorization (PMF) model. The ratios of PAH derivatives to parent PAHs (9-FO/fluorene and 9,10-anthraquinone/anthracene) were significantly higher in the Antarctic samples than in the Arctic and TP samples, implying a higher occurrence of secondary OPAH and NPAH formation in the Antarctic region. To our knowledge, this is the first comparative study that simultaneously investigated the contamination profiles of PAHs and their derivatives in the three polar regions. The findings of this study provide a scientific basis for the development of risk assessment and pollution control strategies in these fragile regions.

Autumn and spring observations of PM2.5-bound polycyclic aromatic hydrocarbons and nitro-polycyclic aromatic hydrocarbons in China and Japan

The transboundary transport of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs (NPAHs) aggravated by the East Asian winter monsoon is a major atmospheric environmental issue in East Asia. To thoroughly elucidate the role of the East Asian monsoon on regional PAH and NPAH pollution in East Asia, PM2.5-bound PAHs and NPAHs were investigated concurrently at five sites in Beijing and Shenyang in China and Tsukuba, Kanazawa, and Wajima in Japan in autumn (November 2018) and spring (March 2019). During both autumn and spring sampling periods, the concentrations of PM2.5, PAHs, and NPAHs at sites in China were 1-2 orders of magnitude higher than those at sites in Japan, and showed an opposite temporal variation, with higher concentrations during the autumn sampling period due to intensive emissions and unfavourable weather conditions. During the sampling periods, PAHs at the Beijing and Shenyang sites had mixed sources of traffic emissions and coal and biomass combustion, while those at the Tsukuba, Kanazawa, and Wajima sites were mainly characterized by domestic traffic emissions. In addition, NPAHs at the five sites were jointly affected by primary combustion sources and atmospheric generation, with a greater contribution of atmospheric generation to the Beijing and Shenyang sites. Based on backwards trajectory clustering and concentration-weighted trajectory analysis, external contributions to PM2.5, PAHs, and NPAHs at each site were relatively stable during the two sampling periods, and potential source areas were mainly distributed in domestic cities and nearby sea areas. Therefore, the apparent temporal differences in the characteristics and sources of pollutants between sites in the two countries indicate that transboundary pollution dominated by the East Asian winter monsoon was unobvious in autumn and spring. The results of the study provide a time-specific solution for the effective management of regional air pollution during the East Asian winter monsoon.

FUNDC1-mediated mitophagy triggered by mitochondrial ROS is partially involved in 1-nitropyrene-evoked placental progesterone synthesis inhibition and intrauterine growth retardation in mice

Intrauterine growth retardation (IUGR) is a major cause of perinatal morbidity and mortality. Previous studies showed that 1-nitropyrene (1-NP), an atmospheric pollutant, induces placental dysfunction and IUGR, but the exact mechanisms remain uncertain. In this research, we aimed to explore the role of mitophagy on 1-NP-evoked placental progesterone (P4) synthesis inhibition and IUGR in a mouse model. As expected, P4 levels were decreased in 1-NP-exposed mouse placentas and maternal sera. Progesterone synthases, CYP11A1 and 3βHSD1, were correspondingly declined in 1-NP-exposed mouse placentas and JEG-3 cells. Mitophagy, as determined by LC3B-II elevation and TOM20 reduction, was evoked in 1-NP-exposed JEG-3 cells. Mdivi-1, a specific mitophagy inhibitor, relieved 1-NP-evoked downregulation of progesterone synthases in JEG-3 cells. Additional experiments showed that ULK1/FUNDC1 signaling was activated in 1-NP-exposed JEG-3 cells. ULK1 inhibitor or FUNDC1-targeted siRNA blocked 1-NP-induced mitophagy and progesterone synthase downregulation in JEG-3 cells. Further analysis found that mitochondrial reactive oxygen species (ROS) were increased and GCN2 was activated in 1-NP-exposed JEG-3 cells. GCN2iB, a selective GCN2 inhibitor, and MitoQ, a mitochondria-targeted antioxidant, attenuated GCN2 activation, FUNDC1-mediated mitophagy, and downregulation of progesterone synthases in JEG-3 cells. In vivo, gestational MitoQ supplement alleviated 1-NP-evoked reduction of placental P4 synthesis and IUGR. These results suggest that FUNDC1-mediated mitophagy triggered by mitochondrial ROS may contribute partially to 1-NP-induced placental P4 synthesis inhibition and IUGR.

Temporal and spatial distributions, source identification, and health risk assessment of polycyclic aromatic hydrocarbons in PM2.5 from 2016 to 2021 in Shenzhen, China

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants in the atmosphere that have drawn intense attention due to their carcinogenicity and mutagenicity. In this work, 1424 air samples were collected between January 2016 and December 2021 in three areas of Shenzhen, China to determine the concentrations of PM2.5 and PAHs and their spatiotemporal variation. Human health risks due to the daily intake and uptake of PAHs and the resulting incremental lifetime cancer risk (ILCR) were also evaluated. PAHs were detected frequently in the samples at concentrations between 0.28 and 32.7 ng/m3 (median: 1.04 ng/m3). PM2.5 and PAH concentrations decreased from 2016 to 2021, and the Yantian area had lower median concentrations of PM2.5 (23.0 μg/m3) and PAHs (0.02 ng/m3) than the Longgang and Nanshan areas. The concentrations of PM2.5 and PAHs were significantly higher in winter than in summer. Analysis of diagnostic ratios indicated that petroleum combustion was the dominant source of airborne PAHs in Shenzhen. The estimated daily intake (EDI) and uptake (EDU) of PAHs by local residents decreased gradually with increasing age, indicating that infants are at particular risk of PAH exposure. However, the incremental lifetime cancer risks (ILCRs) were below the threshold value of 10-6, indicating that inhalation exposure to PAHs posed a negligible carcinogenic risk to Shenzhen residents. While promising, these results may underestimate actual PAH exposure levels, so further analysis of health risks due to PAHs in Shenzhen is needed.

Seasonality of Polyaromatic Hydrocarbons (PAHs) and Their Derivatives in PM2.5 from Ljubljana, Combustion Aerosol Source Apportionment, and Cytotoxicity of Selected Nitrated Polyaromatic Hydrocarbons (NPAHs)

Airborne particulate matter (PM) is a vector of many toxic pollutants, including polyaromatic hydrocarbons (PAHs) and their derivatives. Especially harmful is the fine fraction (PM_2.5), which penetrates deep into the lungs during inhalation and causes various diseases. Amongst PM_2.5 components with toxic potential are nitrated PAHs (NPAHs), knowledge of which is still rudimentary. Three of the measured NPAHs (1-nitropyrene (1-nP), 9-nitroanthracene (9-nA), and 6-nitrochrysene (6-nC)) were detected in ambient PM_2.5 from Ljubljana, Slovenia, along with thirteen non-nitrated PAHs. The highest concentrations of pollutants, which are closely linked with incomplete combustion, were observed in the cold part of the year, whereas the concentrations of NPAHs were roughly an order of magnitude lower than those of PAHs throughout the year. Further on, we have evaluated the toxicity of four NPAHs, including 6-nitrobenzo[a]pyrene (6-nBaP), to the human kidney cell line, HEK293T. The most potent was 1-nP (IC₅₀ = 28.7 µM), followed by the other three NPAHs, whose IC₅₀ was above 400 or 800 µM. According to our cytotoxicity assessment, atmospheric 1-nP is the most harmful NPAH among the investigated ones. Despite low airborne concentrations of NPAHs in ambient air, they are generally considered harmful to human health. Therefore, systematic toxicological assessment of NPAHs at different trophic levels, starting with cytotoxicity testing, is necessary in order to accurately evaluate their threat and adopt appropriate abatement strategies.

Effect of Normalization Methods on Accuracy of Estimating Low- and High-Molecular Weight PAHs Distribution in the Soils of a Coking Plant

Mapping spatial distribution of soil contaminants at contaminated sites is the basis of risk assessment. Hotspots can cause strongly skewed distribution of the raw contaminant concentrations in soil, and consequently can require suitable normalization prior to interpolation. In this study, three normalization methods including normal score, Johnson, and Box-Cox transformation were performed on the concentrations of two low-molecular weight (LMW) PAHs (i.e., acenaphthene (Ace) and naphthalene (Nap)) and two high-molecular weight (HMW) PAHs (i.e., benzo(a)pyrene (BaP) and benzo(b)fluoranthene (BbF)) in soils of a typical coking plant in North China. The estimating accuracy of soil LMW and HMW PAHs distribution using ordinary kriging with different normalization methods was compared. The results showed that all transformed data passed the Kolmogorov-Smirnov test, indicating that all three data transformation methods achieved normality of raw data. Compared to Box-Cox-ordinary kriging, normal score-, and Johnson-ordinary kriging had higher estimating accuracy of the four soil PAHs distribution. In cross-validation, smaller root-mean-square error (RMSE) and mean error (ME) values were observed for normal score-ordinary kriging for both LMW and HMW PAHs compared to Johnson- and Box-Cox-ordinary kriging. Thus, normal score transformation is suitable for alleviating the impact of hotspots on estimating accuracy of the four selected soil PAHs distribution at this coking plant. The findings can provide insights into reducing uncertainty in spatial interpolation at PAHs-contaminated sites.

Variations in traffic-related polycyclic aromatic hydrocarbons in PM2.5 in Kanazawa, Japan, after the implementation of a new vehicle emission regulation

A three-year sampling campaign was conducted at a roadside air pollution monitoring station in the urban area of Kanazawa, Japan. Due to a new emission regulation, PAHs levels decreased over the sampling campaign, exhibiting values of 706 ± 413 pg/m³ in 2017, 559 ± 384 pg/m³ in 2018, and 473 ± 234 pg/m³ in 2019. In each year, similar seasonal variations in PAHs levels were observed, with higher levels observed in winter and lower levels in summer. Among the PAHs isomer ratios, we observed that the ratio of benzo[b]fluoranthene (BbF) and benzo[k]fluoranthene (BkF), [BbF]/([BbF] + [BkF]), and the ratio of indeno[1,2,3-cd]pyrene (IDP) and benzo[ghi]perylene (BgPe), [IDP]/([BgPe] + [IDP]), showed stability over the sampling campaign and were less affected by the new emission regulation, seasonal variations, and regional characteristics. When using the combined ratio ranges of 0.66 - 0.80 ([BbF]/([BbF] + [BkF]) and 0.26-0.49 ([IDP]/([BgPe] + [IDP]), traffic emissions were clearly distinguished from other PAHs emission sources. Principal component analysis (PCA) and positive matrix factorization (PMF) were also performed to further analyse the characteristics of traffic-related PAHs. Overall, this study affirmed the effectiveness of the new emission regulation in the reduction of PAHs emissions and provided a combined range for identifying PAHs traffic emission sources.

Mitochondrial ROS-mediated ribosome stalling and GCN2 activation are partially involved in 1-nitropyrene-induced steroidogenic inhibition in testes

In the past 50 years, testosterone (T) level in men has declined gradually. In this research, we discovered that acute exposure to 1-nitropyrene (1-NP), an environmental stressor from polluted atmosphere, reduced T contents by downregulating steroidogenic proteins in mouse testes and Leydig cells. Acute 1-NP exposure caused GCN2 activation and eIF2α phosphorylation, a marker of integrated stress, in mouse testes and Leydig cells. GCN2iB, a selective GCN2 kinase inhibitor, and siGCN2, the GCN2-targeted short interfering RNA, attenuated 1-NP-induced reduction of steroidogenic proteins in Leydig cells. Mechanistically, mitochondrial membrane potential was reduced and ATP5A, UQCRC2, SDHB and NDUFB8, four OXPHOS subunits, were reduced in 1-NP-exposed Leydig cells. Cellular mitochondrial respiration was inhibited and ATP production was reduced. Moreover, mitochondrial reactive oxygen species (ROS) were elevated in 1-NP-exposed Leydig cells. The interaction between GCN2 and uL10, a marker of ribosome stalling, was observed in 1-NP-exposed Leydig cells. MitoQ, a mitochondria-targeted antioxidant, attenuated1-NP-evoked ATP depletion and ribosome stalling in Leydig cells. Moreover, MitoQ suppressed 1-NP-caused GCN2 activation and eIF2α phosphorylation in Leydig cells. In addition, MitoQ alleviated 1-NP-induced steroidogenic inhibition in mouse testes. In conclusion, mitochondrial ROS-mediated ribosome stalling and GCN2 activation are partially involved in environmental stress-induced steroidogenic inhibition in testes.

PAHs and nitro-PAHs in urban Beijing from 2017 to 2018: Characteristics, sources, transformation mechanism and risk assessment

Polycyclic aromatic hydrocarbons (PAHs) and their nitrated derivatives (NPAHs) attract continuous attention due to their distinct carcinogenicity and mutagenicity. To investigate the characteristics, sources, formation mechanism and health risk assessment of PAHs and NPAHs, PM_2.5 were collected at an urban site in Beijing from 2017 to 2018. The highest PAHs and NPAHs concentrations were 77.92 ± 54.62 ng/m³ and 963.71 ± 695.06 pg/m³ in the winter campaign, which were several times larger than those in other seasonal campaigns. Distinct diurnal variations of nocturnal levels higher than daytime levels were shown for PAHs and NPAHs. Source analysis indicated that besides vehicle exhaust, biomass burning and coal combustion were important sources of PAHs and NPAHs in the fall and winter campaigns. Secondary formation in atmosphere was another source of NPAHs especially in the spring and summer campaigns. NO₂ and RH could positively influence the heterogeneous formation of NPAHs when RH was less than 60%. Quantum calculation results confirmed the formation pathway of 2N-FLA from the OH/NO₃-initiated oxidation of FLA. The results of health risk assessment showed the potential health risks for the residents, especially in the winter campaign. These results indicated that PAHs and NPAHs still deserve attention following with the decrease concentrations of particulate matter.

Spatiotemporal Distribution Patterns and Exposure Risks of PM2.5 Pollution in China

The serious pollution of PM2.5 caused by rapid urbanization in recent years has become an urgent problem to be solved in China. Annual and daily satellite-derived PM2.5 datasets from 2001 to 2020 were used to analyze the temporal and spatial patterns of PM2.5 in China. The regional and population exposure risks of the nation and of urban agglomerations were evaluated by exceedance frequency and population weight. The results indicated that the PM2.5 concentrations of urban agglomerations decreased sharply from 2014 to 2020. The region with PM2.5 concentrations less than 35 μg·m−3 accounted for 80.27% in China, and the average PM2.5 concentrations in 8 urban agglomerations were less than 35 μg·m−3 in 2020. The spatial distribution pattern of PM2.5 concentrations in China revealed higher concentrations to the east of the Hu Line and lower concentrations to the west. The annual regional exposure risk (RER) in China was at a high level, with a national average of 0.75, while the average of 14 urban agglomerations was as high as 0.86. Among the 14 urban agglomerations, the average annual RER was the highest in the Shandong Peninsula (0.99) and lowest in the Northern Tianshan Mountains (0.76). The RER in China has obvious seasonality; the most serious was in winter, and the least serious was in summer. The population exposure risk (PER) east of the Hu Line was significantly higher than that west of the Hu Line. The average PER was the highest in Beijing-Tianjin-Hebei (4.09) and lowest in the Northern Tianshan Mountains (0.71). The analysis of air pollution patterns and exposure risks in China and urban agglomerations in this study could provide scientific guidance for cities seeking to alleviate air pollution and prevent residents’ exposure risks.

Characteristics and Influencing Factors of Polycyclic Aromatic Hydrocarbons Emitted from Open Burning and Stove Burning of Biomass: A Brief Review

To mitigate global warming and achieve carbon neutrality, biomass has become a widely used carbon-neutral energy source due to its low cost and easy availability. However, the incomplete combustion of biomass can produce polycyclic aromatic hydrocarbons (PAHs), which are harmful to human health. Moreover, increasing numbers of wildfires in many regions caused by global warming have greatly increased the emissions of PAHs from biomass burning. To effectively mitigate PAH pollution and health risks associated with biomass usage, the concentrations, compositions and influencing factors of PAH emissions from biomass burning are summarized in this review. High PAH emissions from open burning and stove burning are found, and two- to four-ring PAHs account for a higher proportion than five- and six-ring PAHs. Based on the mechanism of biomass burning, biomass with higher volatile matter, cellulose, lignin, potassium salts and moisture produces more PAHs. Moreover, burning biomass in stoves at a high temperature or with an insufficient oxygen supply can increase PAH emissions. Therefore, the formation and emission of PAHs can be reduced by pelletizing, briquetting or carbonizing biomass to increase its density and burning efficiency. This review contributes to a comprehensive understanding of PAH pollution from biomass burning, providing prospective insight for preventing air pollution and health hazards associated with carbon neutrality.

PM-Bound Polycyclic Aromatic Hydrocarbons and Nitro-Polycyclic Aromatic Hydrocarbons in the Ambient Air of Vladivostok: Seasonal Variation, Sources, Health Risk Assessment and Long-Term Variability

Total suspended particles (TSP) were collected in Vladivostok, Russia, which is a typical port city. This study investigated the concentration, potential sources, and long-term variation in particle PAHs and NPAHs in the atmosphere of Vladivostok. The PAH and NPAH concentrations were higher in winter than in summer (PAHs: winter: 18.6 ± 9.80 ng/m3 summer: 0.54 ± 0.21 ng/m3; NPAHs: winter: 143 ± 81.5 pg/m3 summer: 143 ± 81.5 pg/m3). The diagnostic ratios showed that PAHs and NPAHs mainly came from vehicle emissions in both seasons, while heating systems were the main source of air pollution in winter. The TEQ assessment values were 2.90 ng/m3 and 0.06 ng/m3 in winter and summer, respectively, suggesting a significant excess cancer risk in the general population in winter. The ILCR values conveyed a potential carcinogenic risk because the value was between 1 × 10-5 and 1 × 10-7 and ingestion was a main contributor in Vladivostok. However, it is worth noting that the concentrations of PAHs and NPAHs showed an overall downward trend from 1999 to 2020. An important reason for this is the cogenerations project implemented by the Far Eastern Center for Strategic Research on Fuel and Energy Complex Development in 2010. This research clarified the latest variations in PAHs and NPAHs to provide continuous observation data for future chemical reaction or model prediction research.

3-Bromofluoranthene-induced cardiotoxicity of zebrafish and apoptosis in the vascular endothelial cells via intrinsic and extrinsic caspase-dependent pathways

Fluoranthene, a high-molecular-weight polycyclic aromatic hydrocarbon (PAH), is widely present in air pollutants, including fine inhalable particulate matter. 3-Bromofluoranthene (3-BrFlu), which is a brominated fluoranthene and halogenated PAH, is generated from waste combustion, metallurgical processes, cement production, e-waste dismantling, and photoreaction. Vascular endothelial cells have key functions in the homeostasis and the development of the cardiovascular system. The zebrafish model has been widely employed to study cardiotoxicity and embryotoxicity. However, no evidence has indicated that 3-BrFlu induces cytotoxicity in vascular endothelial cells, or cardiotoxicity and embryotoxicity in zebrafish. In this study, 3-BrFlu induced concentration-dependent changes in embryo- and cardiotoxicity. Cytotoxicity was also induced by 3-BrFlu in a concentration-dependent manner through apoptosis and necrosis in vascular endothelial cells, SVEC4-10 cells. The activities of caspase-3, -8, and -9 were induced by 3-BrFlu via an intrinsic pathway constituting Bcl-2 downregulation, Bad upregulation, and mitochondrial dysfunction; the extrinsic pathway included the expression of death receptors, including tumour necrosis factor α and Fas receptors. These results indicated that 3-BrFlu caused cardio- and embryotoxicity in zebrafish through vascular endothelial cells cytotoxicity resulting from caspase-dependent apoptosis through intrinsic and extrinsic pathways.

Polycyclic aromatic hydrocarbons and nitro-polycyclic aromatic hydrocarbons in five East Asian cities: Seasonal characteristics, health risks, and yearly variations

Total suspended particulate matter and fine particulate matter were collected in five East Asian cities (Sapporo, Sagamihara, Kirishima, Shenyang, and Vladivostok) during warm and cold periods from 2017 to 2018. Nine polycyclic aromatic hydrocarbons (PAHs) and three nitro-polycyclic aromatic hydrocarbons (NPAHs) were detected by high-performance liquid chromatography with a fluorescence detector. The average concentrations of ∑PAHs and ∑NPAHs differed significantly both temporally and spatially and were the lowest in Kirishima during the warm period (∑PAHs: 0.11 ± 0.06 ng m^-3; ∑NPAHs: 1.23 ± 0.96 pg m^-3) and the highest in Shenyang during the cold period (∑PAHs: 49.7 ± 21.8 ng m^-3; ∑NPAHs: 357 ± 180 pg m^-3). The average total benzo[a]pyrene-equivalent concentrations were also higher in Shenyang and Vladivostok than in Japanese cities. According to the results of source apportionment, traffic emissions impacted these cities in both the warm and cold periods, whereas coal combustion-generated effects were obvious in Shenyang and Vladivostok during the cold period. Furthermore, PAHs and NPAHs originating from the Asian continent, including Shenyang and Vladivostok, exerted some influence on Japanese cities, especially in the cold period. Compared to Japanese cities and Vladivostok, yearly variations in ∑PAHs and 1-nitropyrene in Shenyang showed that their concentrations were considerably lower than those reported in past studies, indicating the positive effects of air pollutant control policies in China. These results not only describe the current characteristics and yearly variations of PAHs and NPAHs in typical urban cities in East Asia but also, more importantly, reveal that the effects of the East Asian monsoon play an important role in the analysis of atmospheric behaviours of PAHs and NPAHs. Furthermore, this study supports the role of multinational cooperation to promote air pollution control in East Asia.

Exposure to Atmospheric Particulate Matter-Bound Polycyclic Aromatic Hydrocarbons and Their Health Effects: A Review

Particulate matter (PM) is a major factor contributing to air quality deterioration that enters the atmosphere as a consequence of various natural and anthropogenic activities. In PM, polycyclic aromatic hydrocarbons (PAHs) represent a class of organic chemicals with at least two aromatic rings that are mainly directly emitted via the incomplete combustion of various organic materials. Numerous toxicological and epidemiological studies have proven adverse links between exposure to particulate matter-bound (PM-bound) PAHs and human health due to their carcinogenicity and mutagenicity. Among human exposure routes, inhalation is the main pathway regarding PM-bound PAHs in the atmosphere. Moreover, the concentrations of PM-bound PAHs differ among people, microenvironments and areas. Hence, understanding the behaviour of PM-bound PAHs in the atmosphere is crucial. However, because current techniques hardly monitor PAHs in real-time, timely feedback on PAHs including the characteristics of their concentration and composition, is not obtained via real-time analysis methods. Therefore, in this review, we summarize personal exposure, and indoor and outdoor PM-bound PAH concentrations for different participants, spaces, and cities worldwide in recent years. The main aims are to clarify the characteristics of PM-bound PAHs under different exposure conditions, in addition to the health effects and assessment methods of PAHs.