Source traceability of microplastics in road dust using organic/inorganic plastic additives as chemical indicators.

Microplastics (MPs) are environmental pollutants of great concern around the world. The source of MPs in road dust need to be identified to develop strategies to control and reduce MPs emissions by stormwater runoff, one of the main sources of MPs to the aquatic environment. However, little information on the sources of MPs in road dust is available due to lack of their suitable indicators. In this study organic/inorganic plastic additives were used as chemical indicators to understand the source of MPs in road dust. The polymers, organic additives, and heavy metals in 142 commercial plastic products suspected of being source of MPs in road dust were determined. As the results, 147 organic additives and 17 heavy metals were identified, and different additive profiles were found for different polymer types and use application of plastic products. Further, 17 road dust samples were collected from an urban area in Kumamoto City, Japan. and analyzed the MPs (1-5 mm diameter) and their additive chemicals. Polymethyl methacrylate (PMMA) was the dominant polymer accounting for 86 % in the samples, followed by ethylene vinyl acetate (EVA) and polyvinyl chloride (PVC). In total, 48 organic additives and 14 heavy metals were identified in the MPs samples. The organic/inorganic additive profiles of plastic products and MPs in road dust were compared, and several road dust-associated MPs had similar additive profiles to road paints, braille blocks, road marking sheets, and reflectors. This suggested that the MPs were originated from these plastics on the road surface. Road paint was the most important contributor of MPs in road dust (60 % of the MPs), followed by braille block (23 %), road marking sheet (8.3 %), and reflector (2.4 %). These results indicated that organic/inorganic plastic additives in plastic products can be used as chemical indicators to trace the sources of MPs in road dust.

Microplastics Distribution in Sediments Collected from Myanmar.

Microplastics (MPs) distributions have been increasingly reported in the terrestrial areas worldwide, but little information is available for ASEAN regions. In this study, 68 sediment samples of drainage channels, lakes, rivers and beaches from Myanmar were collected between 2014 and 2018, and analyzed to investigate the status of MPs concentration and prevalence. The high concentrations of MPs in sediments were found in urban cities called Yangon (13,855 pieces/kg dry weight), Mandalay (11,946 pieces/kg), and Pathein (12,583 pieces/kg), which were two orders of magnitude greater than the MPs concentrations in sediments collected in rural towns called Wundwin. These results suggested that the difference in high population densities and high municipal solid waste generation rates are related to the MPs contamination in sediments. Polyethylene, polypropylene and polyethylene terephthalate with fragments, lines/fibers and films/sheets were major polymers and shape in the sediment samples analyzed from Myanmar. To our knowledge, this is the first study to report the distribution of MPs in sediments from Myanmar.

In silico simulations and molecular descriptors to predict in vitro transactivation potencies of Baikal seal estrogen receptors by environmental contaminants.

Baikal seals (Pusa sibirica) are vulnerable to high levels of organic pollutants. Here, we evaluated the transactivation potencies of bisphenols (BPs) and hydroxylated polychlorinated biphenyls (OH-PCBs) via the Baikal seal estrogen receptor α and ß (bsERα and bsERß) using in vitro and in silico approaches. In vitro reporter gene assays showed that most BPs and OH-PCBs exhibited estrogenic activity with bsER sub-type-specific potency. Among the BPs tested, bisphenol AF showed the lowest EC50 for both bsERs. 4'-OH-CB50 and 4'-OH-CB30 showed the lowest EC50 among OH-PCBs tested for bsERα and bsERß, respectively. 4-((4-Isopropoxyphenyl)-sulfonyl)phenol, 4'-OH-CB72, and 4'-OH-CB121 showed weak bsERα-specific transactivation. Only 4-OH-CB107 did not affect both bsERs. In silico docking simulations revealed the binding affinities of these chemicals to bsERs and partially explained the in vitro results. Using the in silico simulations and molecular descriptors as explanatory variables and the in vitro results as objective variables, the quantitative structure-activity relationship (QSAR) models constructed for classification and regression accurately separated bsER-active compounds from non-active compounds and predicted the in vitro bsERα- and bsERß-transactivation potencies, respectively. The QSAR models also suggested that chemical polarity, van der Waals surface area, bridging atom structure, position of the phenolic-OH group, and ligand interactions with key residues of the ligand binding pocket are critical variables to account for the bsER transactivation potency of the test compounds. We also succeeded in constructing computational models for predicting in vitro transactivation potencies of mouse ERs in the same manner, demonstrating the applicability of our approach independent of species-specific responses.

Polymer types and additive concentrations in single-use plastic products collected from Indonesia, Japan, Myanmar, and Thailand.

Marine debris comprising single-use plastic products (SUPs) is ubiquitous in Asian coastal waters, but there is little information on the types of polymers and the concentrations of plastic additives such waste products contain. In this study, 413 SUPs randomly collected from 4 Asian countries between 2020 and 2021 were analyzed to obtain specific polymer and organic additive profiles. Polyethylene (PE), coupled with external polymers, was prominent in the inside of the SUPs, whereas polypropylene (PP) and polyethylene terephthalate (PET) were prevalent in both the insides and outsides of the SUPs. The use of different polymers in the insides and outsides of PE SUPs implies specific and complicated recycling systems are required to maintain the purity of the products. Phthalate plasticizers including dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DiBP), dibutyl phthalate (DBP), and di(2-ethylhexyl) phthalate (DEHP), and the antioxidant butylated hydroxytoluene (BHT) were prevalent in the SUPs (n = 68). High concentrations of DEHP were detected in PE bags from Myanmar (820,000 ng/g) and Indonesia (420,000 ng/g), which were an order of magnitude greater than the concentrations in PE bags collected in Japan. SUPs containing high concentrations of organic additives may be the primary source of harmful chemicals in the environment, and should be responsible for their ubiquitous distribution in ecosystems.

In vivo and in silico assessments of estrogenic potencies of bisphenol A and its analogs in zebrafish (Danio rerio): Validity of in silico approaches to predict in vivo effects.

This study assessed the estrogen-like potencies of bisphenol A (BPA) and its analogs (BPs) using in vivo and in silico approaches in zebrafish. Zebrafish embryos were exposed to 16 BPs, most of which concentration-dependently induced cytochrome P450 19A1b (CYP19A1b) expression. BPs-induced CYP19A1b expression was suppressed by fulvestrant, a nonselective high affinity antagonist for estrogen receptor (Esr) subtypes. For BPs that concentration-dependently induced CYP19A1b expression, we estimated their 50 % effective concentration (EC50) and relative potencies (REPs) with respect to the potency of BPA for inducing CYP19A1b expression. BP C2, Bis-MP, and BPAF showed lower EC50 than BPA, BPE, and BPF, while BPZ and BPB showed moderate EC50. The REP order of the BPs was BP C2 (26) > Bis-MP (24) > BPAF (21) > BPZ (5.8) > BPB (2.7) > BPE (1.5) > BPF (0.63) > 2,4'-BPF (0.22), indicating that some BPs showed greater estrogenic potencies than BPA in our system. We also constructed in silico homology models of ligand binding domains for zebrafish Esr subtypes, including Esr1, Esr2a, and Esr2b. Molecular docking simulations of ligands with the Esr subtypes revealed the interaction energies of some BPs were lower than that of BPA. The interaction energies showed significant positive correlations with their EC50 values for inducing CYP19A1b expression in vivo. This study showed that some BPA analogs have greater estrogenic potencies than BPA and that in silico simulations of interactions between ligands and Esr subtypes may help predict in vivo estrogenic potencies of untested chemicals.

Microplastics in dumping site soils from six Asian countries as a source of plastic additives.

The ubiquitous distribution of microplastics (MP) is a serious environmental issue in Asian countries. In this study, 54 open-dumping site soils collected from Cambodia, India, Indonesia, Laos, the Philippines, and Vietnam were analyzed for MP. Soil samples were also divided into light (floating) and heavy (sedimentation) fractions by density separation and analyzed for plastic additives. The highest abundance of MP was found in a soil from Cambodia at 218,182 pieces/kg. The median of MP in soils ranged from 1411 pieces/kg in India to 24,000 pieces/kg in the Philippines, suggesting that dumping sites are a major source of MP into the environment. Polyethylene, polypropylene, and polyethylene terephthalate were dominant polymers in soil samples analyzed. This indicates that daily-used plastic products are main sources of MP in dumping site soils in Asian countries. The high concentrations and burdens of phthalates and an antioxidant were detected in floating fraction accounting for 40 to 60% of the total additives in soils. Previous studies on soil pollution have assumed that the organic hydrophobic chemicals analyzed are adsorbed on the surface of soil particles. However, this result indicates that approximately half of the additives in dumping site soils were derived from MP, not soil particle. Monitoring study on soil pollution should be considered the occurrence of MP in the matrices.

Monitoring of polymer type and plastic additives in coating film of beer cans from 16 countries.

Plastic debris has gained attention as anthropogenic waste in the environment, but less concerned given to metal waste despite its high abundance in aquatic environment. Metal packaging, such as can, utilizes polymeric coating films as barrier between metals and products which leads to be potential source of microplastic pollution. In this study, 27 beer cans from 16 countries for both body and lid parts as well as inside and outside layers were investigated. Despite the country's origin, epoxy resin was the major polymeric coating used in all beer cans for lid (inside and outside) and body (inside). Whereas poly(1,2-butanediol isophthalate) was frequently used for outside layer of can body. DEHP and BHT were detected in almost all samples with the highest concentration of 5300 ng/g and 520 ng/g. Despite its lower detection frequency, DOA was detected as high as 9600 ng/g in Belgian beer can. There was no apparent relationship present between the home countries of beer cans and amount of additives used. Despite of being broken down, additives concentration in one environmental sample was found to be one to two orders of magnitude higher compared to the new can. This result proved that adsorption of chemical additives took place in the environment and degraded metal debris may become source of microplastic with higher risk of additives pollution in the environment.

Parent and alkylated PAHs profiles in 11 petroleum fuels and lubricants: Application for oil spill accidents in the environment.

Eleven types of petroleum fuels and lubricants including regular gasoline, premium gasoline, jet fuel, kerosene, light oil, bunker A, bunker A-white, bunker A-low sulfur, bunker C, quench oil and lubricant samples were analyzed for parent and alkylated polycyclic aromatic hydrocarbons (PAHs). Naphthalene was the predominant compound in gasolines, jet fuel and kerosene, constituting > 95% of the parent PAHs, whereas dibenzothiophene and other high molecular weight PAHs were predominant in bunker A and bunker C. PAH compositions in petroleum fuels differ because of differences in their refining temperatures and the boiling points of individual PAHs. Principal component analysis classified into four groups of petroleum fuels. Further, oil samples were clearly separated into five groups based on their ratios of select alkyl homologs (C0/(C0+C1) and C4/(C2+C4) naphthalenes): 'gasolines' 'light oil' 'bunker oils' 'kerosene' and 'quench oil'. A wide variety and detailed profiles of PAHs in petroleum fuels and lubricants in this study can be used for baseline data in oil fingerprinting analyses to identify the potential source of oil spill accidents in the environment.

Massive occurrence of benthic plastic debris at the abyssal seafloor beneath the Kuroshio Extension, the North West Pacific.

The abyss (3500-6500 m) covers the bulk of the deep ocean floor yet little is known about the extent of plastic debris on the abyssal seafloor. Using video imagery we undertook a quantitative assessment of the debris present on the abyssal seafloor (5700-5800 m depth) beneath the Kuroshio Extension current system in the Northwest Pacific. This body of water is one of the major transit pathways for the massive amounts of debris that are entering the North Pacific Ocean from Asia. Shallower sites (1400-1500 m depth) were also investigated for comparison. The dominant type of debris was single-use plastics - mainly bags and food packaging. The density of the plastic debris (mean 4561 items/km2) in the abyssal zone was the highest recorded for an abyssal plain suggesting that the deep-sea basin in the Northwest Pacific is a significant reservoir of plastic debris.

Plastic additives in deep-sea debris collected from the western North Pacific and estimation for their environmental loads.

Plastic waste has become a growing concern in terms of marine pollution, but little information is available on plastic debris and its possible risks of chemical additives exposure in the deep-sea. This study focused on identification of polymer type and additive concentrations in 21 plastic debris collected from deep-sea of Sagami Bay, Japan and West Pacific Ocean under the Kuroshio Extension and its recirculation gyre (KERG) zone (water depth: 1388-5819 m). Polyethylene (PE) was dominant polymer (57% of the total) in samples, followed by polyvinylchloride (PVC), epoxy resin, polyester (PES), and polypropylene. In plastic additives, bis (2-ethylhexyl) phthalate (DEHP) was detected to be contained in a PVC sheet at concentration of 48%. Butylated hydroxytoluene (BHT) was also detected in PE plastic debris with median concentration of 12,000 ng/g. PES clothes were detected to contain dyeing mixtures, 1,2,4-trichlorobenzene (1,2,4-TCB), up to 42,000 ng/g. Knowing the estimated number of plastic debris under KE current, the minimum burden of chemical additives were estimated that 720 kg of dibutyl phthalate, 570 kg of BHT, 230 kg of DEHP, and 160 kg of 1,2,4-TCB exist on the seabed of KERG zone. This result strongly suggests that enormous amount of hazardous additives lie within plastic debris on abyssal level of the ocean.

Acesulfame as a suitable sewer tracer on groundwater pollution: A case study before and after the 2016 Mw 7.0 Kumamoto earthquakes.

On April 14th and 16th, 2016, two large-scale earthquakes (Mw 6.2 and 7.0) occurred in Kumamoto, Japan. The sewer system was seriously damaged and there were concerns about groundwater pollution by sewer exfiltration. In this study, artificial sweeteners including acesulfame (ACE) in groundwater were analyzed before and after the earthquakes to evaluate sewage pollution and its temporal variation. Before the earthquakes, ACE was detected in 31 of 49 groundwater samples analyzed, indicating that wastewater may have leaked into groundwater. Groundwater was sampled from the same locations 2, 7, 12, and 30 months after the earthquakes. The detection frequency and median concentration of ACE in groundwater increased significantly 7 months after the earthquakes, from several tens to maximumly 189 times greater than the pre-earthquake concentrations. This suggests the earthquakes caused serious damage to sewer pipes and groundwater may be polluted. However, ACE concentrations drastically decreased or remained low 30 months after the earthquakes, probably due to the recovery and restoration work of sewer infrastructure. This study shows that ACE is an excellent tracer for evaluating sewer exfiltration to groundwater. In addition, it is important to obtain data on sewage tracers under normal condition as part of preparations for large-scale earthquakes.

Plastic additives as tracers of microplastic sources in Japanese road dusts.

Plastic waste and microplastic pollution has been reported around the world. Up to 80% of marine plastic debris is derived from land, thus it is important to identify the terrestrial sources of microplastics to reduce their environmental impact. In this study, the abundance and polymer type of microplastics were characterized for road dusts collected from Kumamoto, Okinawa, and Tokyo, Japan. In addition, the profiles of additives in plastic products on the road and in road dust microplastics were determined to evaluate the potential use of additives as chemical tracers of microplastic sources. The abundance of microplastics in road dusts was 96 ± 85 pieces/kg (dry wt.) (n = 16), 68 ± 77 pieces/kg (n = 12), and 230 ± 50 pieces/kg (n = 8) in Kumamoto, Okinawa and Tokyo, respectively. In Kumamoto and Okinawa, significant correlations were observed between total microplastic abundance in road dusts and daily vehicle traffic. In Tokyo, high population and traffic density may account for the greater abundance of microplastics in road dusts than in the other cities. Polymer analysis shows that poly (diallyl phthalate), polyvinyl chloride, polymethyl methacrylate and polyester accounted for 60% to 70% of the total microplastics analyzed. To determine the potential sources of microplastics, plastic additives were analyzed in road dusts and fragments of road marking from the study area. Five common additives including plasticizers and flame retardants were identified in both road dusts and road markings. This suggests that road markings are a significant source of microplastics in Japanese road dust, and that additive profiles in plastic samples may be suitable tracers for determining the sources of microplastics in road dust.

Reduced bioavailability of polycyclic aromatic hydrocarbons (PAHs) in sediments impacted by carbon manufacturing plant effluent: Evaluation by ex situ passive sampling method.

Potential risks of polycyclic aromatic hydrocarbons (PAHs) in sediments of a Japanese bay contaminated by carbon manufacturing plant effluent were evaluated by calculating toxicity units (TUs). TUs calculated from the measured whole-sediment concentrations (Cwhole) were often higher than or close to 1, signaling a possible toxicity concern to benthic organisms. In contrast, TUs based on the freely dissolved pore water concentrations (Cfree) measured by an ex-situ passive sampling method with polyethylene strips were 0.0007-0.005, much lower than 1, indicating no effect. We also found that the fractions of black carbon in sediments of the contaminated bay were significantly higher than those of reference sites. Overall, we conclude that carbon manufacturing plant effluent substantially increases Cwhole of PAHs in sediments but also increases the fraction of carbonaceous particles that strongly retain PAHs. As a combined result, bioavailable concentrations (as expressed by pore water Cfree) of PAHs do not increase as much as Cwhole. The results of this study indicate that ecotoxicological risks of PAH contamination by carbon manufacturing plants should be evaluated by directly measuring pore water Cfree instead of Cwhole.

Soil concentrations and soil-air exchange of polycyclic aromatic hydrocarbons in five Asian countries.

The Asia Soil and Air Monitoring Program (Asia-SAMP) is a large-scale monitoring program spanning China, Japan, South Korea, Vietnam and India. 47 polycyclic aromatic hydrocarbons (PAHs) were analyzed in 169 concurrently collected surface soil samples across the five study regions. Total PAH concentrations (∑47PAHs) ranged from 13.1 to 7310 ng/g dry weight, with a median value of 272 ng/g dry weight. Higher concentrations of ΣPAHs were recorded in soils from urban areas, followed by soils from rural areas and background soils. Low correlation coefficients were found between PAHs concentrations with population density, surface air temperature and soil organic content. A trend of depleting high molecular weight PAHs and enrichment of low molecular weight PAHs occurred from east to west in Chinese soils. Based on atmospheric PAHs detected in almost the same sampling sites, the equilibrium status of PAHs in the atmosphere and on the ground was investigated. Sample sites with a soil-air equilibrium status for different PAH congeners recorded differences, and differences were recorded between seasons. 2-ring PAHs were mainly volatilized, and 5- & 6-ring PAHs were mainly deposited in all seasons and across all study regions. 3- & 4-ring PAHs were more affected by soil-air transfer, showing a tendency to accumulate in soils in cold regions/seasons and to be re-volatilized into the atmosphere in warm regions/seasons. Partitioning and exchange of PAHs among soil and air were significantly affected by the air temperature.

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.

Organophosphate esters in indoor dust from 12 countries: Concentrations, composition profiles, and human exposure.

A total of 20 organophosphate triesters (OPEs), including seven alkyl-OPEs, three chlorinated (Cl)-OPEs, seven aryl-OPEs, and three oligomeric-OPEs were measured in 341 house dust samples collected from 12 countries during the period 2010-2014. OPEs were ubiquitous in indoor dust, and the total concentrations of OPEs (∑OPEs; sum of 20 OPEs) ranged from 49.4 to 249,000 ng/g dry weight (dw). Generally, Cl-OPEs were the predominant compounds (51% of total) in indoor dust samples, with a median concentration of 800 ng/g, followed by alkyl-OPEs (31%), aryl-OPEs (17%), and oligomeric-OPEs (1%), with median concentrations of 480, 270, and 21.9 ng/g, respectively. ∑OPE concentrations in indoor dust from more industrialized countries (South Korea: median, 31,300; Japan: 29,800; and the United States: 26,500 ng/g dw) were one or two orders of magnitude higher than those from less industrialized countries (Greece: 7140, Saudi Arabia: 5310, Kuwait: 4420, Romania: 4110, Vietnam: 1190, China: 1120, Colombia: 374, India: 276, and Pakistan: 138 ng/g dw). Statistically significant positive correlations (0.114 < r < 0.748, p < 0.05) were found among the concentrations of 16 OPEs in dust samples, indicating similar sources of these compounds. The median estimated daily intakes of ΣOPEs via dust ingestion for children and adults were in the ranges of 0.29-64.8 and 0.07-14.9 ng/kg bw/day, respectively.

Temporal trends in PCB concentrations in mussels collected from areas affected by the Great East Japan Earthquake and Tsunami.

In the Great East Japan Earthquake of 11 March 2011, a magnitude 9.0 earthquake and accompanying tsunami struck the Tohoku region of Japan. The tsunami washed away old equipment containing polychlorinated biphenyls (PCBs) stored in the region's factories, and these PCBs may have leaked out of their casings into the marine environment. In this study, we evaluate marine PCB contamination by comparing mussels collected before (in 2005) and after (June 2011) the tsunami. PCB contamination levels were significantly elevated in mussel samples collected after the tsunami in June 2011 (3 months after the tsunami). This indicates that PCBs (specifically, formulation KC-400) leaked out of old equipment swept away by the tsunami and accumulated in mussels. PCBs were estimated to have an environmental half-life (EHL) in mussels of 4 months. Our results show that an earthquake and subsequent tsunami can cause elevated PCB contamination in the marine environment.

In vitro and in silico AHR assays for assessing the risk of heavy oil-derived polycyclic aromatic hydrocarbons in fish.

In the aftermath of the Great East Japan Earthquake of March 11, 2011, marine fish in Kesennuma Bay, Japan, have been contaminated with heavy oil containing polycyclic aromatic hydrocarbons (PAHs). To estimate the risk of six PAHs (benzo[α]pyrene, dibenzothiophene, phenanthrene, 2,3,5-trimethylnaphthalene, acenaphthene, and 1-methylphenanthrene), which have been detected at high levels in the tissues of fish from Kesennuma Bay, we attempted to evaluate the effects of these PAHs on the fish aryl hydrocarbon receptor (AHR) signaling pathway. We initially measured PAH concentrations and cytochrome P4501A catalytic activities (EROD: ethoxyresorufin-O-deethylase and MROD: methoxyresorufin-O-demethylase) as markers of AHR activation in greenlings (Hexagrammos otakii) collected from Kesennuma Bay in 2014. The results showed that alkylated PAH concentrations and EROD/MROD activities were higher in sites close to the oil-spilled sites than in the control site, suggesting AHR activation by spilled alkylated PAHs. We then investigated AHR-mediated responses to these PAHs in the in vitro reporter gene assay system where red seabream (Pagrus major) AHR1 (rsAHR1) or rsAHR2 expression plasmids were transiently transfected into COS-7 cells. The in vitro assay showed rsAHR isoform-, PAH-, and dose-dependent transactivation potencies. The relative effective concentrations of benzo[α]pyrene, dibenzothiophene, phenanthrene, 2,3,5-trimethylnaphthalene, acenaphthene, and 1-methylphenanthrene that induce 20% of the maximum benzo[α]pyrene response (REC20-BaP) for rsAHR1 activation were 0.052, 38, 79, 88, 270 nM, and no response, respectively, and those for rsAHR2 activation were 0.0049, 32, 53, 88, 60 nM, and no response, respectively. The results showed that the REC20-BaP values of benzo[α]pyrene for both the rsAHR1 and rsAHR2 isoforms were lower than the concentrations (0.041-0.20 nM) detected in the muscle tissue of fish from Kesennuma Bay, while the REC20-BaP values of other PAHs were higher than their tissue concentrations. In silico rsAHR homology modeling and subsequent ligand docking simulation analyses indicated that the rsAHR activation potencies of PAHs could be predicted from a rsAHR2 model. This study shows that in vitro and in silico rsAHR analyses may be a useful tool for assessing the risks to fish contaminated with PAHs.

Development of a novel scheme for rapid screening for environmental micropollutants in emergency situations (REPE) and its application for comprehensive analysis of tsunami sediments deposited by the great east Japan earthquake.

The tsunami triggered by the Great East Japan Earthquake of March 2011, the strongest quake ever recorded in Japan, deposited tsunami sediments along the coastline of the affected area. Because the sediments contained a wide variety of hazardous chemicals, including organic micropollutants, a method for rapidly evaluating the environmental and human health risks of such chemicals is necessary. For this purpose, we propose a novel three-step scheme designated "rapid screening for environmental micropollutants in emergency situations (REPE)". In the first step, samples are subjected to target screening analysis using an automated identification and quantification system (TSA-AIQS) involving gas chromatography mass spectrometry (GC-MS). In the second step, the chemicals detected by TSA-AIQS analysis are quantified precisely by conventional target analysis. The third step is risk assessment of the target chemicals. TSA-AIQS analysis of the tsunami sediments detected 63 substances, including polycyclic aromatic hydrocarbons (both native and alkylated PAHs) at high concentrations. These PAHs were precisely quantified by target analysis, and the concentrations were used to assess the health risks posed by oral intake, which were found to be negligible. Our results suggest that the REPE scheme will be useful for rapid, comprehensive screening and risk assessment in emergency situations.

Occurrence and Source Effect of Novel Brominated Flame Retardants (NBFRs) in Soils from Five Asian Countries and Their Relationship with PBDEs.

This paper presents the first comprehensive survey of 19 novel brominated flame retardants (NBFRs) in soil samples collected among five Asian countries. High variability in concentrations of all NBFRs was found in soils with the geometric mean (GM) values ranging from 0.50 ng/g dry weight (dw) in Vietnam to 540 ng/g dw in the vicinity of a BFR manufacturer in China. In urban, rural, and background locations, the GM concentrations of ∑19NBFRs decreased in the order of Japan > South Korea > China > India > Vietnam. Correlations among different NBFR compounds were positive and statistically significant (p < 0.05), suggesting that they originate from similar sources. Evidence for simultaneous application between polybrominated diphenyl ethers (PBDEs) and NBFRs were also noted. Principal component analysis of NBFR concentrations revealed specific pollution sources for different NBFRs coming from urban, BFR-related industrial, and e-waste sites. For the first time, this study demonstrates a "point source fractionation effect" for NBFRs and PBDEs. The concentrations of all NBFRs and PBDEs were negatively and significantly correlated with the distance from BFR-related industrial and e-waste regions. Positive and significant correlation between population density and NBFR concentrations in soils was identified. Our study revealed that the primary sources effects were stronger than the secondary sources effects in controlling the levels and distribution of NBFRs and PBDEs in soils in these five Asian countries.