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.

Polybrominated diphenyl ethers in plastic products, indoor dust, sediment and fish from informal e-waste recycling sites in Vietnam: a comprehensive assessment of contamination, accumulation pattern, emissions, and human exposure.

Residue concentrations of polybrominated diphenyl ethers (PBDEs) in different kinds of samples including consumer products, indoor dust, sediment and fish collected from two e-waste recycling sites, and some industrial, urban and suburban areas in Vietnam were determined to provide a comprehensive assessment of the contamination levels, accumulation pattern, emission potential and human exposure through dust ingestion and fish consumption. There was a large variation of PBDE levels in plastic parts of obsolete electronic equipment (from 1730 to 97,300 ng/g), which is a common result observed in consumer plastic products reported elsewhere. PBDE levels in indoor dust samples collected from e-waste recycling sites ranged from 250 to 8740 ng/g, which were markedly higher than those in industrial areas and household offices. Emission rate of PBDEs from plastic parts of disposed electronic equipment to dust was estimated to be in a range from 3.4 × 10-7 to 1.2 × 10-5 (year-1) for total PBDEs and from 2.9 × 10-7 to 7.2 × 10-6 (year-1) for BDE-209. Some fish species collected from ponds in e-waste recycling villages contained elevated levels of PBDEs, especially BDE-209, which were markedly higher than those in fish previously reported. Overall, levels and patterns of PBDE accumulation in different kinds of samples suggest significant emission from e-waste sites and that these areas are potential sources of PBDE contamination. Intakes of PBDEs via fish consumption were generally higher than those estimated through dust ingestion. Intake of BDE-99 and BDE-209 through dust ingestion contributes a large proportion due to higher concentrations in dust and fish. Body weight normalized daily intake through dust ingestion estimated for the e-waste recycling sites (0.10-3.46 ng/day/kg body wt.) were in a high range as compared to those reported in other countries. Our results highlight the potential releases of PBDEs from informal recycling activities and the high degree of human exposure and suggest the need for continuous investigations on environmental pollution and toxic impacts of e-waste-related hazardous chemicals.

Persistent organochlorine pollutants in different bivalve species from central Vietnamese coasts: Concentrations, profiles, and biota-sediment accumulation factors.

Concentrations of typical persistent organochlorine pollutants (POCPs) like organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in five bivalve species collected from central Vietnamese coasts were determined to provide insights into spatial distribution and bioaccumulation characteristics of these substances. Concentrations of pollutants decreased in the order: PCBs (median 14.6; range 1.39-74.1), dichlorodiphenyltrichloroethane and its metabolites DDTs (2.92; 0.282-70.7), hexachlorocyclohexanes HCHs (2.46; 0.081-30.1), and endosulfan compounds ENDs (1.67; 0.041-36.6) ng/g wet weight. Considerable levels of legacy POCPs in the biota are likely attributed to illegal and/or unintentional sources. Concentrations and accumulation profiles of POCPs in biota samples were affected by species- and site-specific factors. The biota-sediment accumulation factors predicted enrichment potentials of OCPs (notably ENDs and DDTs) from sediment to biota in some certain areas.

Perfluoroalkyl substances (PFAS) in freshwater fish from urban lakes in Hanoi, Vietnam: concentrations, tissue distribution, and implication for risk assessment.

Concentrations and profiles of 17 perfluoroalkyl substances (PFAS) including 13 perfluorocarboxylic acids (PFA) and 4 perfluoroalkyl sulfonates (PFS) were determined in whole blood, muscle, and liver samples of four freshwater fish species in West Lake and Yen So Lake (Hanoi, Vietnam). Concentrations of total 17 PFAS in fish blood samples ranged from 5.2 to 29 (median 16) ng/mL. Total 17 PFAS levels in liver samples (4.5; 2.7-6.6 ng/g wet weight) were significantly higher than in muscle samples (1.0; 0.51-2.6 ng/g wet weight). More than 90% PFAS burdens in our fish samples were attributed to muscle and blood rather than liver, but contributions of individual compounds varied greatly. The most predominant substances were perfluorooctanesulfonate (PFOS) and PFA with chain lengths from C10 to C14 (i.e., PFDA, PFUnDA, PFDoDA, PFTrDA, and PFTeDA). There is no significant difference in PFAS concentrations between the studied species (i.e., bighead carp, common carp, rohu, and tilapia), but common carp showed specific PFAS profiles as compared to other species (e.g., higher proportions of PFOS and long-chain PFA such as PFTrDA, PFTeDA, and PFHxDA). Daily intake doses of PFOS and perfluorooctanoic acid (PFOA) through fish consumption were markedly lower than the US EPA reference dose of 20 ng/kg/day. Weekly intakes of the sum of PFHxS, PFOS, PFOA, and PFNA in our study were still lower than the EFSA tolerable weekly intake of 4.4 ng/kg/week.

Unintentionally produced polychlorinated biphenyls in pigments: An updated review on their formation, emission sources, contamination status, and toxic effects.

The formation, emission, environmental occurrence, and potential adverse effects of unintentionally produced polychlorinated biphenyls (PCBs) in pigments are reviewed, providing a comprehensive and up-to-date picture on these pollutants. PCBs are typically formed during manufacturing of organic pigments that involve chlorinated intermediates and reaction solvents, rather than those of inorganic pigments. Concentrations and profiles of PCBs vary greatly among pigment types and producers, with total PCB levels ranging from lower than detection limits to several hundred ppm; major components can be low-chlorinated (e.g., CB-11) or high-chlorinated congeners (e.g., CB-209). Pigment-derived PCBs can be released into the environment through different steps including pigment production, application, and disposal. They can contaminate atmospheric, terrestrial, and aquatic ecosystems, and then affect organisms living there. This situation garners scientific and public attention to nonlegacy emissions of PCBs and suggests the need for appropriate monitoring, management, and abatement strategies regarding these pollutants.

Extractable organochlorine (EOCl) and extractable organobromine (EOBr) in GPC-fractionated extracts from high-trophic-level mammals: Species-specific profiles and contributions of legacy organohalogen contaminants.

Previous studies have suggested that unidentified compounds constitute a large proportion of extractable organochlorine (EOCl) and extractable organobromine (EOBr) in the crude extracts without fractionation; however, the proportion of unidentified EOX (X = chlorine, bromine) associated with high-/low-molecular-weight compounds is still unknown. In this study, we applied gel permeation chromatography to fractionate extracts from archived liver samples of high-trophic marine and terrestrial mammals (striped dolphins, cats, and raccoon dogs), for which concentrations of legacy organohalogen contaminants (polychlorinated biphenyls, organochlorine pesticides, and polybrominated diphenyl ethers [PBDEs]) had been previously reported. EOX in high- (>1000 g/mol) and low- (≤1000 g/mol) molecular-weight fractions (EOX-H and EOX-L) were determined by neutron activation analysis. Comparison of EOCl and EOBr enabled the characterization among species. Despite small differences in the concentrations and molecular-weight profiles of EOCl among species, the contribution of chlorine in identified compounds to EOCl-L varied from 1.5% (cats) to 79% (striped dolphins). Considerable species-specific variations were observed in the concentrations of EOBr: striped dolphins exhibited significantly greater concentrations of both EOBr-H and EOBr-L than cats and/or raccoon dogs. Moreover, the contribution of bromine in PBDEs to EOBr-L was >50% in two cats, while it was <6% in other specimens. This is the first report on EOBr mass balance in cetaceans and on EOX mass balance in terrestrial mammals living close to humans. These results suggest the need for analysis of unidentified chlorinated compounds in terrestrial mammals and unidentified brominated compounds in marine mammals.

Air pollution caused by phthalates and cyclic siloxanes in Hanoi, Vietnam: Levels, distribution characteristics, and implications for inhalation exposure.

Contamination status and distribution characteristics of ten phthalic acid esters (PAEs) and three cyclic volatile methyl siloxanes (CSs) were determined in the air (gas and particle) samples collected from indoor and outdoor spaces of several chemistry laboratories, offices, and homes from urban area of Hanoi, the capital city of Vietnam. Air concentrations of Σ10PAEs (median 688; range 142-2390 ng m-3) and Σ3CSs (171; not detected-1100 ng m-3) in the indoor air samples were significantly higher than those measured in the outdoor ones (Σ10PAEs: 161; 34.1-515 ng m-3 and Σ3CSs: 43.2; not detected-258 ng m-3), partly suggesting the predominance of indoor emission sources of these substances. There were significant positive correlations in total air concentrations of phthalates and siloxanes between the indoor and outdoor air samples. The most predominant phthalates were diethyl-, di-n-butyl-, diisobutyl-, and di(2-ethylhexyl) phthalate. For siloxanes, D5 and D6 were more abundant than D4 in most samples. Except for di(2-ethylhexyl)- and di-n-octyl phthalate in some locations, almost all the compounds were likely associated with gas phase than particle phase. Daily intake doses of airborne phthalates and siloxanes, and non-cancer and cancer risks of selected phthalates were estimated for different exposure groups such as adults, children, and university subjects (e.g., laboratory staff and students), indicating relatively low levels of risk.

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 (PM2.5) 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 PM2.5 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.

Contamination status, emission sources, and human health risk of brominated flame retardants in urban indoor dust from Hanoi, Vietnam: the replacement of legacy polybrominated diphenyl ether mixtures by alternative formulations.

This study investigated the occurrence, distribution of several additive brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) and some novel brominated flame retardants (NBFRs) in urban indoor dust collected from ten inner districts of Hanoi, Vietnam to assess the contamination status, emission sources, as well as their associated human exposure through indoor dust ingestion and health risks. Total concentrations of PBDEs and NBFRs in indoor dust samples ranged from 43 to 480 ng g-1 (median 170 ng g-1) and from 56 to 2200 ng g-1 (median 180 ng g-1), respectively. The most abundant PBDE congener in these dust samples was BDE-209 with concentrations ranging from 29 to 360 ng g-1, accounting for 62.6-86.5% of total PBDE levels. Among the NBFRs analyzed, decabromodiphenyl ethane (DBDPE) was the predominant compound with a mean contribution of 98.6% total NBFR amounts. Significant concentrations of DBDPE were detected in all dust samples (median 180 ng g-1, range 54-2200 ng g-1), due to DBDPE as a substitute for deca-BDE. Other NBFRs such as 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), pentabromoethylbenzene (PBEB) and 2,2',4,4',5,5'-hexabromobiphenyl (BB-153) were found at very low levels. Based on the measured BFR concentrations, daily intake doses (IDs) of PBDEs and NBFRs via dust ingestion at exposure scenarios using the median and 95th percentile levels for both adults and children were calculated for risk assessment. The results showed that the daily exposure doses via dust ingestion of all compounds, even in the high-exposure scenarios were also lower than their reference dose (RfD) values. The lifetime cancer risks (LTCR) were much lower than the threshold level (10-6), which indicated the acceptable health risks resulting from indoor BFRs exposure for urban residents in Hanoi.

Antibiotics in surface water of East and Southeast Asian countries: A focused review on contamination status, pollution sources, potential risks, and future perspectives.

This review provides focused insights into the contamination status, sources, and ecological risks associated with multiple classes of antibiotics in surface water from the East and Southeast Asia based on publications over the period 2007 to 2020. Antibiotics are ubiquitous in surface water of these countries with concentrations ranging from <1 ng/L to hundreds µg/L and median values from 10 to 100 ng/L. Wider ranges and higher maximum concentrations of certain antibiotics were found in surface water of the East Asian countries like China and South Korea than in the Southeast Asian nations. Environmental behavior and fate of antibiotics in surface water is discussed. The reviewed occurrence of antibiotics in their sources suggests that effluent from wastewater treatment plants, wastewater from aquaculture and livestock production activities, and untreated urban sewage are principal sources of antibiotics in surface water. Ecological risks associated with antibiotic residues were estimated for aquatic organisms and the prevalence of antibiotic resistance genes and antibiotic-resistant bacteria were reviewed. Such findings underline the need for synergistic efforts from scientists, engineers, policy makers, government managers, entrepreneurs, and communities to manage and reduce the burden of antibiotics and antibiotic resistance in water bodies of East and Southeast Asian countries.

Characterization of mono- to deca-chlorinated biphenyls in a well-preserved sediment core from Beppu Bay, Southwestern Japan: Historical profiles, emission sources, and inventory.

Contamination levels and profiles of mono- to deca-chlorinated biphenyls (PCBs) were characterized in a sediment core dated in 1954-2011 from Beppu Bay, southwestern Japan, providing a comprehensive and detailed picture on the environmental occurrence, temporal trends, and emission sources of these pollutants in the study area. Concentrations of total PCBs in the core ranged from 3.5 to 150 (median 15) ng g-1 dry weight and exhibited depth profile matching with Japanese PCB production and emission patterns (i.e., drastically increasing from the early 1960s, peaking in 1970, and then rapidly decreasing). Origin of PCBs in the studied samples largely associated with Kanechlor mixtures (e.g., KC-300 and KC-400), especially for sediment layers dated between the mid-1960s and early 1970s (i.e., the intensive PCB production period in Japan). In addition, dechlorination and weathering signals and emerging inputs of PCBs were also observed in deeper and shallower sediment segments with notable proportions of some unique congeners such as CB-47/48/51 and CB-11, respectively. Historical fluxes of PCBs in our samples showed quite similar vertical shape as concentrations. In the context of national implementation for complete treatment of PCB-containing waste until 2024, further investigations on spatiotemporal trends and environmental loads of PCBs in Japan are necessary.

Characterization of triclosan and triclocarban in indoor dust from home micro-environments in Vietnam and relevance of non-dietary exposure.

Contamination status, spatial variability, and exposure risk of triclosan (TCS) and triclocarban (TCC) in indoor dusts from different micro-environments were evaluated for the first time in Vietnam as well as in Southeast Asian region. TCS and TCC were measured in 89 dust samples collected from bedrooms, living rooms, and kitchens of private houses in four northern cities including Hanoi, Bac Ninh, Hung Yen, and Nam Dinh, by means of liquid chromatography-tandem mass spectrometry. Concentrations of TCS and TCC ranged from <5 to 1090 (median 33.2) and from <3 to 531 (median 19.3) ng g-1, respectively. Concentrations of TCS and TCC in the kitchen and bedroom dusts were markedly higher than levels found in the living room samples, probably due to their applications in kitchen utensils, household cleaning reagents, and personal care products. A strong positive correlation between TCS and TCC concentrations was detected in the whole dataset (R2 = 0.810, p < 0.001). For samples in which both TCS and TCC were quantified, TCS/TCC ratios ranged from 0.3 to 12 with a median value of 1.8, and did not show big differences between micro-environments. Human exposures to TCS and TCC through dust ingestion were estimated for various age groups with 95% CI daily intake doses ranging from (0.032-0.070) to (0.340-0.740) and from (0.017-0.033) to (0.175-0.345) ng kg-bw-1 d-1 for adults and infants respectively. Although our derived values were much lower than reference doses, more comprehensive risk assessment considering multiple exposure pathways of TCS and TCC is needed.

Polychlorinated biphenyls in settled dusts from an end-of-life vehicle processing area and normal house dusts in northern Vietnam: Occurrence, potential sources, and risk assessment.

Concentrations and congener-specific profiles of total 209 polychlorinated biphenyls (PCBs) were investigated in settled dust samples collected from end-of-life vehicle (ELV) processing, urban, and rural areas in northern Vietnam. Concentrations of total 209 PCBs, seven indicator congeners, and twelve dioxin-like PCBs decreased in the order: ELV working > ELV living ≈ urban > rural dusts. Penta- and hexa-CBs dominated the homolog patterns in all the samples with higher proportions in the ELV dusts compared to the urban and rural house dusts. The abundance and pattern of PCBs in the ELV dusts suggest on-going emissions of these compounds related to processing of vehicular oils and lubricants containing PCBs, whereas the presence of PCBs in the urban and rural house dusts indicate long-time releases. However, levels of some PCBs identified as by-products of pigment manufacturing (e.g., PCB-11 and PCB-209) were higher in the urban house dusts than those from other locations, resulting from human activities utilizing paints and pigments. Daily intake doses (ID), non-carcinogenic hazard quotient (HQ), and lifetime cancer risk (CR) of PCBs through dust ingestion were estimated for ELV workers and residents in the studied areas. The workers and children in the ELV sites were estimated to be at higher risk of PCB exposure, however almost all of the HQ < 1 and CR < 10-4 indicate no serious risk related to dust-bound PCBs.

Polyurethane foam-based passive air sampling for simultaneous determination of POP- and PAH-related compounds: A case study in informal waste processing and urban areas, northern Vietnam.

Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hexabromobiphenyl (BB-153), novel brominated flame retardants (NBFRs), and unsubstituted/methylated polycyclic aromatic hydrocarbons (PAHs/Me-PAHs) were simultaneously monitored in the air samples collected from Vietnamese urban and vehicular waste processing areas by using polyurethane foam-based passive air sampling (PUF-PAS) method. Concentrations (pg m-3) of organic pollutants decreased in the order: PAHs (median 29,000; range 5100-100,000) > Me-PAHs (6000; 1000-33,000) > PCBs (480; 170-1100) > PBDEs (11; 5.3-86) > NBFRs (0.20; n. d. - 51) > BB-153 (n.d.). The difference in total PCB and PBDE concentrations between the urban and waste processing air samples was not statistically significant. Meanwhile, levels of PAHs, Me-PAHs, benzo [a]pyrene equivalents (BaP-EQs), and toxic equivalents of dioxin-like PCBs (WHO-TEQs) were much higher in the waste processing sites. This is the first report on the abundance of mono- and di-CBs (notably CB-11) in the air from a developing country, suggesting their roles as emerging and ubiquitous air pollutants. Our results have indicated potential sources of specific organic pollutants such as dioxin-like PCBs, PAHs, and Me-PAHs from improper treatment of end-of-life vehicles and other vehicle related materials (e.g., waste oils and rubber tires), as well as current emission of PCBs and PBDEs in the urban area in Vietnam. Further atmospheric monitoring studies should be conducted in this developing country that cover both legacy and emerging contaminants with a focus on areas affected by rapid urbanization and informal waste processing activities.

Contamination status and temporal trends of persistent toxic substances in sediment cores from coastal areas of central Vietnam.

Residue concentrations of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) were measured in sediment core samples from two estuary areas of central Vietnam to elucidate recent status and temporal trends of pollution based on the depth profiles. Concentrations of PCBs, PBDEs, and endosulfan compounds were generally higher than those of the remaining OCPs. Peak concentrations of OCPs were found in the sediment layers corresponding to the late 1950s to the early 1980s, implying the intensive application of these insecticides in Vietnam during such periods. Although the highest PCB concentrations were measured in sediment layers dated in the 1970s, increasing PCB residues observed in the shallower layers may be related to the strong industrialization and urbanization in Vietnam. BDE-209 exhibited increasing concentrations and proportions to total PBDEs towards shallower depths, suggesting substantial use and on-going releases of deca-BDE products in recent years.

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.

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.

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.

Characterization of PCDD/Fs and dioxin-like PCBs in flue gas from thermal industrial processes in Vietnam: A comprehensive investigation on emission profiles and levels.

The emission profiles and levels of unintentionally produced persistent organic pollutants (U-POPs) comprising polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) were comprehensively investigated in flue gas released from 20 facilities belonging to 11 thermal industrial processes in Vietnam. Levels and patterns of PCDD/Fs and dl-PCBs in flue gas samples varied widely between sectors and different facilities in the same sector, suggesting different formation mechanisms involved. Flue gas concentrations of PCDD/Fs and dl-PCBs generally decreased in the order: industrial waste incinerator > secondary zinc production > coal fired craft boiler > coal fired power plant ≈ medical waste incinerator > steel production ≈ cement production > secondary copper production > coal fired industrial boiler > secondary tin production ≈ municipal waste incinerator. Results obtained from diagnostic ratio and fingerprint analysis have revealed that the stack emissions of PCDD/Fs and dl-PCBs were probably attributed to the de novo formation and incomplete destruction of input materials containing technical PCB oils or paints. The average emission factors of PCDD/Fs and dl-PCBs ranged from 0.011 to 374 µg WHO-TEQ tonne-1 for the studied facilities. A total emission amount of 4.89-11.4 g WHO-TEQ year-1 was estimated for the 20 facilities investigated in our study. This is the first comprehensive investigation on the unintentional emissions of PCDD/Fs and dl-PCBs from a wide range of industrial sectors 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.