Quantification of parabens in marine fish samples by a rapid, simple, effective sample preparation method.

Parabens (p-hydroxybenzoic acid esters) commonly used preservatives (in cosmetics, pharmaceuticals, and foods) can pose potential effects on environmental health. In this study, seven parabens were quantified in marine fish samples using an ultra-high performance liquid chromatography triple quadrupole mass spectrometer (UHPLC-MS/MS) system. Parabens in the fish samples were extracted and purified by a rapid, simple, and effective procedure comprising sample homogenization with solvent, solid-phase extraction clean-up, and solvent evaporation. Results demonstrated that the recoveries of seven compounds (with relative standard deviation < 15%) were 88-103% in matrix-spike samples and 86-105% in surrogate standards. The method detection limits and method quantification limits of seven parabens were 0.015-0.030 and 0.045-0.090 ng/g-ww (wet weight), respectively. The optimized method was applied to measure the concentration of parabens in the 37 marine fish samples collected from Vietnam coastal waters. The concentration ranges of seven parabens found in round scad and greater lizardfish samples were 6.82-25.3 ng/g ww and 6.21-17.2 ng/g-ww, respectively. Among parabens, methylparaben accounted for the highest contribution in both fish species (43.2 and 44.9%, respectively). Based on the measured concentrations of parabens in marine fish samples, the estimated daily intake was calculated for children and adults with the corresponding values of 0.0477 µg/kg/day and 0.0119 µg/kg/day, respectively. However, the presence of parabens in Vietnamese marine fish may not pose a significant risk to human health.

Co-occurrence of phthalic acid esters (PAEs) and cyclic volatile methylsiloxanes (cVMSs) in fine particulate matter (PM0.5 and PM0.1) collected from an industrial area in Vietnam.

Distribution patterns of 10 phthalic acid diesters (PAEs) and four cyclic volatile methylsiloxanes (cVMSs) were investigated in fine particulate matter (PM0.1 and PM0.5) collected from Bac Ninh, an industrial province in Vietnam during September-October in 2021. Total concentrations of PAEs found in PM0.1 and PM0.5 were in the ranges of 1.76-372 (median: 34.0 ng/m3) and 2.23-895 ng/m3 (median: 15.4 ng/m3), respectively. Among PAEs, di-n-butyl phthalate (DBP) was the most abundant compound found in PM0.1, whereas, di-2-(ethyl)hexyl phthalate (DEHP) was measured at the highest concentration in PM0.5. Total concentrations of cVMSs measured in PM0.1 and PM0.5 were in the ranges of method quantification limit (MQL)-203 (median: 2.10 ng/m3) and MQL-537 ng/m3 (median: 0.389 ng/m3), respectively. Among cVMSs, decamethylcyclopentasiloxane (D5) was found at the highest concentration in both PM0.1 and PM0.5 fractions of particulate matter. The concentration ratios between PAEs and cVMSs in PM0.1/PM0.5 were greater than 1 (except di-n-octyl phthalate: DnOP), suggesting that these chemicals tend to sorb to PM0.1 more preferentially than PM0.5. Among sampling locations, high concentrations of PAEs and cVMSs were found at traffic intersections (Que Vo district) and a craft village (Tu Son city). Relatively stronger correlations existed between cVMSs pairs in PM0.1 and PM0.5 (correlation coefficient: 0.73-1) than those of PAEs (-0.83-0.90). The human exposure doses to PAEs and cVMSs through inhalation of particulate matter were estimated based on the measured concentrations in PM0.1 and PM0.5 fractions. The estimated exposure doses of PAEs and cVMSs for infants (7.1 ng/kg-bw/d and 2.5 ng/kg-bw/d) were higher than those for adults (2.6 ng/kg-bw/d and 0.9 ng/kg-bw/d).

Widespread distribution of phthalic acid esters in indoor and ambient air samples collected from Hanoi, Vietnam.

In the present study, distribution characteristics of ten typical phthalic acid esters (PAEs) were investigated in 90 air samples collected from the urban areas in Hanoi, Vietnam from May to August 2022. The total concentrations of PAEs in indoor and ambient air samples were in the range of 320-4770 ng/m3 and 35.9-133 ng/m3, respectively. Total concentrations of PAEs in indoor air were about one order of magnitude higher than those in ambient air. Among PAEs studied, di-(2-ethyl)hexyl phthalate (DEHP) was measured at the highest levels in all air samples, followed by di-n-octyl phthalate (DnOP) and di-n-butyl phthalate (DnBP). The PAEs concentrations in air samples collected from laboratories at nighttime were significantly higher than those during daytime (p < 0.05). Meanwhile, the distributions of PAEs in various micro-environments in the same house are no statistically significant difference. The median exposure doses of PAEs through inhalation for adults and children were 248 and 725 ng/kg-bw/d, respectively. These exposure levels were still lower than the respective reference doses (RfD) proposed by the US EPA for selected compounds such as diethyl phthalate (DEP), DnBP, and DEHP.

Assessment of cyclic volatile methyl siloxanes (CVMSs) in indoor dust from different micro-environments in northern and central Vietnam.

Comprehensive studies on emerging contaminants like volatile methyl siloxanes in settled dust from different micro-environments are still limited. In this study, concentrations and distribution of cyclic volatile methyl siloxanes (CVMSs) including D3, D4, D5, and D6 were examined in indoor dust samples collected from various micro-environments in northern and central Vietnam. Concentrations of total CVMSs in the dust samples ranged from 86.0 to 5890 (median 755) ng/g and decreased in the order: waste processing workshops (median 1560; range 329-5890) > common houses (650; 115-1680) > university classrooms (480; 86.0-1540) > vehicle repair shops (295; 126-1950) ng/g. This observation suggests that informal waste processing activities are sources of CVMSs. Among the studied CVMSs, D5 was the most predominant compound (41 ± 14%), followed by D6 (26 ± 13%), D4 (23 ± 12%), and D3 (11 ± 11%). Moderate positive correlations between D3/D4, D4/D5, and D5/D6 were found. Median daily intake doses of D3, D4, D5, and D6 through dust ingestion were 0.016, 0.051, 0.11, and 0.054 ng/kg/d, respectively, which were comparable to water consumption and markedly lower than the air inhalation pathway.

Occurrence, emission sources, and risk assessment of polybrominated diphenyl ethers and current-use brominated flame retardants in settled dust from end-of-life vehicle processing, urban, and rural areas, northern Vietnam.

Settled dust samples from Vietnamese end-of-life vehicle (ELV) processing, urban, and rural areas were analyzed for polybrominated diphenyl ethers (PBDEs) and other current-use brominated flame retardants (BFRs). PBDE levels found in dust samples collected from ELV workshops (median 390; range 120-520 ng/g) and nearby living areas (110; 36-650 ng/g) were generally higher than those in common house dust (25-170 ng/g). BDE-209 was the most predominant congener detected in almost all the samples, indicating extensive application of products containing deca-BDE mixtures. The dust samples from ELV workplaces showed a more abundance of lower brominated congeners (e.g., tetra- to hexa-BDEs) that may originate from car interior materials treated by penta-BDE formulations. Concentrations of other BFRs decreased in the order urban > rural > ELV dust, reflecting the current use of these compounds in new consumer products. Decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) were the major alternative BFRs. Daily intake doses and hazard indexes of PBDEs and some other BFRs through dust ingestion were estimated and showed acceptable levels of risk. However, more comprehensive risk assessment considering multiple exposure pathways should be performed, especially for ELV workers and children in the ELV processing and urban areas.

Distribution and ecological risk assessment of phthalic acid esters in surface sediments of three rivers in Northern Vietnam.

Pollution status and distribution characteristics of ten typical phthalic acid esters (PAEs) were investigated in 36 sediment samples collected from three rivers in Northern Vietnam from June to October 2020. The total concentrations of PAEs in sediment samples collected from the To Lich River (n = 9), the Nhue River (n = 12), and the Day River (n = 15) were in ranges of 11,000-125,000 ng/g-dwt (mean/median: 50,000/42,200 ng/g-dwt), 2140-89,900 ng/g-dwt (mean/median: 29,300/20,700 ng/g-dwt), and 1140-43,100 ng/g-dwt (mean/median: 13,800/10,400 ng/g-dwt), respectively. Among ten PAEs studied, di-(2-ethylhexyl) phthalate (DEHP) was found at the highest levels in all samples meanwhile dimethyl phthalate (DMP), diethyl phthalate (DEP), and dipropyl phthalate (DPP) were detected at low frequency and concentration. Significant correlations have existed between the median-chain (C4-C7) PAE pairs in sediment samples. Due to the high accumulation in the sediments, the median-chain PAEs had a higher ecological risk than the short-chain (C1-C3) PAEs. These contaminants may present a longstanding influence on organisms and ecosystems.

A survey of parabens in aquatic environments in Hanoi, Vietnam and its implications for human exposure and ecological risk.

Seven parabens including methylparaben (MeP), ethylparaben (EtP), propylparaben (PrP), iso-propylparaben (iPrP), butylparaben (BuP), benzylparaben (BzP), and heptylparaben (HepP) were determined in bottled water, tap water, river water, lake water, and wastewater samples collected from Hanoi, Vietnam, using solid phase extraction (SPE) followed by ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The highest total concentration of parabens were measured in wastewater (range, 27.3-1050 ng/L; mean/median, 268/175 ng/L), followed by lake water (range, 18.0-254 ng/L; mean/median, 51.7/58.5 ng/L), river water (range, 16.5-52.1 ng/L; mean/median, 32.1/42.6 ng/L), tap water (range, 5.01-54.3 ng/L; mean/median, 28.6/41.1 ng/L), and bottled water (range, 1.56-39.9 ng/L; mean/median, 6.92/9.19 ng/L). Methylparaben and propylparaben were the predominant compounds found in all samples. The mean estimated human exposure dose of parabens through drinking bottled water was 0.27 ng/kg-bw/day, which is 6 orders of magnitude below the safety threshold recommended by the Joint FAO/WHO Expert Committee on Food Additive in 1974 (10 mg/kg-bw/day). Concentrations of parabens measured in river water, lake water, and wastewater samples were assessed to pose low to moderate ecological risks to aquatic organisms (0.1 < RQ < 1). Methyl, ethyl, and propyl parabens exhibited significant correlations in water samples.

Assessment of distributional characteristics and ecological risks of cyclic volatile methylsiloxanes in sediments from urban rivers in northern Vietnam.

In this report, four cVMSs including hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) were determined in 85 sediment samples collected from three rivers in northern Vietnam during the period from May to November 2020. Total mean concentrations of cVMSs ranged from 75.4 to 15,000 ng/g-dw. The highest levels of cVMS were found in sediment samples collected from the To Lich River (range, 260-15,000 ng/g-dw; median, 2840 ng/g-dw), followed by the Nhue River (range, 188-6800 ng/g-dw; median, 1370 ng/g-dw), and the Day River (range, 75.4-4600 ng/g-dw; median, 666 ng/g-dw). Among cVMSs, decamethylcyclopentasiloxane (D5) was found at the highest levels in all samples and ranged from 9.00 to 11,000 ng/g-dw. Significant correlations exist between the concentrations of D4/D6 and D5/D6 pairs in river sediment samples. Although the calculated ecological risk was not high, the presence of cVMSs in the sediment raises concerns about the impact on aquatic life because of their long-term accumulation capacity.

Phthalic acid esters (PAEs) in workplace and house dust from Vietnam: concentrations, profiles, emission sources, and exposure risk.

The occurrence of nine phthalic acid esters (PAEs) were determined in indoor dust samples collected from vehicle repair shops, waste processing workshops, and homes in Vietnam. Concentrations of total PAEs ranged from 585 to 153,000 (median 33,400 ng/g), which fall in the lower end of global range. The PAE levels in workplace dust (median 49,100; range 9210-153,000 ng/g) were significantly higher than those in house dust (median 23,700; range 585-83,700 ng/g), indicating waste processing activities as potential PAE sources. The most predominant compound was di-(2-ethyl)hexyl phthalate (DEHP), accounting for 62 ± 18% of total PAEs. Other major compounds were benzyl butyl phthalate (BzBP) (10 ± 12%), di-n-butyl phthalate (DnBP) (9.7 ± 7.7%), di-n-octyl phthalate (DnOP) (7.9 ± 8.1%), and diisobutyl phthalate (DiBP) (6.9 ± 5.0%). Proportions of BzBP and DnBP in some workplace dust samples were markedly greater than in common house dust, suggesting specific emission sources. Daily intake doses of selected PAEs (e.g., DnBP, DiBP, BzBP, and DEHP) through dust ingestion were much lower than reference doses, implying acceptable levels of risk.

Distribution of cyclic volatile methylsiloxanes in drinking water, tap water, surface water, and wastewater in Hanoi, Vietnam.

In this study, four cyclic volatile methylsiloxanes (cVMSs) were determined in drinking water, tap water, surface water, and wastewater samples collected from Hanoi metropolitan area, Vietnam, during August to December 2020 (dry season) by using solid phase extraction combined with gas chromatography tandem mass spectrometry. Highest concentrations of cVMSs in the range of 63-7400 ng/L (mean/median: 1840/1310 ng/L) were found in wastewater samples. A significant difference existed in the concentrations of cVMSs between influent and effluent of a wastewater treatment plant. The sum concentrations of four cVMSs in lake water, tap water, and bottled water samples were in the ranges of 67.0-1100 ng/L (mean/median: 350/282 ng/L), 19.8-350 ng/L (12.6/12.3 ng/L), and 2.31-28.1 ng/L (10.3/8.23 ng/L), respectively. Among the four cVMSs, decamethylcyclopentasiloxane (D5) was found at the highest concentrations in all water samples analyzed. The mean exposure doses of cVMSs calculated for adults and children through the consumption of drinking were 0.409 and 0.412 ng/kg-bw/day, respectively. Human exposure to cVMSs calculated through drinking water consumption was significantly lower than that reported for inhalation.

Profiles of phthalic acid esters (PAEs) in bottled water, tap water, lake water, and wastewater samples collected from Hanoi, Vietnam.

Contamination levels and distribution patterns of ten typical phthalic acid esters (PAEs) were investigated in various types of water samples collected from Hanoi metropolitan area in Vietnam. Concentrations of 10 PAEs in bottled water, tap water, lake water, and wastewater samples were measured in the ranges of 1640-15,700 ng/L (mean/median: 6400/5820 ng/L), 2100-18,000 ng/L (mean/median: 11,200/9270 ng/L), 19,600-127,000 ng/L (mean/median: 51,800/49,300 ng/L), and 20,700-405,000 ng/L (mean/median: 121,000/115,000 ng/L), respectively. Among PAEs, di-(2-ethylhexyl) phthalate (DEHP) accounted for a major proportion of total concentrations (45%) in wastewater, followed by diisobutyl phthalate (DiBP, 10.3%), and dibutyl phthalate (DBP, 9.53%). Concentrations of PAEs in wastewater decreased significantly with distance from the wastewater treatment plants (WWTPs). Concentrations of PAEs in surface water samples did not vary greatly between locations. PAEs were found in bottled water in the following order: DBP (22.4%), DiBP (22.3%), benzylbutyl phthalate (BzBP, 20.1%), and DEHP (15.5%). The estimated mean exposure doses of 10 PAEs through consumption of drinking water for adults and children in Vietnam were 254 and 256 ng/kg-bw/day, respectively. Capsule: Highest concentrations of PAEs were measured in wastewater, followed by lake water, tap water, and bottled water.

Comprehensive determination of polychlorinated biphenyls and brominated flame retardants in surface sediment samples from Hanoi urban area, Vietnam: Contamination status, accumulation profiles, and potential ecological risks.

Comprehensive and updated information about polychlorinated biphenyls (PCBs) and brominated flame retardants (BFRs) in surface sediments from Hanoi, the capital city of Vietnam, is rather scarce. In this study, concentrations and profiles of 209 PCBs, 41 polybrominated diphenyl ethers (PBDEs), 2,2',4,4',5,5'-hexabromobiphenyl (BB-153), hexabromocyclododecane (HBCD), pentabromoethylbenzene (PBEB), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), and decabromodiphenyl ethane (DBDPE) were determined in sediment samples collected from the Red River and some inner-city rivers of Hanoi. Concentrations (ng/g dry weight, median and range) of pollutants decreased in the order: DBDPE (28; not detected ND - 59) ≈ PCBs (27; 1.7-50) > PBDEs (23; 0.20-61) > HBCD (1.2; ND - 5.2) > BTBPE (0.46; ND - 3.6) > BB-153 (0.004; ND - 0.014) > PBEB (ND). Pollutant levels in the inner-city river sediments were about one to two orders of magnitude higher than those measured in the Red River main stream sediments. Tri-to hexa-CBs are major homologs but detailed profiles vary between individual samples, reflecting source and/or seasonal variations. CB-11 and CB-209 were found at higher proportions in sediments than in technical PCB mixtures, suggesting their novel sources from pigments. Deca-BDE and DBDPE are the most predominant BFRs with an increasing trend predicted for DBDPE. A preliminary ecological risk assessment was conducted for these pollutants in sediments. Total PCBs and deca-BDE in a few inner-city river sediments may exhibit adverse effects on benthic organisms, but no serious risk was estimated in general.

Field evaluation of diffusive gradients in thin-film passive samplers for wastewater-based epidemiology.

There is a need for a simple water sampling technique to enable routine monitoring of community drug consumption through wastewater-based epidemiology (WBE). This study investigates the potential use of diffusive gradients in thin films to sample organic compounds (o-DGT) for WBE. Three types of resin gels (HLB, XAD 18, and XDA-1) within o-DGT samplers each were deployed in triplicate at the inlets of two sewage treatment plants of Southern Asian cities. The target compounds included 15 illicit drugs and 18 antibiotics. A comprehensive evaluation was undertaken regarding each resin's ability to accumulate the target compounds and accuracy by comparing active samples. The organic compounds accumulated on each resin gel were characterised at the molecular level using Fourier transform ion-cyclotron-resonance mass spectrometry (FT-ICR MS). The results showed that the HLB resin performed better than the XAD 18 and XDA-1 resins. Based on calculations using the HLB-DGT data, methamphetamine and heroin were the two most popular illicit drugs consumed among the studied populations, and were followed by ketamine and codeine, which agreed well with the authoritative reports and reference data. The total drug consumption in Hanoi was one order of magnitude higher than that in Guangzhou, thus implying a probably more serious drug situation in the former. Overall, the findings of this study demonstrate that o-DGT passive samplers are a promising tool for WBE studies, particularly at WWTPs or in urban streams where an automatic sampler for taking composite water samples is absent.

Neonicotinoids, fipronil, chlorpyrifos, carbendazim, chlorotriazines, chlorophenoxy herbicides, bentazon, and selected pesticide transformation products in surface water and drinking water from northern Vietnam.

Studies on the occurrence of emerging pesticides in surface and drinking water in Vietnam are limited. In this study, lake water (n = 7), river water (n = 1), tap water (n = 46), and bottled water (n = 3) collected from Hanoi and other four provinces in northern Vietnam were analyzed for selected pesticides (including insecticides such as neonicotinoids, fipronil, and chlorpyrifos; fungicide carbendazim; herbicides such as atrazine, terbuthylazine, simazine, 2,4-dichlorophenoxyacetic acid, 2-methyl-4-chlorophenoxyacetic acid, and bentazon) and some of their degradates by liquid chromatography-tandem mass spectrometry. Carbendazim (median: 86.7 ng/L) and triazines (49.3 ng/L) were the major pesticides found in lake water samples, followed by neonicotinoids and their degradation products (15.1 ng/L), chlorpyrifos and its degradate (13.4 ng/L), fipronil and its degradates (3.76 ng/L), chlorophenoxy acid herbicides (2.10 ng/L), and bentazon (0.62 ng/L). Triazines (164 ng/L) were the major pesticides in river water. Higher concentrations (median: 39.3 ng/L; range: 1.20-127) of selected pesticides were found in tap water from Hanoi than those from four other provinces studied (5.49 ng/L; 4.73-66.8 ng/L). Bottled water samples collected from Hanoi contained lower concentrations of pesticide residues (median: 3.54 ng/L, range: 2.18-8.09) than those of tap water samples. The calculated risks from pesticide exposure through ingestion of tap water by the general populations were low. However, fipronil concentrations in lake water exceeded the benchmark value recommended for freshwater in the United States or the Netherlands. Degradation of acetamiprid into desmethyl-acetamiprid was found in lake water.

Polybrominated diphenyl ethers in indoor and outdoor dust from Southeast Asia: An updated review on contamination status, human exposure, and future perspectives.

Contamination status, potential emission sources, environmental fate, and human exposure risk of polybrominated diphenyl ethers (PBDEs) are reviewed for indoor and outdoor dust from Southeast Asian countries, under an international comparison point of view. PBDEs have been widely detected in house, workplace, car, and road dust samples collected from Indonesia, Philippines, Singapore, Thailand, and Vietnam. The highest PBDE levels up to hundreds of µg/g were found in settled dust from some e-waste processing areas in Thailand and Vietnam. Concentrations of PBDEs in house, car, and road dust from this region were generally lower than those reported in China and Western developed countries. BDE-209 was the most predominant congener in almost all analyzed samples, reflecting the widespread application of materials and products treated with commercial deca-BDE mixtures in this region. The market demand and application rate of commercial PBDE mixtures in Southeast Asia were lower than those documented for other regions in the world. As a result, PBDE contamination levels in the environments (e.g., indoor and outdoor dust) and associated risks in these countries were not significantly high. However, more attention should be paid to informal processing activities and management strategies for modern wastes such as e-waste, plastics, and end-of-life vehicles. There exist several knowledge gaps about spatiotemporal trends, potential sources, risk assessment, inventory, management, and legislation regarding PBDEs in dust from this region, which should be filled by additional comprehensive, detailed studies with relevant inter-country/regional monitoring schemes.

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.

Parabens in personal care products and indoor dust from Hanoi, Vietnam: Temporal trends, emission sources, and non-dietary exposure through dust ingestion.

The occurrence of seven typical parabens was investigated in several types of personal care products (PCPs) sold at supermarkets and in indoor dust samples collected from houses, laboratories, and medical stores in Hanoi, Vietnam. Parabens were frequently detected in PCPs regardless of the paraben indication in their ingredient labels. However, concentrations of parabens in labeled products (median 3280; range 1370-5610 µg/g) were much higher than those found in non-labeled products (69.4; not detected - 356 µg/g). Parabens were also measured in indoor dust samples of this study at elevated concentrations, ranging from not detected to 1650 (median 286 ng/g). Levels of parabens in the indoor dust samples collected in 2019 decreased in the order: house > medical store > laboratory dust, however, the difference was not statistically significant. Interestingly, levels of parabens in Vietnamese house dust exhibited an increasing trend over time, for example, mean/median concentrations of parabens in house dust samples collected in 2014, 2017, and 2019 were 245/205, 310/264, and 505/379 ng/g, respectively. Methylparaben was found at the highest frequency and concentrations in both PCPs and indoor dust samples. Mean exposure doses of total parabens through dust ingestion were estimated to be 2.02, 1.61, 0.968, 0.504, and 0.192 ng/kg-bw/d for infants, toddlers, children, teenagers, and adults, respectively. Further studies on the distribution, emission behavior, potential sources, and negative impacts of parabens in different environmental media in Vietnam are needed.

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.

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.

Bioaccumulation of PCDD/Fs in foodstuffs near Bien Hoa and Da Nang airbases: assessment on sources and distribution.

In this survey, food items were collected from vicinities of Bien Hoa and Da Nang airbase and determined for polychloro-dibenzo-dioxins and polychloro-dibenzo-furans (PCDD/Fs) to assess their accumulation, distribution in the local food items, and risk of PCDD/F exposure through consumption of the local foods. Dioxin compounds were determined using isotope dilution method which is slightly modified from US-EPA method 1613B. The dioxin concentration was the highest in fish followed by eggs, chicken, meat (pork and beef), and vegetables. Particularly, in Bien Hoa airbase, the mean concentrations of dioxin on TEQ and lipid basis (except for vegetables) were 26 pg/g for fish, 13 pg/g for eggs, 20 pg/g for chicken, 4.5 pg/g for meat, and 0.34 pg/g fresh wt for vegetables. In Da Nang airbase, the mean levels of dioxin on TEQ and lipid basis were slightly lower, 12.9 pg/g for fish, 8.7 pg/g for eggs, 5.9 pg/g for chicken, 6.7 pg/g for meat, and 0.17 pg/g for vegetables. It has been interesting to observe that free-range chicken expose to higher level of dioxin than caged chicken. In some free-range chicken, the portion of 2,3,7,8-TCDD was relatively high and implying recent exposure to dioxin.