Investigation of Urinary Metabolites of Organophosphate Esters in Hanoi, Vietnam: Assessment Exposure and Estimated Daily Intake.

In recent years, organophosphate esters (OPEs) have become one of the most common additives in various consumer products worldwide, therefore the exposure and impact of OPEs on human health are drawing a lot of attention. In this study, three metabolites of OPEs including bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), diphenyl phosphate (DPhP) and diethyl phosphate (DEP) were investigated in first-morning void urine samples taken from a population (age range: 3-76 years old) in Hanoi, Vietnam. The most dominant urinary OPE metabolite was DEP with the geometric mean of specific gravity adjust (SG-adjusted) concentration were 1960 ng mL-1 and detected frequency (DF) of 98%. Followed by DPhP (8.01 ng mL-1, DF: 100%) and BDCIPP (2.18 ng mL-1, DF: 51%). The results indicated that gender and age might have associations with the OPE metabolites variation in urine samples. The levels of OPE metabolites in urine samples from females were slightly higher than in males. An increase in age seems to have an association with a decrease in DPhP levels in urine. Exposure doses of parent OPEs were evaluated from the unadjusted urinary concentration of corresponding OPE metabolite. The estimated exposure doses of triethyl phosphate (TEP) (mean: 534,000 ng kg-1 d-1) were significantly higher than its corresponding reference dose, suggesting the high potential risk from the current exposure doses of TEP to human health. The results of this work provided the initial information on the occurrence of three OPE metabolites in urine from Hanoi, Vietnam and estimated exposure dose of corresponding parent OPEs.

Occurrence and ecological risk assessment of organophosphate esters in surface water from rivers and lakes in urban Hanoi, Vietnam.

In this study, an investigation on the pollution status, distribution, and ecological risk to the aquatic organisms of six organophosphate tri-esters (tri-OPEs) and two organophosphate tri-esters (di-OPEs) in surface water in urban Hanoi, Vietnam were conducted. In 37 surveyed water samples (6 rivers and 17 lakes), all eight targeted OPEs were discovered with a detection frequency (DF) of 41-100% and the concentration varied largely from below the method detection limit (

Occurrence and risk of human exposure to organophosphate flame retardants in indoor air and dust in Hanoi, Vietnam.

The presence and distribution of thirteen organophosphate flame retardants (OPFRs) were investigated in indoor air and dust samples collected in Hanoi, Vietnam. The total OPFRs (Æ©OPFRs) concentrations in indoor air and dust samples were 42.3-358 ng m-3 (median 101 ng m-3) and 1290-17,500 ng g-1 (median 7580 ng g-1), respectively. The profile of OPFRs in both indoor air and dust indicated that tris(1-chloro-2-propyl) phosphate (TCIPP) was the most dominant compound with a median concentration of 75.3 ng m-3 and 3620 ng g-1, contributing 75.2% and 46.1% to Æ©OPFRs concentrations in indoor air and dust, respectively, followed by tris(2-butoxyethyl) phosphate (TBOEP), with a median concentration of 16.3 ng m-3 and 2500 ng g-1, contributing 14.1% and 33.6% to Æ©OPFRs concentrations in indoor air and dust, respectively. The levels of OPFRs in the indoor air samples and corresponding indoor dust samples showed a strong positive correlation. The total estimated daily intakes (EDItotal) of Æ©OPFRs (via air inhalation, dust ingestion, and dermal absorption) for adults and toddlers under the median and high exposure scenarios were 36.7 and 160 ng kg-1 d-1, and 266 and 1270 ng kg-1 d-1, respectively. Among the investigated exposure pathways, dermal absorption was a primary exposure pathway to OPFRs for both toddlers and adults. The hazard quotients (HQ) ranged from 5.31 × 10-8 to 6.47 × 10-2 (<1), and the lifetime cancer risks (LCR) were from 2.05 × 10-11 to 7.37 × 10-8 (<10-6), indicating that human health risks from exposure to OPFRs in indoor environments are not significant.

Sediment contamination with polybrominated diphenyl ethers and alternative brominated flame retardants: case study in urban lakes of Hanoi, Vietnam.

Information regarding the contamination of brominated flame retardants (BFRs) in lake sediments from Vietnam and Southeast Asia is still very limited. To fill such knowledge gaps, surface sediment samples from five urban lakes in Hanoi, Vietnam, were analyzed for polybrominated diphenyl ethers (PBDEs) and some other BFRs. Concentrations of total PBDEs ranged from 1.1 to 26 (median 6.6) ng/g dry weight with the most predominant congeners as BDE-209 (62 ± 17%), BDE-99 (10 ± 8%), and BDE-47 (6 ± 5%). Concentrations of other BFRs decreased in the order: decabromodiphenyl ethane (DBDPE) > 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) > hexabromobiphenyl (BB-153) > pentabromoethylbenzene (PBEB), which were about one to two orders of magnitude lower than PBDEs. BDE-209 and DBDPE were highly correlated (Pearson's r = 0.879; p < 0.01), suggesting their similar applications and/or environmental fate. Potential sources of BFRs in lake sediments are estimated to be wastewater discharge, riverine inflow, and atmospheric deposition.

Occurrence, potential sources, and risk assessment of pharmaceuticals and personal care products in atmospheric particulate matter in Hanoi, Vietnam.

Pharmaceutical and personal care products (PCPPs) were recently recognized as emerging pollutants due to their potential for adverse health and environmental impacts. One potential route of exposure, atmospheric particulate matter (APM), for polar PPCP chemicals has to date received limited attention. This study screened for 190 polar PPCP chemicals in outdoor APM samples collected from two locations in Hanoi, Vietnam, and predictions of source and potential effects on human health are presented. Day and night, as well as dry and rainy seasonal samples, were taken, and samples screened by LC-TOF, using sequential window acquisition and all theoretical fragment ion spectra method. Eleven PPCP chemicals were detected above the LOD and in more than one sample. The ∑11PPCP chemicals ranged from 0.61 to 21.9 ng m-3 (median 2.07 ng m-3), with between 2 and 6 compounds identified in individual samples (median 4). The ∑11PPCP chemicals collected near a heavy traffic area was greater than that in a populated residential zone. Night concentrations were significantly greater than day in both dry and rainy seasons (p < 0.05). Butyl methoxydibenzoylmethane, benzophenone-3, acetaminophen, cotinine, and fluorescent brightener 71 were detected in > 50% of samples. These are typically found in sunscreens, cosmetics, antipyretics, tobacco, and dyes. The DIair, hazard quotient (HQ), and hazard index (HI) for adults and children at sampling sites were estimated. The HQ for both adults and children were orders of magnitude less than the risk or were close to or whichever. APM does appear to be a potential additional secondary exposure source of PPCP chemicals to the environment and more work is needed to identify if sources are local or ubiquitous and if there is a greater health risk.

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

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

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.

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

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

Comprehensive Study of Organic Micro-pollutants in Flooded Paddy Soils in Central Vietnam: Levels, Pollution Pathways and Sources.

In order to assess the environmental impacts caused by flood to the paddy field, 940 semi-volatile organic compounds (SVOCs) were screened in paddy soil samples taken in central Vietnam before and after flooding. The concentration of 166 SVOCs in soil samples ranged from 0.031 to 2241 (mean 89.1) µg kg-1 dry wt. Chemicals originating from household sources showed the highest level, followed by chemicals originating from agriculture. Since untreated domestic wastewater used for agricultural irrigation, organic micro-pollutants in domestic wastewater is the main source of pollutants in paddy soil. However, contamination levels of pollutants in paddy soil after flooding were lower than those before flooding, possibly due to the removal of pollutants by floodwater. As a result, pollution characteristic of pollutants at sampling locations were different before flooding while they became similar after flooding due to the dispersion and elution of organic pollutants from soil into floodwaters.

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

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

Simultaneous effect of dissolved organic carbon, surfactant, and organic acid on the desorption of pesticides investigated by response surface methodology.

Desorption of pesticides (fenobucarb, endosulfan, and dichlorodiphenyltrichloroethane (DDT)) from soil to aqueous solution with the simultaneous presence of dissolved organic carbon (DOC), sodium dodecyl sulfate (SDS), and sodium oxalate (Oxa) was investigated in batch test by applying a full factorial design and the Box-Behnken response surface methodology (RSM). Five concentration levels of DOC (8 to 92 mg L-1), SDS (0 to 6.4 critical micelle concentration (CMC)), and Oxa (0 to 0.15 M) were used for the experiments with a rice field topsoil. The results of RSM analysis and analysis of variance (ANOVA) have shown that the experimental data could be well described by quadratic regression equations with determination coefficients (R 2) of 0.990, 0.976, and 0.984 for desorption of fenobucarb, endosulfan, and DDT, respectively. The individual effects and interaction of DOC, SDS, and Oxa were evaluated through quadratic regression equations. When the aqueous solution includes 50 mg L-1 DOC, 3.75 CMC SDS, and 0.1 M Oxa, the maximum desorption concentrations of fenobucarb, endosulfan, and DDT were 96, 80, and 75 µg L-1, respectively. The lowest concentration of SDS, DOC, and Oxa caused the minimum desorption. This point at conditions of concern for flooding water is high content of organic compounds causing potentially high contamination by desorption, and the remarkably lower desorption at organic matter-free conditions. The suspended organic matter is one of the common characteristics of flooding and irrigation water in rice fields, and surfactants from pollution increase the problem with desorption of legacy pesticides in the rice fields.

Screening of inorganic and organic contaminants in floodwater in paddy fields of Hue and Thanh Hoa in Vietnam.

In the rainy season, rice growing areas in Vietnam often become flooded by up to 1.5 m water. The floodwater brings contaminants from cultivated areas, farms and villages to the rice fields resulting in widespread contamination. In 2012 and 2013, the inorganic and organic contaminants in floodwater was investigated in Thanh Hoa and Hue. Water samples were taken at 16 locations in canals, paddy fields and rivers before and during the flood. In total, 940 organic micro-pollutants in the water samples were determined simultaneously by GC-MS method with automatic identification and quantification system (AIQS), while ICP-MS was used for determination of ten trace elements in the samples. The concentrations of 277 organic micro-pollutants and ten elements (As, Cu, Cd, Cr, Co, Pb, Zn, Fe, Mn, Al) ranged from 0.01 to 7.6 µg L-1 and 0.1 to 3170 µg L-1, respectively, in the floodwater. Contaminants originated from industrial sources (e.g. PAH) were detected at low concentrations, ranged from 0.01 to 0.18 µg L-1, while concentrations of pollutants originated from domestic sources (e.g. sterols, pharmaceuticals and personal care products and pesticides) were ranged from 0.01 to 2.12 µg L-1. Isoprocarb had the highest detection frequency of 90%, followed by isoprothiolane (88%) and fenobucarb (71%). The results indicated that contaminants in floodwater come from untreated wastewater from villages, and the agricultural activities are the major sources of increased pesticides resuspended in the floodwater in this study.