Widespread polybrominated diphenyl ether (PBDE) contamination of urban soils in Melbourne, Australia

A critical review on BDE-209: Source, distribution, influencing factors, toxicity, and degradation

As the most widely used polybrominated diphenyl ether, BDE-209 is commonly used in polymer-based commercial and household products. Due to its unique physicochemical properties, BDE-209 is ubiquitous in a variety of environmental compartments and can be exposed to organisms in various ways and cause toxic effects. The present review outlines the current state of knowledge on the occurrence of BDE-209 in the environment, influencing factors, toxicity, and degradation. BDE-209 has been detected in various environmental matrices including air, soil, water, and sediment. Additionally, environmental factors such as organic matter, total suspended particulate, hydrodynamic, wind, and temperature affecting BDE-209 are specifically discussed. Toxicity studies suggest BDE-209 may cause systemic toxic effects on living organisms, reproductive toxicity, embryo-fetal toxicity, genetic toxicity, endocrine toxicity, neurotoxicity, immunotoxicity, and developmental toxicity, or even be carcinogenic. BDE-209 has toxic effects on organisms mainly through epigenetic regulation and induction of oxidative stress. Evidence regarding the degradation of BDE-209, including biodegradation, photodegradation, Fenton degradation, zero-valent iron degradation, chemical oxidative degradation, and microwave radiation degradation is summarized. This review may contribute to assessing the environmental risks of BDE-209 to help develop rational management plans.

The influence of various microplastics on PBDEs contaminated soil remediation by nZVI and sulfide-nZVI: Impedance, electron-accepting/-donating capacity and aging

The microplastics (MPs) existed in the environment widely has resulted in novel thinking about in-situ remediation techniques, such as nano-zero-valent iron (nZVI) and sulfided nZVI (S-nZVI), which were often compromised by various environmental factors. In this study, three common MPs such as polyvinyl chloride (PVC), polystyrene (PS), and polypropylene (PP) in soil were found to inhibit the degradation rate of decabromodiphenyl ether (BDE209) by nZVI and S-nZVI to different degrees due to MPs inhibiting of electron transfer which is the main way to degrade BDE209. The inhibition strength was related to its impedance (Z) and electron-accepting (EAC)/-donating capacity (EDC). Based on the explanation of the inhibition mechanism, the reason for different aging degrees of nZVI and S-nZVI in different MPs was illustrated, especially in PVC systems. Furthermore, the aging of reacted MPs, functionalization and fragmentation in particular, indicated that they were involved in the degradation process. Moreover, this work provided new insights into the field application of nZVI-based materials for removing persistent organic pollutants (POPs).

Insight into the photodegradation and universal interactive products of 2,2',4,4'-tetrabromodiphenyl ether on three microplastics

The transformation process of contaminants on microplastics (MPs) exposed to sunlight has attracted increasing attention. However, the interactions between them are typically disregarded; therefore, this work investigated the photodegradation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) on three MPs (polystyrene (PS), polypropylene (PP) and polyethylene (PE)) and the interactions between these two. The inhibition of aged PS on the elimination of BDE-47 was due to light shielding, while aged PP and PE increased the degradation rate. More hydroxyl radicals (HO•) was detected in the PS system, which resulted in the higher degradation rate of BDE-47 on PS. A total of 33 different products were identified and four reaction pathways were presented, and the reaction mechanisms mainly included debromination, hydroxylation, carbon-oxygen-bond breaking and interactive reactions. The Ecological Structure Activity Relationship (ECOSAR) and Toxicity Estimation Software Tool (TEST) programs were used to evaluate the toxicity of reaction products, and the results indicated that even though BDE-47 was the most toxic, the interaction products were still toxic or harmful to aquatic organisms. This study provides significant information on the photodegradation of contaminants on common microplastics and their interaction, which cannot be ignored.

Key factors controlling colloids-bulk soil distribution of polybrominated diphenyl ethers (PBDEs) at an e-waste recycling site: Implications for PBDE mobility in subsurface environment

Accumulation of polybrominated diphenyl ethers (PBDEs) in surface soils at elevated concentrations is common at e-waste recycling sites. Even though highly insoluble, migration of PBDEs into the vadose zone and groundwater is possible, due to their association with soil colloids. Here, we show that upon equilibration with artificial rainwater surface and subsurface soil samples collected at an e-waste recycling site release significant quantities of colloids, with the total concentrations of 14 PBDE congeners as high as 990 ng/g dw. The concentrations of different congeners vary markedly in the colloids, and that of BDE-209 is the highest in all the samples. Notably, even the colloids released from the soil collected at a depth of 95-105 cm contain high concentrations of PBDEs. Preferential binding of PBDEs to soil colloids is observed, with the colloids-soil distribution coefficients above 10 in certain cases. The extent of preferential binding displays no apparent correlation with the relative hydrophobicity of the PBDEs, nor can it be explained simply by considering the higher specific surface area, pore volume, and clay content of the soil colloids than the respective bulk soil. Principal component analysis shows that multiple soil properties are collectively responsible for the preferential distribution of PBDEs. Specifically, the differences in pore volume, soil organic carbon content, and pore size between colloids and soils are likely the major factors affecting the distribution of high-concentration PBDEs, whereas the differences in clay content, pore volume and specific surface area are the key factors affecting the distribution of low-concentration PBDEs. The findings clearly show that colloids are an important medium with which PBDEs are associated at contaminated sites, and underline the need of understanding colloid-facilitated transport of PBDEs at e-waste sites.

Formal waste treatment facilities as a source of halogenated flame retardants and organophosphate esters to the environment: A critical review with particular focus on outdoor air and soil

Extensive use of halogenated flame retardants (HFRs) and organophosphate esters (OPEs) has generated great concern about their adverse effects on environmental and ecological safety and human health. As well as emissions during use of products containing such chemicals, there are mounting concerns over emissions when such products reach the waste stream. Here, we review the available data on contamination with HFRs and OPEs arising from formal waste treatment facilities (including but not limited to e-waste recycling, landfill, and incinerators). Evidence of the transfer of HFRs and OPEs from products to the environment shows that it occurs via mechanisms such as: volatilisation, abrasion, and leaching. Higher contaminant vapour pressure, increased temperature, and elevated concentrations of HFRs and OPEs in products contribute greatly to their emissions to air, with highest emission rates usually observed in the early stages of test chamber experiments. Abrasion of particles and fibres from products is ubiquitous and likely to contribute to elevated FR concentrations in soil. Leaching to aqueous media of brominated FRs (BFRs) is likely to be a second-order process, with elevated dissolved humic matter and temperature of leaching fluids likely to facilitate such emissions. However, leaching characteristics of OPEs are less well-understood and require further investigation. Data on the occurrence of HFRs and OPEs in outdoor air and soil in the vicinity of formal e-waste treatment facilities suggests such facilities exert a considerable impact. Waste dumpsites and landfills constitute a potential source of HFRs and OPEs to soil, and improper management of waste disposal might also contribute to HFR contamination in ambient air. Current evidence suggests minimal impact of waste incineration plants on BFR contamination in outdoor air and soil, but further investigation is required to confirm this.

Analysis of Polybrominated Diphenyl Ethers and Lipid Composition in Human Breast Milk and Their Correlation with Infant Neurodevelopment

Breastfeeding is recommended over formula feeding, but human breast milk (HBM) composition varies and can be affected by food additives. Whether flame-retardant polybrominated diphenyl ethers (PBDEs) found in HBM interact with lipid components of HBM to impede infant neurodevelopment is a critical public health issue. Using lipidomic analysis, we examined the association of PBDEs in HBM and HBM lipid components with infant neurodevelopment. HBM samples (n = 100) were collected at the beginning stage of breastfeeding and analyzed for 30 PBDE congeners as well as a group of lipid components by using high-resolution gas chromatography, mass spectrometry, and liquid chromatography time-of-flight mass spectrometry. Infants were examined at 8 to 12 months of age by using the Bayley-III to assess neurodevelopment. A total of seven PBDEs, 35 lipids, and 27 fatty acids in HBM showed significant associations with Bayley-III scores. Multivariate analysis confirmed that these candidate PBDEs and lipid components were significant predictors of infant neurodevelopment. Eicosapentaenoic acid and docosapentaenoic acid in HBM showed no association with infant neurodevelopment in the general Taiwanese population. While certain PBDEs may play a role, our findings indicate that the lipid components of HBM are directly important for infant neurodevelopment.

Comparison of decabromodiphenyl ether degradation in long-term operated anaerobic bioreactors under thermophilic and mesophilic conditions and the pathways involved

Anaerobic digestion of decabromodiphenyl ether was carried out and compared in two continuously stirred anaerobic bioreactors for 210 days under thermophilic and mesophilic conditions. Results show that the degradation of decabromodiphenyl ether followed the first-order reaction kinetics, which exhibited a higher removal rate in the thermophilic reactor when compared to the mesophilic one, reaching its maximum of 1.1 μg·day^-1. The anaerobic digestion of decabromodiphenyl ether was found to involve the replacement of bromines from polybrominated diphenyl ether by hydrogen atoms, gradually forming nona-, octa- and hepta-brominated diphenyl ether, respectively. Under the thermophilic condition, the reactors were dominated by Bacillus sp. and Methanosarcina sp. with high bioactivity and high concentrations of debromination microorganisms.

Polybrominated diphenyl ethers in the environment: a wake-up call for concerted action in India

Polybrominated diphenyl ethers (PBDEs) are a class of persistent organic pollutants (POPs) used as flame retardants in the products utilized in day-to-day life. Their bioaccumulation, low volatility, and high persistence in the environment have led to their global spread even to remote and distant regions. The present study identifies gaps in the investigation of the neurotoxic potential of PBDEs, their effects on brain development, toxicokinetic, and their potential as a carcinogen. In India, to date, only human breast milk was assessed for levels of PBDEs, and it is suggested that other human tissues can also be explored. No data on the reproductive toxicity of PBDEs are reported from Indian cohorts. Long-range transport and deposition of PBDEs in colder regions necessitates monitoring of Himalayan regions in India. An inventory of PBDEs is required to be made for addressing the worrisome situation of the unregulated import of E-waste from the developed countries in India. The study also emphasizes providing guidelines for the articulation of policies regarding sound surveillance and management of PBDE production, consumption, and release in the Indian context. It is recommended that a separate cell for monitoring and follow-up of PBDEs should be established in India. Also, the development of better alternatives and environment-friendly remediation technologies for PBDEs is the need of the hour.

Effects of polymer aging on sorption of 2,2',4,4'-tetrabromodiphenyl ether by polystyrene microplastics

The sorption behavior of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) on aged polystyrene (PS) microplastics via seawater soaking, ultraviolet (UV) irradiation, seawater soaking and UV irradiation together was investigated. The effects of environmental factors including salinity, pH, and dissolved organic matter (DOM) on sorption of BDE-47 by the aged PS microplastics were analyzed. The equilibrium sorption capacity of BDE-47 by virgin PS, aged PS with seawater soaking, aged PS with UV irradiation and aged PS with seawater soaking and UV irradiation was 6.16, 4.96, 3.53, and 3.75 ng/g, respectively. The decrease in sorption capacity was related to the increase of surface crystallinity and the appearance of surface oxygen-containing functional groups. The kinetic and isotherm models suggested that aging did not change the sorption mechanism of BDE-47 on PS microplastics. pH had negligible impacts on BDE-47 sorption by virgin and aged PS. Sorption capacity of BDE-47 on aged PS in water with high salinity was lower than that on virgin PS, and DOM has less effect on the sorption of BDE-47 on aged PS.

Levels and distribution of polybrominated diphenyl ethers in humans and environmental compartments: a comprehensive review of the last five years of research

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants (BFRs), present in the environment, animals, and humans. Their levels, distribution, and human exposure have been studied extensively, and over the last decade, various legal measures have been taken to prohibit or minimize their production and use due to the increasing amount of evidence of their harmful effects on human and animal health.Our aim here was to make a comprehensive and up-to-date review of the levels and distribution of PBDEs in the aquatic environment, air, and soil, in indoor dust, and in humans. To fulfill this, we searched through Web of Science for literature data reported in the last five years (2015-2019) on levels of at least six key PBDE congeners in abovementioned matrices. According to our summarized data, significant PBDE mass concentrations/fractions are still being detected in various sample types across the world, which implies that PBDE contamination is an ongoing problem. Secondary sources of PBDEs like contaminated soils and landfills, especially those with electronic and electrical waste (e-waste), represent a particular risk to the future and therefore require a special attention of scientists.

Emerging and legacy contaminants across land-use gradients and the risk to aquatic ecosystems

Information on potentially harmful emerging and legacy chemicals is essential to understand the risks to the environment and inform regulatory actions. The objective of this study was to assess the occurrence, concentration, and distribution of emerging and legacy contaminants across a gradient of land-use intensity and determine the risk posed to aquatic ecosystems. The land-use intensity gradient considered was: background/undeveloped < low-intensity agriculture < high-intensity agriculture < urban residential < urban industrial. Twenty-five sites were sampled for surface water, sediment, and soil. A total of 218 chemicals were analyzed: pesticides, per- and poly-fluoroalkyl substances (PFAS), polybrominated biphenyls and polybrominated diphenyl ethers (PBDEs), phthalates, and short-chain chlorinated paraffins (SCCPs). The risk posed by the analyzed chemicals to the aquatic environment was measured using hazard quotients (HQs), which were calculated by dividing the maximum measured environmental concentration by a predicted no-effect concentration for each chemical. A HQ > 1 was considered to indicate a high risk of adverse effects from the given chemical. A total of 68 chemicals were detected: 19 pesticides, 18 PFAS, 28 PBDEs, two phthalates, and SCCPs (as total SCCPs). There were no significant differences in the overall chemical composition between land uses. However, the insecticide bifenthrin, PFAS, PBDEs, and phthalates were more frequently found in samples from residential and/or industrial sites, suggesting urban land uses are hotspots and potential large-scale sources of these chemicals. Nineteen chemicals had a HQ > 1; most had a restricted spatial distribution limited to high-intensity agriculture and industrial sites in Melbourne. Bifenthrin and the perfluorooctanesulfonic acid (PFOS) had the highest HQs in residential and industrial sites, suggesting an increased risk to aquatic ecosystems in urban settings. The results of this study will enhance future research, predictive methods, and effective targeting of monitoring, and will help guide regulatory management actions and mitigation solutions.

Temporal and spatial surveys of polybromodiphenyl ethers (PBDEs) contamination of soil near a factory using PBDEs in northern Taiwan

Polybrominated diphenyl ethers (PBDEs), previously commonly used as flame retardants, should be monitored in the environment since some are listed as persistent organic pollutants. A contaminated site near a northern Taiwan factory using decabrominated diphenyl ether (deca-BDE) was identified based on a vegetable PBDEs monitoring project in 2013. The subsequent spatial and temporal survey of that contaminated site shows the contamination ingredients in soils were close to ones used by the factory, indicating that contamination was from the factory, possibly through an exhaust vent. The average concentration of deca-BDE in the main contaminated soil was 615 μg/kg d. w. (dry weight) soil in 2015, slightly decreasing to 604 μg/kg d. w. soil in 2016, increasing to 844 μg/kg d. w. soil in 2017, and then slightly decreasing to 670 μg/kg d. w. soil in 2018. The slight change of deca-BDE and the minor change in low brominated congener level indicate a low degradation rate. The contamination of peripheral sites was around 5000 μg/kg d. w. soil for one PBDEs sampling site that was higher than those around or within the main contaminated farm, indicating serious pollution. Concentrations of PBDEs in different soil depths show that depth 2-15 cm accounted for the greatest PBDEs accumulation, indicating that deca-BDE pollution had been present over time and transported into deeper soil. There can be PBDEs uptake by crops consumed by humans, as shown in our previous studies, so continuous monitoring of PBDEs in this site is important and treatments should be established urgently.

Polybrominated Diphenyl Ethers in Surface Soils from the Yellow River Delta Natural Reserve, China: Occurrence, Sources, and Potential Risk

A total of 39 lower brominated PBDE congeners in surface soils from the Yellow River Delta Natural Reserve (YRDNR) were analyzed in the present study. The total concentrations of PBDEs (ΣPBDEs) ranged from "not detected" to 0.732 ng g^-1, with a mean concentration of 0.142 ng g^-1. The concentrations of the ΣPBDEs displayed no correlation with the content of the total organic carbon in the YRDNR. The ΣPBDEs concentrations in the Experimental Area were significantly higher than that of the Buffer Area and Core Area, and ΣPBDEs in soils in the North were lower than that of the South. PentaBDEs and HexaBDEs were the most abundant homologues, and the occurrence of PBDEs in the YRDNR may be attributed to the debromination and long range transport of DecaBDEs. Even though the cancer risk and mass inventory of PBDEs in the present study area were estimated to be very low, due to the widespread presence of PBDEs and the particularity of the natural reserve, vigilance should not be let up on the issue of environmental contamination caused by these compounds despite the gradual phase out of their commercial products in the world.

The occurrence of polybrominated diphenyl ether (PBDE) contamination in soil, water/sediment, and air

As a kind of brominated flame retardants (BFRs), polybrominated diphenyl ethers (PBDEs) are extensively used in different types of electronic equipment, furniture, plastics, and textiles. PBDEs are ubiquitous environmental contaminants that may impact human health and ecosystems. Here we highlight recent findings on the occurrence, contamination status, and transport of PBDEs in soil, water/sediment, and air. Four aspects are discussed in detail: (1) sources of PBDEs to the environment; (2) occurrence and transport of PBDEs in soil; (3) PBDEs in aquatic ecosystems (water/sediment) and their water-sediment partitioning; and (4) the occurrence of PBDEs in the atmosphere and their gas-particle partitioning. Future prospects for the investigation on PBDEs occurrence are also discussed based on current scientific and practical needs.

Trace metals in e-waste lead to serious health risk through consumption of rice growing near an abandoned e-waste recycling site: Comparisons with PBDEs and AHFRs

Despite the endeavour to eradicate informal e-waste recycling, remediation of polluted sites is not mandatory in many developing countries and thus the hazard of pollutants remaining in soil is often overlooked. It is noteworthy that a majority of previous studies only analysed a few pollutants in e-waste to reflect the impact of informal e-waste recycling. However, the actual impact may have been largely underestimated since e-waste contains various groups of pollutants and the effect of some emerging pollutants in e-waste remains unexplored. Thus, this study examined the contamination of metals, PBDEs and AHFRs in the vicinity of an abandoned e-waste recycling site. The accumulation and translocation of these pollutants in rice plants cultivated at the nearby paddy field were measured to estimate the health risk through rice consumption. We revealed that the former e-waste burning site was still seriously contaminated with some metals (e.g. Sn, Sb and Ag, I_geo > 5), PBDEs (I_geo > 3) and AHFRs (I_geo > 3), which can disperse to the nearby paddy field and stream. The rice plants can effectively absorb some metals (e.g. Mo, Cr and Mn, BCF > 1), but not PBDEs and AHFRs (BCF < 0.15), from soil and translocate them to the leaves. Alarmingly, the health risk through rice consumption was high primarily due to Sb and Sn (HQ > 20), whereas PBDEs and AHFRs had limited contribution (HQ < 0.08). Our results imply that abandoned e-waste recycling sites still act as the pollution source, jeopardising the surrounding environment and human health. Since some trace metals (e.g. Sb and Sn) are seldom monitored, the impact of informal e-waste recycling would be more notorious than previously thought. Remediation work should be conducted promptly in abandoned e-waste recycling sites to protect the environment and human health.

Occurrence and distribution of polybrominated diphenyl ethers in soils from an e-waste recycling area in northern China

Polybrominated diphenyl ethers (PBDEs) are widespread persistent organic pollutants (POPs) because of their extensive use in diverse electronic products, which have posed great threats to human health and ecosystem. In this study, a total of 54 soil samples were collected from an e-waste recycling area in Tianjin, northern China for analyzing the occurrence and distribution of 14 PBDE congeners. The concentrations of BDE 209, ∑₁₃PBDEs and ∑₁₄PBDEs in the soils from Ziya e-waste recycling area were 2.9-2666 ng/g dw (dry weight) (average 90 ng/g dw), 3.0-41 ng/g dw (average 13 ng/g dw) and 5.9-2699 ng/g dw (average 103 ng/g dw), respectively. The ∑₁₄PBDEs concentration showed a dramatic decrease from the central area to the surrounding area. Generally, PBDEs in the northern part showed higher levels than the southern part of the e-waste recycling area due to the wind direction in Tianjin. Deep soil was less polluted by PBDEs, which largely comes from the deposition, migration and infiltration of PBDEs in the surface soils. Overall, PBDEs level in the studied area was much lower than some typical e-waste recycling areas in south China, such as Guiyu and Qingyuan, but significantly higher than the non-e-waste recycling areas. BDE 209, BDE 138 and BDE 28 were the three dominant PBDE congeners in the soil. Principal component analysis (PCA) indicated that the commercial penta-BDEs and deca-BDE could be considered as the main sources of PBDEs pollution in this region. Redundancy analysis (RDA) suggested that the local PBDEs sources rather than soil properties influenced the PBDEs distribution in Ziya e-waste recycling area. This study systematically revealed the occurrence and distribution of PBDEs in soils from the biggest established circular economy park in northern China.

Extracellular polymeric substances (EPS) modulate adsorption isotherms between biochar and 2,2',4,4'-tetrabromodiphenyl ether

Extracellular polymeric substances (EPS), chars and persistent organic pollutants (POPs) frequently coexist in the environment. However, a knowledge gap exists regarding their interactions. Therefore, we applied 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) as a model POP to investigate the influence of bovine serum albumin (BSA) and sodium alginate (SA) - representing protein and polysaccharide components of EPS - on POP adsorption to biochars. Surface activities of tested biochars were characterised using nuclear magnetic resonance, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The adsorption capacities of BDE-47 on biochars were significantly improved by both EPS analogues: BSA at concentrations of only 5 mg L^-1 and SA at 80 mg L^-1 at c_e = 1 S_w BDE-47 concentration. However, 80 mg L^-1 BSA decreased the BDE-47 adsorption capacities on biochars at the tested BDE-47 concentrations. Chemisorption and pore filling mechanisms appeared to dominate the adsorption process of BDE-47 on maize straw and wheat straw biochars. After adding BSA (or SA), a hydrophobic partition effect was found to best explain the adsorption process and linearity of adsorption was enhanced. These results progress our understanding of bioavailability and migration of POPs: especially relevant to the water industry and biochar/EPS facilitated removal of these contaminants.

Spatial Distribution of Novel and Legacy Brominated Flame Retardants in Soils Surrounding Two Australian Electronic Waste Recycling Facilities

Informal recycling of electronic waste (e-waste) has been shown to cause significant brominated flame retardant (BFR) contamination of surrounding soils in a number of Asian and West African countries. However, to the authors' knowledge, there have been no published studies demonstrating polybrominated diphenyl ether (PBDE) and novel brominated flame retardant (NBFR) soil contamination from regulated "formal" e-waste processing facilities in developed countries. This study reports on PBDEs (-28, -47, -99, -100, -153, -154, -183, and -209) and NBFRs (PBT, PBEB, HBB, EH-TBB, BTBPE and DBDPE) in 36 soil samples surrounding two Australian e-waste recycling plants and a further eight reference soils. Overall ∑PBDE concentrations ranged 0.10-98 000 ng/g dw (median; 92 ng/g dw) and ∑NBFRs ranged ND-37 000 ng/g dw (median 2.0 ng/g dw). Concentrations in soils were found to be significantly negatively associated with distance from one of the e-waste facilities for ∑penta-BDEs, BDE-183, BDE-209, and ∑NBFR compound groups. ANOVA tests further illustrated the potential for e-waste recycling to significantly elevate concentrations of some BFRs in soils over distances up to 900 m compared to references sites. This study provides the first evidence of soil contamination with PBDEs and NBFRs originating from formal e-waste recycling facilities in Australia, which may have implications for e-waste recycling practices throughout the world.

Multi-component determination of atmospheric semi-volatile organic compounds in soils and vegetation from Tarragona County, Catalonia, Spain

Tarragona County (Spain) is home to the most important chemical/petrochemical industrial complex in Southern Europe, which raises concerns about the presence and effects of the numerous environmental contaminants. In order to assess the levels and patterns of five classes of semi-volatile organic compounds (SVOCs) - polycyclic aromatic hydrocarbons (PAHs), synthetic musks (SMs), polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs) and one organochlorine pesticide, hexachlorobenzene (HCB), 27 samples of soil and vegetation (Piptatherum L.) from different areas (petrochemical, chemical, urban/residential, and background) of Tarragona County were analysed. The results show that PAHs levels in soils ranged from 45.12 to 158.00ng/g and the urban areas presented the highest concentrations, mainly associated with the presence of a nearby highway and several roads with heavy traffic. PAHs levels in vegetation samples ranged from 42.13 to 80.08ng/g, where the greatest influence came from the urban and petrochemical areas. In the case of SMs, levels in soils and vegetation samples ranged from 5.42 to 10.04ng/g and from 4.08 to 17.94ng/g, respectively, and in both cases, background areas (at least 30km away from the main SVOCs emission sources) showed the highest levels, suggesting an influence of the personal care products derived from beach-related tourism in the coast. PCBs (from 6.62 to 14.07ng/g in soils; from 0.52 to 4.41ng/g in vegetation) prevailed in the chemical area in both matrices, probably associated with the presence of two sub-electrical stations located in the vicinities. In general terms, BFRs and HCB values recorded in soil and vegetation samples were quite similar between matrices and sampling areas.

PBDEs and novel brominated flame retardants in road dust from northern Vietnam: Levels, congener profiles, emission sources and implications for human exposure

Polybrominated diphenyl ethers (PBDEs) and selected novel brominated flame retardants (NBFRs) were examined in road dust samples collected from three representative areas in northern Vietnam, including seven inner districts of Hanoi metropolitan area, an industrial park in Thai Nguyen province and a rural commune in Bac Giang province. This study aims to provide basic information on the contamination status, potential sources and human exposure to PBDEs and NBFRs associated with road dust in northern Vietnam. PBDEs were detected in all the samples at a range of 0.91-56 ng g^-1 with a median value of 16 ng g^-1. PBDE concentrations in road dusts from urban sites were significantly higher than those from industrial zone and rural area, suggesting their environmental load related to urbanization in northern Vietnam. BDE-209, major component of deca-BDE technical mixtures, dominated the congener patterns in all samples, accounting for 60.8-91.9% of total PBDE levels. Decabromodiphenyl ethane, an alternative of deca-BDE, was observed in a detection frequency of 100% in urban and industrial areas and at levels comparable to those of BDE-209. Other NBFRs such as pentabromoethylbenzene, hexabromobiphenyl and 1,2-bis-(2,4,6-tribromophenoxy)ethane, were found at trace levels. Daily intake doses of PBDEs via road dust ingestion from 2.3 × 10^-5 to 0.11 ng kg-bw^-1 d^-1 were estimated for residents in study areas, indicating a negligible risk with hazard indexes of 10^-9 to 10^-5 for selected congeners such as BDE-47, 99, 153 and 209.

Critical review of soil contamination by polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFRs); concentrations, sources and congener profiles

Polybrominated diphenyl ethers (PBDEs) have been used in a broad array of polymeric materials such as plastics, foams, resins and adhesives to inhibit the spread of fires since the 1970s. The widespread environmental contamination and well documented toxic effects of PBDEs have led to bans and voluntary withdrawals in many jurisdictions. Replacement novel brominated flame retardants (NBFRs) have, however, exhibited many of the same toxic characteristics as PBDEs and appear to share similar environmental fate. This paper presents a critical review of the scientific literature regarding PBDE and NBFR contamination of surface soils internationally, with the secondary objective of identifying probable pollution sources. An evaluation of NBFR distribution in soil was also conducted to assess the suitability of the newer compounds as replacements for PBDEs, with respect to their land contamination potential. Principle production of PBDEs and NBFRs and their consequent use in secondary polymer manufacture appear to be processes with strong potential to contaminate surrounding soils. Evidence suggests that PBDEs and NBFRs are also released from flame retarded products during disposal via landfill, dumping, incineration and recycling. While the land application of sewage sludge represents another major pathway of soil contamination it is not considered in this review as it is extensively covered elsewhere. Both PBDEs and NBFRs were commonly detected at background locations including Antarctica and northern polar regions. PBDE congener profiles in soil were broadly representative of the major constituents in Penta-, Octa- and Deca-BDE commercial mixtures and related to predicted market place demand. BDE-209 dominated soil profiles, followed by BDE-99 and BDE-47. Although further research is required to gain baseline data on NBFRs in soil, the current state of scientific literature suggests that NBFRs pose a similar risk to land contamination as PBDEs.