Concentrations Of Halogenated Flame Retardants Research Articles

Species-specific and habitat-dependent bioaccumulation of halogenated flame retardants in marine organisms from estuary to coastal seas

Halogenated flame retardants (HFRs) have attracted global attention owing to their adverse effects on ecosystems and humans. The Shandong Peninsula is the largest manufacturing base for HFRs in East Asia, yet its impacts on marine ecosystems are unclear. Seventeen HFRs were analyzed in organisms captured from the Xiaoqing River estuary, Bohai Sea (BS), Yellow Sea and Northern East China Sea to investigate the distribution and bioaccumulation of HFRs on a broad scale. The results showed a downward trend in ΣHFR concentrations from the estuary (37.7 ng/g lw on average) to Laizhou Bay (192 ng/g lw) and to coastal seas (3.13 ng/g lw). The concentrations of ΣHFRs were significantly higher in demersal fish (0.71–198 ng/g lw) and benthic invertebrates (0.81–3340 ng/g lw) than in pelagic fish (0.30–27.6 ng/g lw), reflecting a habitat dependence. The concentrations of higher-brominated homologs were greater in benthic invertebrates, whereas a greater level of lower-brominated PBDE congeners was observed in fish, suggesting different profiles between species. Furthermore, the analogue composition of HFRs in fish was similar to that in the dissolved phase of seawater, whereas the HFR pattern in benthic invertebrates was consistent with the profile in sediment. The concentrations of HFRs in organisms vary widely depending on emissions from anthropogenic activities, whereas bioaccumulation patterns are strongly influenced by species and habitat.

Bioaccessibility of halogenated flame retardants and organophosphate esters in settled dust: Influences of specific dust matrices from informal e-waste and end-of-life vehicle processing areas in Vietnam

Bioaccessibility of halogenated flame retardants (HFRs) and organophosphorus esters (OPEs) is necessarily investigated to provide more accurate risk assessment and information about absorption behavior of these pollutants. In this study, total and bioaccessible concentrations of HFRs (including legacy and alternative substances) and OPEs were determined in settled dust samples collected from Vietnamese e-waste and end-of-life vehicle (ELV) processing areas. Concentrations of both HFRs and OPEs were significantly higher in the e-waste dust than ELV dust. Bioavailability of HFRs and OPEs in dust was determined by using an in vitro assay with human-simulated digestive fluids, dialysis membrane, and Tenax® TA sorptive sink. Bioaccessibility of HFRs was markedly lower than that of OPEs, which could be largely due to higher hydrophobicity of HFRs compared to OPEs. Bioaccessibility of almost hydrophobic compounds were markedly lower in the e-waste dust (containing micronized plastic debris) than in the ELV dust (containing oily materials), suggesting the influence of specific dust matrices on pollutant bioaccessibility. Although the daily uptake doses of selected HFRs and OPEs from dust were markedly higher in the e-waste sites compared to the ELV sites, the direct exposure risk was not significant. Our results suggest that bioaccessibility can partly explain the differences between dust and uptake profiles, which may relate to accumulation profiles of HFRs and OPEs in human samples.

Temporal Trends of Legacy and Current-Use Halogenated Flame Retardants in Lake Ontario in Relation to Atmospheric Loadings, Sources, and Environmental Fate.

Since the phase-out of polybrominated diphenyl ethers (PBDEs), large amounts of alternative halogenated flame retardants (AHFRs) have been introduced to the market. Due to their persistence and toxicity, halogenated flame retardants (HFRs) have become a concern for the ecosystem and human health. However, there remains limited assessment of the atmospheric loadings, sources, and environmental fate of HFRs in Lake Ontario, which receives urban-related inputs and cumulative chemical inputs from the upstream Great Lakes from Canada and the United States. We combined long-term measurements with a modified multimedia model based on site-specific environmental parameters from Lake Ontario to understand the trends and fate of HFRs. All HFRs were detected in the air, precipitation, lake trout, and herring gull egg samples throughout the sampling periods. General decreasing trends were found for PBDEs, while the temporal trends for AHFRs were not clear. Physical-chemical properties and emissions significantly influence the levels, profiles, and trends. Using the probabilistic modeling, HFR concentrations in lake water and sediment were predicted to be close to the measurement, suggesting a good performance for the modified model. The loadings from tributaries and wastewater effluent were the primary input pathways. Transformations in the water and sedimentation were estimated to be the dominant output pathway for the three HFRs.

Influence of hydrodynamic conditions on the fate of halogenated flame retardants along salinity gradients in a highly polluted micro-tidal estuary

Halogenated flame retardants (HFRs) have properties similar to those of hydrophobic organic pollutants (HOPs). However, the understanding of their environmental fate in tidal estuaries remains limited. This study aims to bridge knowledge gaps regarding the land-sea transport of HFRs through riverine discharge into coastal waters. HFR levels were significantly influenced by tidal movement, and decabromodiphenyl ethane (DBDPE) was the predominant compound with a median concentration of 3340 pg L−1 in the Xiaoqing River estuary (XRE), whereas BDE209 had a median concentration of 1370 pg L−1. The Mihe River tributary plays a key role in transporting pollution to the downstream estuary of the XRE in summer, and the increasing suspended particulate matter (SPM) by resuspension in winter significantly affects HFR levels. These concentrations were inversely proportional to diurnal tidal oscillations. Tidal asymmetry caused an increase in SPM during an ebb tide, which increased HFR levels in a micro-tidal estuary such as the Xiaoqing River. The location of the point source and flow velocity influences the HFR concentrations during tidal fluctuations. Tidal asymmetry increases the likelihood of some HFRs being adsorbed by particles exported to the adjacent coast, and some settled down in areas with low hydrodynamic conditions, hindering their flow to the ocean.

Assessment of organohalogenated pollutants in breast milk from the Czech Republic

This biomonitoring survey brings new information on the occurrence of a total of 94 organohalogenated pollutants in 231 human breast milk samples collected in 2019 and 2021 from women living in two regions of the Czech Republic (Karvina and Ceske Budejovice). This study aimed to evaluate the concentrations of 6 indicator polychlorinated biphenyls (PCBs), 10 organochlorine pesticides (OCPs), 34 halogenated flame retardants (HFRs), 29 perfluoroalkyl and polyfluoroalkyl substances (PFAS) and 15 polychlorinated naphthalenes (PCNs). PCBs, OCPs, most of HFRs and PCNs were identified/quantified by gas chromatography coupled to (tandem) mass spectrometry (GC–MS(/MS)), while PFAS, hexabromocyclododecane isomers (HBCD), brominated phenols, and tetrabromobisphenol A (TBBPA) by ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC–MS/MS). The mean value of the sum of the 6 indicator PCBs was 123.12 nanogram per gram of lipid weight (ng g−1 lw). Hexachlorobenzene (HCB), β-hexachlorocyclohexane (β-HCH) and p,p’-dichlorodiphenyl-dichloroethylene (p,p’-DDE) were the most abundant OCPs, detected in 100 % (mean 11.8 ng g−1 lw), 94.8 % (mean 6.1 ng g−1 lw) and 100 % (mean 101.5 ng g−1 lw) of samples, respectively. PCN congeners 20, 52 and 66 were detected in <1 % of the samples. The HFRs concentrations were relatively low compared to the levels of OCP; The detection rate of polybrominated diphenyl ethers (PBDEs, # 47, 99 and 153) ranged 21–68 % with a mean concentrations of 0.34 ng g−1 lw - 0.42 ng g−1 lw. PFAS concentrations were also low, with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) dominant in this group (means of 22 pg ml−1 and 21 pg ml−1, respectively). Our results confirmed the long-term trend of declining levels of banned POPs in Czech mothers. The amounts of PCBs and OCPs were higher in older breastfeeding primiparous women.

Investigating the relationship between the skin microbiome and flame retardant exposure of the endangered St. Lawrence Estuary beluga

The endangered beluga (Delphinapterus leucas) population in the St. Lawrence Estuary (SLE) in eastern Canada, the largest estuary in the world, is declining. Elevated tissue concentrations of a wide range of environmental contaminants, for example, halogenated flame retardants (HFRs) including polybrominated diphenyl ethers (PBDEs), might play a role in the non-recovery of this population. In mammals, HFRs have been reported to impair the metabolic regulation, including amino acid and fatty acid pathways. In the present study, we collected both blubber and skin swab samples from tissue biopsies from 56 adult SLE belugas and analyzed their blubber for the concentrations of a comprehensive suite of PBDEs and other HFRs. Using 16S rRNA marker and shotgun metagenomic approaches using skin swabs, we investigated, for the first time, the SLE beluga skin microbiome and the SLE water microbiome, providing valuable comparative taxonomic and functional microbiome information. We found that belugas have a unique skin microbiome that is distinct from surrounding SLE water, regardless of the beluga sex or location in the SLE. We further characterized the core microbiome of SLE beluga skin and surrounding SLE water, and identified bacterial taxa and gene functional pathways associated with the skin microbiome that correlated with beluga blubber HFR concentrations. Namely, we identified the phylum Nitrospinae and candidate phylum PAUC34f as potential taxa of interest that are associated with blubber HFR concentrations. We hypothesize that the biodegradation of HFRs within the beluga blubber and skin results in an increase in local metabolite concentrations that leads to the proliferation of Nitrospinae and PAUC32f. This work demonstrates the utility of studying the core microbiome of the SLE beluga skin using a swab method that could be adapted to field sampling. Further studies of the temporal effects of contaminant exposure on SLE beluga skin and SLE water microbiomes is warranted for potentially better monitoring and protecting this marine mammal which is at risk.

Biotransformation of Dec-604 and potential effect on thyroid deiodinase activity in highly flame retardant-exposed gulls

Several halogenated flame retardants (HFRs) have been identified as thyroid disruptors in birds including the polybrominated diphenyl ether (PBDE) mixtures, which have been replaced with other HFRs such as Dechlorane-604 (Dec-604). Dec-604 Component B (Dec-604 CB), a putative debrominated product of Dec-604, has been frequently reported in urban-adapted ring-billed gulls (Larus delawarensis) breeding in the Montreal area (QC, Canada). The metabolic pathways of Dec-604 are yet to be characterized, although the occurrence of Dec-604 CB in gulls may suggest that enzyme-mediated dehalogenation may occur, potentially involving the thyroid deiodinases. The objective of this study was to investigate the effect of Dec-604 on type 1 deiodinase (DIO1) in the presence of thyroxine (T4) in an in vitro DIO1 assay using liver microsomes of ring-billed gulls that are highly exposed to HFRs in the Montreal area, and to determine whether DIO1 is involved in the in vitro debromination of Dec-604. We tested the in vitro activity of DIO1 in gull liver microsomes in the presence of five concentrations of Dec-604 ranging from 0.86 to 86.21 nM. HFR concentrations (Σ40HFR) were also determined in liver samples of gulls. Results showed that total DIO1 activity in gull liver microsomes was increased by three of the five concentrations of Dec-604. No relationship between liver Σ40HFR concentrations and DIO1 activity was observed, except for T2 formation rates that significantly decreased with increasing liver HFR concentrations. Moreover, greater Dec-604 CB to Dec-604 concentration ratios in activated gull microsomes (with the DIO1 cofactor dithiothreitol) were found at the intermediate Dec-604 concentration compared to controls. These results suggested that liver microsome DIO1 activity may be perturbed in ring-billed gulls exposed to Dec-604, and be involved at least in part, in the debromination of Dec-604 leading to the formation of Dec-604 CB.

Halogenated flame retardants in wild, prey-sized mud carp from an e-waste recycling site in South China, 2006–2016: Residue dynamics and ecological risk assessment

The crude e-waste recycling has been regulated in China since the late 2000s; however, information on the recent levels and the ecological risks of e-waste derived contaminants such as halogenated flame retardants (HFRs) in the e-waste sites are limited. We therefore examined the concentrations of several HFRs in wild, prey-sized mud carps collected from a typical e-waste site in 2006, 2011 and 2016, to understand the exposure dynamics and ecological risk of these chemicals. Several ecological and biological parameters including δ15N, δ13C, body size and lipid content of the fish were also examined, to ensure an overall uniformity of the sample set among the sampling years. Among the HFRs measured, polybrominated diphenyl ethers (PBDEs) were detected at the highest concentrations (contributing >90% to ∑HFRs), followed by Dechlorane Plus (DPs), polybrominated biphenyls (PBBs), and alternative brominated flame retardants (ABFRs). The fish concentrations of ∑PBDEs, ∑PBBs and ∑DPs significantly dropped by 65%, 57% and 53% from 2006 to 2011, and 12%, 74% and 51% from 2011 to 2016, respectively; likely reflecting the positive impact of the environmental regulations on crude e-waste recycling. The ∑ABFRs concentrations were also decreased by 80% from 2006 to 2011, but increased by 127% from 2011 to 2016; suggesting possible fresh input of these novel HFRs in recent years. In addition to the changes in the HFR concentrations, contaminant profiles in the fish were also changed, possibly due to environmental degradation of the HFRs. Despite our conservative method of risk assessment, we found that PBDEs posed an important risk both for the mud carp and for piscivorous wildlife that inhabit the e-waste site.

Severe contamination and time trends of legacy and novel halogenated flame retardants in multiple environmental media from Lake Shihwa, Korea: Effectiveness of regulatory action

Novel halogenated flame retardants (HFRs) were introduced to industrial markets as alternatives to legacy brominated FRs (BFRs), such as polybrominated diphenyl ethers (PBDEs). In the present study, PBDEs and their brominated and chlorinated alternatives, novel BFRs (NBFRs) and dechlorane plus (DP), were measured in multiple environmental matrices in a highly industrialized lake in Korea. Legacy and novel HFRs were detected in multiple samples, indicating ubiquitous contamination. Concentrations of HFRs in water and sediment observed in creeks running through machine, textiles, and automobile industrial complexes were significantly higher than those observed in inside and outside of the lake. Higher bioaccumulation levels of HFRs were observed in inshore compared with offshore waters. Results suggest that multi-matrix distribution of legacy and novel HFRs was dependent on the geographical proximity to industrial sources. Compared with previous studies, the highest levels of PBDEs and NBFRs were recorded in water samples on a global scale, implying on-going emissions from industrial activities. Decabromodiphenyl ethane (DBDPE) was a dominant compound in water samples, whereas the concentrations of PBDEs, NBFRs, and DP in sediment were similar to each other. This suggests a shift in consumption from legacy to novel HFRs, preferentially in water environments. A significant declining trend in PBDEs was observed in water and sediment collected between 2008 and 2015, indicating the effectiveness of regulatory actions. Based on their environmental occurrence and bioaccumulation potential, pentabromoethylbenzene and bis(2-ethylhexyl) tetrabromophthalate may pose emerging concerns regarding contamination of aquatic environments.

Gulls foraging in landfills: Does atmospheric exposure to halogenated flame retardants result in bioaccumulation?

Several bird species have adapted to foraging in landfills, although these sites are known to represent significant sources of emissions of toxic semi-volatile chemicals including the halogenated flame retardants (HFRs) (e.g., polybrominated diphenyl ethers (PBDEs) and emerging compounds). The objective of this study was to investigate the association between atmospheric exposure to PBDEs and selected emerging HFRs and their bioaccumulation in landfill-foraging birds. We determined HFR concentrations in liver of 58 GPS-tagged ring-billed gulls (Larus delawarensis) breeding in a colony near Montreal (Canada) as well as their atmospheric exposure determined using a miniature bird-borne passive air sampler. PBDE mixtures were the most abundant HFRs determined in passive air samplers (daily exposure rates of ∑9PentaBDE: 47.4 ± 6.5 pg/day; DecaBDE: 36.0 ± 6.3 pg/day, and ∑3OctaBDE: 3.4 ± 0.5 pg/day) and liver (∑9PentaBDE: 68.1 ± 8.9 ng/g ww; DecaBDE: 52.3 ± 8.1 ng/g ww, and ∑3OctaBDE: 12.8 ± 2.1 ng/g ww), and their concentrations increased with the presence probability of gulls in landfills. We found a spatial relationship between the local sources of atmospheric exposure to PBDEs and the sites associated with greatest PBDE concentrations in liver. Specifically, the atmospheric exposure index was correlated with the bioaccumulation index (Pearson r for ∑9PentaBDE: r = 0.63, p < 0.001; DecaBDE: r = 0.66, p < 0.001, and ∑3OctaBDE: r = 0.42, p < 0.001). However, we found no correlation at the individual level between daily exposure rates of HFRs in passive air samplers and their liver concentrations. This suggests that complex exposure pathways combined with toxicokinetic factors shaped HFR profiles in gull liver, potentially confounding the relationships with atmospheric exposure.

Organohalogen compounds of emerging concern in Baltic Sea biota: Levels, biomagnification potential and comparisons with legacy contaminants

While new chemicals have replaced major toxic legacy contaminants such as polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT), knowledge of their current levels and biomagnification potential in Baltic Sea biota is lacking. Therefore, a suite of chemicals of emerging concern, including organophosphate esters (OPEs), short-chain, medium-chain and long-chain chlorinated paraffins (SCCPs, MCCPs, LCCPs), halogenated flame retardants (HFRs), and per- and polyfluoroalkyl substances (PFAS), were analysed in blue mussel (Mytilus edulis), viviparous eelpout (Zoarces viviparus), Atlantic herring (Clupea harengus), grey seal (Halichoerus grypus), harbor seal (Phoca vitulina), harbor porpoise (Phocoena phocoena), common eider (Somateria mollissima), common guillemot (Uria aalge) and white-tailed eagle (Haliaeetus albicilla) from the Baltic Proper, sampled between 2006 and 2016. Results were benchmarked with existing data for legacy contaminants. The mean concentrations for ΣOPEs ranged from 57 to 550 ng g−1 lipid weight (lw), for ΣCPs from 110 to 640 ng g−1 lw for ΣHFRs from 0.42 to 80 ng g−1 lw, and for ΣPFAS from 1.1 to 450 ng g−1 wet weight. Perfluoro-4-ethylcyclohexanesulfonate (PFECHS) was detected in most species. Levels of OPEs, CPs and HFRs were generally similar or higher than those of polybrominated diphenyl ethers (PBDEs) and/or hexabromocyclododecane (HBCDD). OPE, CP and HFR concentrations were also similar to PCBs and DDTs in blue mussel, viviparous eelpout and Atlantic herring. In marine mammals and birds, PCB and DDT concentrations remained orders of magnitude higher than those of OPEs, CPs, HFRs and PFAS. Predator-prey ratios for individual OPEs (0.28–3.9) and CPs (0.40–5.0) were similar or somewhat lower than those seen for BDE-47 (5.0–29) and HBCDD (2.4–13). Ratios for individual HFRs (0.010–37) and PFAS (0.15–47) were, however, of the same order of magnitude as seen for p,p′-DDE (4.7–66) and CB-153 (31–190), indicating biomagnification potential for many of the emerging contaminants. Lack of toxicity data, including for complex mixtures, makes it difficult to assess the risks emerging contaminants pose. Their occurence and biomagnification potential should trigger risk management measures, particularly for MCCPs, HFRs and PFAS.

Occurrence of Halogenated and Organophosphate Flame Retardants in Sediments and Eels (Anguilla anguilla) From Bizerte Lagoon, Tunisia

Contamination by classic (polybromodiphenyl ethers, PBDEs) and emerging halogenated flame retardants (HFRs) like pentabromobenzene (PBEB), hexabromobenzene (HBB), decabromodiphenyl ethane (DBDPE ) and halogenated norbornenes (HNs), as well as organophosphate flame retardants (OPFRs) were investigated in sediment and eel (Anguilla Anguilla) samples from Bizerte Lagoon, northern Tunisia. This is the first time that OPFR levels have been reported in this area, showing higher concentrations than HFRs: from 9.77 to 164 ng/g dry weight (dw) and from 19.7 to 2154 ng/g lipid weight (lw) for sediment and eel samples, respectively. As regards HFRs, concentrations ranged from 3.30 to 28.5 ng/g dw in sediments and from 4.72 to 151 ng/g lw in eels. The relationship between OPFR and HFR concentrations in sediment and total organic content (TOC) was examined. Results suggested that OPFR levels were significantly correlated with TOC, whereas no correlation was found for HFRs and TOC. The study of potential health risks by eel consumption suggested that there is no significant human health risk associated with the dietary intakes for PBDEs.

Distribution behaviour in body compartments and in ovo transfer of flame retardants in North American Great Lakes herring gulls

Polybrominated diphenyl ethers (PBDEs) and other halogenated flame retardants (HFRs) continue to be an environmental concern. In the Laurentian Great Lakes, herring gulls (Larus argentatus) are an important wildlife sentinel species, although very little information is available regarding the body distribution (limited to e.g. liver and blood) of these contaminants and in relation to depuration via in ovo transfer. Maternal transfer rates and distribution were presently determined in six body compartments from eight female, Great Lakes herring gulls and separate egg compartments from their entire clutch. Among the 25 PBDEs and 23 non-PBDE HFRs assessed, only six PBDE congeners (BDE-47/99/100/153/154/209), hexabromocyclododecane (HBCDD), and Dechlorane Plus (syn- and anti-DDC-CO) were frequently detectable and quantifiable. Σ6BDE concentrations were an order of magnitude greater than non-PBDE HFR concentrations, and were greatest in the adipose (9641 ± 2436 ng/g ww), followed by egg yolk (699 ± 139 ng/g ww) > muscle (332 ± 545 ng/g ww) > liver (221 ± 65 ng/g ww) > plasma (85.4 ± 20.4 ng/g ww) > brain (54.6 ± 10.6 ng/g ww) > red blood cells (RBCs; 23.5 ± 5.6 ng/g ww) > albumen (7.3 ± 1.3 ng/g ww). Σ2DDC-CO and HBCDD were frequently below the method limit of quantification in the brain, RBCs, plasma, and albumen. Additionally, novel methoxylated-polybrominated diphenoxybenzene contaminants were detected and quantified in herring gull tissues and eggs. The primary difference in PBDE congener profiles was the resistance of both BDE-153 and -154 towards accumulation in the brain, and a corresponding increase in BDE-209 accumulation, which may suggest congener-specific differences in crossing the blood-brain barrier in herring gulls. Maternal transfer rates of PBDEs and non-PBDE HFRs were low (∼4.7 and ∼2.9 % respectively), suggesting that in ovo transfer is not a significant mode of depuration for these compounds.

Changes in plasma biochemistry in breeding ring-billed gulls: Effects of anthropogenic habitat use and contaminant exposure

Gulls (Larids) have become successful at exploiting anthropogenic areas for foraging. However, little is known on the health implications of using anthropogenic habitats and on the associated exposure to environmental contaminants, particularly with respect to plasma biochemistry that is routinely used to diagnose physiological disorders and diseases. The objective of the present study was to investigate the effects of anthropogenic habitat use and exposure to ubiquitous halogenated flame retardants (HFRs) on plasma biochemistry of urban-breeding ring-billed gulls (Larus delawarensis) from one of the largest colonies in North America. Miniature GPS dataloggers were used to characterize foraging habitat use of individual gulls (n = 39) at the regional scale (urban, waste management facilities, agricultural fields, and St. Lawrence River) in the Montreal area (QC, Canada), and plasma was analyzed for a suite of biochemical measures (waste products, lipids, glucose, ions, proteins, and enzymes) and HFRs. Several confounding biological and environmental variables were also assessed including sex, body condition, time spent fasting while incubating, plasma thyroid hormone levels, time of day, capture date, and ambient temperature. As ring-billed gulls (males and females combined) spent more time foraging in urban areas, their plasma concentrations of cholesterol, albumin and activity of alkaline phosphatase increased significantly. Moreover, as the gulls spent more time foraging in agricultural fields, their plasma concentrations of phosphorous and activity of aspartate aminotransferase increased significantly. Only the activity of aspartate aminotransferase was significantly positively related to plasma HFR concentrations (PBDEs and dechlorane-related compounds). Time spent fasting while incubating, plasma thyroid hormone levels, body condition, time of day, and capture date were significantly related to certain plasma biochemical measures. The present results suggest that both the use of anthropogenic habitats for foraging and exposure to HFRs may affect the plasma biochemistry of ring-billed gulls breeding in the densely-populated Montreal area, suggesting potential adverse health effects for avian wildlife living in highly urbanized environments.

A new advance in the potential exposure to “old” and “new” halogenated flame retardants in the atmospheric environments and biota: From occurrence to transformation products and metabolites

The atmosphere occurrence of the most frequency used halogenated flame retardants (HFRs), including “old” chemicals such as polybrominated diphenyl ethers (PBDEs), tetrabromobisphenol A, hexabromocyclododecanes, and “new” chemicals such as decabromodiphenyl ethane, dechlorane plus, and short-chain chlorinated paraffins (SCCPs) were mainly reviewed. From data collected, these chemicals have reached all corners of the globe, and the atmospheric concentrations of HFRs were closely associated with production and usage of commercial products. The highest air concentrations of HFRs were measured at industrial and urban area with higher population density. The levels of “old” HFRs are decreasing or leveling off, while the “new” groups continue to grow. In addition, a large number of potential transformation products were also tentatively discovered and a few were structurally identified in both atmosphere and biota. Dehalogenation appears to be the most important atmospheric degradation processes. While, in animals and human body, the hydroxylated metabolites are of significant concern due to enhanced toxicological effects. However, due to limited availability of authentic standards, only a few compounds, such as hydroxylated PBDEs have been identified in the atmospheric environments and biota. Further studies are needed to elucidate possible transformation pathways and to enhance the monitoring of transformation products.

Seasonal trends of legacy and alternative flame retardants in river water in a boreal catchment.

Boreal forests store large amounts of atmospherically deposited (semi-)persistent organic pollutants (POPs). The terrestrial POPs may be exported to streams and rivers through processes that are heavily impacted by seasonality. In this screening study, concentrations of 4 legacy and 45 alternative flame retardants (FRs) were determined in the dissolved and particulate phase in streams within a relatively pristine boreal catchment in northern Europe (Krycklan Catchment Study; 3 sites) and in rivers more impacted by human activities further downstream towards the Baltic Sea (3 sites). The sampling included the main hydrological seasons (snow-free, snow-covered, and spring flood) and was conducted during two consecutive years (2014-2016). Of the 49 analyzed FRs, 11 alternative halogenated FRs (HFRs), 13 alternative organophosphorus FRs (OPFRs), and 4 legacy polybrominated diphenyl ethers (PBDEs) were detected in at least one sample. The average bulk (dissolved + particulate) concentrations of ∑FRs (including all sites) were highest for ∑HFRs (38 ± 70 ng L-1), followed by the ∑OPFRs (3.9 ± 4.9 ng L-1) and the ∑PBDEs (0.0040 ± 0.016 ng L-1). Bulk concentrations of HFRs, OPFRs, and PBDEs were highly variable with season and sampling location, e.g., during spring flood, bulk concentrations were up to 600 times, 3.7 times, and 4.9 times higher for HFRs, OPFRs and PBDEs, respectively, than during periods of lower flow. Bulk concentrations of ∑OPFRs, were elevated at all sites ~6 days before the actual start of the spring flood in 2015, suggesting that hydrophobicity fractionation had occurred within the snowpack. Similar to previous studies of other POPs in the same headwater catchment, there was a general trend that levels of ∑FRs were higher at the mire site than at the forested site. Annual fluxes of FRs were found to be ~15 times higher downstream the city of Umeå compared to at the outlet of the pristine catchment. This study should be regarded as a screening study considering the large number of diverse FRs analyzed and variability in the results.

Atmospheric Occurrence of Legacy Pesticides, Current Use Pesticides, and Flame Retardants in and around Protected Areas in Costa Rica and Uganda.

Protected areas have developed alongside intensive changes in land use and human settlements in the neighboring landscape. Here, we investigated the occurrence of 21 organochlorine pesticides (OCPs), 14 current use pesticides (CUPs), 47 halogenated flame retardants (HFRs), and 19 organophosphate esters (OPEs) in air around Las Cruces (LC) and La Selva (LS) Biological Stations, Costa Rica, and Kibale National Park (KNP), Uganda using passive air samplers (PAS) with polyurethane foam (PUF) discs (PAS-PUF). Significantly higher concentrations of CUPs were observed around LS, while LC had a higher concentration of OCPs. Land use analysis indicated that LS had a higher fraction of agriculture than LC (33% vs 14%), suggesting the higher CUPs concentration at LS was related to pesticide intensive crops, while higher OCPs concentration at LC may be attributed to the area's long agricultural history characterized by small-scale subsistence farming or long-range transport. In Uganda, CUPs and OCPs were generally lower than in Costa Rica, but high concentrations of HFRs were observed inside KNP, possibly due to human activity at research camps near the protected forest. This is the first study that documented the occurrence of anthropogenic chemicals in the air at protected areas with tropical forests.

Halogenated flame retardants in mangrove sediments from the Pearl River Estuary, South China: Comparison with historical data and correlation with microbial community

Polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCDD) and dechlorane plus (DP) were measured in sediments collected from three mangrove wetlands of the Pearl River Estuary (PRE) in South China. This study aims to investigate the distribution of these halogenated flame retardants (HFRs) and the correlations between HFRs and microbial community structure in mangrove sediments. Concentrations of PBDEs, DBDPE, BTBPE, TBBPA, HBCDD and DP in mangrove sediments ranged from 6.97 to 216.1, 3.70–26.0, 0.02–0.73, 0.02–37.5, 0.44–127.5 and 0.07–2.23 ng/g dry weight, respectively. Higher levels of PBDEs, BTBPE, HBCDD and DP were observed in sediments from Futian mangrove wetland of Shenzhen, the only nature reserve located in the downtown of China. The highest concentration of TBBPA found in mangrove sediments from Guangzhou was proximate to a ferry terminal and a dockyard where TBBPA is widely used in the coatings. PBDEs were the predominant HFRs in mangrove sediments, with an average contribution of 63.0%. Mangrove sediments from Guangzhou and Zhuhai showed an enrichment of (−)-α-HBCDD, (−)-β-HBCDD and (−)-γ-HBCDD. Concentrations of HFRs in mangrove sediments from Guangzhou increased significantly from 2012 to 2015, which was probably due to the establishment and rapid development of Nansha Free Trade Zone of Guangzhou. Redundancy analysis showed that HFRs may cause a shift of microbial community structure in mangrove sediments and the variations were significantly correlated with TBBPA, syn-DP and BTBPE.

Determination of HFRs and OPFRs in PM2.5 by ultrasonic-assisted extraction combined with multi-segment column purification and GC-MS/MS

Toxic chemicals such as flame retardants are associated with atmospheric fine particles (PM2.5), which are an important pollutant in the world. In this study, a sensitive method using gas chromatography-tandem triple quadrupole mass spectrometry combined with ultrasonic-assisted extraction and multi-phase column purification was developed for simultaneously determination of 29 flame retardants including halogenated flame retardants (HFRs) and organophosphate flame retardants (OPFRs) in PM2.5 samples. Extraction time, as well as the type and volume of elution solvent were optimized. The recoveries of all target flame retardants from PM2.5 samples were in the range of 70%‒130%, with good repeatability and reproducibility (0.39%‒17.4%). The instrumental detection limits (IDLs) and method quantitation limits (MQLs) of HFRs were in the range of 0.004‒5.44 pg and 0.002‒2.52 pg m−3, while those of OPFRs were 0.003‒0.23 pg and 0.07‒5.41 pg m−3, respectively. The developed method has been successfully applied for analysis of target flame retardants in atmospheric PM2.5 collected from the cities of Guangzhou and Taiyuan, China. HFRs were found at concentrations of 45.7‒1230 pg m−3 and 51.2‒82.3 pg m−3 in Guangzhou and Taiyuan. The concentrations of HFRs were lower than those of OPFRs, which were detected at concentrations of 6004‒49,800 pg m−3 and 16,741‒34,346 pg m−3 in Guangzhou and Taiyuan. Accordingly, the analytical method is robust and useful for further elucidating the contamination profiles of flame retardants in PM2.5.

Changes in thyroid axis responses in two ring-billed gull sub-populations differentially exposed to halogenated flame retardants

Developing bird embryos may be affected by a number of thyroid disrupting chemicals through maternal transfer. However, thyroid disruption in developing embryos of wild birds remains largely unstudied, especially with respect to exposure to ubiquitous environmental contaminant classes including halogenated flame retardants (HFRs). The objective of the present study was to investigate responses of the hypothalamic-pituitary-thyroid (HPT) axis of developing birds that are exposed to elevated concentrations of HFRs in their environment. Ring-billed gulls (Larus delawarensis) were collected at the external pipping stage (i.e., just prior to hatching) from two sub-populations that are differentially exposed to HFRs in the St. Lawrence River (QC, Canada). Plasma levels of thyroid hormones (THs) and transcription levels of thyroid-related genes in three tissues (i.e., liver, thyroid gland and brain) were related to liver concentrations of HFRs in pipping gulls from these two colonies. Liver polybrominated diphenyl ether (PBDE) concentrations were negatively correlated with plasma total T4 and total T4/T3 in pipping ring-billed gulls. Moreover, plasma TH levels and hepatic PBDE concentrations were correlated with the transcription of genes involved in metabolism (deiodinases type 1, 2 and 3) and synthesis (sodium iodide symporter and thyroglobulin) in the thyroid gland, negative feedback loop (thyrotropin and corticotropin releasing hormones) in the brain and the pituitary and targeted action (TH receptors) in the three tissues of gulls. The present study suggested that the alteration of TH homeostasis in developing wild birds through changes in the transcription of several thyroid-related genes may be related to potential PBDE-mediated effects.