Trophic transfer of naturally produced brominated aromatic compounds in a Baltic Sea food chain

Transcriptomic and functional effects from a chemical mixture based on the exposure profile in Baltic Sea salmon, on metabolic and immune functions in zebrafish embryo

The Baltic Sea is one of the world's most contaminated seas with long-standing adverse health status of its wildlife such as the Baltic Sea salmon, resulting in reduced fecundity and increased mortality. While adverse health effects have been reported among wild fish from the Baltic Sea, the toxicity mechanisms underlying these adversities, and the chemical effect drivers mediating them are poorly understood. To address this knowledge gap, we utilized the zebrafish (Danio rerio) embryo model to determine molecular and functional effects brought on by exposure to a technical mixture including 9 organohalogen compounds detected in serum from wild-caught Baltic Sea salmon. To align with the salmon exposure scenario, an internal dose regimen was opted to establish same relative proportions of the compounds in the zebrafish (whole body) as observed in the salmon serum. Through transcriptomic profiling, we identified dose-dependent effects on immune system and metabolism as two critical functions overlapping with adverse effects observed in wild fish from the Baltic Sea. We then determined likely effect drivers by comparing gene responses of the mixture with those of individual mixture components. Aligned with our transcriptome results, the number of total macrophages was reduced and the zebrafish's ability to respond to a tissue damage suppressed in a dose-dependent manner. This study brings forth a key advancement in delineating the impact of chemical pollutants on the health of wild fish in the Baltic Sea.

Air-surface exchange of halomethoxybenzenes in a Swedish subarctic catchment

Halomethoxybenzenes (HMBs) and related halomethoxyphenols are produced naturally in the marine and terrestrial environment and some also have anthropogenic origins. They are relatively volatile and water soluble and undergo atmospheric exchange with water bodies and soil. Here we report air-surface exchange of HMB compounds brominated anisoles and chlorinated dimethoxybenzenes in a Subarctic lake and catchment in Sweden during September 2022. HMBs were isolated from water on solid-phase extraction cartridges and from ground litter/soil by solvent extraction and determined by capillary gas chromatography - quadrupole mass spectrometry. Identified compounds in lake and stream water in the 10-100 pg L-1 range were 1,2,4,5-tetrachloro-3,6-dimethoxybenzene (DAME) > 2,4-dibromoanisole (DiBA) ≥ 2,4,6-tribromoanisole (TriBA) > 1,2,3,4-tetrachloro-5,6-dimethoxybenzene (tetrachloroveratrole, TeCV). DAME and the related compound 2,3,5,6-tetrachloro-4-methoxyphenol (DA) are reported in Subarctic litter/soil in the range 0.005-1.1 mg kg-1 dry weight (dw), whereas DiBA and TriBA were not detected in any litter/soil sample and TeCV in only one. Exchanges were assessed from concentrations in water and soil, air concentrations from a monitoring station at Pallas, Finland, and the physicochemical properties of the HMBs. Fluxes to and from the lake were estimated using the two-film gas exchange model. Net loadings (deposition minus volatilization) for the month of September were - 23, -15 and - 68 g for DiBA, TriBA and DAME, respectively, which amounted to about 4-7 % of the estimated lake inventory. An exchange assessment for DAME from litter/soil showed significant net volatilization at five sites, net deposition at one site and near-equilibrium at one site. The Torneträsk catchment appeared close to steady state with respect to HMB exchange during September 2022. The situation could be different during the warmer and colder seasons, and extending the study to cover these periods is a suggested next step.

Hidden dangers: High levels of organic pollutants in hadal trenches

The "V"-shaped structure of hadal trenches acts as a natural collector of organic pollutants, drawing attention to the need for extensive research in these areas. Our review identifies significant concentrations of organic pollutants, including persistent organic pollutants, black carbon, antibiotic-resistant genes, and plastics, which often match those in industrialized regions. They may trace back to both human activities and natural sources, underscoring the trenches' critical role in ocean biogeochemical cycles. We highlight the complex lateral and vertical transport mechanisms within these zones. Advanced methodologies, including stable isotope analysis, biomarker identification, and chiral analysis within isotope-based mixing models, are crucial for discerning the origins and pathways of these pollutants. In forthcoming studies, we aim to explore advanced methods for precise pollutant tracing, develop predictive models to forecast the future distribution and impacts of pollutants in hadal zones and on the Earth's larger ecological systems.

Natural and anthropogenic organic brominated compounds in the southwestern Atlantic ocean: Bioaccumulation in coastal and oceanic dolphin species

Marine pollution is considered a current driver of change in the oceans and despite the urgency to develop more studies, there is limited information in the southern hemisphere. This study aimed to analyze the levels and profiles of natural (MeO-PBDEs) and anthropogenic (BFRs: PBDEs, HBB, PBEB) organic brominated compounds in adipose tissue of two species of dolphins with different distribution and trophic requirements from the Southwestern Atlantic Ocean; the short-beaked common dolphin (Delphinus delphis) and the Fraser's dolphin (Lagenodelphis hosei). In addition, we aim to investigate maternal transfer and biological pattern relationship (sex, age, sexual maturity) in short-beaked common dolphin bioaccumulation. The levels of both groups of contaminants were in the same order of magnitude as those reported for other marine mammals on both a regional and global scale. BFRs profiles were dominated by BDE 28 and BDE 47 in short-beaked common dolphin and Fraser's dolphin, respectively, whereas 2-MeO-BDE 68 was the most abundant natural compound in both species. Evidence of maternal transfer, temporary increase in BDE 154 levels and no influence of sex, age, or sexual maturity on brominated compound concentration was observed in short-beaked common dolphin. This study fills a gap in the knowledge of the Southwestern Atlantic Ocean providing new information on emerging organic pollutants bioavailability for dolphins and, therefore, for the different trophic webs. In addition, it serves as a baseline for further contamination assessments.

Metabolite alterations in zebrafish embryos exposed to hydroxylated polybrominated diphenyl ethers

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) are formed by metabolism from the flame retardants polybrominated diphenyl ethers (PBDEs). In the aquatic environment, they are also produced naturally. OH-PBDEs are known for their potential to disrupt energy metabolism, the endocrine system, and the nervous system. This is the first study focusing on the effects of OH-PBDEs at the metabolite level in vivo. The aim of the current study was to investigate the metabolic effects of exposure to OH-PBDEs using metabolomics, and to identify potential biomarker(s) for energy disruption of OH-PBDEs. Zebrafish (Danio rerio) embryos were exposed to two different concentrations of 6-OH-BDE47 and 6-OH-BDE85 and a mixture of these two compounds. In total, 342 metabolites were annotated and 79 metabolites were affected in at least one exposure. Several affected metabolites, e.g. succinic acid, glutamic acid, glutamine, tyrosine, tryptophan, adenine, and several fatty acids, could be connected to known toxic mechanisms of OH-PBDEs. Several phospholipids were strongly up-regulated with up to a six-fold increase after exposure to 6-OH-BDE47, a scarcely described effect of OH-PBDEs. Based on the observed metabolic effects, a possible connection between disruption of the energy metabolism, neurotoxicity and potential immunotoxicity of OH-PBDEs was suggested. Single compound exposures to 6-OH-BDE47 and 6-OH-BDE85 showed little overlap in the affected metabolites. This shows that compounds of similar chemical structure can induce different metabolic effects, possibly relating to their different toxic mechanisms. There were inter-concentration differences in the metabolic profiles, indicating that the metabolic effects were concentration dependent. After exposure to the mixture of 6-OH-BDE47 and 6-OH-BDE85, a new metabolic profile distinct from the profiles obtained from the single compounds was observed. Succinic acid was up-regulated at the highest, but still environmentally relevant, concentration of 6-OH-BDE47, 6-OH-BDE85, and the mixture. Therefore, succinic acid is suggested as a potential biomarker for energy disruption of OH-PBDEs.

A Review of Hydroxylated and Methoxylated Brominated Diphenyl Ethers in Marine Environments

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs) are present in the marine environment worldwide. Both OH-PBDEs and MeO-PBDEs are known natural products, whereas OH-PBDEs may also be metabolites of PBDEs. There is growing concern regarding OH-PBDEs as these compounds seem to be biological active than PBDEs. In the present study, we reviewed the available data on the contamination of OH/MeO-PBDEs in the marine environment worldwide, including seawater, marine sediment, marine plants, invertebrates, fish, seabirds and mammals. Bioaccumulation and biomagnification of OH/MeO-PBDEs in the marine food web were summarized as well. This study also proposes the future research of OH/MeO-PBDEs, including the production and the synthesis pathway of OH/MeO-PBDEs, the toxicokinetics of OH/MeO-PBDEs and the toxicology and human exposure risk assessment.

Assessment of the contamination by 2,4,6-tribromophenol of marine waters and organisms exposed to chlorination discharges

2,4,6-tribromophenol (TBP) is implied in the production of brominated flame retardants but is also a major chlorination by-product in seawater. A growing number of studies indicate that TBP is highly toxic to the marine biota, but the contribution of anthropogenic sources among natural production is still under question concerning its bioaccumulation in marine organisms. Here, several water sampling campaigns were carried out in the industrialized Gulf of Fos (northwestern Mediterranean Sea, France) and clearly showed the predominant incidence of industrial chlorination discharges on the TBP levels in water, at the 1-10 ng L^-1 level in average and reaching up to 580 ng L^-1 near the outlets. The bioaccumulation of TBP was measured in 90 biota samples from the Gulf of Fos. The concentrations found in European conger muscle tissues (140-1000 ng g^-1 lipid weight, in average), purple sea urchin gonads (830-880 ng g^-1 lipid weight, in average), and Mediterranean mussel body (1500-2000 ng g^-1 lipid weight, in average) were above all published references. Significant correlations with fish length (European conger) and gonad somatic index (purple sea urchin) were also identified. Comparatively, fish, urchins and mussels from other Mediterranean sites analyzed within this study showed a lower bioaccumulation level of TBP, consistently with what found elsewhere. Industrial outflows were thus identified as hotspots for TBP in seawater and marine organisms. The environmental risk assessment indicated a high potential toxicity in the industrial Gulf of Fos, in particular near the outlets, and a limited threat to human but toxicological references are lacking.

Substances of emerging concern in Baltic Sea water: Review on methodological advances for the environmental assessment and proposal for future monitoring

The Baltic Sea is among the most polluted seas worldwide. Anthropogenic contaminants are mainly introduced via riverine discharge and atmospheric deposition. Regional and international measures have successfully been employed to reduce concentrations of several legacy contaminants. However, current Baltic Sea monitoring programs do not address compounds of emerging concern. Hence, potentially harmful pharmaceuticals, UV filters, polar pesticides, estrogenic compounds, per- and polyfluoroalkyl substances, or naturally produced algal toxins are not taken into account during the assessment of the state of the Baltic Sea. Herein, we conducted literature searches based on systematic approaches and compiled reported data on these substances in Baltic Sea surface water and on methodological advances for sample processing and chemical as well as effect-based analysis of these analytically challenging marine pollutants. Finally, we provide recommendations for improvement of future contaminant and risk assessment in the Baltic Sea, which revolve around a combination of both chemical and effect-based analyses.

First report on hydroxylated and methoxylated polybrominated diphenyl ethers in terrestrial environment from the Arctic and Antarctica

Terrestrial plants, which account for the world's largest biomass and constitute the basis of most food webs, take up, transform, and accumulate organic chemical contaminants from the ambient environment. In this study, we determined the concentrations and congener profiles of polybrominated diphenyl ethers (PBDEs) and hydroxylated and methoxylated polybrominated diphenyl ethers (OH-PBDEs and MeO-PBDEs) in surface soil and vegetation samples collected from the Arctic (Svalbard) and Antarctica (King George Island) during the Chinese Scientific Research Expeditions. The concentrations of total PBDEs (∑PBDEs) in soil and vegetation samples collected from the Arctic (5.6-270 pg/g dry weight) were higher than those from Antarctica (2.3-33 pg/g dw), whereas the concentrations of ∑MeO-PBDEs and ∑OH-PBDEs were lower in Arctic terrestrial samples (n.d.-0.75 and 0.0008-1.1 ng/g dw, respectively) than in samples from Antarctica (0.007-4.0 and 0.034-25 ng/g dw, respectively). Long-range atmospheric transport and human activities were potential sources of PBDEs in polar regions, whereas the dominance of ortho-substituted MeO-PBDE and OH-PBDE congeners in terrestrial matrices indicated the importance of natural sources. To the best of our knowledge, this study represents the first report on the levels and behaviors of MeO-PBDEs and OH-PBDEs in terrestrial environment of polar regions.

Hepatic demethylation of methoxy-bromodiphenyl ethers and conjugation of the resulting hydroxy-bromodiphenyl ethers in a marine fish, the red snapper, Lutjanus campechanus, and a freshwater fish, the channel catfish, Ictalurus punctatus

Methoxylated bromodiphenyl ethers (MeO-BDEs), marine natural products, can be demethylated by cytochrome P450 to produce hydroxylated bromodiphenyl ethers (OH-BDEs), potentially toxic metabolites that are also formed by hydroxylation of BDE flame retardants. The OH-BDEs may be detoxified by glucuronidation and sulfonation. This study examined the demethylation of 6-MeO-BDE47, 2'-MeO-BDE68 and 4'-MeO-BDE68, in hepatic microsomes from the red snapper, Lutjanus campechanus, a marine fish likely to be exposed naturally to MeO-BDEs, and the channel catfish, Ictalurus punctatus, a freshwater fish in which pathways of xenobiotic biotransformation have been studied. We further studied the glucuronidation and sulfonation of the resulting OH-BDEs as well as of 6-OH-2'-MeO-BDE68 in hepatic microsomes and cytosol fractions of these fish. The three studied biotransformation pathways were active in both species, with high individual variability. The range of activities overlapped in the two species. Demethylation of MeO-BDEs, studied in the concentration range 10-500 μM, followed Michaelis-Menten kinetics in both fish species, however enzyme efficiencies were low, ranging from 0.024 to 0.334 μL min.mg protein. Conjugation of the studied OH-BDEs followed Michaelis-Menten kinetics in the concentration ranges 1-50 μM (glucuronidation) or 2.5-100 μM (sulfonation). These OH-BDEs were readily glucuronidated and sulfonated in the fish livers of both species, with enzyme efficiencies one to three orders of magnitude higher than for demethylation of the precursor MeO-BDEs. The relatively low efficiencies of demethylation of the MeO-BDEs, compared with higher efficiencies for OH-BDE conjugation, suggests that MeO-BDEs are more likely than OH-BDEs to bioaccumulate in tissues of exposed fish.

Identification of novel halogenated naturally occurring compounds in marine biota by high-resolution mass spectrometry and combined screening approaches

Marine animals, plants or bacteria are a source of bioactive naturally-occurring halogenated compounds (NHCs) such as bromophenols (BPs), bromoanisoles (BAs) and hydroxylated or methoxylated analogues of polybrominated diphenyl ethers (HO-PBDEs, MeO-PBDEs) and bromobiphenyls (HO-BBs, MeO-BBs). This study applied a comprehensive screening approach using liquid chromatography high-resolution mass spectrometry and combining target, suspect and non-target screening with the aim to identify new hydroxylated NHCs which might be missed by commonly applied gas chromatographic methods. 24 alga samples, 4 sea sponge samples and 7 samples of other invertebrates were screened. Target screening was based on 19 available reference standards of BPs, (di)OH-BDEs and diOH-BBs and yielded seven unequivocally identified compounds. 6-OH-BDE47 was the most frequently detected compound with a detection frequency of 31%. Suspect screening yielded two additional compounds identified in alga samples as well as 17 and 8 compounds identified in sea sponge samples of Lamellodysidea sp. and Callyspongia sp., respectively. The suspect screening results presented here confirmed the findings of previous studies conducted on sea sponge samples of Lamellodysidea sp. and Callyspongia sp. Additionally, in Lamellodysidea sp. and Callyspongia sp. 13 and 4 newly identified NHCs are reported including heptabrominated diOH-BDE, monochlorinated pentabrominated diOH-BDE, hexabrominated OH-MeO-BDE and others. Non-target screening allowed the identification of 31 and 20 polyhalogenated compounds in Lamellodysidea sp. and Callyspongia sp. samples, respectively. Based on the obtained fragmentation spectra, polybrominated dihydroxylated diphenoxybenzenes (diOH-PBDPBs), such as hepta-, octa- and nonabrominated diOH-BDPBs, could be identified in both species. To our knowledge, this study is the first report on the environmental presence of OH-PBDPBs.

Correlating seasonal changes of naturally produced brominated compounds to biomarkers in perch from the Baltic Sea

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs), naturally produced by algae and cyanobacteria in the Baltic Sea, are potent disrupters of energy metabolism as well as endocrine disruptors and neurotoxins. In this study, European perch (Perca fluviatilis) from the Baltic Sea were sampled from May until October. OH-PBDEs and ten biomarkers were measured in each individual (n = 84 over 18 sampling time points) to study potential correlations between exposure to OH-PBDEs and changes in biomarkers. Several biomarkers showed significant non-linear seasonal variation. In the perch, ethoxyresorufin-O-deethylase (EROD) activity, plasma lactate concentration, and plasma glucose concentration showed a significant positive log-linear correlation with OH-PBDEs, whereas lipid percentage and liver somatic index showed a significant negative log-linear correlation with OH-PBDEs. These results strengthen the concern that OH-PBDEs could cause negative health effects for fish in the Baltic Sea.

Polybrominated diphenyl ethers and their methoxylated congeners in Douro river estuary biota: Seasonal occurrence and risk assessment

Especially added on many industrial and domestic products as flame retardants (FRs), polybrominated diphenyl ethers (PBDEs) are among the chemicals of high environmental concern because of their potential harmfulness for environmental and human health. Seafood consumption is considered the main source of PBDEs and their methoxylated congeners (MeO-BDEs) for humans. The present study aims to investigate the seasonal occurrence of six PBDEs and eight MeO-BDEs congeners using Douro river biota (different trophic levels) as sentinels, as well as to evaluate the human exposure risk to PBDEs through seafood consumption. Biota samples (n = 273) were collected from one of the most important Portuguese estuaries in the north-western coast of Portugal at four different seasons (2019-2020). The analyses were performed by an environmental-friendly extraction procedure followed by Gas Chromatography coupled to a triple quadrupole detector (GC-MS/MS). PBDEs were detected in all seafood samples analysed, with means ranging from 0.02 ng g^-1 ww (flounder in autumn) to 3.75 ng g^-1 ww (mussel in winter). Levels of lower-brominated PBDE congeners were significantly higher than higher-brominated ones in all seasons (p < 0.01). MeO-BDEs ranged from 0.001 ng g^-1 ww (grey mullet in summer) to 5.66 ng g^-1 ww (green crab in spring). Crabs and mussels presented the highest means of PBDEs and MeO-BDEs. Regarding the health risk assessment of the studied PBDE congeners (47, 99, and 153), consumption of Douro river fish is not a case of concern for consumers.

Inevitable human exposure to emissions of polybrominated diphenyl ethers: A perspective on potential health risks

Polybrominated diphenyl ethers (PBDEs) serve as flame retardants in many household materials such as electrical and electronic devices, furniture, textiles, plastics, and baby products. Though the use of PBDEs like penta-, octa- and deca-BDE greatly reduces the fire damage, indoor pollution by these toxic emissions is ever-growing. In fact, a boom in the global market projections of PBDEs threatens human health security. Therefore, efforts are made to minimize PBDEs pollution in USA and Europe by encouraging voluntary phasing out of the production or imposing compelled regulations through Stockholm Convention, but >500 kilotons of PBDEs still exist globally. Both 'environmental persistence' and 'bioaccumulation tendencies' are the hallmarks of PBDE toxicities; however, both these issues concerning household emissions of PBDEs have been least addressed theoretically or practically. Critical physiological functions, lipophilicity and toxicity, trophic transfer and tissue specificities are of utmost importance in the benefit/risk assessments of PBDEs. Since indoor debromination of deca-BDE often yields many products, a better understanding on their sorption propensity, environmental fate and human toxicities is critical in taking rigorous measures on the ever-growing global deca-BDE market. The data available in the literature on human toxicities of PBDEs have been validated following meta-analysis. In this direction, the intent of the present review was to provide a critical evaluation of the key aspects like compositional patterns/isomer ratios of PBDEs implicated in bioaccumulation, indoor PBDE emissions versus human exposure, secured technologies to deal with the toxic emissions, and human toxicity of PBDEs in relation to the number of bromine atoms. Finally, an emphasis has been made on the knowledge gaps and future research directions related to endurable flame retardants which could fit well into the benefit/risk strategy.

Bioactive Properties of Marine Phenolics

Phenolic compounds from marine organisms are far less studied than those from terrestrial sources since their structural diversity and variability require powerful analytical tools. However, both their biological relevance and potential properties make them an attractive group deserving increasing scientific interest. The use of efficient extraction and, in some cases, purification techniques can provide novel bioactives useful for food, nutraceutical, cosmeceutical and pharmaceutical applications. The bioactivity of marine phenolics is the consequence of their enzyme inhibitory effect and antimicrobial, antiviral, anticancer, antidiabetic, antioxidant, or anti-inflammatory activities. This review presents a survey of the major types of phenolic compounds found in marine sources, as well as their reputed effect in relation to the occurrence of dietary and lifestyle-related diseases, notably type 2 diabetes mellitus, obesity, metabolic syndrome, cancer and Alzheimer's disease. In addition, the influence of marine phenolics on gut microbiota and other pathologies is also addressed.

Occurrence and fate studies (sunlight exposure and stable carbon isotope analysis) of the halogenated natural product MHC-1 and its producer Plocamium cartilagineum

MHC-1 is a halogenated natural product (HNP) produced by the red seaweed Plocamium cartilagineum. MHC-1 concentrations of 550-2700 μg/g dry weight were found in Plocamium collected by divers at Heligoland (Germany). Compared to that MHC-1 concentrations were much lower in samples collected on beaches in Ireland and Portugal. Exposure of leaves of Plocamium to sunlight showed that MHC-1 was readily transformed by hydrodebromination. At Heligoland in March, MHC-1 (δ¹³C value -45.2‰) was lighter in carbon by ~15‰ compared to the bulk δ¹³C value (‰) of Plocamium (-30.7‰). Collected at the same time and location at Heligoland, samples of Halichondria and Mastocarpus sp. were richer in carbon (by ~10‰) as Plocamium. However, the δ¹³C value of MHC-1 in Halichondria (-44.6‰) and Mastocarpus sp. (-42.1‰) was as negative as in Plocamium. This was indirect proof that MHC-1 was produced by Plocamium and then released into the water phase from where it then was bioconcentrated by Halichondria and Mastocarpus sp. In agreement with that, concentrations of MHC-1 in Halichondria and Mastocarpus sp. were much lower than in Plocamium. In addition, a potential isomer of MHC-1 (compound X) was detected in all samples from Heligoland at ~2% of the MHC-1 level.

Will Climate Change Influence Production and Environmental Pathways of Halogenated Natural Products?

Thousands of halogenated natural products (HNPs) pervade the terrestrial and marine environment. HNPs are generated by biotic and abiotic processes and range in complexity from low molecular mass natural halocarbons (nHCs, mostly halomethanes and haloethanes) to compounds of higher molecular mass which often contain oxygen and/or nitrogen atoms in addition to halogens (hHNPs). nHCs have a key role in regulating tropospheric and stratospheric ozone, while some hHNPs bioaccumulate and have toxic properties similar those of anthropogenic-persistent organic pollutants (POPs). Both chemical classes have common sources: biosynthesis by marine bacteria, phytoplankton, macroalgae, and some invertebrate animals, and both may be similarly impacted by alteration of production and transport pathways in a changing climate. The nHCs scientific community is advanced in investigating sources, atmospheric and oceanic transport, and forecasting climate change impacts through modeling. By contrast, these activities are nascent or nonexistent for hHNPs. The goals of this paper are to (1) review production, sources, distribution, and transport pathways of nHCs and hHNPs through water and air, pointing out areas of commonality, (2) by analogy to nHCs, argue that climate change may alter these factors for hHNPs, and (3) suggest steps to improve linkage between nHCs and hHNPs science to better understand and predict climate change impacts.

Multiple Metabolic Pathways of 2,4,6-Tribromophenol in Rice Plants

Bromophenols occur naturally and are used globally as man-made additives in various industrial products. They are decomposition products of many emerging organic pollutants, such as tetrabromobisphenol A, polybrominated dibenzo- p-dioxin (PBDD), polybrominated diphenyl ethers (PBDE), and others. To characterize their biotransformation pathways, bromophenol congener 2,4,6-tribromophenol, being used most frequently in the synthesis of brominated flame retardants and having the greatest environmental abundance, was selected to hydroponically expose rice plants. After exposure for 5 days, 99.2% of 2,4,6-tribromophenol was metabolized by rice. Because of the lack of relative reference standards, an effective screening strategy was used to screen for potential metabolites that were further qualitatively identified by gas and liquid chromatography combined with high-resolution mass spectrometry. Forty transformation products were confirmed or tentatively identified at different confidence levels, including 9 phase I and 31 phase II metabolites. A large number of metabolites (39) were found in rice root, and 10 of them could be translocated and detected in rice stems or leaves. Many transformation pathways were proposed, including debromination, hydroxylation, methylation, coupling reactions, sulfation, and glycosylation. It was remarkable that a total of seven hydrophobic, persistent, and toxic OH-PBDEs and PBDD/Fs were found, indicating the biotic dimeric reactions of 2,4,6-tribromophenol that occurred in the rice plants. These results improve our understanding of the transformation and environmental fates of bromophenols, and they indicate new potential sources for OH-PBDEs and PBDD/Fs in the environment, especially in food chains.

Bromoanisoles and methoxylated bromodiphenyl ethers in macroalgae from Nordic coastal regions

Marine macroalgae are used worldwide for human consumption, animal feed, cosmetics and agriculture. In addition to beneficial nutrients, macroalgae contain halogenated natural products (HNPs), some of which have toxic properties similar to those of well-known anthropogenic contaminants. Sixteen species of red, green and brown macroalgae were collected in 2017-2018 from coastal waters of the northern Baltic Sea, Sweden Atlantic and Norway Atlantic, and analyzed for bromoanisoles (BAs) and methoxylated bromodiphenyl ethers (MeO-BDEs). Target compounds were quantified by gas chromatography-low resolution mass spectrometry (GC-LRMS), with qualitative confirmation in selected species by GC-high resolution mass spectrometry (GC-HRMS). Quantified compounds were 2,4-diBA, 2,4,6-triBA, 2'-MeO-BDE68, 6-MeO-BDE47, and two tribromo-MeO-BDEs and one tetrabromo-MeO-BDE with unknown bromine substituent positions. Semiquantitative results for pentabromo-MeO-BDEs were also obtained for a few species by GC-HRMS. Three extraction methods were compared; soaking in methanol, soaking in methanol-dichloromethane, and blending with mixed solvents. Extraction yields of BAs did not differ significantly (p > 0.05) with the three methods and the two soaking methods gave equivalent yields of MeO-BDEs. Extraction efficiencies of MeO-BDEs were significantly lower using the blend method (p < 0.05). For reasons of simplicity and efficiency, the soaking methods are preferred. Concentrations varied by orders of magnitude among species: ∑2BAs 57 to 57 700 and ∑5MeO-BDEs < 10 to 476 pg g-1 wet weight (ww). Macroalgae standing out with ∑2BAs >1000 pg g-1 ww were Ascophyllum nodosum, Ceramium tenuicorne, Ceramium virgatum, Fucus radicans, Fucus serratus, Fucus vesiculosus, Saccharina latissima, Laminaria digitata, and Acrosiphonia/Spongomorpha sp. Species A. nodosum, C. tenuicorne, Chara virgata, F. radicans and F. vesiculosus (Sweden Atlantic only) had ∑5MeO-BDEs >100 pg g-1 ww. Profiles of individual compounds showed distinct differences among species and locations.

Fast and environmental-friendly methods for the determination of polybrominated diphenyl ethers and their metabolites in fish tissues and feed

Environmental-friendly, cost-effective and fast methods were developed and validated for the analysis of seven PolyBrominated Diphenyl Ethers (PBDEs) and eight methoxylated PBDEs (MeO-PBDEs) in three distinct seafood matrices (muscle, liver and plasma) and feed using a Quick, Easy, Cheap, Efficient, Rugged and Safe (QuEChERS) extraction approach for solid samples and a Dispersive Liquid-Liquid Microextraction method (DLLME) for plasma. Instrumental analyses were performed with gas chromatography coupled to triple quadrupole mass spectrometry using electron impact source (GC-EI-MS/MS) and negative ion chemical ionization (GC-NICI-MS) to assess BDE-209. Statistical validation showed recoveries for all target substances near 100% with average Relative Standard Deviation (RSD) lower than 9% and recovery standards higher than 65% (average RSD below 20%). Average calculated Method Detection Limits (MDLs) were lower than 65 pg·g^-1 wet weight (WW) for muscle, 5.35 ng·g^-1 WW for liver, 4.50 ng·g^-1 WW for feed, and 0.60 ng·mL^-1 for plasma samples. Quality assurance and quality control practices were comprehensively described. Methods scored high in an analytical Eco-scale, thus being classified as "an excellent green analysis". Finally, real seafood samples collected in local markets and local fishermen were analyzed. Positive samples presented both PBDEs and MeO-PBDEs in safe amounts (0.28-125.80 ng·g^-1 WW) for human consumption.

Polybrominated diphenyl ethers and their hydroxylated and methoxylated derivatives in seafood obtained from Puget Sound, WA

Synthetic polybrominated diphenyl ethers (PBDEs) are ubiquitous environmental contaminants and known to occur in most food items. Consumer fish products have been identified as having some of the highest PBDE levels found in USA food sources. Natural formation of hydroxylated (OH-) and methoxylated (MeO-) PBDEs are also known to occur in simple marine organisms, which may be bioaccumulated by seafood. In this study, we report findings of an initial survey of PBDE, OH-PBDE and MeO-PBDE content in common seafood items available to residents living in the Puget Sound region of Washington State. Seafood samples were either purchased from local grocery stores or caught off the coast of SE Alaska and in Puget Sound. The edible portions of the seafood were analyzed, which for finfish was white muscle (skinless fillets) and for shellfish, either the entire soft tissue (bivalves) or processed meat (calamari, shrimp and scallops). Results indicated that finfish typically had higher levels of PBDEs compared to shellfish with BDE-47 and BDE-99 as the most common congeners detected. Among shellfish, bivalves (clams and mussels) were notable for having much higher levels of OH- and MeO-PBDEs compared to other types of seafood with 6'-OH-BDE-47 and 2'-MeO-BDE-68 being the more common OH- and MeO- congeners, respectively. Based on our results and recent updates to daily fish consumption rates, estimated intake rates for Washington State residents will be between 34 and 644ngPBDEs/day, depending on species consumed. For the OH- and MeO- forms, daily exposure is much more variable but typically would range between 15 and 90ng/day for most seafood types. If shellfish are primarily consumed, OH-PBDE intake could be as high as 350ng/day. These daily intake rates for PBDEs are higher than most dietary intake rates calculated for populations in other world regions.

Hydroxylated and methoxylated polybrominated diphenyl ethers in a marine food web of Chinese Bohai Sea and their human dietary exposure

Hydroxylated (OH-) and methoxylated (MeO-) polybrominated diphenyl ethers (PBDEs) have been identified ubiquitous in wildlife and environment. However, understanding on their trophic accumulation and human exposure was hitherto limited. In this study, the occurrences and trophic behaviors were demonstrated for OH- and MeO-PBDEs using the biota samples collected from Dalian, a coastal city near Chinese Bohai Sea. ∑OH-PBDEs exhibited a wider concentration range (<MDL (method detection limit)-25 ng/g dry weight (dw)) compared with ∑MeO-PBDEs (<MDL-2 ng/g dw) and ∑PBDEs (<MDL-2 ng/g dw). The congener profiles and distribution patterns revealed that majority of OH- and MeO-PBDEs in marine biota were naturally produced and largely attributed to preying on lower trophic level biota. Though tertiary consumers accumulated more MeO-PBDEs and PBDEs, these chemicals did not show statistically significant biomagnification in the selected food web. Conversely, trophic dilution was determined for ortho-substituted OH-tetraBDEs and OH-pentaBDEs, revealing that trophic dilution was prevalent for naturally produced OH-PBDEs. The dietary intake evaluation of OH-PBDEs (0.4 ng/kg/d) and MeO-PBDEs (0.8 ng/kg/d) via seafood consumption showed that coastal residents were in higher exposure risks to OH-PBDEs and MeO-PBDEs via the massive seafood consumption.

Effects of Hydroxylated Polybrominated Diphenyl Ethers in Developing Zebrafish Are Indicative of Disruption of Oxidative Phosphorylation

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) have been detected in humans and wildlife. Using in vitro models, we recently showed that OH-PBDEs disrupt oxidative phosphorylation (OXPHOS), an essential process in energy metabolism. The goal of the current study was to determine the in vivo effects of OH-PBDE reported in marine wildlife. To this end, we exposed zebrafish larvae to 17 OH-PBDEs from fertilisation to 6 days of age, and determined developmental toxicity as well as OXPHOS disruption potential with a newly developed assay of oxygen consumption in living embryos. We show here that all OH-PBDEs tested, both individually and as mixtures, resulted in a concentration-dependant delay in development in zebrafish embryos. The most potent substances were 6-OH-BDE47 and 6'-OH-BDE49 (No-Effect-Concentration: 0.1 and 0.05 µM). The first 24 h of development were the most sensitive, resulting in significant and irreversible developmental delay. All substances increased oxygen consumption, an effect indicative of OXPHOS disruption. Our results suggest that the induced developmental delay may be caused by disruption of OXPHOS. Though further studies are needed, our findings suggest that the environmental concentrations of some OH-PBDEs found in Baltic Sea wildlife in the Baltic Sea may be of toxicological concern.

Perspective on pre- and post-natal agro-food exposure to persistent organic pollutants and their effects on quality of life

BACKGROUND

Adipose tissue constitutes a continual source of internal exposure to organic pollutants (OPs). When fats mobilize during pregnancy and breastfeeding, OPs could affect foetal and neonatal development, respectively.

SCOPE AND APPROACH

The main aim of this review is to deal with pre- and post-natal external exposure to organic pollutants and their effects on health, proposing prevention measures to reduce their risk. The goal is the development of a biomonitoring framework program to estimate their impact on human health, and prevent exposure by recommending some changes in personal lifestyle habits.

KEY FINDINGS AND CONCLUSIONS

It has been shown that new studies should be developed taking into account their cumulative effect and the factors affecting their body burden. In conclusion, several programs should continuously be developed by different health agencies to have a better understanding of the effect of these substances and to develop a unified public policy.

Occurrence, spatial distribution, and ecological risks of typical hydroxylated polybrominated diphenyl ethers in surface sediments from a large freshwater lake of China

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) have been frequently observed in marine aquatic environments; however, little information is available on the occurrence of these compounds in freshwater aquatic environments, including freshwater lakes. In this study, we investigated the occurrence and spatial distribution of typical OH-PBDEs, including 2'-OH-BDE-68, 3-OH-BDE-47, 5-OH-BDE-47, and 6-OH-BDE-47 in surface sediments of Taihu Lake. 3-OH-BDE-47 was the predominant congener, followed by 5-OH-BDE-47, 2'-OH-BDE-68, and 6-OH-BDE-47. Distributions of these compounds are drastically different between sampling site which may be a result of differences in nearby point sources, such as the discharge of industrial wastewater and e-waste leachate. The positive correlation between ∑OH-PBDEs and total organic carbon (TOC) was moderate (r = 0.485, p < 0.05), and site S3 and S15 were excluded due to point source pollution, suggesting that OH-PBDEs concentrations were controlled by sediment TOC content, as well as other factors. The pairwise correlations between the concentrations of these compounds suggest that these compounds may have similar input sources and environmental behavior. The target compounds in the sediments of Lake Taihu pose low risks to aquatic organisms. Results show that OH-PBDEs in Lake Taihu are largely dependent on pollution sources. Because of bioaccumulation and subsequent harmful effects on aquatic organisms, the concentrations of OH-PBDEs in freshwater ecosystems are of environmental concern.

Occurrence and trophic magnification of polybrominated diphenyl ethers (PBDEs) and their methoxylated derivatives in freshwater fish from Dianshan Lake, Shanghai, China

In this study, polybrominated diphenyl ethers (PBDEs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs) were analyzed in eleven freshwater fish species from Dianshan Lake, Shanghai, China. The highest concentrations of PBDEs and MeO-PBDEs were found in snakehead, with mean values of 38 ng g^-1 lw and 4.2 ng g^-1 lw, respectively. BDE-47 was the predominant congener of PBDEs, followed by BDE-154. Congener pattern variation of PBDEs was observed among different fish species, implying differences in biotransformation potential among fish. Yellow catfish showed highest concentrations of BDE-99, -153 and -183, suggesting that it is more resistant to debromination than any other fish analyzed in the present study. Trophic magnification factors were in the range of 1.35-1.81 for all the PBDE congeners, but not for 2'-MeO-BDE-68. Negative relationship was observed between PBDEs concentration and sample size (length and weight), indicating fish size dilution effect.

Sea-air exchange of bromoanisoles and methoxylated bromodiphenyl ethers in the Northern Baltic

Halogenated natural products in biota of the Baltic Sea include bromoanisoles (BAs) and methoxylated bromodiphenyl ethers (MeO-BDEs). We identified biogenic 6-MeO-BDE47 and 2'-MeO-BDE68 in Baltic water and air for the first time using gas chromatography - high resolution mass spectrometry. Partial pressures in air were related to temperature by: log p/Pa=m/T(K)+b. We determined Henry's law constants (HLCs) of 2,4-dibromoanisole (2,4-DiBA) and 2,4,6-tribromoanisole (2,4,6-TriBA) from 5 to 30°C and revised our assessment of gas exchange in the northern Baltic. The new water/air fugacity ratios (FRs) were lower, but still indicated net volatilization in May-June for 2,4-DiBA and May - September for 2,4,6-TriBA. The net flux (negative) of BAs from Bothnian Bay (38,000km²) between May - September was revised from -1319 to -532kg. FRs of MeO-BDEs were >1, suggesting volatilization, although this is tentative due to uncertainties in their HLCs and binding to dissolved organic carbon.