Bacterial O-methylation of halogen-substituted phenols

Sources and environmental fate of halomethoxybenzenes

Halomethoxybenzenes are pervasive in the atmosphere at concentration levels that exceed, often by an order of magnitude, those of the persistent organic pollutants with which they share the attributes of persistence and potential for long-range transport, bioaccumulation, and toxic effects. Long ignored by environmental chemists because of their predominantly natural origin-namely, synthesis by terrestrial wood-rotting fungi, marine algae, and invertebrates-knowledge of their environmental pathways remains limited. Through measuring the spatial and seasonal variability of four halomethoxybenzenes in air and precipitation and performing complementary environmental fate simulations, we present evidence that these compounds undergo continental-scale transport in the atmosphere, which they enter largely by evaporation from water. This also applies to halomethoxybenzenes originating in terrestrial environments, such as drosophilin A methyl ether, which reach aquatic environments with runoff, possibly in the form of their phenolic precursors. Our findings contribute substantially to the comprehension of sources and fate of halomethoxybenzenes, illuminating their widespread atmospheric dispersal.

Cultivation-dependent and cultivation-independent investigation of O-methylated pollutant-producing bacteria in three drinking water treatment plants

O-methylated pollutants (OMPs) are emerging contaminants in drinking water and mainly produced through bacterial O-methylation. However, the information of OMP-producing bacteria (OMPPB) in drinking water treatment plant (DWTP) is largely unknown so far. In this study, the OMPPB in water samples from three DWTPs (XL, JX and NX) were investigated by using cultivation-dependent and cultivation-independent technologies. Four OMPs were detected and their odor and toxicity risks were assessed. Formation potentials (FPs) of 2,4,6-trichloanisole, 2,3,6-trichloanisole, 2,4,6-tribromoanisole, pentachloroanisole and diclofenac methyl ester were determined in water samples and their values shifted significantly among DWTPs. A most probable number (MPN) method was established to quantify OMPPB numbers and the relationships between total haloanisole FPs (HAFPs) (y) and OMPPB numbers (x) in three DWTPs could be described by the following functions: y = 0.496×^0.373 (XL), y = 0.041×^0.465 (JX) and y = 0.218×^0.237 (NX). Several genera like Bacillus, Ralstonia, Brevundimonas, etc. were newly found OMPPB among the cultivable bacteria, and their OMP products were evaluated in terms of quantity and environment risks (odor, toxicity and bioaccumulation). High-throughput sequencing revealed treatment process was the main driving factor to shape the OMPPB community structures and Mantel test showed HAFP profile was significantly influenced by Mycobacterium and Pelomonas. PICURSt2 analysis discovered four phenolic O-methyltransferases (OMTs) and four carboxylic OMTs which might be responsible for OMP formation. Several strategies were recommended to assess risk and control contamination brought by OMPPB in DWTPs.

Halomethoxybenzenes in air of the Nordic region

Halomethoxybenzenes (HMBs) are a group of compounds with natural and anthropogenic origins. Here we extend a 2002-2015 survey of bromoanisoles (BAs) in the air and precipitation at Råö on the Swedish west coast and Pallas in Subarctic Finland. New BAs data are reported for 2018 and 2019 and chlorinated HMBs are included for these and some previous years: drosophilin A methyl ether (DAME: 1,2,4,5-tetrachloro-3,6-dimethoxybenzene), tetrachloroveratrole (TeCV: 1,2,3,4-tetrachloro-5,6-dimethoxybenzene), and pentachloroanisole (PeCA). The order of abundance of HMBs at Råö was ΣBAs > DAME > TeCV > PeCA, whereas at Pallas the order of abundance was DAME > ΣBAs > TeCA > PeCA. The lower abundance of BAs at Pallas reflects its inland location, away from direct marine influence. Clausius-Clapeyron (CC) plots of log partial pressure (P_air)/Pa versus 1/T suggested distant transport at both sites for PeCA and local exchange for DAME and TeCV. BAs were dominated by distant transport at Pallas and by both local and distant sources at Råö. Relationships between air and precipitation concentrations were examined by scavenging ratios, SR = (ng m^-3)_precip/(ng m^-3)_air. SRs were higher at Pallas than Råö due to greater Henry's law partitioning of gaseous compounds into precipitation at colder temperatures. DAME is produced by terrestrial fungi. We screened 19 fungal species from Swedish forests and found seven of them contained 0.01-3.8 mg DAME per kg fresh weight. We suggest that the volatilization of DAME from fungi and forest litter containing fungal mycelia may contribute to atmospheric levels at both sites.

Triclosan and triclocarban as potential risk factors of colitis and colon cancer: Roles of gut microbiota involved

In recent decades there has been a dramatic increase in the incidence and prevalence of inflammatory bowel disease (IBD), a chronic inflammatory disease of the intestinal tissues and a major risk factor of developing colon cancer. While accumulating evidence supports that the rapid increase of IBD is mainly caused by exposure to environmental risk factors, the identities of the risk factors, as well as the mechanisms connecting environmental exposure with IBD, remain largely unknown. Triclosan (TCS) and triclocarban (TCC) are high-volume chemicals that are used as antimicrobial ingredients in consumer and industrial products. They are ubiquitous contaminants in the environment and are frequently detected in human populations. Recent studies showed that exposure to TCS/TCC, at human exposure-relevant doses, increases the severity of colitis and exacerbates colon tumorigenesis in mice, suggesting that they could be risk factors of IBD and associated diseases. The gut toxicities of these compounds require the presence of gut microbiota, since they fail to induce colonic inflammation in mice lacking the microbiota. Regarding the functional roles of the microbiota involved, gut commensal microbes and specific microbial β-glucuronidase (GUS) enzymes mediate colonic metabolism of TCS, leading to metabolic reactivation of TCS in the colon and contributing to its subsequent gut toxicity. Overall, these results support that these commonly used compounds could be environmental risk factors of IBD and associated diseases through gut microbiota-dependent mechanisms.

Efficient biodegradation of tetrabromobisphenol A by the novel strain Enterobacter sp. T2 with good environmental adaptation: Kinetics, pathways and genomic characteristics

T2, a gram-positive bacterium capable of rapidly degrading tetrabromobisphenol A (TBBPA), and affiliated with the genus Enterobacter, was isolated for the first time from sludge that had been contaminated for several years. The TBBPA degradation data fitted the first-order model well. Under optimal conditions (pH of 7, temperature of 31 °C, TBBPA concentration of 5 mg L^-1, and inoculum size of 5%), 99.4% of the initially added TBBPA was degraded after 48 h. TBBPA degradation fitted the first-order model with the half-life of 3.3 h. These results illustrated that the TBBPA degradation capability of strain T2 was significantly better than that of previously reported bacteria. A total of 17 intermediates were detected, among which five were reported for the first time. Whole-genome sequencing revealed that strain T2 had a chromosome with the total length of 4 854 376 bp and a plasmid with the total length of 21 444 bp. It harbored essential genes responsible for debromination, such as cyp450, gstB, gstA, and HADH, and genes responsible for subsequent complete mineralization, such as bioC, yrrM, Tam, and Ubil. A key protein of haloacid dehalogenases responsible for the biodegradation of TBBPA may also be involved in the regulation of TBBPA degradation in natural environment. In soil bioremediation experiments, strain T2 showed excellent environmental adaptation. It was able to biodegrade TBBPA and its typical intermediate bisphenol A efficiently. Therefore, it could potentially be applied to treat TBBPA-contaminated sites.

Review of the environmental occurrence, analytical techniques, degradation and toxicity of TBBPA and its derivatives

BFRs (brominated flame retardants) are a class of compounds that are added to or applied to polymeric materials to avoid or reduce the spread of fire. Tetrabromobisphenol A (TBBPA) is one of the known BFR used many in industries today. Due to its wide application as an additive flame retardant in commodities, TBBPA has become a common indoor contaminant. Recent researches have raised concerns about the possible hazardous effect of exposure to TBBPA and its derivatives in humans and wildlife. This review gives a thorough assessment of the literature on TBBPA and its derivatives, as well as environmental levels and human exposure. Several analytical techniques/methods have been developed for sensitive and accurate analysis of TBBPA and its derivatives in different compartments. These chemicals have been detected in practically every environmental compartment globally, making them a ubiquitous pollutant. TBBPA may be subject to adsorption, biological degradation or photolysis, photolysis after being released into the environment. Treatment of TBBPA-containing waste, as well as manufacturing and usage regulations, can limit the release of these chemicals to the environment and the health hazards associated with its exposure. Several methods have been successfully employed for the treatment of TBBPA including but not limited to adsorption, ozonation, oxidation and anaerobic degradation. Previous studies have shown that TBBPA and its derivative cause a lot of toxic effects. Diet and dust ingestion and have been identified as the main routes of TBBPA exposure in the general population, according to human exposure studies. Toddlers are more vulnerable than adults to be exposed to indoor dust through inadvertent ingestion. Furthermore, TBBP-A exposure can occur during pregnancy and through breast milk. This review will go a long way in closing up the knowledge gap on the silent and over ignored deadly effects of TBBPA and its derivatives and their attendant consequences.

Polystyrene Nanoplastics Inhibit the Transformation of Tetrabromobisphenol A by the Bacterium Rhodococcus jostii

Microplastics (MPs) and nanoplastics (NPs) in the environment pose significant risks to organisms of different trophic levels. While the toxicity of MPs and NPs have been extensively investigated, it remains unknown whether these particles affect microbial transformation of organic pollutants. Here, we show that 20 and 100 nm polystyrene NPs (PS-NPs) can inhibit the transformation of tetrabromobisphenol A (TBBPA) by Gram-positive bacterium Rhodococcus jostii in a concentration-dependent manner. We found that smaller PS-NPs were more inhibitory than larger ones and that both PS-NPs affected biotransformation in several ways. PS-NPs adsorbed TBBPA on their surface and reduced the bioavailable concentration of TBBPA for transformation by R. jostii. Furthermore, PS-NPs induced oxidative stress, increased membrane permeability, and downregulated O-methyltransferase enzymes that transform TBBPA into their methylated derivatives. Our results demonstrate that PS-NPs can impact microbial transformation of organic pollutants, and these effects should be accounted for in future environmental risk assessments.

Naturally occurring organobromine compounds (OBCs) including polybrominated dibenzo-p-dioxins in the marine sponge Hyrtios proteus from The Bahamas

Halogenated natural products (HNPs) were identified from organic extracts of the marine sponge Hyrtios proteus from The Bahamas using gas chromatography with electron capture negative ion mass spectrometry and non-targeted gas chromatography with electron ionization mass spectrometry. The HNPs found have similar properties to anthropogenic persistent organic pollutants (POPs). Two ortho-methoxy brominated diphenyl ethers (MeO-BDEs) 2'-MeO-BDE 68 and 6-MeO-BDE 47 were the most abundant compounds. Fourteen other MeO-BDEs were detected along with several polybrominated dibenzo-p-dioxins (PBDDs) (1,3,7-triBDD, 1,3,6,8-tetraBDD and 1,3,7,9-tetraBDD) and MeO-PBDDs. Further analysis of a higher trophic level octopus (Octopus maya) from the same FAO fishing area showed that the major HNPs detected in Hyrtios proteus were also predominant. Moreover, HNPs were more than 30-fold higher in abundance than the major POPs in the octopus, i.e., polychlorinated biphenyls. Hence, Caribbean marine organisms, including those potentially used for food, harbor relatively high concentrations of HNPs.

Biotransformation of halophenols into earthy-musty haloanisoles: Investigation of dominant bacterial contributors in drinking water distribution systems

Microorganisms in drinking water distribution systems (DWDSs) can O-methylate toxic halophenols (HPs) into earthy-musty haloanisoles (HAs). However, the dominant HA-producing bacterial species and their O-methylation properties are still unknown. In this study, eight bacterial strains from DWDS were isolated and the community abundances of the related genera in bulk water and biofilms as well as their O-methylation properties were investigated. Among the genera discovered in this study, Sphingomonas and Pseudomonas are dominant and play important roles in DWDSs. All bacteria could simultaneously convert five HPs to the corresponding HAs. Two Sphingomonas ursincola strains mainly produced 2,3,6-trichloroanisole (2,3,6-TCA) (2.48 × 10^-9-1.18 × 10^-8 ng/CFU), 2,4,6-trichloroanisole (2,4,6-TCA) (8.12 × 10^-10-3.11 × 10^-9 ng/CFU) and 2,4,6-tribromoanisole (2,4,6-TBA) (2.95 × 10^-9-3.21 × 10^-9 ng/CFU), while two Pseudomonas moraviensis strains preferred to generate 2-monochloroanisole (2-MCA) (1.19 × 10^-9-3.70 × 10^-9 ng/CFU) and 2,4-dichloroanisole (2,4-DCA) (3.81 × 10^-9-1.20 × 10^-8 ng/CFU). Among the chloramphenicol-susceptible strains, four strains contained inducible O-methyltransferases (OMTs), while the O-methylations of the others were expressed constitutively. All bacteria could use S-adenosyl methionine as methyl donor. Potential taste and odor (T & O) risks of five HAs in DWDS followed an order of 2,4,6-TBA > 2,4,6-TCA > 2,3,6-TCA > 2,4-DCA > 2-MCA. The recommended 2,4,6-TCP criteria for T & O control is 0.003-0.07 mg/L.

Uptake, phytovolatilization, and interconversion of 2,4-dibromophenol and 2,4-dibromoanisole in rice plants

The structural analogs, 2,4-dibromophenol (2,4-DBP) and 2,4-dibromoanisole (2,4-DBA), have both natural and artificial sources and are frequently detected in environmental matrices. Their environmental fates, especially volatilization, including both direct volatilization from cultivation solution and phytovolatilization through rice plants were evaluated using hydroponic exposure experiments. Results showed that 2,4-DBA displayed stronger volatilization tendency and more bioaccumulation in aboveground rice tissues. Total volatilized 2,4-DBA accounted for 4.74% of its initial mass and was 3.43 times greater than 2,4-DBP. Phytovolatilization of 2,4-DBA and 2,4-DBP contributed to 6.78% and 41.7% of their total volatilization, enhancing the emission of these two contaminants from hydroponic solution into atmosphere. In this study, the interconversion processes between 2,4-DBP and 2,4-DBA were first characterized in rice plants. The demethylation ratio of 2,4-DBA was 12.0%, 32.0 times higher than methylation of 2,4-DBP. Formation of corresponding metabolites through methylation and demethylation processes also contributed to the volatilization of 2,4-DBP and 2,4-DBA from hydroponic solution into the air phase. Methylation and demethylation processes increased phytovolatilization by 12.1% and 36.9% for 2,4-DBP and 2,4-DBA. Results indicate that phytovolatilization and interconversion processes in rice plants serve as important pathways for the global cycles of bromophenols and bromoanisoles.

Halogenated natural products in birds associated with the marine environment: A review

Halogenated natural products (HNPs) are widespread compounds found at high concentrations in top predators such as seabirds. This paper reviews available data on methoxylated polybrominated diphenyl ethers (MeO-BDEs), heptachloro-1'-methyl-1,2'-bipyrrole (Q1) and 1,1'-dimethyl-2,2'-bipyrroles (HDBPs) in these animals. In all, 25 papers reported such HNPs in seabirds. White tailed sea eagle from Sweden was the seabird species with higher MeO-BDEs levels in eggs and blood, while in liver the European shag from Norway was the one. Regarding HDBPs, glaucous gull livers from North Water Polynya and Leach's storm petrel eggs from South Canada (NE Atlantic) showed the highest levels, while brown skua eggs presented the highest concentration of Q1. DBP-Br₄Cl₂ and DBP-Br₆ were the most abundant HDBPs in seabirds, although only one study investigated DBP-Br₆. Furthermore, 2'-MeO-BDE-68/6'-MeO-BDE-47 ratios were lower than one in mostly of the studies (91%). The main sources of methoxylated congeners found in seabirds might to be from sponges and/or associated organisms (bacteria). The scarcity of data in seabirds showed the gap in knowledge. Few studies were done especially in tropical areas and Southern Hemisphere and the most were conducted in the northwest part of the globe. This review arouses the need of knowledge about the distribution of these compounds in seabirds worldwide as well as it encourages toxicological studies to better understand the possible effects of HNPs on seabirds.

Dissipation, transformation and accumulation of triclosan in soil-earthworm system and effects of biosolids application

Triclosan (TCS), widely used as an antimicrobial ingredient, is usually introduced into soil by biosolids application, and has presented potential risk in agro-ecosystem. The dissipation pathways of TCS in soil were analyzed in the presence and absence of earthworms (including Metaphire guillelmi and Eisenia fetida). Meanwhile the accumulation and transformation potentials of TCS in the two earthworms were evaluated. Results indicated that about 44% of initial TCS amount dissipated in sterile soil after 56-day incubation, which may mainly result from the bound-residues formation. In contrast, TCS in non-sterile soil dissipated more quickly with a t_1/2 of 12 days, suggesting that microbial degradation was responsible for TCS dissipation. Triclosan was methylated to methyl triclosan (MTCS) in soil, which however contributed little for TCS dissipation. The presence of M. guillelmi accelerated TCS dissipation with the reduced t_1/2 to 8 days, and inhibited MTCS formation in soil, while E. fetida had no significant (P > 0.05) effects on the fate of TCS. E. fetida accumulated more TCS than M. guillelmi, with bioaccumulation factors up to 11 vs. 0.6. It was also proved that methylation metabolism occurred in earthworms (including gut microorganisms), and M. guillelmi had higher metabolic efficiency compared to E. fetida. Even though eliminations of TCS and MTCS were rapid (except for TCS in M. guillelmi), the residues of the two compounds in both earthworms remained at high levels, having the potential to transfer in the terrestrial food web. In addition, results showed that biosolids application changed TCS persistence, as well as bioavailability dependent on earthworm species. When biosolids at 1% added, more residual TCS and MTCS in soil were observed, while TCS accumulation in E. fetida decreased, however, methylation metabolism in both earthworm species was not affected. The findings provide important information for a more precise risk assessment of biosolids land-application. CAPSULE: Triclosan dissipation, methylation and bioavailability in soils were affected by biosolids amendment and dependent on earthworm species with different accumulation and metabolic potentials.

Formation of odorant haloanisoles and variation of microorganisms during microbial O-methylation in annular reactors equipped with different coupon materials

Taste and odor (T & O) issues in drinking water have become serious problems which cannot be ignored by customers. Several studies have confirmed that microbes in water can biotransform halophenols (HPs) to haloanisoles (HAs) with earthy and musty flavors via microbial O-methylation. In this paper, the formation of 2-chloroanisole (2-CA), 2,4-dichloroanisole (2,4-DCA), 2,4,6-trichloroanisole (2,4,6-TCA), 2,3,6-trichloroanisole (2,3,6-TCA) and 2,4,6-tribromoanisole (2,4,6-TBA), and the microbial variation during the microbial O-methylation were investigated in annular reactors (ARs) with three coupon materials. For precursors, 42.5% of 2-CP and 68.9% of 2,4-DCP decayed during the reaction. Among the five HAs, the formation rate constant followed an order of 2,4,6-TCA > 2-CA > 2,4,6-TBA > 2,4-DCA ~ 2,3,6-TCA, while [HA]_max followed a totally opposite one. The simulated flow velocity had no significant effect (p > 0.05) on HA formation. Ductile iron (DI) AR could produce more HAs than stainless steel (SS) and polyvinyl chloride (PVC) ARs. The final HA molar concentration followed an order of 2,3,6-TCA > 2,4-DCA > 2,4,6-TBA ~ 2,4,6-TCA > 2-CA, which might be explained by multiple factors including HP's dissociation degree, halogen atom's steric hindrance and specificity of HP O-methyltransferases. During the reaction, the microbial biomass dramatically increased 6.8-9.0 times in bulk water but dropped significantly on coupon biofilms. The effect of HPs significantly changed the bacterial communities on coupon in terms of composition and diversity, and declined the relative abundance of HA-producing bacteria, while fungi and their HA-producing genus showed better resistance ability towards HPs. By using Pearson correlation analysis, a significant correlation (p = 0.0003) was found between [HA]_max and initial coupon biofilm biomass. Finally, a linear relationship was established between initial total biomass and HA formation potential.

Occurrence and concentrations of halogenated natural products derived from seven years of passive water sampling (2007-2013) at Normanby Island, Great Barrier Reef, Australia

Polydimethylsiloxane (PDMS) based passive water samplers deployed at Normanby Island, Great Barrier Reef (Australia) from 2007 to 2013 were analyzed for halogenated natural products (HNPs). Altogether, 38 samples, typically deployed for 30 days, were studied. Five HNPs (Q1, 2'‑MeO-BDE 68, BC-10, 2,4‑dibromoanisole and 2,4,6‑tribromoanisole) were detected in all samples. Most samples (>90%) featured 2,2'‑diMeO-BB 80, 6‑MeO-BDE 47, 2',6‑diMeO-BDE 68 and 2,4‑dibromophenol. In addition, tetrabromo‑N‑methylpyrrole (TBMP) was detected in ~80% and Cl₆-DBP in ~30% of the samples. Estimated time weighted maximum water concentrations were >150 pg Q1 and 60 pg 2'‑MeO-BDE 68 per L seawater. Typically, the concentrations were varying from year to year. Moreover, time weighted average water concentration estimates did not reveal consistent maximum trend levels within a given year. Additional screening analysis via GC/MS indicated the presence of several polyhalogenated 1'‑methyl‑1,2'‑bipyrroles (PMBPs), 1,1'‑dimethyl‑2,2'‑bipyrroles (PDBPs), and 1‑methylpyrroles (PMPs) along with four brominated N‑methylindoles and several other polyhalogenated compounds at Normanby Island.

Transformation of tetrabromobisphenol A by Rhodococcus jostii RHA1: Effects of heavy metals

Tetrabromobisphenol A (TBBPA) is one of the most widely used brominated flame retardants in the world but it is also a pollutant of global concern. In the present study, we studied the transformation of ¹⁴C-labeled TBBPA by a polychlorinated-biphenyl-degrading bacterium, Rhodococcus jostii RHA1 (RHA1), under oxic conditions. During the 5-day incubation, TBBPA was biotransformed rapidly first to its monomethyl ether MeO-TBBPA and then to its more hydrophobic but less toxic dimethyl ether diMeO-TBBPA. The biotransformation followed pseudo-first-order decay kinetics, with a half-life of TBBPA of 0.32 days and only 0.6% of the initially added amount being mineralized. Considering the frequent co-occurrence of TBBPA with heavy metals in the natural environment, we also investigated the effects of three heavy metals (Cd, Cu, and Fe) on the transformation of TBBPA by strain RHA1. While TBBPA transformation was not significantly altered by Cd, it was accelerated by Cu and Fe, presumably due to the effects of these two essential metals on O-methyltransferase activity. Overall, the present study showed that RHA1 is an effective transformer of TBBPA and that certain essential metals, including Cu and Fe, promote the transformation.

PBDEs and their structural analogues in marine environments: Fate and expected formation mechanisms compared with diverse environments

The concentrations and relative distributions of 27 polybrominated diphenyl ethers (PBDEs) and 17 methoxylated (MeO-) and 8 hydroxylated (OH-) BDEs were determined in marine environments including sediments, bivalves, and seawater along the southern coast of South Korea to understand their fates and possible formation mechanisms. The relative and substituent distributions of the PBDEs and their structural analogues varied according to the characteristics of the media. PBDEs were dominant in marine sediments and seawater, whereas MeO-BDEs made the highest contributions in bivalves. Similar patterns were previously identified in inland environments in Korea, except in river water where OH-BDEs were dominant. The natural formation of structural analogues might be the main mechanism in marine, as ortho-substituted naturally occurring MeO- and OH-BDEs were dominant in all media and seemed to be more produced than in inland environments. In addition, the higher concentrations of meta-substituted MeO-BDEs nearshore than offshore was observed. This is the first study comparing marine (near- and offshore) and inland to understand the differences in their fate and possible formation mechanisms in each environmental conditions.

Environmental concentrations and toxicology of 2,4,6-tribromophenol (TBP)

2,4,6-Tribromophenol is the most widely produced brominated phenol. In the present review, we summarize studies dealing with this substance from an environmental point of view. We cover concentrations in the abiotic and biotic environment including humans, toxicokinetics as well as toxicodynamics, and show gaps of the current knowledge about this chemical. 2,4,6-Tribomophenol occurs as an intermediate during the synthesis of brominated flame retardants and it similarly represents a degradation product of these substances. Moreover, it is used as a pesticide but also occurs as a natural product of some aquatic organisms. Due to its many sources, 2,4,6-tribromophenol is ubiquitously found in the environment. Nevertheless, not much is known about its toxicokinetics and toxicodynamics. It is also unclear which role the structural isomer 2,4,5-tribromophenol and several degradation products such as 2,4-dibromophenol play in the environment. Due to new flame retardants that enter the market and can degrade to 2,4,6-tribromophenol, this compound will remain relevant in future years - not only in aquatic matrices, but also in house dust and foodstuff, which are an important exposure route for humans.

Atmospheric Transport and Deposition of Bromoanisoles Along a Temperate to Arctic Gradient

Bromoanisoles (BAs) arise from O-methylation of bromophenols, produced by marine algae and invertebrates. BAs undergo sea-air exchange and are transported over the oceans. Here we report 2,4-DiBA and 2,4,6-TriBA in air and deposition on the Swedish west coast (Råö) and the interior of arctic Finland (Pallas). Results are discussed in perspective with previous measurements in the northern Baltic region in 2011-2013. BAs in air decreased from south to north in the order Råö > northern Baltic > Pallas. Geometric mean concentrations at Pallas increased significantly (p < 0.05) between 2002 and 2015 for 2,4-DiBA but not for 2,4,6-TriBA. The logarithm of BA partial pressures correlated significantly to reciprocal air temperature at the coastal station Råö and over the Baltic, but only weakly (2,4-DiBA) or not significantly (2,4,6-TriBA) at inland Pallas. Deposition fluxes of BAs were similar at both sites despite lower air concentrations at Pallas, due to greater precipitation scavenging at lower temperatures. Proportions of the two BAs in air and deposition were related to Henry's law partitioning and source regions. Precipitation concentrations were 10-40% of those in surface water of Bothnian Bay, northern Baltic Sea. BAs deposited in the bay catchment likely enter rivers and provide an unexpected source to northern estuaries. BAs may be precursors to higher molecular weight compounds identified by others in Swedish inland lakes.

Polyhalogenated compounds (chlorinated paraffins, novel and classic flame retardants, POPs) in dishcloths after their regular use in households

Dishcloths are routinely used in the clean-up process following daily kitchen activities and are thus subject to contamination commensurate with their frequent use. Here we analyzed dishcloths for the occurrence of polyhalogenated compounds after 14days of use in household kitchens. Analysis of 19 dishcloths revealed the presence of 29 polyhalogenated contaminants with total mean/median concentrations of 6,900/3,600ng/dishcloth, respectively. The spectrum featured classic and novel halogenated flame-retardants (HFRs) like polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), decabromodiphenyl ethane (DBDPE), pentabromoethylbenzene (PBEB), chlordene plus and dechlorane plus, as well as typical chloropesticides and background contaminants (e.g. hexachlorobenzene (HCB), p,p'-dichlorodiphenyldichloroethene (p,p'-DDE), polychlorinated biphenyls (PCBs) and lindane). The individual dishcloths showed highly variable fingerprints of polyhalogenated compounds. If present, medium-chain chlorinated paraffins (MCCPs) were by far the most prominent compound class with up to 55,400ng/dishcloth. Without consideration of chlorinated paraffins, the mean concentration of other polychlorinated compounds (270ng/dishcloth) was generally one order of magnitude lower than the mean concentration of brominated flame retardants (BFRs) (1,700ng/dishcloth). Our study verified that a wide range of polyhalogenated compounds is readily available in the kitchen environment. Furthermore, dishcloths are ordinarily handled without gloves or hand protection, given the observed concentrations of polyhalogenated compounds in dishcloths, such handling may serve as an additional exposure pathway for human users. Evaluation of this thesis was supported by conduction of a dermal uptake assessment.

Uptake and biotransformation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in four marine microalgae species

Hydroxylated- and methoxylated- polybrominated diphenyl ethers (OH-PBDEs and MeO-PBDEs) are more toxic than PBDEs and occur widely in the marine environment, and yet their origins remain controversial. In this study, four species of microalgae (Isochrysis galbana, Prorocentrum minimum, Skeletonema grethae and Thalassiosira pseudonana) were exposed to BDE-47, which is synthetic and is the predominant congener of PBDEs in the environment. By chemical analysis after incubation of 2 to 6 days, the efficiency of uptake of BDE-47 and, more importantly, the potential of undergoing biotransformation to form OH-PBDEs and MeO-PBDEs by the microalgae were investigated. Growth rates of these axenic microalgae were not affected upon exposure to environmentally relevant concentrations (0.2–20 μg BDE-47 L⁻¹), and accumulation ranged from 0.772 ± 0.092 μg BDE-47 g⁻¹ lipid to 215 ± 54 μg BDE-47 g⁻¹ lipid within 2 days. Debromination of BDE-47 and formation of BDE-28 occurred in all microalgae species (0.01 to 0.87%), but biotransformation to OH-PBDEs was only found in I. galbana upon exposure to extremely high concentration. The results of this study showed that biotransformation of microalgae species is unlikely an explanation for the OH-PBDEs and MeO-PBDEs found in the marine environment.

Triclosan exposure, transformation, and human health effects

Triclosan (TCS) is an antimicrobial used so ubiquitously that 75% of the US population is likely exposed to this compound via consumer goods and personal care products. In September 2016, TCS was banned from soap products following the risk assessment by the US Food and Drug Administration (FDA). However, TCS still remains, at high concentrations, in other personal care products such as toothpaste, mouthwash, hand sanitizer, and surgical soaps. TCS is readily absorbed into human skin and oral mucosa and found in various human tissues and fluids. The aim of this review was to describe TCS exposure routes and levels as well as metabolism and transformation processes. The burgeoning literature on human health effects associated with TCS exposure, such as reproductive problems, was also summarized.

Levels, profiles and dietary sources of hydroxylated PCBs and hydroxylated and methoxylated PBDEs in Japanese women serum samples

Human exposure to polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) may result in retention of specific congeners of hydroxylated PCBs (OH-PCBs) and hydroxylated/methoxylated PBDEs (OH-/MeO-PBDEs) in serum. However, dietary sources and biotransformation of OH-/MeO-PBDEs in humans are poorly understood. Therefore, this study was conducted to investigate the levels, profiles, and exposure sources of OH-/MeO-PBDEs along with OH-PCBs present in human serum. Twenty serum samples pooled from women of four age groups (30s/40s/50s/60s) living in four districts of Japan were analyzed for OH-/MeO-PBDEs, and their profiles were then compared with those of seafood (seaweed and fish). The major component of OH-PCBs in the phenolic fraction of serum was 4-OH-CB187 (mean: 85pgg^-1 wet weight (ww)). Total OH-PCBs accounted for about 1/20 of the total PCBs (mean; 1800pgg^-1 ww). In contrast, the predominant component of OH-PBDEs in serum was 6-OH-BDE47 (mean: 183pgg^-1 ww), which was about 20-fold higher than BDE-47 (mean; 8.7pgg^-1 ww). In the neutral fraction, 2'-MeO-BDE68 was primarily found at a similar concentration (mean 5.6pgg^-1 ww) to BDE-47. Both 4-OH-PCB187 and 2'-MeO-BDE68 were significantly correlated with woman's age (p<0.01), but not with 6-OH-BDE47 or BDE-47. The profiles of OH-PBDEs in serum were consistent with those in edible seaweeds (Sargassum fusiforme) sold for human consumption, whereas MeO-PBDEs had a similar profile as those in edible fish (Serranidae sp.) from Japanese coastal waters. These findings indicate that the profiles of OH-PBDEs and MeO-PBDEs in Japanese serum are different from those in other countries, and their sources may be specific edible seaweeds and fish, respectively. This is the first report of profiles and dietary sources of OH/MeO-PBDEs in human serum from Japan.

Perspectives of using fungi as bioresource for bioremediation of pesticides in the environment: a critical review

Pesticides are used for controlling the development of various pests in agricultural crops worldwide. Despite their agricultural benefits, pesticides are often considered a serious threat to the environment because of their persistent nature and the anomalies they create. Hence removal of such pesticides from the environment is a topic of interest for the researchers nowadays. During the recent years, use of biological resources to degrade or remove pesticides has emerged as a powerful tool for their in situ degradation and remediation. Fungi are among such bioresources that have been widely characterized and applied for biodegradation and bioremediation of pesticides. This review article presents the perspectives of using fungi for biodegradation and bioremediation of pesticides in liquid and soil media. This review clearly indicates that fungal isolates are an effective bioresource to degrade different pesticides including lindane, methamidophos, endosulfan, chlorpyrifos, atrazine, cypermethrin, dieldrin, methyl parathion, heptachlor, etc. However, rate of fungal degradation of pesticides depends on soil moisture content, nutrient availability, pH, temperature, oxygen level, etc. Fungal strains were found to harbor different processes including hydroxylation, demethylation, dechlorination, dioxygenation, esterification, dehydrochlorination, oxidation, etc during the biodegradation of different pesticides having varying functional groups. Moreover, the biodegradation of different pesticides was found to be mediated by involvement of different enzymes including laccase, hydrolase, peroxidase, esterase, dehydrogenase, manganese peroxidase, lignin peroxidase, etc. The recent advances in understanding the fungal biodegradation of pesticides focusing on the processes, pathways, genes/enzymes and factors affecting the biodegradation have also been presented in this review article.

Fate of Tetrabromobisphenol A (TBBPA) and Formation of Ester- and Ether-Linked Bound Residues in an Oxic Sandy Soil

Bound-residue formation is a major dissipation process of most organic xenobiotics in soil. However, both the formation and nature of bound residues of tetrabromobisphenol A (TBBPA) in soil are unclear. Using a 14C-tracer, we studied the fate of TBBPA in an oxic soil during 143 days of incubation. TBBPA dissipated with a half-life of 14.7 days; at the end of incubation, 19.6% mineralized and 66.5% formed bound residues. Eight extractable metabolites were detected, including TBBPA methyl ethers, single-ring bromophenols, and their methyl ethers. Bound residues (mostly bound to humin) rapidly formed during the first 35 days. The amount of those humin-bound residues then quickly decreased, whereas total bound residues decreased slowly. By contrast, residues bound to humic acids and fulvic acids increased continuously until a plateau was reached. Ester- and ether-linked residues accounted for 9.6-27.0% of total bound residues during the incubation, with ester linkages being predominant. Residues bound via ester linkages consisted of TBBPA, TBBPA monomethyl ether, and an unknown polar compound. Our results indicated that bound-residue formation is the major pathway of TBBPA dissipation in oxic soil and provide first insights into the chemical structure of the reversibly ester-linked bound residues of TBBPA and its metabolites.

Investigation of bioaccumulation and biotransformation of polybrominated diphenyl ethers, hydroxylated and methoxylated derivatives in varying trophic level freshwater fishes

The concentrations and distributions of polybrominated diphenyl ethers (PBDEs) and their hydroxylated and methoxylated derivatives (OH- and MeO-BDEs) were determined in seven representative fish species from a river in the Republic of Korea. The PBDEs and their derivatives were found to be accumulated in the internal organs of the fish to different extents. PBDEs were preferentially accumulated in the internal organs rather than muscle tissue, and especially, showed increasing accumulation tendencies with increasing bromination level in liver. The OH-BDEs and MeO-BDEs were preferentially accumulated in the liver and gastrointestinal tract, respectively. MeO-BDE concentrations were found to increase according to relative trophic level, suggesting that the PBDE derivatives can be biomagnified to a greater extent than the parent PBDEs in freshwater food webs. In a comparison with the dissolved analyte concentrations in the water that were measured by using semi-permeable membrane devices, the greater uptake of non-ortho substituted MeO-BDEs by fish was observed.

A broad cocktail of environmental pollutants found in eggs of three seabird species from remote colonies in Norway

Eggs of 3 seabird species, common eider (Somateria mollisima), European shag (Phalacrocorax aristotelis aristotelis), and European herring gull (Larus argentatus), were surveyed for a broad range of legacy and emerging pollutants to assess chemical mixture exposure profiles of seabirds from the Norwegian marine environment. In total, 201 chemical substances were targeted for analysis ranging from metals, organotin compounds, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and associated metabolites, chlorinated paraffins, chlorinated and nonchlorinated organic pesticides, per- and polyfluoroalkyl substances (PFAS), dechlorane plus, octachlorostyrene, brominated flame retardants (BFRs), organophosphorous compounds, brominated and alkyl phenols, cyclic siloxanes, and phthalates. Of the chemicals targeted, 149 substances were found above the detection limits, with metals dominating the contaminant profile and comprising 60% of the total contaminant load. Polychlorinated biphenyls, pesticides, organophosphorous compounds, and PFAS were the dominant contaminant classes of organic pollutants found within the seabird species, with the highest loads occurring in herring gulls, followed by shag, and common eider. New generation pollutants (e.g., PFAS, organophosphorous compounds, and alkylphenols) were detected at similar or higher concentrations than the legacy persistent organic pollutants (POPs). Time trends of reported concentrations of legacy POPs appear to have decreased in recent decades from the Norwegian coastal environment. Concentrations of detected pollutants do not appear to have a negative effect on seabird population development within the sampling area. Additional stress caused by pollutants, however, may affect seabird health more at the individual level.

Degradation and metabolism of tetrabromobisphenol A (TBBPA) in submerged soil and soil-plant systems

Contamination by tetrabromobisphenol A (TBBPA), the most widely used brominated flame retardant, is a matter of environmental concern. Here, we investigated the fate and metabolites of (14)C-TBBPA in a submerged soil with an anoxic-oxic interface and planted or not with rice (Oryza sativa) and reed (Phragmites australis) seedlings. In unplanted soil, TBBPA dissipation (half-life 20.8 days) was accompanied by mineralization (11.5% of initial TBBPA) and the substantial formation (60.8%) of bound residues. Twelve metabolites (10 in unplanted soil and 7 in planted soil) were formed via four interconnected pathways: oxidative skeletal cleavage, O-methylation, type II ipso-substitution, and reductive debromination. The presence of the seedlings strongly reduced (14)C-TBBPA mineralization and bound-residue formation and stimulated debromination and O-methylation. Considerable radioactivity accumulated in rice (21.3%) and reed (33.1%) seedlings, mainly on or in the roots. While TBBPA dissipation was hardly affected by the rice seedlings, it was strongly enhanced by the reed seedlings, greatly reducing the half-life (11.4 days) and increasing monomethyl TBBPA formation (11.3%). The impact of the interconnected aerobic and anaerobic transformation of TBBPA and wetland plants on the profile and dynamics of the metabolites should be considered in phytoremediation strategies and environmental risk assessments of TBBPA in submerged soils.

Spatial distributions of methoxylated and hydroxylated polybrominated diphenyl ethers in the East China Sea--a seaward increasing trend

Methoxylated (MeO-) and hydroxylated (OH-) polybrominated diphenyl ethers (PBDEs) in marine environments have been of increasing concern due to their potential ecological toxicities and worldwide occurrence. However, few reports have been referred to their occurrence and distributions in marine sediments despite large numbers of studies on marine organisms have been reported. In the present paper, nine MeO-BDEs, ten OH-BDEs and three phytoplankton biomarkers (PBs) of brassicasterol, dinosterol and alkenones have been measured in surface sediments from the East China Sea. 6-MeO-BDE47, 2'-MeO-BDE68 and 6-OH-BDE47 were predominant congeners, ranging from 5.2 to 599.5 pg g(-1)dw, 5.2 to 562.4 pg g(-1)dw, and 11.4 to 129.1 pg g(-1)dw, respectively. Their spatial patterns all presented a seaward increasing trend and higher levels of these compounds were mainly concentrated in the outer shelf influenced by the Kuroshio Current. The patterns further prove that these ortho-substituted MeO-BDEs and OH-BDEs in marine sediments are natural compounds. Furthermore, alkenones also presented a seaward increasing trend. Statistical analysis shows that there are significant correlations between MeO-BDEs, OH-BDEs and alkenones, impling the potential of coccolithophorids for producing these natural compounds and their global distribution, especially in open oceans. Comparison between TOC and the ratio of 6-MeO-BDE47/6-OH-BDE47 suggests that TOC should be a potential controlling factor of the conversion between MeO-BDE and OH-BDE pairs.

Fate and metabolism of tetrabromobisphenol A in soil slurries without and with the amendment with the alkylphenol degrading bacterium Sphingomonas sp. strain TTNP3

Transformation of ring-(14)C-labelled tetrabromobisphenol-A (TBBPA) was studied in an oxic soil slurry with and without amendment with Sphingomonas sp. strain TTNP3, a bacterium degrading bisphenol-A. TBBPA degradation was accompanied by mineralization and formation of metabolites and bound-residues. The biotransformation was stimulated in the slurry bio-augmented with strain TTNP3, via a mechanism of metabolic compensation, although this strain did not grow on TBBPA. In the absence and presence of strain TTNP3, six and nine metabolites, respectively, were identified. The initial O-methylation metabolite (TBBPA-monomethyl ether) and hydroxytribromobisphenol-A were detected only when strain TTNP3 was present. Four primary metabolic pathways of TBBPA in the slurries are proposed: oxidative skeletal rearrangements, O-methylation, ipso-substitution, and reductive debromination. Our study provides for the first time the information about the complex metabolism of TBBPA in oxic soil and suggests that type II ipso-substitution could play a significant role in the fate of alkylphenol derivatives in the environment.

Biotransformation of the flame retardant tetrabromobisphenol-A (TBBPA) by freshwater microalgae

Tetrabromobisphenol-A (TBBPA) is the most widely used brominated flame retardant. However, little is known about its biotransformation by algae in aquatic environments. The authors investigated transformations of TBBPA by 6 freshwater green microalgae and identified its transformation products. Transformation experiments were conducted under axenic conditions in a laboratory for 10 d. The results showed that TBBPA could be transformed by the selected microalgae, with nearly complete removal by Scenedesmus quadricauda and Coelastrum sphaericum following 10-d incubation. Five transformation products were positively identified by mass spectrometry: TBBPA sulfate, TBBPA glucoside, sulfated TBBPA glucoside, TBBPA monomethyl ether, and tribromobisphenol-A. The mechanisms involved in the biotransformation of TBBPA include sulfation, glucosylation, O-methylation, and debromination, which could be an important step for its further degradation. This suggests that microalgae can play an important role in the fate of TBBPA in aquatic environments. The present study is the first report on algal transformation of TBBPA, and the proposed transformation products could have significant environmental implications.

Anthropogenic (PBDE) and naturally-produced (MeO-PBDE) brominated compounds in cetaceans--a review

This paper reviews the available data on brominated flame retardants, the polybrominated diphenyl ethers (PBDEs), as well as on the naturally-produced methoxylated polybrominated diphenyl ethers (MeO-PBDEs) in cetacean tissues around the world. Levels and possible sources of both compound classes are discussed. Odontocete cetaceans accumulate higher PBDE concentrations than mysticete species. PBDE contamination was higher in cetaceans from the Northern hemisphere, whereas MeO-PBDE levels were higher in animals from the Southern hemisphere. Southern resident killer whales from NE Pacific presented the highest levels reported in biota, followed by bottlenose dolphins from North Atlantic (U.K. and U.S. coast). Many species presented PBDE concentrations above threshold levels for health effects in odontocetes. Time trend studies indicate that PBDE concentrations in odontocetes from Japan, China, U.S. and Canada coastal zones have increased significantly over the past 30 years. Studies from U.K. waters and NE Atlantic showed a decrease and/or stability of PBDE levels in cetacean tissues in recent decades. The highest MeO-PBDE concentrations were found in dolphins from Tanzania (Indian Ocean), bottlenose dolphins from Queensland, Australia (SW Pacific), and odontocetes from coastal and continental shelf waters off southeastern Brazil (SW Atlantic). The upwelling phenomenon and the presence of coral reef complexes in these tropical oceans may explain the large amounts of the naturally-produced organobromines. Considering that these bioaccumulative chemicals have properties that could cause many deleterious effects in those animals, future studies are required to evaluate the potential ecotoxicological risks.

Novel octabrominated phenolic diphenyl ether identified in blue mussels from the Swedish West Coast

Hydroxylated (OH-) and methoxylated (MeO-) polybrominated diphenyl ethers (PBDEs) are compounds present in the marine environment and OH-PBDEs are of toxicological concern and are therefore of interest to monitor in the environment. A phenolic octaBDE was tentatively identified in the phenolic fraction of previously analyzed mussel samples after methylation of the halogenated phenolic compounds (HPCs). The aim of the present study was to confirm the identity of this compound in blue mussels and investigate whether the analyte is diOH- and/or OH-MeO-octaBDE. Two reference standards, 6,6'-dimethoxy-2,2',3,3',4,4',5,5'-octabromodiphenyl ether (6,6'-diMeO-BDE194) and 6-ethoxy-6'-methoxy-2,2',3,3',4,4',5,5'-octabromodiphenyl ether (6-EtO-6'-MeO-BDE194) were prepared via O-arylation of 2,3,4,5-tetrabromo-6-methoxyphenol and 2,3,4,5-tetrabromo-6-ethoxyphenol, respectively, with a novel unsymmetrical diaryliodonium salt, 2,3,4,5-tetrabromo-6-methoxydiphenyliodonium triflate. The GC retention time and GC/MS spectrum of the synthesized 6,6'-diMeO-BDE194 correspond well with the analyte in the methylated phenolic fraction of a mussel extract from a previous study. Structural analysis performed in this study indicate that the synthesized 6,6'-diMeO-BDE194 and 6-EtO-6'-MeO-BDE194 correspond well with 6-hydroxy-6'-methoxy-2,2',3,3',4,4',5,5'-octabromodiphenyl ether (6-OH-6'-MeO-BDE194) after methylation and ethylation, respectively, of the HPCs in the mussel extracts. The compound 6-OH-6'-MeO-BDE194 was identified and quantified in new mussels, sampled in 2012 from two locations on the Swedish west coast, with geometric mean concentrations of 3700 and 410 ng/g fat, respectively.

Dietary exposure to phenolic and methoxylated organohalogen contaminants in relation to their concentrations in breast milk and serum in Japan

This study investigated human exposure to neutral, phenolic, and methoxylated organohalogen contaminants (OHCs) in a duplicate diet study to evaluate their concentrations in breast milk and serum of Okinawan people from Japan during 2004-2009. Dietary intakes of phenolic OHCs were predominantly 2,4,6-tribromophenol (TriBP), followed by tetrabromobisphenol A (TBBPA), and 6-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (6-OH-BDE47). After exposure, TriBP and TBBPA were transferred to breast milk, whereas 6-OH-BDE47 was selectively retained in serum. Despite a lower dietary exposure to pentachlorophenol and 4-hydroxy-CB187, both were retained in serum. For the methoxylated OHCs, 2,4,6-tribromoanisole (TriBA) and 6-methoxy-BDE47 were the predominant dietary contaminants, of which TriBA was present in both breast milk and serum, whereas 6-methoxy-BDE47 was selectively transferred to breast milk. These findings suggest that dietary exposure to phenolic and methoxylated OHCs may result in differential partitioning between breast milk and serum with different pharmacokinetic or exposure routes.

Degradation, metabolism, and bound-residue formation and release of Tetrabromobisphenol A in soil during sequential anoxic-oxic incubation

Tetrabromobisphenol A (TBBPA) is one of the most commonly used flame retardants and has become an environmental contaminant worldwide. We studied the fate of (14)C-labeled TBBPA in soil under static anoxic (195 days) and sequential anoxic (125 days)-oxic (70 days) conditions. During anoxic incubation, TBBPA dissipated with a half-life of 36 days, yielding four debromination metabolites: bisphenol A (BPA) and mono-, di-, and tribrominated BPA. At the end of anoxic incubation, all four brominated BPAs completely disappeared, leaving BPA (54% of initial TBBPA) as the sole detectable organic metabolite. TBBPA dissipation was accompanied by trace mineralization (<1.3%) and substantial bound-residue formation (35%), probably owing to chemical binding to soil organic matter. Subsequent oxic incubation was effective in degrading accumulated BPA (half-life 11 days) through mineralization (6%) and bound-residue formation (62%). However, 42% of the anoxically formed bound residues was released as TBBPA and lower brominated BPAs, which were then persistent during oxic incubation. Our results provide the first evidence for release of bound residues during alteration of the redox environment and indicate that sequential anoxic-oxic incubation approaches-considered effective in remediation of environments containing halogenated xenobiotics-do not completely remove xenobiotics from environmental matrices.

Polybrominated diphenyl ethers and their methoxylated and hydroxylated analogs in Brown Bullhead (Ameiurus nebulosus) plasma from Lake Ontario

Polybrominated diphenyl ethers (PBDEs), methoxylated PBDEs (MeO-PBDEs) and hydroxylated PBDEs (OH-PBDEs) were detected and quantified in Brown Bullhead (Ameiurus nebulosus) from Lake Ontario. Samples were collected in 2006 from three different locations near the city of Toronto: Frenchman's Bay, Toronto Island, and Tommy Thompson Park. A total of 117 plasma samples were pooled into 19 samples, separating males and females by site of capture. Pooled samples were analyzed for 36 PBDEs, 20 MeO-PBDEs and 20 OH-PBDEs, but only six PBDEs, five MeO- and eight OH-compounds were confirmed against standards currently available. These peaks were quantified as "identified" peaks, while peaks matching ion ratios but not matching the retention time of the available standards were quantified as "unidentified" peaks. Both "identified" and "unidentified" concentrations were combined to obtain a total concentration. No significant variations were obtained for total PBDE concentrations, ranging from 3.33 to 9.02 ng g(-1)wet weight. However, OH- and MeO-PBDE totals ranged over 1 order of magnitude among the samples (not detected - 3.57 ng g(-1)wet weight for OH-PBDEs and not detected -0.10 ng/g wet weight for MeO-PBDE). The results of this study suggested that these compounds are ubiquitous in biota. Source estimation of MeO- and OH-PBDEs in freshwater fish were discussed. Considering that up to date no freshwater sources for MeO- or OH-PBDEs have been reported, concentrations found should be mainly related to bioaccumulation from anthropogenic sources, although other sources could not be dismissed.

Fate of triclosan in field soils receiving sewage sludge

The anti-microbial substance triclosan can partition to sewage sludge during wastewater treatment and subsequently transfer to soil when applied to land. Here, we describe the fate of triclosan in a one-year plot experiment on three different soils receiving sludge. Triclosan and methyl-triclosan concentrations were measured in soil samples collected monthly from three depths. A large fraction of triclosan loss appeared to be explained by transformation to methyl-triclosan. After 12 months less than 20% of the initial triclosan was recovered from each soil. However, the majority was recovered as methyl-triclosan. Most of the chemical recovered at the end of the experiment (both triclosan and methyl-triclosan) was still in the top 10 cm layer, although there was translocation to lower soil horizons in all three soils. Between 16.5 and 50.6% of the applied triclosan was unaccounted for after 12 months either as a consequence of degradation or the formation of non-extractable residues.

Marine sponge: a potential source for methoxylated polybrominated diphenyl ethers in the Asia-Pacific food web

Marine sponges collected in Palau, Micronesia, were investigated for hydroxylated or methoxylated analogues of brominated diphenyl ethers (BDEs), brominated dibenzo-p-dioxin (BDD), and brominated biphenyls. The neutral fractions of Haliclona sp. and Callyspongia sp. contained 2'-methoxy-2,3',4,5'-tetraBDE, 6-methoxy-2,2',4,4'-tetraBDE, 2',6-dimethoxy-2,3',4,5-tetraBDE 2,2'-dimethoxy-3,3',5,5'-tetrabromobiphenyl, several methoxy-triBDEs, and dimethoxy-penta-/hexaBDEs. The methoxylated BDEs in sponges were strikingly similar to those of local fish living in the western Pacific Ocean. The total concentrations of these compounds (ΣMeO-PBDE) in both sponges were 63.5 μg/g extractable organic matter (EOM) for Haliclona sp. and 36.5 μg/g EOM for Callyspongia sp., which were about 2 orders of magnitude higher than the levels seen in tropical coral reef fish (unicornfish or surgeonfish) (280-290 ng/g lipid) and groupers (550 ng/g lipid) from Okinawan coastal waters. The phenolic fractions of both sponges contained hydroxy-methoxy tetra-/pentaBDEs as well as hydroxy-tetraBDD, in addition to the corresponding phenolic tetraBDE analogues. Although the total concentrations of phenolic products (27-80 μg/g EOM) in both sponges fell within a range comparable to the methoxylated products, ΣOH-PBDE in local fish were trace level (less than 10 ng/g lipid of) or undetectable. This survey indicates that marine sponges are a possible source of the MeO-PBDE analogues that biomagnify via the food chain to the higher trophic organisms in the western Pacific, whereas the distribution of the corresponding hydroxylated analogues is limited.

Anthropogenic and naturally occurring polybrominated phenolic compounds in the blood of cetaceans stranded along Japanese coastal waters

We determined the residue levels and patterns of hydroxylated polybrominated diphenyl ethers (OH-PBDEs), and related compounds, such as PBDEs, methoxylated PBDEs (MeO-PBDEs), and bromophenols (BPhs) in the blood of eleven cetacean species stranded along the Japanese coasts. The dominant OH- and MeO-PBDE isomers found in all cetaceans were 6OH-BDE47 and 6MeO-BDE47. Additionally, 2,4,6-triBPh was dominant isomer in all cetaceans. In contrast, specific differences in the distribution of para- and meta- OH-PBDE isomers and some BPhs (potential PBDEs metabolites) were found among the cetaceans. Residue levels of ΣMeO-PBDEs and 6OH-BDE47 + 2'OH-BDE68, and 2,4,6-triBPh and 6OH-BDE47 + 2'OH-BDE68 showed a significant positive correlation. These results may suggest that the large percentages of OH-PBDEs, MeO-PBDEs and 2,4,6-triBPh might share common source (i.e. biosynthesis by marine organisms), or metabolic pathway in cetacean species. Significant correlations were found between the concentrations of BDE99 and 2,4,5-triBPh. This result suggested that 2,4,5-triBPh in cetaceans could be a metabolite of BDE99.

Microbially mediated O-methylation of bisphenol A results in metabolites with increased toxicity to the developing zebrafish (Danio rerio) embryo

Bisphenol A (BPA) is used in the manufacture of plastics, and has been identified in various environmental matrices, including human serum and breast milk. The prevalence of BPA in the environment and the potential exposure to humans underscores the need to more fully understand the fate of BPA in the environment and the resulting effects and toxicity to humans and other organisms. Here we demonstrate that Mycobacterium species, including Mycobacterium vanbaalenii strain PYR-1, are able to O-methylate BPA to its mono- and dimethyl ether derivatives (BPA MME and BPA DME, respectively). The O-methylation of BPA results in metabolites with increased toxicity as shown from differences in survival and occurrence of developmental lesions in developing zebrafish embryos exposed to BPA, BPA MME, and BPA DME. The mono- and dimethyl ether derivatives were more toxic than BPA, resulting in increased mortality at 5 (LC(50) = 0.66 and 1.2 mg L(-1)) and 28 (LC(50) = 0.38, <0.5 mg L(-1)) days post fertilization. Furthermore, exposure to either of the O-methylated metabolites resulted in an increase in the incidence of developmental lesions as compared to BPA exposure. These data illustrate a new mechanism for microbial transformation of BPA, producing metabolites warranting further study to understand their prevalence and effects in the environment.

Seasonal variations of hydroxylated and methoxylated brominated diphenyl ethers in blue mussels from the Baltic Sea

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs) found at high levels in the Baltic biota are mainly natural products, but can also be formed through metabolism or abiotic oxidation of polybrominated diphenyl ethers (PBDEs). The formation of OH-PBDEs is of concern since there is growing evidence of phenolic toxicity. This study investigates seasonal variations in levels of OH-PBDEs and MeO-PBDEs, focusing on an exposed species, the blue mussel (Mytilus edulis), sampled in the Baltic Sea in May, June, August and October of 2008. Both the OH-PBDE and MeO-PBDE levels in the mussels showed seasonal variations from May to October, the highest concentration of each congener appearing in June. The seasonal variation was more marked for OH-PBDEs than in MeO-PBDEs, but all congeners showed the same trends, except 6-MeO-BDE47 and 2'-MeO-BDE68, which did not significantly decline in concentrations after June. Biotic or abiotic debromination is suggested as a possible reason for the rapid decrease in methoxylated penta- and hexa-BDE concentrations observed in blue mussels from June to August, while the tetraBDE concentrations were stable. In addition, 1,3,7/1,3,8-tribrominated dibenzo-p-dioxins showed the same seasonal variation. The seasonal variations indicates natural formation and are unlikely to be due to transformation of anthropogenic precursors. The levels of PBDEs were fairly constant over time and considerably lower than those of the OH-PBDEs and MeO-PBDEs. The timing of the peaks in concentrations suggests that filamentous macro-algae may be important sources of these compounds found in the blue mussels from this Baltic Sea location.