Polybrominated diphenyl ethers (PBDEs) and their methoxylated derivatives in pike from Swedish waters with emphasis on temporal trends, 1967-2000

Temporal trends of five tetra- to hexabromodiphenyl ethers [BDE47, BDE99, BDE100, BDE153 and BDE154) and two methoxy-tetraBDEs [6-methoxy-2,2',4,4'- tetraBDE (6-MeO-BDE47) and 2'-methoxy-2,3',4,5'- tetraBDE (2'-MeO-BDE68)] in pike from Lake Bolmen for the years 1967-2000, are presented. All BDE congeners show increasing trends up to the mid-1980s (Sigma5PBDE from 60 to 1600 pg/g wet weight in 1989, i.e. a more than 25-fold increase), and then decrease or level off. The decreasing trends of PBDEs after the 1980s were considerably slower in the present study than was found in a study of an environmental matrix from the Baltic Proper covering the same time period. This difference suggests local sources near Lake Bolmen. The MeO-BDEs show initially decreasing concentrations, which for 6-MeO-BDE47 continues until the early 1990s. The concentrations of 6-MeO-BDE47 in herring from five locations along the Swedish coast increased from south to north in the Baltic Sea. No correlation between the concentrations of the BDE congeners and the MeO-BDEs was observed, indicating sources other than PBDEs for these compounds. The presence of MeO-BDEs in fish from lakes with different characteristics suggests a natural production not favoured by eutrophication, or dependent on sampling season and geographical location.     

Formation of 2'-hydroxy-2,3',4,5'-tetrabromodipheyl ether (2'-HO-BDE68) from 2,4-dibromophenol in aqueous solution under simulated sunlight irradiation

Hydroxylated polybrominated diphenyl ethers (HO-PBDEs) have received significant attention due to their toxicities and universal presence in the environmental matrices. However, their origins are not fully understood. We explored the feasibility of the generation of HO-PBDEs through photochemical processes from bromophenol, a commonly detected pollutant with anthropogenic source in freshwater and natural source in the marine environment. The results showed that when 2,4-dibromophenol (2,4-diBP) was irradiated in aquatic solutions under simulated sunlight, significant amounts of 2′-hydroxy-2,3′,4,5′-tetrabromodipheyl ether (2′-HO-BDE68) were rapidly formed as the dimeric product of 2,4-diBP. The formation of 2′-HO-BDE68 intensified with the increase of light intensity and with the initial concentration increase of 2,4-diBP, whereas it weakened with an increase in pH. Moreover, Fe(III) and fulvic acid played important roles in the formation of 2′-HO-BDE68. This study provides important insight into a possible source of HO-PBDEs from bromophenols in natural aquatic systems through photochemical approaches.     

Is BDE-175 an important enough component of commercial octabromodiphenyl ether mixtures to be listed in Annex A of the Stockholm Convention?

Commercial octabromodiphenyl ether mixtures, containing hexabromodiphenyl ethers and heptabromodiphenyl ethers were listed in Annex A of the Stockholm Convention on May 2009 (Fourth Conference of the Parties) (UNEP, 2009a). Four compounds are specifically mentioned: 2,2′,4,4′,5,5′-hexabromodiphenyl ether (BDE-153), 2,2′,4,4′,5,6′-hexabromodiphenyl ether (BDE-154), 2,2′,3,3′,4,5′,6-heptabromodiphenyl ether (BDE-175), and 2,2′,3,4,4′,5′,6-heptabromodiphenyl ether (BDE-183). Presumably they were identified as key components of commercial mixtures and found to be present in environmental samples. However, since BDE-175 and BDE-183 co-elute on common HRGC columns, the presence of BDE-175 as an important component in technical octa-BDE mixtures has not been illustrated. The successful HRGC/LRMS separation of a 1:1 mixture of BDE-175 and BDE-183, as well as ¹H NMR analysis of technical material, has allowed us to confirm that this congener is not present in technical products (e.g. Great Lakes DE-79™) in quantifiable amounts.     

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.     

Non-polar halogenated natural products bioaccumulated in marine samples. II. Brominated and mixed halogenated compounds

Several identified and potential natural brominated bioaccumulative compounds were studied in this work. 4,6-dibromo-2-(2('),4(')-dibromo)phenoxyanisole (BC-2) previously detected in Australian marine mammals and isolated from sponges, was synthesized. Two byproducts (a tetrabromo isomer and a tribromo congener) were investigated as well. The byproducts of the synthesis were not identified in the environmental samples investigated. Previously described natural brominated compounds (BC-1, BC-2, BC-3, BC-10, BC-11, MHC-1) and anthropogenic brominated diphenyl ethers (BDE-47, BDE-99, BDE-100, BDE-154) were detected in a sample of human milk. The sample was from a woman from the Faeroe Islands who frequently consumed fish as well as whale blubber and meat. The most abundant compound originated from the natural tetrabromo phenoxyanisole BC-3 which may have a 3:1 distribution of bromine on the two phenyl units. This sample also accumulated a dibromochloroanisole, as well as a previously unknown mixed halogenated compound (MHC-X) and an unknown, most likely aromatic brominated compound. Co-elutions on a DB-5 column were found for BDE-99 and BC-11 as well as BDE-154 and the unknown brominated compound. This suggests that quantification of these two compounds has to be carried out carefully.Two samples of lower trophic level, namely Baltic cod liver and Mexican mussel tissue, were investigated as well. The cod liver samples contained BDE congeners but also abundant signals for the natural 2,3,3('),4,4('),5,5(')-heptachloro-1(')-methyl-1,2(')-bipyrrole Q1 and tribromoanisole (TBA). The mussel sample contained Q1, TBA, another halogenated anisole, BC-1, BC-2, and BC-3, as well as additional, potential natural brominated compounds in the elution range of tribromophenoxyanisoles.     

Generation and analysis of mixed chlorinated/brominated homologs of the halogenated natural product heptachloro-1'-methyl-1,2'-bipyrrole

The 2,3,3′,4,4′,5,5′-heptachloro-1′-methyl-1,2′-bipyrrole (Q1, MBP-79) and further halogenated 1′-methyl-1,2′-bipyrroles (MBPs) are a class of marine natural products repeatedly detected in seafood and marine mammals from all over the world. Only Q1 is currently commercially available as reference standard and the full synthesis of mixed brominated-chlorinated compound is rather complicated. For this reason, synthetic Q1 (240 mg) was transferred into bromine-containing MBPs by UV-irradiation in the presence of bromine. Bromine, which rapidly vanished from the solutions, was re-newed during the reaction in order to generate higher amounts of Br-containing MBPs. A total of ∼150 mg Q1 was transferred after ∼10 min irradiation with high amounts of Br₂ to give 30.5 mg BrCl₆-MBPs along with lower proportions of Br₂Cl₅-, Br₃Cl₄-, Br₄Cl₃- and traces of Br₅Cl₂-MBPs. Longer UV-irradiation in the presence of Br₂ even allowed for the detection of Br₆Cl-MBPs and traces of Br₇-MBP. However, this reaction also provided some unknown by-products. A sample stored in the dark and later in in-door light (no UV irradiation) also eliminated Q1 after 76 d in favour of heptahalogenated MBPs with up to three bromine substituents. The irradiation products were separated on silica, and fractions containing only Q1 and BrCl₆-MBPs were then further fractionated by non-aqueous RP-HPLC. A pure isolate of the major BrCl₆-MBP (∼1.5 mg) was characterized by GC/MS and ¹³C NMR to be 2-bromo-3,3′,4,4′,5,5′-hexachloro-1-methyl-1,2′-bipyrrole (Br-MBP-75). Partial GC enantioseparation of the axially chiral Br-MBP-75 was achieved on a β-PMCD column. A full enantioseparation was managed by enantioselective HPLC using a NUCLEOCEL DELTA S column. Low amounts of pure BrCl₆-MBP enantiomers could be trapped.     

Identification and quantification of products formed via photolysis of decabromodiphenyl ether

Background, aim, and scope  Decabromodiphenyl ether (DecaBDE) is used as an additive flame retardant in polymers. It has become a ubiquitous environmental contaminant, particularly abundant in abiotic media, such as sediments, air, and dust, and also present in wildlife and in humans. The main DecaBDE constituent, perbrominated diphenyl ether (BDE-209), is susceptible to transformations as observed in experimental work. This work is aimed at identifying and assessing the relative amounts of products formed after UV irradiation of BDE-209. Materials and methods  BDE-209, dissolved in tetrahydrofuran (THF), methanol, or combinations of methanol/water, was exposed to UV light for 100 or 200 min. Samples were analyzed by gas chromatography/mass spectrometry (electron ionization) for polybrominated diphenyl ethers (PBDEs), dibenzofurans (PBDFs), methoxylated PBDEs, and phenolic PBDE products. Results  The products formed were hexaBDEs to nonaBDEs, monoBDFs to pentaBDFs, and methoxylated tetraBDFs to pentaBDFs. The products found in the fraction containing halogenated phenols were assigned to be pentabromophenol, dihydroxytetrabromobenzene, dihydroxydibromodibenzofuran, dihydroxytribromodibenzofuran, and dihydroxytetrabromodibenzofuran. The PBDEs accounted for approximately 90% of the total amount of substances in each sample and the PBDFs for about 10%. Discussion  BDE-209 is a source of PBDEs primarily present in OctaBDEs but also to some extent in PentaBDEs, both being commercial products now banned within the EU and in several states within the USA. It is notable that OH-PBDFs have not been identified or indicated in any of the photolysis studies performed to date. Formation of OH-PBDFs, however, may occur as pure radical reactions in the atmosphere. Conclusions  Photolysis of decaBDE yields a wide span of products, from nonaBDEs to hydroxylated bromobenzenes. It is evident that irradiation of decaBDE in water and methanol yields OH-PBDFs and MeO-PBDFs, respectively. BDE-202 (2,2′,3,3′,5,5′,6,6′-octabromodiphenyl ether) is identified as a marker of BDE-209 photolysis. Recommendations and perspectives  BDE-209, the main constituent of DecaBDE, is primarily forming debrominated diphenyl ethers with higher persistence which are more bioaccumulative than the starting material when subjected to UV light. Hence, DecaBDE should be considered as a source of these PBDE congeners in the environment. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Spectral characterization of two bioaccumulated methoxylated polybrominated diphenyl ethers

Two methoxylated polybrominated diphenyl ethers (MeO-PBDEs) were isolated from a True's beaked whale (Mesoplodon mirus) and identified by NMR (1H, 1H-1H and 1H-13C) and high resolution mass spectrometry as 2-(2',4'-dibromophenoxy)-3,5-dibromoanisole (6-MeO-BDE47) and 2-(2',4'-dibromophenoxy)-4,6-dibromoanisole (2'-MeO-BDE68). Previously the structures of these bioaccumulated compounds have been determined by comparison of their mass spectra and gas chromatographic (GC) retention times with those of authentic standards. While this method is accepted and generally successful, NMR of the isolated compounds allows us to definitively identify the congeners. Our characterizations are consistent with those made for MeO-PBDEs in other organisms, identified by chromatographic methods.     

Heterogeneous reductive dehalogenation of PCB contaminated transformer oil and brominated diphenyl ethers with zero valent iron

Reductive dechlorination and debromination of halogenated biphenyls (PCBs) and diphenyl ethers (PBDEs) occurs efficiently at moderately elevated temperatures (350-600 °C) with zero valent iron (iron powder) in a nitrogen atmosphere. The proton donors tested were waste transformer oil, iso-octane, and n-decane. Observation of production of biphenyl and diphenyl ether and their condensation products indicates that the reaction is not simple pyrolysis, but a reduction. No halogenated organic products are observed.     

Organohalogen compounds in blubber of Indo-Pacific bottlenose dolphin (Tursiops aduncus) and spinner dolphin (Stenella longirostris) from Zanzibar, Tanzania

Blubber samples of Indo-Pacific bottlenose (Tursiops aduncus) and spinner (Stenella longirostris) dolphins from Zanzibar, East Africa, were analyzed for a wide range of organohalogen compounds. Methoxylated polybrominated diphenyl ethers (MeO-BDEs), presumably biogenic, were found at higher concentrations than anthropogenic organochlorine pesticides (OCPs). Only traces of industrial pollutants, such as polychlorinated biphenyls, were detected. The OCP levels found off Zanzibar were lower than those reported from other regions while MeO-BDE levels were higher. The relative composition of the OCPs indicated recent use of lindane (γ-hexachlorocyclohexane) and aged residues of DDT and technical HCH. Placental transfer was estimated to 2.5% and 0.5% of the total burden of OCPs and MeO-BDEs, respectively. Overall transfer from mother to calf in Indo-Pacific bottlenose dolphins was estimated to 72% and 85% for the OCPs and MeO-BDEs burdens, respectively. Health effects of MeO-BDEs are not known, but structural similarities with well-known environmental toxins are cause for concern.     

Widespread occurrence of polyhalogenated aromatic ethers in the marine atmosphere

Methyl ethers of halogenated phenols have been identified in marine air samples from the North and South Hemispheres. The compounds are tribromoanisole, pentachloroanisole and tetrachlorohydroquinone dimethyl ether. The concentrations of these compounds are in the pg m⁻³ range, and they are among the more abundant high-molecular weight halocarbons in the remote marine troposphere. A probable source of these compounds is the microbial methylation of the biocide pentachlorophenol and tribromophenol of either pollutant or natural origin.     

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.     

Assessment of thyroid hormone activity of halogenated bisphenol A using a yeast two-hybrid assay

The thyroid hormone agonist/antagonist activities of halogenated derivatives of bisphenol A (BPA) were assessed using a yeast two-hybrid assay incorporating the human thyroid hormone α (TRα), both with and without possible metabolic activation by rat liver S9 preparation. In the absence of the rat liver S9 preparation, 3,3′,5,5′-tetrabromobisphenol A (TBBPA), 3,3′,5,5′-tetrachlorobisphenol A (TCBPA), and 3,3′,5-trichlorobisphenol A (3,3′,5-triClBPA) exhibited agonist activity, whereas 3-chlorobisphenol A (3-ClBPA), 3,5-dichlorobisphenol A (3,5-diClBPA), 3,3′-dichlorobisphenol A (3,3′-diClBPA), and BPA did not. The activities of TBBPA and TCBPA increased markedly (7.6-fold and 3.1-fold, respectively) after their metabolic activation with the rat liver S9 preparation. TBBPA, TCBPA, and 3,3′,5-triClBPA inhibited the binding of triiodothyronine (T3) to TRα at 2 × 10⁻⁵ M without rat liver S9 treatment and 4 × 10⁻⁶ M with rat liver S9 treatment, demonstrating their T3 antagonist activity. These results revealed that metabolic activation by rat liver S9 significantly increased the agonist/antagonist potential of some halogenated BPAs.     

Acute oral toxicity and liver oxidant/antioxidant stress of halogenated benzene, phenol, and diphenyl ether in mice: a comparative and mechanism exploration

The lethal doses (LD₅₀s) of fluorinated, chlorinated, brominated, and iodinated benzene, phenol, and diphenyl ether in mice were ascertained respectively under the consistent condition. The acute toxicity of four benzenes orders in fluorobenzene (FB)?<?iodobenzene?<?chlorobenzene≈bromobenzene, that of four phenols orders in 4-iodophenol≈4-bromophenol?<?4-chlorophenol (4-MCP)?<?4-fluorophenol (4-MFP), and that of four diphenyl ethers orders in 4,4′-iododiphenyl ether?<?4,4′-difluorodiphenyl ether?<?4,4′-dichlorodiphenyl ether≈4,4′-dibromodiphenyl ether. General behavior adverse effects were observed, and poisoned mouse were dissected to observe visceral lesions. FB, 4-MCP, and 4-MFP produced toxic faster than other halogenated benzenes and phenols, as they had lower octanol–water partition coefficients. Pathological changes in liver and liver/kidney weight changes were also observed. Hepatic superoxide dismutase, catalase activities, and malondialdehyde level were tested after a 28-day exposure, which reflects a toxicity order basically consistent with that reflected by the LD₅₀s. By theoretical calculation and building models, the toxicity of benzene, phenol, and diphenyl ether were influenced by different structural properties.     

The air-water exchange of polychlorinated biphenyls and polybrominated diphenyl ethers at an urban lake, a receipt water body for the effluent from a municipal sewage treatment plant

The effluents and sludge from municipal sewage treatment plants (MSTPs) are considered as potential sources of many contaminants to the ambient environments. In the present work, the air-water exchange of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) was studied using passive air samplers at an urban lake, which receives the effluents from a MSTP in Beijing, China. The concentrations of PCBs and PBDEs in atmosphere were in the range 15.5-108 ng sample⁻¹ and 2.37-27.8 ng sample⁻¹, respectively, during the sampling period (August, 2007-July, 2008). The predominant PCBs and PBDEs were lowly halogenated congeners. The calculation for the exchange fluxes of PCBs and PBDEs using fugacity model showed that, the net exchange fluxes in different seasons were closely related to the halogen number of different congeners. Except for CBs-28 and 52, the net exchange fluxes was mainly directed from air to water for most of predominant congeners, which implied that the lower chlorinated CBs were dominated by volatilization process rather than the dry/wet depositions and diffusion between air-water interface, additionally, for heavy congeners, the dry/wet deposition process was an important source of PCBs and PBDEs in this lake.     

Glucuronidation of hydroxylated polybrominated diphenyl ethers and their modulation of estrogen UDP-glucuronosyltransferases

Polybrominated diphenyl ethers (PBDEs) can be metabolically converted to their hydroxylated metabolites (OH-PBDEs). The estrogenic effects of PBDEs may be mediated by OH-PBDEs, but the mechanisms of which are still not understood. This study investigated the glucuronidation of 11 OH-PBDEs and their potential in modulating UDP-glucuronosyltransferases (UGTs) activity of 17β-estradiol (E2) in rat liver microsomes. The number of bromine atoms at phenolic ring was observed as the most influential factor of OH-PBDEs glucuronidation. 2′-OH-BDE-28 having one bromine atom at phenolic ring showed the fastest metabolic rates with t_1/2 value of 3.86 min, while 6-OH-BDE-137 having four bromine atoms at phenolic ring was the poorest substrate with t_1/2 value over 60 min. Regarding to the modulation of E2-UGTs activity, the phenolic hydroxyl group in OH-PBDEs played an essential role. Depending on the substitution patterns of bromine and hydroxyl group, OH-PBDEs inhibited or stimulated E2-UGTs activity. Ten of OH-PBDEs inhibited both 3-glucuronidation and 17-glucuronidation of E2 with IC₅₀ values varying from 3.80 to 129.38 μM, while 3′-OH-BDE-100 exhibited stimulating effects on 3-glucuronidation with EC₅₀ value of 35.95 μM. Kinetic analysis suggested noncompetitive inhibition mode of E2 glucuronidation by 3′-OH-BDE-7, 6-OH-BDE-47 and 2′-OH-BDE-68 with K_i values varying from 11.95 to 67.22 μM. This study demonstrated OH-PBDEs exhibited large interindividual differences in glucuronidation and modulation of E2-UGTs activity. By inhibiting the formation of E2 glucuronidation, OH-PBDEs may increase E2 bioavailability in target tissue, thereby exerting an indirect estrogenic effect.     

Comparison of organohalogen compounds in a white-tailed sea eagle egg laid in 1941 with five eggs from 1996 to 2001

Eggs laid by white-tailed sea eagles (Haliaeetus albicilla), one in 1941 and five eggs between 1996 and 2001, all from the same geographical region of the Baltic Sea, were screened for organohalogen substances. The 1941 egg contained hexachlorobenzene (HCB), but did not contain either of the pesticides hexachlorocyclohexane (HCH) or p,p′-DDT, nor any metabolites of the latter. In contrast, the more recent eggs (REs) contained all of these compounds. Of the seven polychlorinated biphenyls (PCBs) analyzed (CB28, −52, −101, −118, −138/−163, −153 and 180), only the more highly chlorinated congeners were detected in the 1941 sample, with CB153 followed by CB180 showing the highest concentrations. All eggs demonstrated the same congener pattern with respect to the more highly chlorinated PCBs, but concentrations were approximately 70-230 times higher in the REs. All of the polychlorinated-p-dioxin and dibenzofuran (PCDD/Fs) congeners analyzed were detected in the eggs, with the dominant congener being 2,3,4,7,8-PeCDF (1250 pg/g l.w. in 1941 and 1540 pg/g l.w. (GM) for the REs, respectively). None of the other congeners exceeded 400 pg/g l.w., and the concentrations of 2,3,7,8-TCDD, 2,3,7,8-TCDF and 1,2,3,7,8-PeCDF were all lower in the REs. None of five congeners of polybrominated diphenyl ethers (PBDEs) found in the REs was detected in the egg from 1941. The three methoxylated brominated diphenyl ethers (MeO-BDEs) analyzed were found at similar levels and with a similar congener pattern in REs as in the egg from 1941.In conclusion, this study has shown the absence of DDE and PBDE and the presence of HCB and PCBs in a white-tailed sea eagle egg laid in 1941, and a strong increase of PCBs, DDE and PBDE in white-tailed sea eagle eggs from the same area in 1996-2001. The MeO-BDEs were found in similar concentrations in the analyzed eggs. The 1941 sample shows substantial concentrations of PCDD/Fs, noteworthy in the same magnitude as in the recent samples, illustrating the historical and recent exposure of these compounds.     

Determination of chlorinated pesticides, polychlorinated biphenyls, and polybrominated diphenyl ethers in human milk from Bizerte (Tunisia) in 2010

Thirty persistent organohalogen compounds including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) were determined in breast milk samples (n = 36) of primipara and multipara mothers from Bizerte in 2010. The analytical procedure involved the application of liquid-liquid extraction and gas chromatography with electron capture detector (GC-ECD) or mass spectrometry detector (GC-MS) for identification and quantification. Organohalogen compounds were found in all the analyzed samples, with predominance of p,p′-DDE, p,p′-DDT, p,p′-DDD, HCB and PCBs. The mean concentration of ∑DDTs in breast milk was 1163.9 ng g⁻¹ lipid wt. The ratio of p,p′-DDE/p,p′-DDT was low, suggesting that there is fresh intake of commercial DDT products in Bizerte. The mean levels of HCB and PCB were 286.8 and 331.2 ng g⁻¹ lipid wt respectively. These results were compared with the levels obtained in a previous study carried out in the same area in 2003. A general decrease of ∑DDTs levels and an increase of PCB levels were observed. Among the 10 PBDE congeners evaluated, BDE-28, BDE-47, BDE-99, BDE-66, BDE-138, BDE-100, BDE-154, BDE-153, and BDE-183 were detected in the analyzed samples at different frequency. The total PBDE concentrations ranged from 2.5 to 22.6 ng g⁻¹ lipid wt in the samples, with a mean and median value of 10.7 and 9.8 ng g⁻¹ lipid wt respectively. To our knowledge, this is the first data of PBDEs in Tunisian human milk. The present study shows that age and parity are factors influencing the levels of some organohalogen compounds in human milk.     

Radiocarbon content of synthetic and natural semi-volatile halogenated organic compounds

Some halogenated organic compounds, such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polybrominated diphenyl ethers (PBDEs), have been suggested to have natural sources but separating these compounds from their commercially synthesized counterparts is difficult. Molecular-level 14C analysis may be beneficial since most synthetic compounds are manufactured from petrochemicals (14C-free) and natural compounds should have "modern" or "contemporary" 14C levels. As a baseline study, we measured, for the first time, the 14C abundance in commercial PCB and PBDE mixtures, a number of organochlorine pesticides, as well as one natural product 2-(3',5'-dibromo-2'-methoxyphenoxy)-3,5-dibromoanisole. The latter compound was isolated from a marine sponge and is similar in structure to a PBDE. All of the synthetic compounds were 14C-free except for the pesticide toxaphene. which had a modern 14C abundance, as did the brominated natural compound. The result for toxaphene was not surprising since it was commercially synthesized by the chlorination of camphene derived from pine trees. These results suggest that measuring the 14C content of halogenated organic compounds may be quite useful in establishing whether organic compounds encountered in the environment have natural or synthetic origins (or both) provided that any synthetic counterparts derive from petrochemical feedstock.     

Distribution of polybrominated diphenyl ethers in breast milk from North China: Implication of exposure pathways

The breast milk concentrations of polybrominated diphenyl ethers (PBDEs; sum of eight congeners: BDE-28, 47, 99, 100, 153, 154, 183 and 209) were determined (by high resolution gas chromatographic high resolution mass spectrometry) in samples from primiparous women collected in 2006 in Tianjin, China. Dietary and lifestyle habits of the participants were obtained by questionnaires. The median total PBDE concentration (including BDE-28, 47, 99, 100, 153, 154, 183) was 2500 pg g⁻¹ lipid weight, ranging from 1700 to 4500 pg g⁻¹ lipid weight. These levels were in the same range as those from Europe and Japan but much lower than those from North America. The congener profile in China was also different from other countries. The contribution of BDE-28 was around 15%, much higher than any other country, implying that a different Penta-BDE formulation might be used in the Chinese market. The lower ratio of the sum of BDE-47, 99, and 100 to the sum of BDE-153 and 154 suggested that Octa-products were in more demand in China. A significant correlation was found between a woman’s PBDE concentration and the time she used electronic appliances (h/d). This implies that electronics are a potential source of PBDEs to people. Inhalation or ingestion of particulate matter (such as dust) may also be an important exposure pathway. There was no significant correlation between the PBDE concentration and the consumption of meat, fish, and milk. Further research is needed to determine the specific contribution of each exposure route and their health effects.