Hidden plastics of Lake Ontario, Canada and their potential preservation in the sediment record.

Microplastics are a source of environmental pollution resulting from degradation of plastic products and spillage of resin pellets. We report the amounts of microplastics from various sites of Lake Ontario and evaluate their potential for preservation in the sediment record. A total of 4635 pellets were sampled from the Humber Bay shoreline on three sampling dates. Pellet colours were similar to those from the Humber River bank, suggesting that the river is a pathway for plastics transport into Lake Ontario. Once in the lake, high density microplastics, including mineral-polyethylene and mineral-polypropylene mixtures, sink to the bottom. The minerals may be fillers that were combined with plastics during production, or may have adsorbed to the surfaces of the polymers in the water column or on the lake bottom. Based on sediment depths and accumulation rates, microplastics have accumulated in the offshore region for less than 38 years. Their burial increases the chance of microplastics preservation. Shoreline pellets may not be preserved because they are mingled with organic debris that is reworked during storm events.

Identification and occurrence of analogues of dechlorane 604 in Lake Ontario sediment and their accumulation in fish.

The dechlorane family of flame retardants, which includes Mirex (also known as Dechlorane), Dechlorane Plus (DP), and Dechloranes (Dec) 602, 603, and 604, were manufactured at a facility along the Niagara River, upstream of Lake Ontario. Some of these compounds remain in use. In a previous study, we found Mirex and Dec602 to have greater bioaccumulation potentials than Dec604 and DP based on calculated biota-sediment accumulation factors (BSAFs). In this study, analogues of Dec604, containing fewer bromines and mixed substitutions of bromine and chlorine, were identified in Lake Ontario sediment and fish using high and ultrahigh resolution mass spectrometric techniques. The tribromo-Dec604 (Br3Dec604) analogue, known as Dechlorane 604 Component B (Dec604 CB), was present in lake trout and whitefish at concentrations of 10-60 ng/g lipid weight, approximately 50-200 times greater than concentrations measured for Dec604. In addition, BrDec604 and Br2Dec604 analogues, and mixed Br2Cl2Dec604, Br3ClDec604, Br2ClDec604, and BrCl2Dec604 analogues were also present. We have shown that solutions of Dec604 and Dec604 CB exposed to UV-light undergo photodebromination and give rise to the analogues found in sediment and fish. Dec604 CB and other lesser halogenated analogues of Dec604 show greater bioaccumulation potentials than Dec604, Dec602 and DP, based on BSAFs, which highlight the need to consider likely impurities and degradation products in the assessment of persistent, bioaccumulative, and toxic compounds.

Perfluoroalkyl substances and extractable organic fluorine in surface sediments and cores from Lake Ontario.

Fourteen perfluoroalkyl substances (PFASs) including short-chain perfluorocarboxylates (PFCAs, C4-C6) and perfluoroalkane sulfonates (PFSAs, C4 and C6) were measured in surface sediment samples from 26 stations collected in 2008 and sediment core samples from three stations (Niagara, Mississauga, and Rochester basins) collected in 2006 in Lake Ontario. Perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), and perfluoroundecanoate (PFUnDA) were detected in all 26 surface sediment samples, whereas perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonamide (FOSA), perfluorododecanoate (PFDoDA) and perfluorobutanoate (PFBA) were detected in over 70% of the surface sediment samples. PFOS was detected in all of the sediment core samples (range: 0.492-30.1ngg(-1) d.w.) over the period 1952-2005. The C8 to C11 PFCAs, FOSA, and PFBA increased in early 1970s. An overall increasing trend in sediment PFAS concentrations/fluxes from older to more recently deposited sediments was evident in the three sediment cores. The known PFCAs and PFSAs accounted for 2-44% of the anionic fraction of the extractable organic fluorine in surface sediment, suggesting that a large proportion of fluorine in this fraction remained unknown. Sediment core samples collected from Niagara basin showed an increase in unidentified organic fluorine in recent years (1995-2006). These results suggest that the use and manufacture of fluorinated organic compounds other than known PFCAs and PFSAs has diversified and increased.

Identification and determination of the dechlorination products of Dechlorane 602 in Great Lakes fish and Arctic beluga whales by gas chromatography-high resolution mass spectrometry.

During the course of our studies of in-use chlorinated flame retardants, such as Dechlorane Plus(®) and Dechloranes 602 and 604, blubber of beluga whales from the Canadian Arctic and lake trout and whitefish from the North American Great Lakes were found to contain two novel dechlorination products of Dechlorane 602 (Dec602). The structures of these compounds were characterized by experiments performed using both gas chromatography-high resolution mass spectrometry and Fourier transform mass spectrometry with a prepared technical mixture of monohydro and dihydroDec602 derivatives. These Dec602 derivatives are analogous to the well-known monohydro and dihydro photochemical degradation products of Mirex. The ratio of the two monohydroDec602 diastereomers varied between Lake Ontario fish and those from the upper lakes, but only one isomer was found in Arctic beluga, indicating that one isomer is either more stable or more bioaccumulative. Dechlorane Plus(®), Dec603, and Dec 604 were not detected in Arctic beluga, but Dec602 and its monohydroDec602 derivative were measured in approximately equal concentrations, ranging from 25 to 300 pg/g lipid. In Great Lakes fish, concentrations of the monohydroDec602 derivatives were also close to those of Dec602, ranging from 2 to 67 ng/g lipid and were greatest in Lake Ontario. This study reports on the first measurements of dechlorane-related compounds in Arctic biota and the first detection of monohydroDec602 degradation products and their accumulation in biota.

Fate, distribution, and contrasting temporal trends of perfluoroalkyl substances (PFASs) in Lake Ontario, Canada.

Lake Ontario water and sediment collected from tributary, nearshore, and open lake sites were analyzed for perfluoroalkyl substances (PFASs), namely perfluoroalkyl carboxylic acids (PFCAs, F(CF(2))(n)CO(2)(-); n=6-11,13) and perfluoroalkane sulfonic acids (PFSAs, F(CF(2))(n)SO(3)(-); n=6,8,10). Survey results of surface sediment and water indicated that shorter chained PFASs were predominant in and near urban/industrial area watersheds, while longer chained PFASs were predominant in fine-grained sediment from major depositional basins. Niagara River suspended solids (1981-2006) demonstrated temporal trends that may have been influenced by recent changes in North American production and use of PFASs. Perfluorooctane sulfonate (PFOS) reached a peak concentration in 2001 of 1.1 ng/g, followed by a decrease from 2001 to 2006 (half-life=9 years). Perfluorooctanoic acid (PFOA) increased from 2001 to 2006 (doubling time= 2 years) reaching a peak concentration of 0.80 ng/g. In contrast, three sediment cores from western, central, and eastern Lake Ontario showed increasing temporal trends to surface sediment for all PFASs. PFOA and PFOS concentrations increased from 1988 to 2004 (doubling time= ~ 4 years) in the western Lake Ontario core. The observed variations in temporal trends from different environmental compartments may be a result of the physico-chemical properties of PFASs, ongoing emissions, and the environmental transformation and degradation of PFAS precursor compounds.

Historic trends of dechloranes 602, 603, 604, dechlorane plus and other norbornene derivatives and their bioaccumulation potential in lake ontario.

Temporal trends and seasonal variation of Dechloranes (Dec) 602, 603, 604, and Chlordene Plus (CP) in Niagara River suspended sediment, a Lake Ontario sediment core, and Lake Ontario lake trout were investigated, with Mirex and Dechlorane Plus (DP) included for comparison. Temporal concentration trends were generally consistent in each of the media for all compounds with the lowest concentrations observed in or after the late 1990s. In Niagara River suspended sediments, all compounds showed seasonal variation over a year with distinct profiles observed. The relative concentration patterns observed were total DP > Mirex > Dec 602 and Dec 604 > Dec 603 > CP in suspended sediments and sediment cores, whereas Mirex was highest in lake trout, followed by Dec 602 and DP. Dec 602 concentrations were 50 to 380 times greater than those of DP in lake trout, indicating Dec 602 has a greater bioaccumulation potential. The estimated biota-sediment accumulation factor (BSAF) for Dec 602 was much greater than for DP in Lake Ontario, and was greater than those calculated for PBDEs, indicating that assessment of some dechlorane compounds is merited if use is ongoing or planned.

Liquid chromatography/atmospheric pressure photoionization tandem mass spectrometry for analysis of Dechloranes.

Liquid chromatography/atmospheric pressure photoionization tandem mass spectrometry (LC/APPI-MS/MS) was investigated as an instrumental method for the analysis of the halogenated norbornene flame retardants, Mirex, Dechloranes 602, 603, 604, and Dechlorane Plus (DP). The LC separation was optimized by screening a variety of stationary and mobile phases, resulting in a short LC separation time of 5 min. Different atmospheric pressure ionization approaches were examined including electrospray ionization, atmospheric pressure chemical ionization, and APPI, each with and without post-column addition. APPI without post-column addition was chosen for providing the best ionization response. The optimized LC/APPI-MS/MS approach resulted in instrument detection limits ranging between 25 and 50 pg. Good linearity was also achieved (up to 25.0 ng/µL; R >0.999). The method was applied to extracts of environmental samples including surface water, fish and sediments for screening purposes, and the results agreed well with those obtained by gas chromatography/mass spectrometry.

Liquid chromatography/tandem mass spectrometry for analysis of 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) and 1,2,5,6-tetrabromocyclooctane (TBCO).

Although the two flame retardants 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) and 1,2,5,6-tetrabromocyclooctane (TBCO) have been widely used, a selective instrumental method of analysis for these compounds has not been developed to date. In this study, we demonstrate the feasibility to utilize liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the separation and analysis of α- and ß-TBCO and α-, ß-, γ-, and δ-TBECH. Acetone was initially used in a tetrahedron solvent system for LC optimization. A simple isocratic elution allowed near-baseline separation of these compounds. Different ionization approaches and mechanisms were investigated. The mass spectrometric transition of [M + O(2)](-) => Br(-) (459.8 => 78.9) was a selective detection method for the target analytes. Good instrument detection limits (5 pg for γ-/δ-TBECH, 125 pg for α-/ß-TBECH, and 30 pg for α-/ß-TBCO with 2.0 µL injection) were obtained. Excellent linearity up to 50 ng/µL (R(2) >0.999) was also achieved. This method has been applied to environmental samples (surface water) for screening purposes with recoveries ranging from 76-92% (CV%: 5-8%). This method shows significant improvement over previous methods.

Dechloranes 602, 603, 604, Dechlorane Plus, and Chlordene Plus, a newly detected analogue, in tributary sediments of the Laurentian Great Lakes.

A chlorinated compound (Chlordene Plus, CP), structurally related to Dechloranes (Dec) 602, 603, 604, and Dechlorane Plus (DP), was identified, and concentrations and spatial trends of Dec 602, 603, 604, CP, and DP in tributary sediments of the Laurentian Great Lakes are reported. The dechloranes were widely detected with their concentrations varying considerably across the Great Lakes basin. Spatial trends of Dec 602, 604, and DP in Canadian tributary sediments were similar to that of BDE 209, which suggested these flame retardant chemicals in tributaries were associated with industrial and urban areas. The highest concentrations of Dec 602, 604, and DP observed in tributaries of the Niagara River confirmed that past or ongoing manufacturing of these compounds at plants along the river were important sources to Lake Ontario. Dec 603 was detected in technical products of aldrin and dieldrin, and its spatial trend was consistent with historic pesticide usage. Similarly, CP was detected in technical products of chlordene and chlordane, and it was found in higher concentrations in sediments near urban areas, possibly related to past chlordane use in home termite control.

Identification and screening analysis of halogenated norbornene flame retardants in the Laurentian Great Lakes: Dechloranes 602, 603, and 604.

Dechlorane (Dec) 602, Dechlorane (Dec) 603, Dechlorane (Dec) 604, and Dechlorane Plus (DP) are flame retardant substitutes for mirex. Dec 602, 603, and 604 were detected in sediment and fish from the Laurentian Great Lakes. Lake Ontario surface sediments had the highest concentrations of Dec 602 and 604 at 6.0 and 4.0 ng/g dry weight, respectively. Temporal analysis of a Lake Ontario sediment core indicates that Dec 602 and 604 trends are similar to DP peaking in the early 1980s. Lake trout and whitefish from Lake Ontario also had the highest concentrations of Dec 602 and 604 at 34 and 1.2 ng/g lipid. Concentrations of Dec 602 were higher than those of DP in all fish samples, indicating that Dec 602 is likely more bioavailable and/or more readily bioaccumulates than DP. Spatial trends for Dec 602 and 604 in sediment and fish indicate that manufacturing plants along the Niagara River upstream of Lake Ontario were important sources of Dec 602 and 604 to the Great Lakes, while Dec 603 in the Great Lakes is likely from atmospheric deposition. The findings of this first report of Dec 602, 603, and 604 in the Laurentian Great Lakes basin suggests further investigation of halogenated norbornene flame retardants in the environment is merited.

Compounds structurally related to Dechlorane Plus in sediment and biota from Lake Ontario (Canada).

The historical occurrence of Dechlorane Plus (DP) and detection of novel compounds structurally related to DP is described in a dated Lake Ontario sediment core. Our core was collected near the mouth of the Niagara River, which is known to be a major source of DP to the lake. Maximum DP concentrations (920 ng g(-1), dry weight) were observed between 1976 and 1980, the highest reported to date. Following that time, we observed a dramatic decrease in DP concentration which coincided with the enactment of United States federal and state laws to mitigate free release of chemicals into the Niagara River and installation of an industrial wastewater treatment facility. During the course of our research, four new substances structurally related to DP were also identified. These compounds were thought to arise from the Diels-Alder reactions resulting from impurities present in 1,5-cyclooctadiene, a feedstock used in production of DP. To confirm our hypothesis, Diels-Alder reactions were performed on the individual impurities. Using different stationary-phase capillary gas chromatography columns and high-resolution mass spectrometry, we were able to positively identify some of these novel compounds in the core. Interestingly, we also were able to identify a monoadduct compound, formed by addition of 1 mol of hexachlorocyclopentadiene to 2 mol of 1,3-cyclooctadiene, in lake trout. The concentration of this monoadduct was approximately 2 orders of magnitude greater than that of DP, suggesting that it is more bioaccumulative.

Perfluoroalkyl contaminants in window film: indoor/outdoor, urban/rural, and winter/summer contamination and assessment of carpet as a possible source.

Window film concentrations of ionic perfluoroalkyl contaminants (PFCs) were determined indoors and outdoors at urban, suburban, and rural sites in or near Toronto, Ontario, Canada, to identify locations of relatively elevated concentrations and the nature of potential sources. The role of carpet installation and floor wax application as possible sources was also evaluated by sampling indoor window films at five sites before and after new carpet installations, at one site before and after a floor wax application, and at two carpet stores. Low concentrations were found in all outdoor window films, with comparable relative proportions of individual PFCs among sites, suggesting similar sources to the outdoor environment and rapid air mixing. PFCs in indoor window film were up to 20-fold greater than outdoor, providing some evidence that a significant proportion of PFCs originate from the indoor environment, although precipitation wash-off of outdoor window film may be confounding these results. For both indoor and outdoor film, PFC concentrations generally changed between the summer and winter but the chemical profiles were similar between seasons. Concentrations of PFCs in window films increased one month post carpet installation at three of the five sites, suggesting that some of the carpets may have been a source to the indoor environment. Indoor window films from two carpet stores (sigmaPFC = 16 and 7 pg/cm2) contained higher concentrations than the other indoor locations (sigmaPFC = < MDL to 4.3 pg/cm2), which may reflect the carpets stored within these buildings. The use of window film allowed collection of a wide range of samples and the results can be used to focus the efforts of more traditional air sampling campaigns.

Trophodynamics of some PFCs and BFRs in a western Canadian Arctic marine food web.

The trophodynamics of per- and polyfluorinated compounds and bromine-based flame retardants were examined in components of a marine food web from the western Canadian Arctic. The animals studied and their relative trophic status in the food web, established using stable isotopes of nitrogen (delta15N), were beluga (Delphinapterus leucas) > ringed seal (Phoca hispida) > Arctic cod (Boreogadus saida) > Pacific herring (Clupea pallasi) approximately equal to Arctic cisco (Coregonus autumnalis) > pelagic amphipod (Themisto libellula) > Arctic copepod (Calanus hyperboreus). For the brominated diphenyl ethers, the lipid adjusted concentrations of the seven congeners analyzed (Sigma7BDEs: -47, -85, -99, -100, -153, -154, and -209) ranged from 205.4 +/- 52.7 ng/g in Arctic cod to 2.6 +/- 0.4 ng/g in ringed seals. Mean Sigma7BDEs concentrations in Arctic copepods, 16.4 ng/g (n = 2, composite sample), were greater than those in the top trophic level (TL) marine mammals and suggests that (i) Arctic copepods are an important dietary component that delivers BDEs to the food web and (ii) because these compounds are bioaccumulative, metabolism and depletion of BDE congeners in top TL mammals is an important biological process. There were differences in the concentration profiles of the isomers of hexabromocyclododecane (HBCD) in the food web. The most notable difference was observed for beluga, where the alpha-isomer was enriched (accounting for approximately 90% of the SigmaHBCD body burden), relative to its primary prey species, Arctic cod, where the alpha-isomer accounted for only 20% of the SigmaHBCD body burden (beta: 4% and gamma: 78%). For the C8-C11 perfluorinated carboxylic acids, the trophic magnification factors (TMFs) were all greater than unity and increased with increasing carbon chain length. PFOS and its neutral precursor, PFOSA, also had TMF values greater than one. There were also pronounced differences in the PFOSA to PFOS ratio in ringed seal (0.04) and in beluga (1.4) and suggests that, in part, there are differences in the efficacy of biotransforming PFOSA by whale and seal top predators that both preferentially feed on Arctic cod.

Structural characterization and thermal stabilities of the isomers of the brominated flame retardant 1,2,5,6-tetrabromocyclooctane (TBCO).

1,2,5,6-Tetrabromocyclooctane (TBCO) is a commercial brominated flame retardant that is employed mainly as an additive in textiles, paints and plastics. Very little is known about its presence or behavior in the environment or its analysis. TBCO can exist as two diastereomers, the stereochemistries of which have not been previously reported. We have named the first eluting isomer, under HPLC conditions, as alpha-TBCO (alpha-TBCO) and the later eluting isomer as beta-TBCO (beta-TBCO) when using an Acquity UPLC BEH C(18) column with methanol/acetonitrile/water as the mobile phase. The structural elucidation of these two isomers was accomplished by 1H NMR spectroscopy, GC/MS, LC/MS and X-ray structure determinations. alpha-TBCO is (1R,2R,5S,6S)-1,2,5,6-tetrabromocyclooctane and beta-TBCO is rac-(1R,2R,5R,6R)-1,2,5,6-tetrabromocyclooctane. As with some other brominated cycloaliphatic compounds, TBCO is thermally labile and the isomers easily interconvert. A thermal equilibrium mixture of alpha- and beta-TBCO consists of approximately 15% and 85% of these isomers, respectively. Separation of the two diastereomers, with minimal thermal interconversion between them, is achievable by careful selection of GC-capillary column length and injector temperature. LC/MS analyses of TBCO also presents an analytical challenge due to poor resolution of the isomers on chromatographic stationary phases, and weak intensity of molecular ions (or major fragment ions) when using LC-ESI/MS. Only bromide ions were seen in the mass spectra. APCI and APPI also failed to produce the molecular ion with sufficient intensity for identification.

Occurrence and sources of polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls in surficial sediments of Lakes Superior and Huron.

Concentrations and congener profile patterns of 2378-substituted PCDD/Fs and DLPCBs in offshore, nearshore and tributary sediments of Lakes Superior and Huron are reported, and spatial trends and source contributions assessed. PCDD/F concentrations ranged from 5 to 18,000 pg/g dw (Lake Superior) and 3 to 6100 pg/g dw (Lake Huron); DLPCBs ranged from 9 to 11,000 pg/g dw (Lake Superior) and 9 to 27,000 pg/g dw (Lake Huron). Our analysis indicated atmospheric deposition is a primary source to depositional areas of both lakes; however, greater PCDD/F and DLPCB concentrations were observed at several nearshore and tributary sites, and were attributed to corresponding land use in the watershed. Statistical analysis and pattern comparison suggested that industrial inputs mainly associated with wood treatment plants, pulp and paper mills, mining operations, and chlorine-based chemical manufacturing also contributed to contamination by PCDD/Fs and DLPCBs in certain nearshore and offshore areas of Lakes Superior and Huron.

The analysis of halogenated flame retardants by GC-HRMS in environmental samples.

The analytical conditions required to determine polybrominated diphenylethers (PBDEs) and a variety of other halogenated flame retardants (HFRs) by gas chromatography-high resolution mass spectrometry (HRMS) in environmental samples are reported. HRMS can be used to analyze brominated diphenylethers (BDEs), 2,2',4,4',5,5'-hexabromobiphenyl (BB-153) as well as for a number of other emerging HFRs like allyl 2,4,6-tribromophenyl ether (ATE), 2-bromoallyl 2,4,6-tribromophenyl ether (BATE), 2,3-dibromopropyl 2,4,6-tribromophenyl ether (DPTE), octabromotrimethylphenylindane (OBIND), pentabromoethylbenzene (PBEB), hexabromobenzene (HBB), 1,2-bis (2,4,6-tribromophenoxy) ethane (BTBPE), decabromodiphenylethane (DBDPE), Dechlorane Plus (DP), hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO), tetrabromoethylcyclohexane (TBECH), 1,2,5,6-tetrabromocylcooctane (TBCO), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTeBB), and bis(2-ethly-1-hexyl)tetrabromophthalate (BEHTBP). The detection in environmental matrices and use of these non-BDE flame retardants is reviewed. A method for the analysis of PBDEs by isotope dilution HRMS and 16 other halogenated compounds primarily used as flame retardants is reported. A survey of selected environmental samples, which included Lake Ontario surface and tributary sediments, municipal wastewater effluent, sludge, and mussel tissues, detected PBDEs, DP, DBDPE, BTBPE, PBEB, BB-153, and HBB.

Factors influencing trends of polychlorinated naphthalenes and other dioxin-like compounds in lake trout (Salvelinus namaycush) from Lake Ontario, North America (1979-2004).

Concentrations of polychlorinated naphthalenes (PCNs) were determined in archived lake trout (Salvelinus namaycush) from Lake Ontario, North America, collected between 1979 and 2004 to evaluate their temporal trends and the factors influencing their trends. Concentrations of PCNs, as well as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and non- and mono-ortho-substituted polychlorinated biphenyls (DL-PCBs), which were measured for comparative purposes, declined by eight-, seven-, and fivefold, respectively, between 1979 and 2004. Apparent elimination rate constants (k2) were calculated as the slopes of the regression lines of concentration versus time for PCN, DL-PCB, and PCDD/F congeners to compare the rate of decrease among congeners within and between compound classes. The k2 values for PCNs that had two pairs or three adjacent carbons unsubstituted with chlorine (congeners that can be biotransformed by vertebrates) were not significantly different from zero, indicating no decline in fish. For PCN congeners having no adjacent carbons unsubstituted with chlorine, the k2 values generally increased with hydrophobicity and degree of chlorination. This pattern differed from that of PCDD/Fs and DL-PCBs and from previous findings for non-DL-PCBs, for which the rate of contaminant decline decreased with hydrophobicity, and the pattern also differed from expectations based on thermodynamics. Differences in the rate of decline of PCN congeners may be caused by changes in source or mixture formulations over time and/or metabolic dechlorination of the less stable, higher-chlorinated PCNs 73, 74, and 75 to lower-chlorinated congeners. Based on suggested dioxin toxic equivalency factors, PCN concentrations in these whole lake trout may be sufficient to trigger consumption restrictions in Ontario, Canada, and our results suggest that PCNs merit incorporation into monitoring and assessment programs.

Brominated and chlorinated flame retardants in Lake Ontario, Canada, lake trout (Salvelinus namaycush) between 1979 and 2004 and possible influences of food-web changes.

Concentrations of non-polybrominated diphenyl ether (PBDE) brominated (hexabromocyclododecane [HBCD], 1,2-bis[2,4,6-tribromophenoxy]ethane [BTBPE], and pentabromoethylbenzene [PEB]) and chlorinated (Dechlorane Plus [DP] as well as short- and medium-chain chlorinated paraffins [SCCP and MCCP, respectively]) flame retardants were evaluated in archived Lake Ontario, Canada, lake trout (Salvelinus namaycush) samples collected between 1979 and 2004. Polybrominated diphenyl ethers also were analyzed to provide a point of reference for comparison to previous studies. Concentrations of the dominant PBDE congeners (BDEs 28, 47, 99, 100, 153, and 154) increased significantly from 1979 until the mid-1990s, then either leveled off or decreased significantly between 1998 and 2004, a result that corresponds to those of previous studies. In contrast, BDE 209 increased approximately fourfold between 1998 and 2004. The temporal trends of the non-PBDE flame retardants varied, with sum (sigma) HBCD and DP showing significant overall decreases; BTBPE, sigmaSCCP, and sigmaMCCP showing parabolic trends; and PEB showing no overall change during the study period. Because many of the non-PBDE chemicals may be used as replacements for penta- and octa-BDE mixtures, these results will provide a baseline to evaluate future usage patterns. Possible changes in food-web structure, evaluated through stable nitrogen isotopes (delta15N), may be influencing our interpretations of contaminant trends in lake trout and are hypothesized to be partially responsible for the observed decrease in concentrations of BDEs 28, 47, 99, 100, 153, and 154 between 1998 and 2004. Retrospective analyses evaluating temporal trends in stable isotope values at the base of the food web, however, are recommended to test this hypothesis further.

Examination of isomer specific bioaccumulation parameters and potential in vivo hepatic metabolites of syn- and anti-Dechlorane Plus isomers in juvenile rainbow trout (Oncorhynchus mykiss).

Juvenile rainbow trout (Oncorhynchus mykiss) were exposed in the laboratory to elevated doses of syn- and anti-isomers of Dechlorane Plus (DP) via their diet for 49 days (uptake phase), followed by 112 days of untreated food (depuration phase) to examine bioaccumulation parameters and possible metabolic products. Three groups of 60 fish were used in the study. Two groups were exposed separately to food fortified with known concentrations of syn- (0.79 +/- 0.03 microg/g, lipid weight) and anti-DP (1.17 +/- 0.12 microg/g, lipid weight) while a third control group was fed unfortified food. Neither isomer reached steady-state after 49 days of exposure. Only the syn-isomer accumulated linearly in the fish (whole-body minus liver) during the dosing phase with a calculated uptake rate constant of 0.045 +/- 0.005 (arithmetic mean +/- 1 x standard error) nmoles per day. A similar uptake rate was also observed for this isomer in the liver. The elimination of both isomers from the whole fish (minus liver) obeyed first order depuration kinetics (syn-: r2 = 0.6427, p < 0.001, anti-: r2 = 0.5350, p < 0.005) with calculated half-lives (t1/2) of 53.3 +/- 13.1 (syn-) and 30.4 +/- 5.7 (anti-) days. Elimination of the isomers from the liver was difficult to interpret because of suspected enterohepatic circulation and redistribution of the isomers in the liver during clearance from other tissues. The biomagnification factor (BMF, determined in whole fish minus liver) of the syn-isomer (5.2) was greater than the anti-isomer (1.9) suggesting that the former isomer is more bioavailable. A suite of metabolites were screened for in the liver including dechlorinated, hydroxylated, methoxylated and methyl sulfone degradates. Even with the purposely high dose used in the uptake phase, none of these degradates could be detected in the extracts. This suggests that if metabolites of DP are detected in fish from aquatic food webs their presence is likely not from in vivo biotransformation of the parent compound.