Jonathan P Benskin

AXYS Analytical Services Ltd., Sicamous, British Columbia, Canada

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Publications (27)117.31 Total impact

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    ABSTRACT: There are multiple sources of biological and technical variation in a typical ecotoxicology study that may not be revealed by traditional endpoints but that become apparent in an omics dataset. As researchers increasingly apply omics technologies to environmental studies, it will be necessary to challenge ourselves to understand and control the main source(s) of variability to facilitate meaningful interpretation of such data. For instance, can variability in omics studies be addressed by changing our approach to study design and data analysis? Are there statistical methods that we can employ to correctly interpret omics data and make use of unattributed, inherent variability? In the present article, we review experimental design and statistical considerations applicable to using omics methods in systems toxicology studies. In addition to highlighting potential sources that contribute to experimental variability, this review suggests strategies with which to reduce and/or control such variability so as to improve reliability, reproducibility, and ultimately the application of omics data for systems toxicology. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Environmental Toxicology and Chemistry 04/2015; DOI:10.1002/etc.3002 · 2.83 Impact Factor
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    ABSTRACT: Per-and polyfluoroalkyl substances (PFASs) including perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are ubiquitous in the environment. Investigations into their fate and potential phase-partitioning behaviour require separation of solid from aqueous phases via filtration. However, sorption of aqueous-phase PFASs on filtration media may lead to underestimation of PFAS concentrations in the aqueous phase. We investigated the sorption of perfluoroalkyl carboxylates (PFCAs), perfluoroalkyl sulfonates (PFSAs), perfluoroalkyl phosphonic acids (PFPAs), perfluoroalkyl phosphinic acids (PFPiAs), polyfluoroalkyl phosphate monoesters (monoPAPs), polyfluoroalkyl phosphate diesters (diPAPs), fluorotelomer sulfonates (FTSs), and perfluorooctane sulfonamide (PFOSA) on filtration media. The effects of concentration (3 spiking levels), filter media (4 types), matrix (4 matrices) and compound structure on sorption are reported. Glass fibre filtration resulted in the least sorption, while polytetrafluoroethylene (PTFE) filters resulted in the most sorption (up to 98%). Analyte concentration had no significant effect. Sorption was generally consistent across matrix type except for samples affected by aqueous film forming foam (AFFF) deployment, which displayed high sorption of PFOS on nylon filters. Sorption usually increased with increasing number of carbon or fluorine atoms and was most pronounced for PFPiAs and diPAPs (30-75% sorption). Overall, glass fiber filters are recommended over nylon filters in environmental samples when phase separation is required. Use of filtration media for PFAS must be preceded by matrix-specific testing to account for unpredictable effects. Environ Toxicol Chem © 2014 SETAC.
    Environmental Toxicology and Chemistry 01/2015; 34(1). DOI:10.1002/etc.2751 · 2.83 Impact Factor
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    ABSTRACT: The health of Skeena River Sockeye salmon (Onchorhychus nerka) has been of increasing concern due to declining stock returns over the last decade. In the present work, in-migrating Sockeye from the 2008 run were evaluated using a mass spectrometry-based, targeted metabolomics platform. Our objectives were to a) investigate natural changes in a subset of the hepatic metabolome arising from migration-associated changes in osmoregulation, locomotion, and gametogenesis, and b) compare the resultant profiles with animals displaying altered hepatic vitellogenin A (vtg) expression at the spawning grounds, which was previously hypothesized as a marker of xenobiotic exposure. Of 203 metabolites monitored, 95 were consistently observed in Sockeye salmon livers and over half of these changed significantly during in-migration. Among the most dramatic changes in both sexes were a decrease in concentrations of taurine (a major organic osmolite), carnitine (involved in fatty acid transport), and two major polyunsaturated fatty acids (eicosapentaenoic acid and docosahexaenoic acid). In females, an increase in amino acids was attributed to protein catabolism associated with vitellogenesis. Animals with atypical vtg mRNA expression demonstrated unusual hepatic amino acid, fatty acid, taurine and carnitine profiles. The cause of these molecular perturbations remains unclear, but may include xenobiotic exposure, natural senescence, and/or inter-individual variability. These data provide a benchmark for further investigation into the long term health of migrating Skeena Sockeye.
    Environmental Science and Technology 09/2014; 48(19). DOI:10.1021/es503266x · 5.48 Impact Factor
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    ABSTRACT: The commercial chemotherapeutant formulations SLICE® and AlphaMax® [active ingredients emamectin benzoate (EB) and deltamethrin respectively] are used in fin fish aquaculture to control parasitic sea lice. In some regions, the use of these substances has drawn concern from the commercial fishing industry regarding potential adverse effects on non-target organisms. In the present work, biodegradation of EB and deltamethrin, and their commercial formulations, was investigated over 135 days at 4 and 10°C in fresh marine sediments collected from underneath an active open net-pen salmon farm. EB incubated as either pure substance or commercial formulation was recalcitrant at both temperatures under abiotic and biotic conditions. Deltamethrin incubated alone or as its commercial formulation degraded slowly at 10°C (t1/2 = 330 ± 107 and 201 ± 27.1 days respectively). At 4°C, deltamethrin degradation was only significant following incubation as commercial formulation (t1/2 = 285 ±112 days). Degradation rates of EB and deltamethrin as pure substances versus their commercial formulations were not statistically different. Depletion of deltamethrin was observed in 10°C inactive sediments indicating that transformation occurred (at least in part) via an abiotic pathway. Overall, these data provide further insight into the fate and persistence of EB from the ongoing use of SLICE® in British Columbia's salmon aquaculture industry. AlphaMax® is not registered in Canada but is used in other salmon farming countries to control sea lice.
    Aquaculture Research 07/2014; DOI:10.1111/are.12509 · 1.32 Impact Factor
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    ABSTRACT: Concentrations of 119 pharmaceuticals and personal care products (PPCPs) and 13 perfluoroalkyl substances (PFASs) in marine sediments measured throughout Puget Sound (n = 10) and Bellingham Bay (n = 30), Washington, USA, are reported. These data are among the first measurements of PPCPs and PFASs in marine sediments from the Pacific Northwest and provide a comparison to previous measurements of these chemicals in influent, effluent, and biosolids from municipal wastewater treatment plants throughout the region. The concentrations of both PPCPs and PFASs in sediments from Puget Sound and Bellingham Bay ranged from very low to non-detectable for most compounds. Only 14 of the 119 PPCPs and 3 of 13 PFASs were quantifiable in sediments. Diphenhydramine (an antihistamine) was most frequently detected (87.5% of samples), with a maximum concentration of 4.81 ng/g dry weight and an estimated mean detected concentration of 1.68 ng/g. Triclocarban (an antibacterial) was detected in 35.0% of the samples, with a maximum concentration of 16.6 ng/g dry weight. Perfluoroalkyl substances were detected in 2.5% of analyses. Perfluorobutanoate, perfluorooctane sulfonate, and perfluorooctane sulfonamide were detected in 7, 5, and 1 sample(s) each, respectively, with the highest concentrations observed for perfluorooctane sulfonate (1.5 ng/g). Detected concentrations were often highest within the industrial harbor in Bellingham Bay and near the cities of Seattle and Bremerton. Environ Toxicol Chem 2013;32:1701-1710. © 2013 SETAC.
    Environmental Toxicology and Chemistry 08/2013; 32(8):1701-1710. DOI:10.1002/etc.2281 · 2.83 Impact Factor
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    ABSTRACT: A method for quantitative characterization of naphthenic acid (NA) isomer groups by carbon number and extent of cyclization was developed and validated with water samples from northern Alberta. Following solid phase extraction, NAs undergo derivatization with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) allowing detection by positive electrospray ionization tandem mass spectrometry (+ESI)-MS/MS. NA-EDC derivatives produce a common product ion by MS/MS, regardless of structure of the starting NA. Thus, approximately constant relative response factors (RRFs) were assumed for the various isomer groups that elute at a given point in the elution gradient (supported by calculated RRFs for individual model NAs), facilitating quantification using a single standard (1-pyrenebutyric acid). To reduce the impact of major background fatty acids on NA data, the method employed an optimized liquid chromatography method that separated straight chain (Z=0) analytes from other NAs. Method validation was performed at two spiking levels (7.72μg and 38.6μg total refined Merichem per 500mL of reagent water) and good accuracy (mean recoveries of 82.4±2.5% and 93.0±2.6%, respectively; range ~50-130%) and precision (<17% RSD) were achieved at both spiking levels for all 60 NA isomer groups. The method also performed well in an independent method comparison study in which method accuracy values of 107%, 120%, and 121% were obtained for 2 spiked reagent waters (1mg/L and 50mg/L NAs) and spiked Athabasca River water (0.035mg/L NAs), respectively. Application of the method to samples from northern Alberta revealed that NA concentrations decreased in the order: process water (52.8mg/L)>tailings pond water (30.6mg/L)>well water (0.086mg/L)>surface water (0.007mg/L), and that samples were distinguishable by NA isomer profile using Principal components analysis.
    Journal of Chromatography A 03/2013; 1293. DOI:10.1016/j.chroma.2013.03.040 · 4.26 Impact Factor
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    ABSTRACT: Investigations into the biodegradation potential of perfluorooctane sulfonate (PFOS)-precursors have focused on low molecular weight substances (e.g. N-ethyl perfluorooctane sulfonamido ethanol (EtFOSE)) in waste water treatment plant (WWTP) sludge. Few data are available on PFOS-precursor biodegradation in other environmental compartments, and nothing is known about the stability of high-molecular weight perfluorooctane sulfonamide-based substances such as the EtFOSE-based phosphate (SAmPAP) diester in any environmental compartment. In the present work, the biodegradation potential of SAmPAP diester and EtFOSE by bacteria in marine sediments was evaluated over 120 days at 4 and 25°C. At both temperatures, EtFOSE was transformed to a suite of products, including N-ethyl perfluorooctane sulfonamidoacetate, perfluorooctane sulfonamidoacetate, N-ethyl perfluorooctane sulfonamide, perfluorooctane sulfonamide and perfluorooctane sulfonate. Transformation was significantly more rapid at 25°C (t1/2 = 44 ± 3.4 days; error represents standard error of the mean (SEM)) compared to 4°C (t1/2 = 160 ± 17 days), but much longer than previous biodegradation studies involving EtFOSE in sludge (t1/2 ~0.7 - 4.2 days). In contrast, SAmPAP diester was highly recalcitrant to microbial degradation, with negligible loss and/or associated product formation observed after 120 days at both temperatures, and an estimated half life of >380 days at 25°C. We hypothesize that the hydrophobicity of SAmPAP diester reduces its bioavailability, thus limiting biotransformation by bacteria in sediments. The lengthy biodegradation half life of EtFOSE and recalcitrant nature of SAmPAP diester in part explains the elevated concentrations of PFOS-precursors observed in urban marine sediments from Canada, Japan, and the U.S, over a decade after phase-out of their production and commercial application in these countries.
    Environmental Science & Technology 01/2013; 47(3). DOI:10.1021/es304336r · 5.48 Impact Factor
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    ABSTRACT: Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are normally the dominant perfluoroalkyl substances (PFASs) in human serum, but here a Canadian family of seven was identified with particularly high exposure to perfluorohexane sulfonate (PFHxS). Disproportionately high serum PFHxS concentrations (range 27.5 - 423 ng/mL) and moderately high PFOS (range 15.2 - 108 ng/mL) and PFOA (range 2.40 - 9.23 ng/mL) concentrations were detected in the family members, with all three chemicals being highest in the youngest children. We therefore sought to identify the source(s) and pathway(s) of this unusual exposure, and to study the excretion of PFASs for this family. Serum, urine, and stool were sampled from family members, carpet, dust, and air were sampled in the home, and a questionnaire was administered. Over 15 years, the family's household carpets were treated 8 times with Scotchgard™ formulations. Elevated concentrations of PFHxS were detected in household dust (2780 ng/g dust) and in family room carpet (2880 ng/g carpet), and the primary mode of excretion for the major PFASs was through urine. The high PFHxS and moderately high PFOS concentrations in serum and household samples are consistent with the known PFAS content of certain Scotchgard™ formulations, and exposure was likely through dust ingestion and/or inhalation.
    Environmental Science & Technology 10/2012; 46(23). DOI:10.1021/es3034654 · 5.48 Impact Factor
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    ABSTRACT: Concentrations and isomer profiles for 24 per- and polyfluoroalkyl substances (PFASs) were monitored over 5 months (February-June, 2010) in municipal landfill leachate. These data were used to assess the role of perfluoroalkyl acid (PFAA) precursor degradation on changes in PFAA concentrations over time. The influence of total organic carbon, total suspended solids, pH, electrical conductivity (EC), leachate flow rates, and meteorological data (precipitation, air temperature) on leachate PFAS concentrations was also investigated. Perfluoropentanoate and perfluorohexanoate were typically the dominant PFASs in leachate, except for March-April, when concentrations of perfluorooctane sulfonate, perfluorooctanoate, and numerous PFAA-precursors (i.e., (N-alkyl) perfluorooctane sulfonamides and fluorotelomer carboxylic acids) increased by a factor of 2-10 (∼4 μg/L to ∼36 μg/L ΣPFASs). During this time, isomer profiles of PFOA became increasingly dominated by the linear isomer, likely from transformation of linear, telomer-manufactured precursors. While ΣPFAA-precursors accounted for up to 71% of ΣPFASs (molar basis) in leachate from this site, leachate from a second landfill displayed only low concentrations of precursors (<1% of ΣPFASs). Overall, degradation of PFAA-precursors and changes in leachate pH, EC, and 24-h precipitation were important factors controlling PFAS occurrence in leachate. Finally, 8.5-25 kg/yr (mean 16 kg/yr) of ΣPFASs was estimated to leave the landfill via leachate for subsequent treatment at a wastewater treatment plant.
    Environmental Science & Technology 10/2012; 46(21). DOI:10.1021/es302471n · 5.48 Impact Factor
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    ABSTRACT: A rapid (<23 min) new HPLC-MS/MS method was developed for simultaneous characterization of 24 per- and polyfluoroalkyl compounds in landfill leachate. In addition to isomer-specific analysis of perfluorooctane sulfonate and perfluorooctanoate, branched from linear isomer separation was accomplished for C6 and C10 perfluoroalkyl sulfonates, C6, C7 and C9-C11 perfluoroalkyl carboxylates, perfluorooctane sulfonamide and, for the first time, 3 perfluorooctane sulfonamidoacetates. The method utilizes a fused-core pentafluorophenylpropyl (PFP) stationary phase and is approximately 4 times faster than previous comprehensive isomer-specific HPLC-MS/MS methods. This is the first isomer-specific methodology which can be adopted for routine analysis without sacrificing throughput from lengthy run times or limited target lists.
    Journal of Chromatography A 05/2012; 1247:165-70. DOI:10.1016/j.chroma.2012.05.077 · 4.26 Impact Factor
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    ABSTRACT: The environmental occurrence of perfluorooctane sulfonate (PFOS) can arise from its direct use as well as from transformation of precursors ((N-alkyl substituted) perfluorooctane sulfonamides; FOSAMs). Perfluorooctane sulfonamidoethanol-based phosphate (SAmPAP) esters are among numerous potential PFOS-precursors which have not been previously detected in the environment and for which little is known about their stability. Based on their high production volume during the 1970s-2002 and widespread use in food contact paper and packaging, SAmPAP esters may be potentially significant sources of PFOS. Here we report for the first time on the environmental occurrence of SAmPAP diester in marine sediments from an urbanized marine harbor in Vancouver, Canada. SAmPAP diester concentrations in sediment (40-200 pg/g dry weight) were similar to those of PFOS (71-180 pg/g). A significant (p < 0.05) correlation was observed between SAmPAP diester and N-ethyl perfluorooctane sulfonamido acetate (an anticipated degradation product of SAmPAP diester). ∑PFOS-precursor (FOSAM) concentrations in sediment (120-1100 pg/g) were 1.6-24 times greater than those of PFOS in sediment. Although SAmPAP diester was not detected in water, PFOS was observed at concentrations up to 710 pg/L. Among the per- and polyfluoroalkyl substances monitored in the present work, mean log-transformed sediment/water distribution coefficients ranged from 2.3 to 4.3 and increased with number of CF(2) units and N-alkyl substitution (in the case of FOSAMs). Overall, these results highlight the importance of FOSAMs as potentially significant sources of PFOS, in particular for urban marine environments.
    Environmental Science & Technology 05/2012; 46(12):6505-14. DOI:10.1021/es300823m · 5.48 Impact Factor
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    ABSTRACT: We report here on the spatial distribution of C(4), C(6), and C(8) perfluoroalkyl sulfonates, C(6)-C(14) perfluoroalkyl carboxylates, and perfluorooctanesulfonamide in the Atlantic and Arctic Oceans, including previously unstudied coastal waters of North and South America, and the Canadian Arctic Archipelago. Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) were typically the dominant perfluoroalkyl acids (PFAAs) in Atlantic water. In the midnorthwest Atlantic/Gulf Stream, sum PFAA concentrations (∑PFAAs) were low (77-190 pg/L) but increased rapidly upon crossing into U.S. coastal water (up to 5800 pg/L near Rhode Island). ∑PFAAs in the northeast Atlantic were highest north of the Canary Islands (280-980 pg/L) and decreased with latitude. In the South Atlantic, concentrations increased near Rio de la Plata (Argentina/Uruguay; 350-540 pg/L ∑PFAAs), possibly attributable to insecticides containing N-ethyl perfluorooctanesulfonamide, or proximity to Montevideo and Buenos Aires. In all other southern hemisphere locations, ∑PFAAs were <210 pg/L. PFOA/PFOS ratios were typically ≥1 in the northern hemisphere, ∼1 near the equator, and ≤1 in the southern hemisphere. In the Canadian Arctic, ∑PFAAs ranged from 40 to 250 pg/L, with perfluoroheptanoate, PFOA, and PFOS among the PFAAs detected at the highest concentrations. PFOA/PFOS ratios (typically ≫1) decreased from Baffin Bay to the Amundsen Gulf, possibly attributable to increased atmospheric inputs. These data help validate global emissions models and contribute to understanding of long-range transport pathways and sources of PFAAs to remote regions.
    Environmental Science & Technology 05/2012; 46(11):5815-23. DOI:10.1021/es300578x · 5.48 Impact Factor
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    ABSTRACT: The extent to which different manufacturing sources and long-range transport pathways contribute to perfluorooctanoate (PFOA) in the world's oceans, particularly in remote locations, is widely debated. Here, the relative contribution of historic (i.e., electrochemically fluorinated) and contemporary (i.e., telomer) manufacturing sources was assessed for PFOA in various seawater samples by an established isomer profiling technique. The ratios of individual branched PFOA isomers were indistinguishable from those in authentic historic standards in 93% of the samples examined, indicating that marine processes had little influence on isomer profiles, and that isomer profiling is a valid source apportionment tool for seawater. Eastern Atlantic PFOA was largely (83-98%) of historic origin, but this decreased to only 33% close to the Eastern U.S. seaboard. Similarly, PFOA in the Norwegian Sea was near exclusively historic, but the relative contribution decreased to ∼50% near the Baltic Sea. Such observations of contemporary PFOA in coastal source regions coincided with elevated concentrations, suggesting that the continued production and use of PFOA is currently adding to the marine burden of this contaminant. In the Arctic, a spatial trend was observed whereby PFOA in seawater originating from the Atlantic was predominantly historic (up to 99%), whereas water in the Archipelago (i.e., from the Pacific) was predominantly of contemporary origin (as little as 17% historic). These data help to explain reported temporal and spatial trends from Arctic wildlife biomonitoring, and suggest that the dominant PFOA source(s) to the Pacific and Canadian Arctic Archipelago are either (a) from direct emissions of contemporary PFOA via manufacturing or use in Asia, or (b) from atmospheric transport and oxidation of contemporary PFOA-precursors.
    Environmental Science & Technology 12/2011; 46(2):677-85. DOI:10.1021/es202958p · 5.48 Impact Factor
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    ABSTRACT: Perfluorooctane sulfonate (PFOS) is the most prominent perfluoroalkyl contaminant in humans and wildlife, but there is great uncertainty in exposure pathways, particularly with respect to the importance of PFOS-precursors (PreFOS). We explored the hypothesis that nonracemic proportions of chiral PFOS in serum are qualitative and semiquantitative biomarkers of human PreFOS exposure. A new chiral HPLC-MS/MS method was developed for alpha-perfluoromethyl branched PFOS (1m-PFOS, typically 2-3% of total PFOS) and applied to enantiomer fraction (EF) analysis in biological samples. In blood and tissues of rodents exposed subchronically to electrochemical PFOS, 1m-PFOS was racemic (EF = 0.485-0.511) and no evidence for enantioselective excretion was found in this model mammal. 1m-PFOS in serum of pregnant women, from Edmonton, was significantly nonracemic, with a mean EF (±standard deviation) of 0.432 ± 0.009, similar to pooled North American serum. In a highly exposed Edmonton family (mother, father, and 5 children) living in a house where ScotchGard had been applied repeatedly to carpet and upholstery, EFs ranged from 0.35 to 0.43, significantly more nonracemic than in pregnant women. Semiquantitative estimates of % serum 1m-PFOS coming from 1m-PreFOS biotransformation in both subpopulations were in reasonable agreement with model predictions of human exposure to PFOS from PreFOS. The data were overall suggestive that the measured nonracemic EFs were influenced by the relative extent of exposure to PreFOS. The possibility of using 1m-PFOS EFs for assessing the relative contribution of 1m-PreFOS (or PreFOS in general) in biological samples requires further application before being fully validated, but could be a powerful tool for probing general sources of PFOS in environments where the importance of PreFOS is unknown.
    Environmental Science & Technology 09/2011; 45(20):8907-14. DOI:10.1021/es2023434 · 5.48 Impact Factor
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    ABSTRACT: Atmospheric deposition of perfluorinated carboxylic acids (PFCAs) in remote regions might arise from transport and degradation of precursors (e.g., perfluorooctanesulfonyl fluoride (PFOSF)-based products or fluorotelomer alcohols (FTOHs)) or direct transport (e.g., PFCAs in the vapor phase or on particles). To probe the dominant atmospheric source of PFCAs, historical trends in environmental FTOH, PFOSF, and direct perfluorooctanoate (PFOA) emissions were compared to the flux of PFCAs (sum of C7-C13 perfluoroalkyl chain lengths) and PFCA isomer signatures in dated sediment cores from two remote alpine lakes in the Canadian Rocky Mountains. Contributions from PFOSF-based substances and direct transport of PFOA were ruled to be minimal because no branched isomers were detected in either core and temporal trends for direct emission of PFOA did not match the flux measurements. PFCA flux to Lake Opabin sediment agreed well with reported FTOH emissions, including a peak in mid-2003 and subsequent decline. In Lake Oesa, agreement between PFCA flux and FTOH emissions was also good up to 2004, but a subsequent decline was only detected for some PFCA congeners through 2008, while others continued to increase. Overall, both the isomer profiles and the temporal trend data suggest that FTOH oxidation is the dominant atmospheric source of PFCAs to these high alpine lakes. The efficacy of recent industry phase-out initiatives was difficult to assess due to the divergent temporal trends in samples after 2003; thus, continued monitoring is suggested at remote sites such as these.
    Environmental Science & Technology 08/2011; 45(17):7188-94. DOI:10.1021/es2011176 · 5.48 Impact Factor
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    ABSTRACT: Perfluorochemicals (PFCs) are detectable in the general population and in the human environment, including house dust. Sources are not well characterized, but isomer patterns should enable differentiation of historical and contemporary manufacturing sources. Isomer-specific maternal-fetal transfer of PFCs has not been examined despite known developmental toxicity of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in rodents. We elucidated relative contributions of electrochemical (phased out in 2001) and telomer (contemporary) PFCs in dust and measured how transplacental transfer efficiency (TTE; based on a comparison of maternal and cord sera concentrations) is affected by perfluorinated chain length and isomer branching pattern. We analyzed matching samples of house dust (n = 18), maternal sera (n = 20), and umbilical cord sera (n = 20) by isomer-specific high-performance liquid chromatography tandem mass spectrometry. PFOA isomer signatures revealed that telomer sources accounted for 0-95% of total PFOA in house dust (median, 31%). This may partly explain why serum PFOA concentrations are not declining in some countries despite the phase-out of electrochemical PFOA. TTE data indicate that total branched isomers crossed the placenta more efficiently than did linear isomers for both PFOS (p < 0.01) and PFOA (p = 0.02) and that placental transfer of branched isomers of PFOS increased as the branching point moved closer to the sulfonate (SO3-) end of the molecule. Results suggest that humans are exposed to telomer PFOA, but larger studies that also account for dietary sources should be conducted. The exposure profile of PFOS and PFOA isomers can differ between the mother and fetus-an important consideration for perinatal epidemiology studies of PFCs.
    Environmental Health Perspectives 07/2011; 119(11):1659-64. DOI:10.1289/ehp.1003265 · 7.03 Impact Factor
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    ABSTRACT: A method for isomer profiling of perfluorinated compounds (PFCs) in water was developed and applied to quantitatively assess the contributions from electrochemical (ECF) and telomer manufacturing processes around source regions of North America, Asia, and Europe. With the exception of 3 sites in Japan, over 80% of total perfluorooctanoate (PFOA, C(7)F(15)COO(-)) was from ECF, with the balance attributable to strictly linear (presumably telomer) manufacturing source(s). Comparing PFOA isomer profiles in samples from China, with PFOA obtained from a local Chinese manufacturer, indicated <3% difference in overall branched isomer content; thus, exclusive contribution from local ECF production cannot be ruled out. In Tokyo Bay, ECF, linear-telomer, and isopropyl-telomer sources contributed to 33%, 53%, and 14% of total PFOA, respectively. Perfluorooctane sulfonate (PFOS, C(8)F(17)SO(3)(-)) isomer profiles were enriched in branched content (i.e., >50% branched) in the Mississippi River but in all other locations were similar or only slightly enriched in branched content relative to historical ECF PFOS. Isomer profiles of other PFCs are also reported. Overall, these data suggest that, with the exception of Tokyo Bay, ECF manufacturing has contributed to the bulk of contamination around these source regions, but other sources are significant, and remote sites should be monitored.
    Environmental Science & Technology 11/2010; 44(23):9049-54. DOI:10.1021/es102582x · 5.48 Impact Factor
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    ABSTRACT: The extent to which perfluorooctanesulfonate precursors (PreFOS) play a role in human or environmental exposure to perfluorooctanesulfonate (PFOS) is not well characterized. The diversity of manufactured PreFOS and its degradation products (e.g. C(8)F(17)SO(2)R and C(8)F(17)SO(2)NR'R'', where R is H or F, and R' and R'' are various) has made it difficult to track their fate. Temporal trends of PFOS in both humans and wildlife are discrepant, thus it is difficult to predict future exposure, and hypotheses about the role of PreFOS have been raised. Although abiotic degradation of commercially important PreFOS materials requires further research, current data suggest that the yield of PFOS is negligible or minor. On the other hand, in vivo biotransformation of PreFOS yields PFOS as the major metabolite, and >32% yields have been observed. In Canadians, exposure to PreFOS was equivalent or greater than direct PFOS exposure prior to 2002. In most ocean water, PFOS is dominant to PreFOS, but in the oceans east of Greenland there may be more PreFOS than PFOS, consistent with the fact that whales and humans in this region also show evidence of substantial PreFOS exposure. Quantitative assessments of PFOS body-burdens coming from PreFOS are complicated by the fact that PreFOS partitions to the cellular fraction of blood, thus biomonitoring in serum under predicts PreFOS relative to PFOS. Many unknowns exist that prevent accurate modelling, thus analytical methods that can distinguish directly manufactured PFOS, from PFOS that has been biotransformed from PreFOS, should be applied in future human and environmental monitoring. Two new source tracking principles are presented and applied to human serum.
    Journal of Environmental Monitoring 10/2010; 12(11):1979-2004. DOI:10.1039/c0em00295j · 2.11 Impact Factor
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    ABSTRACT: On August 2, 2005, Air France Flight 358 descended on Lester B. Pearson International Airport (Toronto, ON, Canada) during adverse weather conditions and overran the runway, leading to an onboard fire which destroyed the aircraft. Large quantities (48000L) of aqueous film-forming foam (AFFF) were applied to the burning fuselage within meters of Etobicoke Creek. Local authorities could not confirm the identity of the AFFF formulation applied, but chemical analyses of fish livers collected 9 days post-AFFF application indicated that no perfluorinated acids (PFAs) were elevated at the site of application or downstream. This, and higher concentrations of a fluorotelomer sulfonate in fish liver collected downstream, suggests that an AFFF containing telomerized polyfluorinated material was likely used. However, as an urbanized stream within a heavily developed commercial, industrial, and residential watershed, background levels of perfluorinated compounds in Etobicoke Creek were considerable at all sites. Enlarged fish livers adjacent the AFFF-application site, commensurate with depressed peroxisomal beta-oxidation and hepatic oxidative stress, demonstrate some short-term impact of the AFFF on exposed fish within 9 days of its release. Most fish biochemical responses had recovered to normal values by 120 days, although there was some indication that AFFF-associated contamination shifted further downstream over this interval. This study suggests contemporary AFFFs exert relatively low toxicity on fish communities under realistic exposure scenarios.
    Aquatic toxicology (Amsterdam, Netherlands) 02/2010; 98(2):120-9. DOI:10.1016/j.aquatox.2010.02.005 · 3.51 Impact Factor
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    ABSTRACT: Perfluorooctane sulfonate (PFOS; C(8)F(17)SO(3) (-)) bioaccumulation and toxicity have been demonstrated in both aquatic and terrestrial organisms. The majority of investigations have examined total PFOS concentrations in wildlife and in toxicity testing, but isomer-specific monitoring studies are less common, and no laboratory-based study of PFOS isomer accumulation in fish has been reported. The present study examined accumulation and maternal transfer of PFOS isomers in zebrafish and tissue-specific accumulation of PFOS isomers in trout parr. A median lethal dose (LC50) of 22.2 and 2.5 mg/L was calculated for adult zebrafish and trout parr, respectively. A two-week PFOS exposure resulted in tissue-specific PFOS accumulation in trout, with maximum concentrations identified in the liver tissue (>50 microg/g). Prior exposure to PFOS as alevin did not affect the accumulation of PFOS in tissues later in life. In both species, accumulation of branched PFOS isomers generally occurred to a lesser extent than linear PFOS, which may explain the relative deficiency of branched PFOS isomers in some aquatic species in the field. Analysis of exposed trout tissues indicated that isomer discrimination may occur at the level of elimination or uptake and elimination processes in the kidney or gill, respectively. When zebrafish underwent a reproductive cycle in the presence of PFOS, approximately 10% (wt) of the adult PFOS body burden was transferred to the developing embryos, resulting in a higher total PFOS concentration in eggs (116 +/- 13.3 microg/g) than in the parent fish (72.1 +/- 7.6 microg/g). The isomer profile in eggs was not significantly different from that of adults, suggesting that the maternal transfer of branched and linear PFOS isomers in fish is largely nonisomer specific.
    Environmental Toxicology and Chemistry 01/2010; 29(9):1957-66. DOI:10.1002/etc.257 · 2.83 Impact Factor

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617 Citations
117.31 Total Impact Points


  • 2013–2015
    • AXYS Analytical Services Ltd.
      Sicamous, British Columbia, Canada
    • Washington State Department of Ecology
      • Environmental Assessment Program
      Olympia, Washington, United States
  • 2012–2014
    • Fisheries and Oceans Canada
      • Institute of Ocean Sciences
      Ottawa, Ontario, Canada
  • 2007–2012
    • University of Alberta
      • Department of Laboratory Medicine and Pathology
      Edmonton, Alberta, Canada