Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Organophosphorus flame-retardant and plasticizer analysis, including recommendations form the first worldwide interlaboratory study
Brandsma, S.H. ; Boer, J. de; Leonards, P.E.G. ; Cofino, W.P. ; Covaci, A. - \ 2013
TrAC : Trends in Analytical Chemistry 43 (2013). - ISSN 0165-9936 - p. 217 - 228.
tandem mass-spectrometry - indoor environments - gas-chromatography - population characteristics - chemical-ionization - organic-compounds - phthalate-esters - water samples - new-model - air
The first worldwide interlaboratory study on organophosphorus flame retardants (PFRs) was organized to improve the quality of the data reported in the literature. The study involved standard solutions, dust, fish oil and sediment samples. The differences in coefficients of variation (CV) between the samples were related more to PFR concentration (with high blanks being reported by some laboratories) and less to matrix type. Not all participating laboratories suffered from blank problems, which indicated that it was possible to control the blanks. We include recommendations on how to improve analytical performance, especially to reduce contamination of blanks.
Identification and quantification of methylated PAHs in sediment by two-dimensional gas chromatography / mass spectrometry
Skoczynska, E.M. ; Leonards, P.E.G. ; Boer, J. de - \ 2013
Analytical Methods 5 (2013)1. - ISSN 1759-9660 - p. 213 - 218.
polycyclic aromatic-hydrocarbons - toxic events - oil-spill - cells - mutagenicity - ms
Alkylated polycyclic aromatic hydrocarbons (alkyl-PAHs) are ubiquitously present in the environment and they are recognized as a toxicologically hazardous group. The biggest obstacle in the assessment of environmental risks of alkyl-PAHs is identification and quantification; the complete (chromatographic) separation of alkylated homologues is difficult if not impossible. Therefore, alkyl-PAHs are usually identified as a group of isomers with the same degree of alkylation and quantified as one group using one chromatographic response factor. In this study we demonstrate that the relative response factors of twenty-three methylated PAHs with the same molecular weight of 242 (six methyl-chrysenes, twelve benz[a]anthracenes and five benzo[c]phenanthrenes) range from 0.1 for 12-methylbenz[a]anthracene and 4-methylbenzo[c]phenanthrene to 1.7 for 6-methylbenz[a]anthracene. Quantification of methylated PAHs with equal molecular weights as a group using the same relative response factor can thus overestimate or underestimate their concentrations and, therefore, the toxicological risk of an environmental sample. A two-dimensional gas chromatography method was developed with which fourteen methylated PAHs (Mw = 242) could be separated. Twelve of them were identified and quantified in Elbe River sediment.
Field performance of the Chemcatcher passive sampler for monitoring hydrophobic organic pollutants in surface water
Vrana, B. ; Mills, G.A. ; Leonards, P.E.G. ; Kotterman, M.J.J. ; Weideborg, M. ; Hajslova, J. ; Kocourek, V. ; Tomaniova, M. ; Pulkrabova, J. ; Suchanova, M. ; Hajkova, K. ; Herve, S. ; Ahkola, H. ; Greenwood, R. - \ 2010
Journal of Environmental Monitoring 12 (2010)4. - ISSN 1464-0325 - p. 863 - 872.
semipermeable-membrane devices - calibration - substances
Six field trials were carried out to assess the performance of the Chemcatcher passive sampler alongside spot sampling for monitoring priority hydrophobic organic pollutants (polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides) in a wide range of conditions in surface water. The trials were performed in three European rivers: Elbe (Czech Republic), Alna (Norway) and Meuse (Netherlands), in two seasons (April-June 2004, and September-October 2004). Samplers spiked with performance reference compounds (PRCs) were deployed for either 14 or 28 days. Ten spot samples of water were collected over the course of the trial and filtered through a 0.7 mu m glass fibre filter. Concentrations of pollutants measured using the Chemcatcher were compared with the average concentrations found in spot samples. This study describes the operational performance of Chemcatcher for measuring hydrophobic (log K-OW 3.7-6.8) chemicals in surface water. Site specific Chemcatcher sampling rates up to 0.5 L d(-1) were found using the PRC approach that reduced the uncertainty in estimates of sampling kinetics where temperature, local flow conditions and biofouling potential varied between sites and seasons, and with time during sampler exposure. The limits of quantification of sampled analytes ranged from one to tens ng L-1. Highest sensitivity was achieved for compounds with a favourable combination of low instrument quantification limits and high sampling rates including dieldrin, hexachlorobenzene, lindane, pentachlorobenzene, and PAHs with less than five aromatic rings. The direct comparison of time weighted average (TWA) concentrations (mostly close to method limits of detection) obtained using passive and spot sampling was possible for lindane, hexachlorobenzene, and PAHs <4 rings. Implications of using the Chemcatcher in regulatory monitoring programmes such as the European Union Water Framework Directive are discussed.
Endocrine effects of hexabromocyclododecane (HBCD) in a one-generation reproduction study in Wistar rats
Ven, L.T.M. van der; Kuil, T. van de; Leonards, P.E.G. ; Slob, W. ; Lilienthal, H. ; Litens, S. ; Herlin, M. ; Hakansson, H. ; Canton, R.F. ; Berg, M. ; Visser, T.J. ; Loveren, H. van; Vos, J.G. ; Piersma, A.H. - \ 2009
Toxicology Letters 185 (2009)1. - ISSN 0378-4274 - p. 51 - 62.
brominated flame retardants - high-fat diet - sprague-dawley rats - oral dose toxicity - response elements - thyroid-hormone - breast-milk - inner-ear - flutamide - retinoids
The brominated flame retardant (BFR) hexabromocyclododecane was tested in a one-generation reproduction assay in Wistar rats, enhanced for endocrine parameters. A solution of the compound in corn oil was mixed in the feed, targeting at dietary exposure of 0-0.1-0.3-1-3-10-30-100 mg/kg body weight/day (mkd) in parental rats during 10 (males) or 2 (females) weeks premating, during gestation and lactation, and in their F1 offspring from weaning until final necropsy. Effects were assessed in F1 animals. Livers of these animals showed increased HBCD concentrations, in a dose-dependent way. The trabecular bone mineral density of the tibia was dose-dependently decreased in females (BenchMark Dose Lower confidence bound, BMDL = 0.056 mkd). The IgG response after immunization with sheep red blood cells (SRBC) was increased in males (BMDL = 0.46 mkd). Further sensitive effects were decreased weight of the testis (BMDL = 1.5 mkd), increased fraction of neutrophilic granulocytes (BMDL = 7.7 mkd), decreased concentration of apolar retinoids in female livers (BMDL = 1.3 mkd), and decreased plasma alkaline phosphatase in females (BMDL = 8.6 mkd). CYP19/aromatase activity in the ovary was correlated to the concentration of gamma-HBCD in the liver. A developmental origin of these effects is considered, and this is also true for sensitive effects observed in neurobehavioural testing in littermates from the same experiment, i.e. in the brain-stem auditory evoked potentials and in a catalepsy test [Lilienthal, H., Van der Ven, L.T.M., Piersma, A.H., Vos, J.G. Neurobehavioral effects of the brominated flame retardant hexabromocyclododecane (HBCD) in rats after pre- and postnatal exposure, in press]. The low BMDLs of these effects may raise concern for human health, particularly when based on body burdens of HBCD, which leads to critical margins of exposure particularly for the occupational setting
Identification of Hydroxylated Metabolites of Hexabromocyclododecane in Wildlife and 28-days Exposed Wistar Rats
Brandsma, S.H. ; Ven, L.T.M. van der; Boer, J. de; Leonards, P.E.G. - \ 2009
Environmental Science and Technology 43 (2009)15. - ISSN 0013-936X - p. 6058 - 6063.
mass-spectrometry - thermal-stability - products - fish
We studied the presence of hydroxylated metabolites of hexabromocyclododecane (HBCD) in three wildlife species (tern egg, seal, and flounder) and in Wistar rats exposed to 30 and 100 mg HBCD/kg bw/day for 28 days. A nondestructive extraction, fractionation, and cleanup method was developed to separate the hydroxylated HBCD metabolites from the biotic sample matrix. Four different groups of hydroxylated HBCD metabolites were identified in rat adipose, liver, lung, and muscle tissues by liquid and gas chromatography (LC and GC) combined with mass spectrometry (MS): monohydroxy metabolites of HBCD, pentabromocyclododecene (PBCDe), tetrabromocyclododecene (TBCDe), and dihydroxy-HBCD. Dihydroxy-PBCDe was identified by GC-MS but could not be confirmed by LC-MS. Debromination of HBCD to PBCDe was another metabolic pathway observed. In tern eggs from the Western Scheldt the monohydroxy-HBCD was found and in the blubber of harbor seal (Wadden Sea) the monohydroxy metabolites of HBCD and PBCDe were found. No hydroxylated metabolites were detected in the tissue of flounder (Wadden Sea). To our knowledge, this is the first study to identify different hydroxylated metabolite groups of HBCD in rat and wildlife samples.
PCBs and the energy cost of migration in the European eel (Anguilla anguilla L.)
Ginneken, V. van; Palstra, A.P. ; Leonards, P.E.G. ; Nieveen, M. ; Murk, A.J. - \ 2009
Aquatic Toxicology 92 (2009). - ISSN 0166-445X - p. 213 - 220.
polychlorinated-biphenyls - aromatic-hydrocarbons - sexual-maturation - silver eels - vitamin-a - exposure - metabolism - 3,3',4,4'-tetrachlorobiphenyl - netherlands - induction
The effect of polychlorinated biphenyls (PCBs) on the energy consumption of fasting silver European eel (Anguilla anguilla L.) was studied over a 27-day period during which the animals were at rest or were swimming 800 km in Blazka swim tunnels. Three-year-old female hatchery eels (silver stage) between 73 and 80 cm long weighing around 1 kg were dosed intraperitoneally with PCBs at a nominal dosage of 10× the consumption standard as a mixture representative for planar (7 mug PCB126/kg eel), non-planar (5 mg PCB153/kg eel) and metabolizable PCBs (50 mug PCB77/kg eel) found in wild eel, or only with the vehicle (corn oil, 10 ml/kg eel). Four major observations were made: (1) PCB-exposed animals lose less weight compared to their unexposed controls; (2) PCB-concentrations on a lipid basis are 2.8-14 times higher in swimming compared to resting animals; (3) the standard metabolic rate is significantly lower in the PCB-exposed animals than in unexposed controls. In addition, PCB-exposure significantly reduces oxygen consumption during swimming, and starting at 400 km (18 days) this effect increases with time; (4) the relative spleen and liver weight significantly increased in the PCB-swim animals but not in the PCB-rest animals. The swimming animals lost about 75% more weight compared to resting animals and had about 50% lower plasma fat content. Hematocrit, haemoglobin, plasma pH, ion levels (sodium and potassium), and plasma lactate were not affected by PCB-exposure or swimming. Apparently, the current levels of PCBs and other dioxin-like compounds may seriously impair the reproduction of the European eel
Toxicity of analytically cleaned pentabromodiphenyl ether after prolonged exposure in estuarine European flounder (Platichthys flesus), and partial life-cycle exposure in fresh water zebrafish (Danio rerio)
Kuiper, R.V. ; Vethaak, A.D. ; Canton, R.F. ; Anselmo, H. ; Dubbeldam, M. ; Brandhof, E.J. Van den; Leonards, P.E.G. ; Wester, P.W. ; Berg, M. - \ 2008
Chemosphere 73 (2008)2. - ISSN 0045-6535 - p. 195 - 202.
polybrominated diphenyl ethers - brominated flame retardants - carp cyprinus-carpio - cytochrome-p450 activity - embryonic exposure - liver morphology - thyroid-hormone - pbde mixture - north-sea - in-vivo
Residues of polybrominated diphenylethers (PBDEs). extensively applied as flame retardants, are widely spread in the aquatic environment and biota. The present study investigates effects of the environmentally relevant lower brominated diphenylethers in two fish species in vivo under controlled laboratory conditions. Euryhaline flounder (Platichthys flesus) and freshwater zebrafish (Dunio rerio) were exposed to a range of concentrations of a commercial pentabromodiphenylether mixture, DE-71. Chemical analysis of exposed fish showed a pattern of PBDE congeners that was very similar to that in wild fish. The resulting range included environmentally relevant, as well as higher levels. Animals were investigated histopathologically with emphasis on endocrine and reproductive organs. In zebrafish, hatching of embryos and larval development were assessed. Biochemical parameters were investigated in flounder as markers for Suggested dioxin-like activity (ethoxyresorufin-O-deethylase = EROD), and activation of endogenous estrogen synthesis (gonad aromatase activity). Thyroid hormones were analyzed in plasma in both species. Benchmark analysis using internal PBDE concentrations showed a mild dose-dependent decrease of hepatic EROD and ovarian aromatase activities, and plasma thyroxin levels in flounder, and an increase of plasma thyroid hormone levels in zebrafish. These trends did not result in statistically significant differences from control fish, and major histopathological changes were not observed. Reproduction in zebrafish appeared to be the most sensitive parameter with statistically significantly reduced larval survival and non-significant indications for decreased egg production at internal levels that were more than 55 times the highest environmental recordings. The present results indicate limited risk for endocrine or reproductive effects of current environmental PBDE contamination in fish.
GCxGC-ECD: a promising method for the determination of dioxins and dioxin-like PCBs in food and feed
Haglund, P. ; Korytar, P. ; Danielsson, C. ; Diaz, J. ; Wiberg, K. ; Leonards, P.E.G. ; Brinkman, U.A.Th. ; Boer, J. de - \ 2008
Analytical and Bioanalytical Chemistry 390 (2008)7. - ISSN 1618-2642 - p. 1815 - 1827.
2-dimensional gas-chromatography - dibenzo-p-dioxins - performance liquid-chromatography - 2-(1-pyrenyl)ethyldimethylsilylated silica column - ortho substituted chlorobiphenyls - electron-capture detection - flight mass-spectrometry - polychlorinated-biphenyls
There is a need for cost-efficient alternatives to gas chromatography (GC)¿high-resolution mass spectrometry (HRMS) for the analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs) in food and feed. Comprehensive two-dimensional GC¿micro electron capture detection (GC×GC-¿ECD) was tested and all relevant (according to the World Health Organisation, WHO) PCDD/Fs and PCBs could be separated when using a DB-XLB/LC-50 column combination. Validation tests by two laboratories showed that detectability, repeatability, reproducibility and accuracy of GC×GC-¿ECD are all statistically consistent with GC-HRMS results. A limit of detection of 0.5 pg WHO PCDD/F tetrachlorodibenzo-p-dioxin equivalency concentration per gram of fish oil was established. The reproducibility was less than 10%, which is below the recommended EU value for reference methods (less than 15%). Injections of vegetable oil extracts spiked with PCBs, polychlorinated naphthalenes and diphenyl ethers at concentrations of 200 ng/g showed no significant impact on the dioxin results, confirming in that way the robustness of the method. The use of GC×GC-¿ECD as a routine method for food and feed analysis is therefore recommended. However, the data evaluation of low dioxin concentrations is still laborious owing to the need for manual integration. This makes the overall analysis costs higher than those of GC-HRMS. Further developments of software are needed (and expected) to reduce the data evaluation time. Combination of the current method with pressurised liquid extraction with in-cell cleanup will result in further reduction of analysis costs.
Toxicity of tetrabromobisphenol A (TBBPA) in zebrafish (Danio rerio) in a partial life-cycle test
Kuiper, R.V. ; Brandhof, E.J. Van den; Leonards, P.E.G. ; Ven, L.T.M. van der; Wester, P.W. ; Vos, J.G. - \ 2007
Archives of Toxicology 81 (2007)1. - ISSN 0340-5761 - p. 1 - 9.
brominated flame retardants - tetrachlorobisphenol-a - endocrine disruption - hormonal activity - rainbow-trout - bisphenol-a - in-vitro - reproduction - exposure - estrogen
Toxicological effects of the widely used flame retardant, tetrabromobisphenol A (TBBPA) were assessed in a partial life-cycle test with zebrafish (Danio rerio). Exposure of adult fish during 30 days to water-borne TBBPA in nominal concentrations ranging from 0 (control) to 1.5 ¿M was followed by exposure of the offspring in early life stages up to 47 days posthatching (dph) to the same concentrations. Adults exposed to 3 and 6 ¿M showed severe disorientation and lethargy shortly after beginning of exposure and were euthanized. Because semistatic exposure resulted in fluctuating water concentrations, pooled fish samples were chemically analyzed for internal dose assessment. Egg production was decreased in fish exposed to TBBPA concentrations of 0.047 ¿M and higher, and a critical effect level of 7.2 ¿g/g lipid with a lower 5% confidence limit of 3.9 ¿g/g lipid for 50% decreased egg production was calculated. Histology of adult ovaries indicated a relative increase of premature oocytes in two surviving females exposed to 1.5 ¿M. Hatching of TBBPA-exposed larvae was decreased except in animals exposed to 0.375 ¿M. In the highest exposure concentration, early posthatching mortality was high (81%) in larvae and the surviving juveniles showed a significant predominance of the female phenotype. Exposure of eggs from control parents up to 6 ¿M TBBPA resulted in increasing malformation and pericardial fluid accumulation from 1.5 ¿M; at higher concentrations, all embryos failed to hatch. The presented results indicate decreased reproductive success in zebrafish at environmentally relevant TBBPA concentrations.
Polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls in fish from the Netherlands: concentrations, profiles and comparison with DR CALUX bioassay results
Leeuwen, S.P.J. van; Leonards, P.E.G. ; Traag, W.A. ; Hoogenboom, L.A.P. ; Boer, V.C.J. de - \ 2007
Analytical and Bioanalytical Chemistry 389 (2007)1. - ISSN 1618-2642 - p. 321 - 333.
polybrominated diphenyl ethers - toxic equivalency factors - eels anguilla-anguilla - calux-bioassay - international validation - organochlorine compounds - dietary-intake - great-lakes - pcbs - marine
Fish from Dutch markets were analysed for concentrations of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) and compared with the new European maximum residue levels (MRLs), set in 2006. In a first study on 11 different fish and shellfish from various locations, concentrations of PCDD/Fs were nearly all below the MRL for PCDD/Fs [4 pg toxic equivalents (TEQ) per gram wet weight (ww)] and nearly all below 8 pg total TEQ/g ww, the new MRL for the sum of PCDD/Fs and DL-PCBs. Some samples exceeded the total TEQ MRL, such as anchovy, tuna and sea bass. Furthermore, 20 (out of 39) wild eel samples exceeded the specific MRL for eel (12 pg total TEQ/g ww), as the study revealed PCDD/F TEQ levels of 0.2-7.9 pg TEQ/g ww and total TEQ values of 0.9 to 52 pg/g ww. TEQ levels in farmed and imported eel were lower and complied with the MRLs. Smoking eel, a popular tradition in the Netherlands, only had marginal effects on PCDD/F and DL-PCB concentrations. Owing to volatilization, concentrations of lower-chlorinated PCBs were reduced to below the limit of quantification after smoking. DL-PCBs contributed 61-97% to the total TEQ in all eel samples. This also holds for other fish and shellfish (except shrimps): DL-PCB contributed (on average) from 53 (herring) to 83% (tuna) to the total TEQ. Principal-component analysis revealed distinctive congener profiles for PCDD/Fs and non-ortho PCBs for mussels, pikeperch, herring and various Mediterranean fish. The application of new TCDD toxic equivalency factors (TEFs) set by the World Health Organization in 2006 (to replace the 1997 TEFs) resulted in lower TEQ values, mainly owing to a decreased mono-ortho PCB contribution. This decrease is most pronounced for eel, owing to the relative high mono-ortho PCB concentrations in eel. Consequently, a larger number of samples would comply with the MRLs when the new TEFs are applied. The DR CALUX (R) assay may be used for screening total TEQ levels in eel, in combination with gas chromatography-high resolution mass spectrometry confirmation of suspected samples. An almost 1:1 correlation was found when the 1997 TEFs were applied, but, surprisingly, a 1.4-fold overestimation occurred with application of the 2006 TEFs.
Modelling and field application of the Chemcatcher passive sampler calibration data for the monitoring of hydrophonic organic pollutants in water
Vrana, B. ; Mill, G.A. ; Kotterman, M.J.J. ; Leonards, P.E.G. ; Booij, K. ; Greenwood, R. - \ 2007
Environmental Pollution 145 (2007)3. - ISSN 0269-7491 - p. 895 - 904.
semipermeable-membrane devices - aquatic environments - in-situ - contaminants - accumulation - extraction
Passive sampling of dissolved pollutants in water has been gaining acceptance for environmental monitoring. Previously, an integrative passive sampler consisting of a C18 Empore® disk receiving phase saturated with n-octanol and fitted with low density polyethylene membrane, was developed and calibrated for the measurement of time weighted average (TWA) concentrations of hydrophobic pollutants in water. In this study, the exchange kinetics were modelled to obtain a better understanding of the mechanism of the accumulation process and to enable the measurement of TWA concentrations of hydrophobic pollutants in the field. An empirical relationship that enables the calculation of in situ sampling rates of chemicals using performance reference compounds was derived and its application was demonstrated in a field study in which TWA aqueous concentrations estimated from sampler data for target analytes were compared with TWA concentrations obtained from spot samples of water collected regularly during the sampler deployment period. The exchange kinetics of hydrophobic organic pollutants between passive sampler and water were modelled to enable the measurement of time weighted average concentrations of pollutants. The applicability of the model was tested in a field study
Development of biodegradation testing within a whole effluent assessment scheme: petrochemical application
Leonards, P.E.G. ; Postma, J.F. - \ 2007
IJmuiden : IMARES (Report / Wageningen IMARES C003/07) - 56
biodegradatie - beoordeling - bioaccumulatie - petrochemische industrie - afvoerwater - milieueffect - aquatische toxicologie - waterorganismen - biodegradation - assessment - bioaccumulation - petrochemical industry - effluents - environmental impact - aquatic toxicology - aquatic organisms
This study was performed for Concawe to obtain information on the development of an approach for assessing biodegradation of petrochemical effluents and the impact on assessing the toxicity and potential to bioaccumulate of the constituents. Whole Effluent Assessments (WEA) are being investigated as a potential tool for controlling aqueous discharges and minimizing environmental impact. The key parameter in such assessments relates to the toxicity of the effluent to aquatic organisms. Increasingly concern over long-term toxicity and the potential for toxicity to persist after discharge requires investigation.
Monofluorinated analogues of polybrominated diphenyl ethers as analytical standards: Synthesis, NMR, and GC-MS characterization and molecular orbital studies
Luthe, G. ; Leonards, P.E.G. ; Reijerink, G.S. ; Liu, H.L. ; Johansen, J.E. ; Robertson, L.W. - \ 2006
Environmental Science and Technology 40 (2006)9. - ISSN 0013-936X - p. 3023 - 3029.
brominated flame retardants - polychlorinated biphenyl - exposure - samples - salmon - pbdes - fetal - milk - pcb
Polybrominated diphenyl ethers (PBDEs), a group of 209 individual congeners distinguishable by the number and position of bromines,are produced for use as flame retardants in consumer goods. PBDEs have become ubiquitous environmental contaminants, present in increasing levels in the environment and humans. In the present study, 10 individual monofluorinated analogues of PBDEs (F-PBDEs) and one difluorinated PBDE (FF-PBDE) were synthesized and characterized, and their gas chromatographic (GC) and mass spectrometric (MS) characteristics determined. The synthesis method utilized a nucleophilic reaction of bromophenols with diphenyliodonium salts and the perbromination of fluorosubstituted diphenyl ethers. Reaction yields were between 10% and 59% with >= 98% purity. Apart from the aromatic ring carrying the fluorine atom, only minor chemical nuclear magnetic resonance (NMR) shift changes were observed in comparison to the corresponding parent PBDEs, with the exception that the J(F,H) coupling was stronger. Our preliminary data show that F-PBDEs and PBDEs have comparable retention times in gas chromatography with F-PBDEs demonstrating in general shorter or identical retention times, depending on the pattern of fluorine substitution. We also calculated the torsion angles and the dipole moments for both and report that there is a good correlation between GC retention times and the torsion angles but not with dipole moments. In MS, the difference of the ion peaks of the F-PBDE/PBDE pairs is m/z 19 (F), which allows a simultaneous MS detection without separation. On the basis of GC
Biolonical validation of a sample preparation method for ER-CALUX bioanalysis of estrogenic activity in sediment using mixtures of xeno-estrogens
Houtman, C.J. ; Houten, Y.K. Van; Leonards, P.E.G. ; Brouwer, A. ; Lamoree, M.H. ; Legler, J. - \ 2006
Environmental Science and Technology 40 (2006)7. - ISSN 0013-936X - p. 2455 - 2461.
in-vitro bioassays - cell-proliferation - xenoestrogens - chemicals - assay
The combined estrogenic effects of mixtures of environmental pollutants in the in vitro ER-CALUX (chemical activated luciferase gene expression) bioassay were examined to biologically validate a sample preparation method for the analysis of estrogenic compounds in sediment. The method used accelerated solvent extraction (ASE) and gel permeation chromatography (GPC) and was validated with respect to recovery of biological response taking mixture effects into account. Four mixtures of three to six xeno-estrogenic compounds (bisphenol A, 4-nonylphenol, (4,4`-dichlorodiphenyl)trichloroethane, (2,4`-dichlorodiphenyl)trichloroethane, dieldrin, 4-n-octylphenol, ¿-chlordane, dibutylphthalate, (4,4`-dichlorodiphenyl)dichloroethylene, and 2,4,5-trichlorobiphenyl) were prepared. Experimentally determined mixture effects were well described by the concept of concentration addition (CA), as expected for similarly acting compounds. Observed estradiol equivalence factors of the mixtures (on average 1.2 ± 0.3) agreed very well with the value predicted according to CA. The sample preparation method was then applied to pure mixtures of standards and to sediment spiked with one of the mixtures. Recoveries of estrogenic compounds were estimated by determination of their mixture potencies in ER-CALUX and compared to the mixture effects predicted by CA. Recoveries of estrogenic activity were between 80 and 129%, indicating that the additive behavior of mixtures of xeno-estrogens is well conserved during sample preparation. Together with an average repeatability of 18.3%, low average limit of detection (2.6 ± 1.8 pg of EEQ/g), and coefficient of variance (3.5 ± 3.3%), this demonstrated the suitability of the sample preparation method for the analysis of mixtures of (xeno-)estrogenic compounds in sediment with the ER-CALUX assay
Determination of in vitro relative potency (REP) values for mono-ortho polychlorinated biphenyls after purification with active charcoal
Peters, A.K. ; Leonards, P.E.G. ; Zhao, B. ; Bergman, A. ; Denison, M.S. ; Berg, M. van den - \ 2006
Toxicology Letters 165 (2006)3. - ISSN 0378-4274 - p. 230 - 241.
dioxin-like compounds - aryl-hydrocarbon receptor - toxic equivalency factors - dibenzo-p-dioxins - monkeys macaca-fascicularis - o-deethylase induction - ah receptor - risk-assessment - h4iie cells - dependent induction
The TEF system for dioxin-like compounds has included assignment of TEF values for mono-ortho polychlorinated biphenyls (MO-PCBs). Small traces of aryl hydrocarbon receptor (AhR)-active impurities could result in artifactually higher relative potency (REP) values. MO-PCBs -105, -118, -156, and -167 were purified on an active charcoal column to remove AhR agonists that could be present as impurities. Activation or inhibition of AhR-dependent gene expression by purified MO-PCBs was studied in stably transfected cell lines (HlG1.1c3 mouse, H4G1.1c2 rat hepatoma), containing an AhR-responsive (AhR-EGFP) reporter gene. In addition, EROD activity was used as marker for CYP1A1 activity in these cell lines. MO-PCBs -105,-118,-156 induced AhR-EGFP expression in both rodent cell lines, with PCB-156 (10 mu M) being most effectively; inducing gene expression to similar to 27% of TCDD (mouse cells) and 62.5 +/- 3.4% (rat cells) of TCDD. This concurred with increased EROD activity in both cell lines to maxima of 20.5 +/- 1.5% and 68 +/- 3.2% of TCDD, respectively. No induction was observed for PCB-167. In the HIG1.1c3 mouse cells, PCB-105, -118 and -156 (10 mu M) significantly reduced TCDD-induced AbR-EGFP expression to 50.9 +/- 2.9%, 58.3 +/- 2.2% and 70.8 +/- 1.3% of TCDD. Reduced EROD activity was also observed, of 39.3 +/- 2.8%, 67 +/- 5% and 48.3 +/- 4% compared to TCDD. PCB-167 did not result in significant reduction. In rat cells, only PCB-156 resulted in significant decrease in TCDD-induced AhR-EGFP expression of 35%, suggesting species differences play a role. Our results suggest that purification of MO-PCBs is an essential step in determining accurate REP values, and could very likely lead to lower TEF values than those presently assigned by the WHO. (c) 2006 Elsevier Ireland Ltd. All rights reserved.
Determination of the brominated flame retardant, hexabroomcyclodocane in sediments and biota by liquid chromatography-electrospray ionization mass spectrometry
Morris, S. ; Bersuder, P. ; Allchin, C.R. ; Zegers, B. ; Boon, J.P. ; Leonards, P.E.G. ; Boer, J. de - \ 2006
TrAC : Trends in Analytical Chemistry 25 (2006)4. - ISSN 0165-9936 - p. 343 - 349.
diphenylethers
A method involving reversed-phase, liquid chromatography coupled to electrospray ionisation mass spectrometry (LC-ESI-MS) was developed for separation, detection and quantitation of the alpha-, beta- and gamma-diastereoisomers of hexabromocyclododecane (HBCD). To address the lack of environmental data of this high-production-volume chemical, and to begin to understand the behaviour, the fate and the effects of these stereoisomers, a diastereoisomer-specific method is necessary. Currently, HBCD stereomeric separation is not possible using gas chromatography; thermally-induced rearrangements as well as decomposition of the compound occur at temperatures > 240 degrees C by the initial elimination of hydrogen bromide. The extraction of HBCDs, and subsequent clean-up procedures are similar to those used for polybrominated diphenylethers, and include Soxhlet, homogenisation, mechanical shaking, sulphuric acid treatment and gel-permeation chromatography. Single-quadrupole and ion-trap mass analysers as well as LC separations were optimised using pure and individual HBCD stereoisomers, and determinations were performed using selected ion monitoring (m/z 640.7) of the [M-H](-) ion. This article presents options for analyte extraction and information regarding instrument optimisation, and demonstrates that LC-MS is a suitable technique for quantifying HBCD stereoisomers in complex environmental matrices. Crown Copyright (c) 2005 Published by Elsevier Ltd. All rights reserved.
In vivo and in vitro Ah-receptor activation by commercial and fractionated pentabromodiphenylether using zebrafish (Danio rerio) and the DR-CALUX assay
Kuiper, R.V. ; Murk, A.J. ; Leonards, P.E.G. ; Grinwis, G.C.M. ; Berg, M. van den; Vos, J.G. - \ 2006
Aquatic Toxicology 79 (2006)4. - ISSN 0166-445X - p. 366 - 375.
polybrominated diphenyl ethers - brominated flame retardants - trout oncorhynchus-mykiss - flounder platichthys-flesus - rainbow-trout - 2,3,7,8-tetrachlorodibenzo-p-dioxin tcdd - immunohistochemical localization - cytochrome-p450 activity - decabromodiphenyl eth
The present study addresses the toxicity of a commercial pentabrominated diphenylether (PeBDE) flame retardant mixture, DE-71, in a model aquatic vertebrate. Four weeks¿ exposure of juvenile zebrafish (Danio rerio) to water-borne DE-71 resulted in dose-dependent induction of CYP1A immunoreactivity, predominantly in the endocardium and the endothelium of larger blood vessels, such as ventral aorta and branchial arteries, as well as the larger hepatic and pancreatic blood vessels. To investigate the impact of possible contaminating PBDD/Fs in the DE-71 product, the study was repeated after DE-71 had been fractionated into a non-planar (cleaned PBDEs) and a planar fraction (PBDD/Fs). Zebrafish were exposed under similar conditions to the planar and cleaned DE-71 fractions, and to uncleaned DE-71. In addition, the above fractions were chemically analyzed and tested in a reporter gene assay (DR-CALUX) for their aromatic hydrocarbon-receptor (AhR) stimulating potencies. A relatively strong CALUX response was detected from the planar DE-71 fraction (19.7 ng TCDD equivalent (TEQ)/g DE-71), coinciding with a strong induction of CYP1A immunoreactivity in zebrafish. CYP1A immunoreactivity in zebrafish exposed to uncleaned DE-71 was intense, although the CALUX response was 10-fold less compared to the planar fraction. Only weak CYP1A immunoreactivity was found in fish exposed to cleaned DE-71, and none in control animals; no CALUX response was detected in cleaned DE-71. The present findings indicate that chemical impurities of the commercial PeBDE product account for AhR-mediated effects. Analytical isolation of a planar fraction from the commercial product increased the in vitro (DR-CALUX) signal 10 times. Immunohistochemistry showed a strong tissue specific reaction to DE-71 in vivo at these relatively low TEQ levels regardless of chemical pretreatment of the mix, reflecting the sensitivity of CYP1A induction in juvenile zebrafish to AhR agonists
Gebromeerde vlamvertragers in zwevend stof
Leonards, P.E.G. - \ 2006
IJmuiden : IMARES (Rapport / IMARES C043/06) - 26
bemonsteren - zwevende deeltjes - broomhoudende vlamvertragers - waddenzee - eems-dollard - sampling - suspended solids - brominated flame retardants - wadden sea
Gebromeerde vlamvertragers (PBDE's, HBCD en TBBP-A) werden geanalyseerd in zwevend stof afkomstig van de Waddenzee en Eems-Dollard die bemonsterd werden in november/december 2005. De hoogste gehalten werden voor BDE209 aangetroffen (10 tot 34 ng/g droge stof). Lagere gehalten werden gevonden voor BDE47, BDE99 en BDE100 (
A chemical and toxicological profile of Dutch North Sea surface sediments
Klamer, H.J.C. ; Leonards, P.E.G. ; Lamoree, M.H. ; Villerius, L.A. ; Akerman, J.E. ; Bakker, J.F. - \ 2005
Chemosphere 58 (2005)11. - ISSN 0045-6535 - p. 1579 - 1587.
polycyclic aromatic-hydrocarbons - polybrominated diphenyl ethers - flame retardants - coastal waters - irgarol-1051 - extracts - biota - river - assay
Chemical and toxicological profiles were assessed in surface sediments (fraction
Accumulation of organochlorines and brominated flame retardants in estuarine and marine food chains: Field measurements and model calculations
Veltman, K. ; Hendriks, J. ; Huijbregts, M. ; Leonards, P.E.G. ; Heuvel-Greve, M.J. van den; Vethaak, D. - \ 2005
Marine Pollution Bulletin 50 (2005)10. - ISSN 0025-326X - p. 1085 - 1102.
polybrominated diphenyl ethers - carp cyprinus-carpio - different trophic levels - seals phoca-vitulina - rate constants - equilibrium ratios - species weight - bioaccumulation - contaminants - metabolism
Food chain accumulation of organochlorines and brominated flame retardants in estuarine and marine environments is compared to model estimations and fresh water field data. The food chain consists of herbivores, detritivores and primary and secondary carnivores i.e. fish, fish-eating birds and marine mammals. Accumulation of polychlorinated biphenyls is predicted well by OMEGA for herbi-detritivores and primary and secondary carnivorous fish. Ratios are similar to those found for fresh water species. Accumulation ratios for fish-eating birds and mammals are overestimated by the model, which is attributed partly to biotransformation of meta¿para unsubstituted congeners. Additionally, birds may feed in other less polluted areas. For brominated diphenylethers (BDE) accumulation patterns are highly species and congener specific. Accumulation depends on both Kow and metabolization capacities. BDE47 is the predominant congener in lower trophic levels. For marine birds and mammals accumulation ratios of BDE99 and 100 are similar to or higher than ratios of persistent PCBs
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