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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    Sand intake by laying hens and its effect on egg production parameters
    Meulen, J. van der; Kwakernaak, C. ; Kan, C.A. - \ 2008
    Journal of Animal Physiology and Animal Nutrition 92 (2008)4. - ISSN 0931-2439 - p. 426 - 431.
    whole barley - performance - dioxins - grit - soil - chicken - animals - energy - diets - feed
    Soil intake may be the most prominent source of environmental contaminants for free range and organic hens, but there are no quantitative data concerning soil intake by domestic hens. Consumption of soil of 14¿32 g a day can be estimated from literature, but such a dilution of nutrient intake seems incompatible with high productivity. In this study laying hens were fed pelleted diets with 0%, 10%, 20%, 25% and 30% of sand addition to determine its effect on productivity. Feed intake, feed and nutrient (feed minus sand) conversion ratio, egg production, egg weight and body weight gain were measured over a 4-week period. Acid insoluble ash concentration in the faeces was measured to determine the accuracy of estimating the soil ingestion by the soil-ingestion equation for wildlife as a way to determine soil ingestion of free range and organic hens under practical circumstances. The hens were able to compensate the dilution of the diet with 20%, 25% and 30% of sand by increasing their feed intake. Feed intake increased significantly and feed to egg conversion ratio decreased significantly with increasing sand levels in the diet. The nutrient to egg conversion ratio of the diet without sand tended to be worse than for the diets with sand, presumably due to the total absence of coarse material in the diet. There were no differences in egg production and egg weight between hens fed the different diets but body weight gain was significantly lower for the hens fed the diets with 20%, 25% and 30% of sand. Estimation of sand ingestion was done by the soil-ingestion equation for wildlife. Provided that the actual dry matter digestibility coefficient of the nutrient part of the diet is taken into account, estimating the soil ingestion according to the soil-ingestion equation for wildlife seems an appropriate way to determine soil ingestion for free range and organic hens under practical circumstances.
    Effect of flock Size on Dioxin Levels in eggs from Chickens kept Outside
    Kijlstra, A. ; Traag, W.A. ; Hoogenboom, L.A.P. - \ 2007
    Poultry Science 86 (2007)9. - ISSN 0032-5791 - p. 2042 - 2048.
    biologische landbouw - pluimveehouderij - scharrelhouderij - eieren - dioxinen - uitloop - organic farming - poultry farming - free range husbandry - eggs - dioxins - outdoor run - laying hens - range - contamination - soil - pcbs - wildlife - systems - area
    To decrease dioxin uptake by the general population the European Union (EU) has set limits to the dioxin content of many foodstuffs including eggs. Eggs from free foraging chickens are known to have a higher dioxin content compared with confined laying hens, and the question is whether these eggs can adhere to current EU regulations. The aim of the study was to investigate parameters that are involved in the contamination of eggs from chickens raised under organic conditions. Samples from 34 organic farms including soil and earthworm samples were collected between September and December of the year 2003. Dioxin levels were assayed by gas chromatography-mass spectrometry. Various parameters were collected by on farm interviews. Egg dioxin content varied between 0.4 and 8.1 pg of toxic equivalents (TEQ)/g of egg fat with a mean of 2.2 pg of TEQ/g of egg fat. Nine out of 34 farms exceeded the EU limit of 3 pg of TEQ/g of egg fat. In addition, dioxin-like polychlorinated biphenyls (DL-PCB) were measured, and 8 samples exceeded the limit for the sum of dioxins and DL-PCB. Overall, egg samples from 10 farms were noncompliant with the dioxin or total TEQ limits. No statistically significant relation could be observed between egg dioxin levels and the concentration observed in soil or earthworms. A statistically significant association was observed between flock size and egg dioxin and DL-PCB content. This effect is most likely attributable to the fact that flock size is related to the time chickens spend outside. Restricting outdoor run use on one of the farms resulted in a decrease of the egg dioxin content to a level that was within the EU limits. This demonstrates that the most likely contamination source is the soil or soil organisms but that the behavior of the hens determines the extent of the contamination. Following the completion of this study, a dioxin monitoring protocol has been set up in the Netherlands to prevent marketing of eggs with raised dioxin levels.
    Trendanalyse van gehalten aan aflatoxine B1 en dioxinen/dioxine-achtige PCB's in diervoeders
    Adamse, P. ; Jong, J. de; Jongbloed, A.W. ; Raamsdonk, L.W.D. van; Egmond, H.J. van - \ 2007
    Wageningen : RIKILT (Rapport / RIKILT 2007.001) - 49
    diervoeding - veevoeding - besmetters - voedselbesmetting - kennis - voedselveiligheid - aflatoxinen - dioxinen - ruwe grondstoffen - voedselketens - polychloorbifenylen - animal nutrition - livestock feeding - contaminants - food contamination - knowledge - food safety - aflatoxins - dioxins - raw materials - food chains - polychlorinated biphenyls
    In dit rapport wordt met behulp van historische waarden inzicht gegeven in het verloop van de gehalten aan contaminanten in diervoeders in Nederland. Het onderzoek heeft zich in eerste instantie beperkt tot het analyseren van trends in het vóórkomen van aflatoxine B1 en dioxinen/dioxineachtige PCB's in een beperkte selectie diervoedergrondstoffen.
    Onderzoek naar dioxines, dioxine achtige PCB's en indicator-PCB's in paling uit Nederlandse binnenwateren
    Hoogenboom, L.A.P. ; Kotterman, M.J.J. ; Hoek-van Nieuwenhuizen, M. van; Lee, M.K. van der; Traag, W.A. - \ 2007
    Wageningen : RIKILT (Rapport / RIKILT 2007.003) - 32
    palingen - waterverontreiniging - dioxinen - polychloorbifenylen - nederland - kennis - binnenwateren - ecotoxicologie - eels - water pollution - dioxins - polychlorinated biphenyls - netherlands - knowledge - inland waters - ecotoxicology
    In deze inventariserende studie werden 62 monsters paling uit open water onderzocht op dioxines en PCB’s, afkomstig van 22 verschillende locaties en in meerderheid gebieden waar hoge gehaltes verwacht werden.
    Onderzoek dioxines in gras en bodem in de Rijnmond en de overdracht naar melk
    Traag, W.A. ; Zeilmaker, M. ; Eijkeren, J.C.H. ; Hoogenboom, L.A.P. - \ 2006
    Wageningen : RIKILT (Rapport / RIKILT 2006.015) - 21
    dioxinen - grassen - bodem - analytische methoden - melk - nederland - kennis - rijnmondgebied - dioxins - grasses - soil - analytical methods - milk - netherlands - knowledge - rijnmondgebied
    Onderzoek naar dioxinegehaltes in door particulieren geteelde groenten en fruit afkomstig uit de Rijnmond
    Traag, W.A. ; Hoogenboom, L.A.P. ; Portier, L. ; Ede, K.I. van; Heneweer, M. ; Immerzeel, J. ; Onstenk, C.G.M. ; Kraats, C. van de; Velthuis, E.G. ; Vlaanderen, J. van - \ 2006
    Wageningen : RIKILT (Rapport / RIKILT 2006.012) - 13
    dioxinen - voedselbesmetting - groenten - vruchten - nederland - kennis - rijnmondgebied - dioxins - food contamination - vegetables - fruits - netherlands - knowledge - rijnmondgebied
    Dioxins in organic eggs: a review
    Vries, M. de; Kwakkel, R.P. ; Kijlstra, A. - \ 2006
    NJAS Wageningen Journal of Life Sciences 54 (2006)2. - ISSN 1573-5214 - p. 207 - 221.
    dioxinen - toxicologie - eieren - bodemchemie - diervoedering - biologische landbouw - kwaliteitsnormen - dioxins - toxicology - eggs - soil chemistry - animal feeding - organic farming - quality standards - dibenzo-p-dioxins - adaptive significance - chickens - tissue - soil - 2,3,7,8-tetrachlorodibenzo-p-dioxin - bioaccumulation - biotransfer - metabolism - excretion
    Eggs contribute for about 4% to the daily dioxin intake of humans. Research among layer farms in the Netherlands and other EU countries has shown that organic eggs contain more dioxin than conventional ones and that a significant number of organic farms produce eggs with a dioxin content that exceeds the EU standard. The hens' intake of dioxins from various sources leads to an increase in the dioxin content of organic eggs. These sources include plants, feed, soil, worms and insects, and compared with hens on conventional and free-range farms, organic hens make more use of these sources due to better access to the outdoor run. Plants appear to be relatively unimportant as a source of dioxins. Also commercial organic feed generally has very low dioxin contents, but not much is known about non-commercial feed. Consumption of worms and insects and particularly ingestion of soil are important causes of high dioxin levels in eggs. Management interventions, like a reduction of the time the hens spend outside, may decrease the dioxin levels in organic eggs but at the same time may interfere with the image of the organic production systems
    Development, validation and routine application of the in vitro REA and DR-CALUX reporter gene bioassays for the screening of estrogenic compounds and dioxins in food and feed
    Bovee, T.F.H. - \ 2006
    Wageningen University. Promotor(en): Ivonne Rietjens; Ron Hoogenboom; Michel Nielen. - [S.l.] : S.n. - ISBN 9789085043935 - 133
    biotesten - dioxinen - oestrogenen - bioassays - dioxins - oestrogens
    A dedicated cell-line was developed by the Department of Toxicology of Wageningen University in a joined project with the University of California in Davis and the RIKILT-WUR - Institute of Food Safety in Wageningen. This DR-CALUX ® bioassay was tested, optimised and validated for its use to determine low elevated levels of dioxins in bovine milk around the existing limits. It was shown that this mammalian cell based test is very sensitive for 2,3,7,8-substituted dioxins and related PCBs, thereby reflecting the relative potencies (TEF) of these compounds as set by the World Health Organisation (WHO). These toxic equivalency factors (WHO-TEFs) express the toxicity of a compound in comparison to the most toxic compoundcongener 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, TEF=1). The response obtained with a mixture of dioxins was additive, in accordance with the TEQ-principle. Milk fat was isolated by centrifugation followed by clean-up of the fat with n-pentane, removal of the fat on a 33% H2SO4silica column, and determination of Ah receptor agonist activity with the DR-CALUX ® bioassay. To investigate the performance of this 33% H2SO4silica method, milk fat was cleaned with activated carbon and spiked with a mixture of 17 different 2,3,7,8-substituted PCDD and PCDF congeners at 1, 3, 6, 9, 12 and 15 pg WHO-TEQ per g fat, as confirmed by GC/MS. In this concentration range, the method showed a recovery of TEQs around 67% (58-87%). The reproducibility showed a coefficient of variation (CV) varying between 4% and 54%, with the exception of the sample spiked at 1 pg WHO-TEQ/g (CV 97%). The repeatability determined with the sample spiked at 6 pg WHO-TEQ per g showed a CV of 10% These results clearly demonstrate that the reproducibility of the silica-CALUX procedure with samples containing more than 1 pg WHO-TEQ per g fat is relatively good, in particular regarding the fact that no internal standards could be used in the assay for correction of data for varying recoveries. The fact that the CV was much higher for the sample spiked at the lowest level, confirmed the calculated limit of quantification of 1 pg WHO-TEQ per g fat. The current tolerance limit for bovine milk in the EU is 3 pg WHO-TEQ per g fat, with an action limit of 2 pg WHO-TEQ per g fat. Therefore, the DR-CALUX ® bioassay can be a useful pre-screening tool for selecting milk samples that may contain dioxin levels exceeding this tolerance limit. This was supported by the results obtained with 22 field samples, since all five samples exceeding the 2 pg WHO-TEQ per g fat concentration gave a higher response in the DR-CALUX ® bioassay.

    The DR-CALUX ® bioassay in combination with the 33% H2SO4clean-up procedure results in a specific test for the determination of dioxins and dioxin-like PCBs, allowing the screening of relatively large sets of samples for the presence of unacceptable high levels of these compounds. This results in a reduction of costs involved in the analysis of food for the presence of these compounds, enabling more intense monitoring programs.

    Following the successful optimisation and validation of the test for milk fat, the bioassay was first used at RIKILT in the food and feed area during the 1998 Brazilian citrus pulp incident. The test procedure was subsequently optimised and validated for animal feed. During the German bakery waste incident in 2003, animal feed was contaminated with dioxins due to the use of waste wood for drying of the material. Besides Germany, the material was also shipped to the Netherlands. Levels up to 12 ng WHO-TEQ/kg were detected, being about 15 times over the current limit of 0.75 ng WHO-TEQ/kg. A combined strategy of screening with the DRCALUX ® -bioassay and the HRGC/HRMS confirmatory method was used in the Netherlands to rapidly control the incident. Pigs were contaminated by the incident but only to a very limited extent. Despite the rather low limits for pig meat (1 pg WHO-TEQ per g fat), the DR-CALUX ® bioassay, in combination with an extra acid pre-treatment of the fat samples, showed excellent performance, confirming once again the value of this bioassay. Shown during the recent incidents with kaolinic clay (2004) and the contaminated HCl used for gelatine production (2006), the assay is still the best availablescreening test for dioxins and dioxin-like PCBs.

    The second aim of the research in this thesis was to develop, validate and apply a new recombinant yeast screen to detect chemicals with an estrogenic mode of action in animal feed, urine and illegal preparations. A recombinant yeast cell that stably expresses the human estrogen receptor α (hERα) and yeast enhanced green fluorescent protein (yEGFP) as a reporter protein in response to estrogens was developed at the RIKILT. The EC50 revealed by the RIKILT yeast Estrogen bioAssay (REA) was 0.5 nM for 17b-estradiol and was comparable with reported EC50 values for yeast estrogen bioassays that contain β-galactosidase as a reporter. However, the yEGFP assay can be performed completely in 96 well plates within 4 hours and does not need require cell wall disruption, nor does it need the addition of a substrate. This makes the test sensitive, rapid and convenient with high reproducibility and small variation. The robustness and ease of the yeast cells in combination with the qualities ofyEGFP,ensure that the assay will be suited to be used as a high through put system.

    The properties of the RIKILT yeast Estrogen bioAssay expressing thehERα(REA) were further studied by testing a series of estrogenic compounds. In addition, a similar assay was developed based on the stable expression of human estrogen receptor β (hERβ). When exposed to 17b-estradiol, the maximum transcriptional activity of the hERb cytosensor was only about 40% of the activity observed with hERa, but the concentration where half-maximal activation is reached (EC50), was about 5 times lower. The relative estrogenic potencies (REP), defined as the ratio between the EC50 of 17b-estradiol and the EC50 of the compound, of the synthetic hormones dienestrol, hexestrol and especially mestranol were higher with ERa than with ERβ, while DES was slightly more potent with ERb. The gestagens progesterone and medroxyprogesterone-acetate showed no response, whereas the androgen testosterone showed a very weak response and only at high concentrations. The isoflavones genistein, genistin, daidzein and daidzin, the coumestran coumestrol and the flavonoid naringenin were relatively more potent with ERb than with ERa. Coumestrol and genistein were by far the most potent of these compounds with ERb. However, 8-prenylnaringenin, a phytoestrogen present in hops, was relatively more potent with ERa than with ERb and was actually the most potent phytoestrogen with ERa. The data demonstrate that the REA shows clear dose-response curves when exposed to estrogenic compounds. Since good dose-response curves can be obtained after only 4 h of exposure, the often questioned permeability of the yeast cell wall does not seem to be an obstacle in our yeast estrogen bioassays.

    The RIKILT yeast Estrogen bioAssay stably expressing human estrogen receptor α (REA) was validated as a qualitative screening method for the determination of estrogenic activity in calf urine and animal feed. These validations were performed according to EC Decision 2002/657, which prescribes the determination of the detection capability (CCb), the specificity and the stability. To determine these performance characteristics, twenty blank urine samples of 19 week old calves were collected and spiked with 17b-estradiol (E2b) at 1 ng/ml-1, diethylstilbestrol (DES) at 1 ng/ml-1, 17a-ethynylestradiol (EE2) at 1 ngml-1a-zearalanol at 50 ngml-1 or mestranol at 10 ng/ml-1. Following enzymatic deconjugation and solid phase extraction, 100 ml equivalents of these blank and spiked urine samples were screened for estrogenic activity in a 96 well plate using the REA. All of these blank and low estrogen spiked feed samples fulfilled the CCα and CCβ criterions, meaning that all 20 blank urine samples gave a signal below the determined decision limit CCα and were thus classified as compliant and at least 19 out of the 20 spiked samples gave a signal above this CCα (β=5%) and were thus classified as suspect. The specificity of the method was determined with blank urine samples spiked with a high dose of testosterone or progesterone (1000 ng/ml-1). No response to these substances was detected in the REA. There was also no interference of a high dose of testosterone or progesterone on the response of a low dose of the estrogens. Stability of urine samples was checked with spiked urine samples that were kept frozen for up to 90 days, showing that urine samples could be stored at -20°C for up to 60 days without changing the screening result of the assay. The assay was validated for animal feed in a simalar way, using twenty blank animal feed samples, including milk replacers and wet and dry feed samples.

    As all the performance characteristics met the criteria that were put forward in EC Decision 2002/657 for validation of a qualitative screening method, the described clean-up/yeast estrogen bioassay procedures were proven to be valid for the determination of estrogenic activity in calf urine and animal feed. The clean-up procedures for urine and feed samples are relatively simple and the yeast estrogen bioassay, using yEGFP as a reporter protein, is sensitive, rapid, convenient and reproducible. Due to the good sensitivity of the bioassay, only 2 ml of urine or 1 gram of feed were enough to be processed. Combined this resulted in a low cost bioassay that is suited to be used as a high through-put system for the screening of estrogenic activity in calf urine and animal feed. Like the DR CALUX ® assay, Tthe method acquired an ISO 17025 accreditation status in the Netherlands for both of these matrices. The examples of the MPA-incident with wet pig feed and the fishfeed,described in Chapter 7 of the thesis, demonstrate the applicability of the bioassay method as an early warning system for pharmaceutical waste and hormone use respectively. This is the first successful example of a developed, validated and applied bioassay for the screening of hormonal substances in feed. At present this method has been in routine use at RIKILT for more than two years.

    Overall the work presented in this thesis shows that bioassays are valuable tools for rapid and high throughput screening of samples for both known and unknown compounds. As such they may contribute to an earlier detection of new emerging risks and prevent the use of illegal growth-promoting agents with thus far unknown identity.
    Inventarisatie en evaluatie dioxinen in het Nederlandse aquatische milieu: status 2005
    Leonards, P.E.G. ; Dulfer, W.J. ; Evers, E.H.G. ; Guchte, C. van de - \ 2005
    IJmuiden : RIVO (Rapport / Nederlands Instituut voor Visserij Onderzoek (RIVO) C061/05-A) - 45
    dioxinen - polychloorbifenylen - emissie - aquatische ecologie - aquatisch milieu - dioxins - polychlorinated biphenyls - emission - aquatic ecology - aquatic environment
    This report describes an inventory of the present day’s situation of actions and effects of actions on the emission of dioxin, furan and dioxin-like PCBs to the Dutch aquatic environment. The standards for dioxins, furans and dioxin-like PCBs in food and the environment, and a risk evaluation for local areas in the Netherlands in relation to the function of the water are discussed.
    Dioxins in Food and Feed - Reference Methods and New Certified Reference Materials (DIFFERENCE)
    Leeuwen, S.P.J. van; Goeyens, L. ; Loco, J. van; Carbonelle, S. ; Overmeire, I. van; Beernaert, H. ; Cleuvenbergen, R. van; Schoeters, G. ; Bjoerklund, E. ; Sporring, S. ; Abalos, M. ; Abad, E. ; Rivera, J. ; Santos, J. ; Traag, W.A. ; Hoogenboom, R. ; Haglund, P. ; Wiberg, K. ; Holst, C. von; Maquet, A. ; Pasini, A.L. ; Fraise, D. ; Becher, G. ; Korytar, P. ; Leonards, P.E.G. ; Boer, J. de - \ 2005
    IJmuiden : RIVO (Report / RIVO-Netherlands Institute for Fisheries Research no. C022/05) - 75
    dioxinen - voedselanalyse - voedselveiligheid - vergelijkingen - referentienormen - polychloorbifenylen - polychloordibenzodioxinen - dioxins - food analysis - food safety - comparisons - reference standards - polychlorinated biphenyls - polychlorinated dibenzodioxins
    The European research project DIFFERENCE (“Dioxins in Food and Feed – Reference methods and New Certified Reference Materials”) was focussed on the development of an alternative methods for analysis of polychlorinated dibenzodioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs) using comprehensive multi-dimensional gas chromatography (GC×GC), gas chromatography combined with low resolution ion-trap mass spectrometry (GCLRMS/ MS), the CALUX bioassay and an Ah-PCR technique. GC combined with high resolution mass spectrometry (HRMS) was used as a reference method in all comparisons.
    Effects of In Utero Exposure to 4-hydroxy-2,3,3',4',5-pentachlorobiphenyl (4-OH-CB107) on Developmental Landmarks, Steroid Hormone Levels, and Female Estrous Cyclicity in Rats
    Meerts, I.A.T.M. ; Hoving, S. ; Berg, J.H.J. van den; Weijers, B.M. ; Swarts, J.J.M. ; Beek, E.M. van der; Bergman, A. ; Koeman, J.H. - \ 2004
    Toxicological sciences 82 (2004)1. - ISSN 1096-6080 - p. 259 - 267.
    polychlorinated-biphenyls aroclor-1254 - hydroxylated pcb metabolites - reproductive decline - mouse - hypothyroidism - dioxins - dibenzofurans - inhibition - induction - estradiol
    Previous studies have revealed that one of the major metabolites of PCBs detected in human blood, 4-OH-2,3,3',4',5-pentaCB (4-OH-CB107), accumulated in fetal liver, brain, and plasma and reduced maternal and fetal thyroid hormone levels after prenatal exposure to pregnant rats from gestational days (GD) 10¿16. In the present study, the effects of 4-OH-CB-107 on developmental landmarks, steroid hormone levels, and estrous cyclicity of rat offspring after in utero exposure to 4-OH-CB107 was investigated. Pregnant rats were exposed to 0, 0.5, and 5.0 mg 4-OH-CB107 per kg bw from GD 10 to GD 16. Another group of rats was exposed to Aroclor 1254 (25 mg/kg bw) to study the differences between effects caused by parent PCB congeners and the 4-OH-CB107 alone. A significant, dose-dependent prolongation of the estrous cycle was observed in 75% and 82% of female offspring exposed to 0.5 and 5.0 mg 4-OH-PCB107, respectively, compared to 64% of Aroclor 1254 (25 mg/kg) exposed offspring. The diestrous stage of the estrous cycle was prolonged, resembling a state of pseudopregnancy, which might reflect early signs of reproductive senescence. Plasma estradiol concentrations in female rat offspring were significantly increased (50%) in the proestrous stage after exposure to 5 mg 4-OH-CB107 per kg bw. No effects on estradiol levels were observed in Aroclor 1254 treated animals. These results indicate that in utero exposure to 4-OH-CB107 leads to endocrine-disrupting effects, especially in female offspring. The possible impact on neurobehavior following exposure to 4-OH-CB107 will be reported elsewhere
    Carry-over of dioxins and PCBs from feed and soil to eggs at low contamination levels
    Traag, W.A. ; Kan, C.A. ; Zeilmaker, M. ; Hoogerbrugge, R. ; Eijkeren, J. van; Hoogenboom, L.A.P. - \ 2004
    onbekend : Rikilt - Institute of Food Safety (Report / RIKILT 2004.016) - 77
    pluimveehouderij - dioxinen - polychloorbifenylen - voedselbesmetting - bodemverontreiniging - bioaccumulatie - poultry farming - dioxins - polychlorinated biphenyls - food contamination - soil pollution - bioaccumulation
    In order to study the relationship between dioxin and PCB levels in feed and eggs, laying hens were fed with compound feed containing six different levels of dioxins, dioxin-like PCBs and indicator PCBs for a period of 56 days. This was followed by a period of another 56 days on clean feed.Data were successfully modelled in order to predict the levels after different exposure scenario’s. Overall, these data show that exposure to dioxins and dioxin-like PCBs rapidly results in increased levels in eggs and that the current EU limit for feed cannot guarantee egg levels below the EU-limit. Therefore, dioxin levels in chicken feed should be as low as possible and the current limit for dioxins in feed should be further reduced, at least in the case of chicken feeds. More in general, it is important to further harmonize the tolerance limits for feed and edible products like meat, eggs and milk. Information about the carry-over of contaminants in farm animals is essential for this purpose.
    Is saneren wel altijd nodig?
    Jonker, M.T.O. ; Koelmans, A.A. ; Sinke, A. ; Brils, A. - \ 2004
    H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 37 (2004). - ISSN 0166-8439 - p. 28 - 30.
    verontreinigingsbeheersing - polychloorbifenylen - polycyclische koolwaterstoffen - dioxinen - besluitvorming - schoonmaken - waterorganismen - waterbodems - pollution control - polychlorinated biphenyls - polycyclic hydrocarbons - dioxins - decision making - cleaning - aquatic organisms - water bottoms
    Recent onderzoek heeft aangetoond dat zowel roet- en kooldeeltjes als verweerde olieresiduen giftige organische verontreinigingen,zoals PAK, extreem sterk kunnen binden. Deze materialen zijn wijd verspreid in waterbodems en kunnen ervoor zorgen dat de giftige stoffen vele malen minder worden opgenomen door organismen dan tot nu toe werd aangenomen. De huidige risico-evaluatieprocedure voor waterbodems gaat volledig voorbij aan dit feit, waardoor risico's kunnen worden overschat. Het is daardoor mogelijk dat saneringen plaatsvinden die in feite niet noodzakelijk zijn. De in dit onderzoek ontwikkelde methode kan helpen om hierover uitsluitsel te geven
    Intra- and interlaboratory calibration of the DR Calux bioassay for the analysis of dioxins and dioxin-like chemicals in sediments
    Besselink, H.T. ; Schipper, C.A. ; Klamer, H. ; Leonards, P.E.G. ; Verhaar, H. ; Felzel, E. ; Murk, A.J. ; Thain, J. ; Hosoe, K. ; Schoeters, G. ; Legler, J. ; Brouwer, A. - \ 2004
    Environmental Toxicology and Chemistry 23 (2004)12. - ISSN 0730-7268 - p. 2781 - 2789.
    dioxinen - toxiciteit - biotesten - waterbodems - ecotoxicologie - dioxins - toxicity - bioassays - water bottoms - ecotoxicology - equivalency factors tefs - in-vitro bioassay - round-robin - pcbs - pcdds - pcdfs - support - water - assay
    In the Fourth National Policy Document on Water Management in the Netherlands, it is defined that in 2003, in addition to the assessment of chemical substances, special guidelines for the assessment of dredged material should be recorded. The assessment of dredged material is based on integrated chemical and biological effect measurements. Among others, the DR CALUX® (dioxin responsive–chemically activated luciferase expression) bioassay has tentatively been recommended for inclusion in the dredged material assessment. To ensure the reliability of this bioassay, an intra- and interlaboratory validation study, or ring test, was performed, organized by the Dutch National Institute for Coastal and Marine Management (RIKZ) in cooperation with BioDetection Systems BV (BDS)
    In the Fourth National Policy Document on Water Management in the Netherlands [1], it is defined that in 2003, in addition to the assessment of chemical substances, special guidelines for the assessment of dredged material should be recorded. The assessment of dredged material is based on integrated chemical and biological effect measurements. Among others, the DR CALUX(R) (dioxin responsive-chemically activated luciferase expression) bioassay has tentatively been recommended for inclusion in the dredged material assessment. To ensure the reliability of this bioassay, an intra- and interlaboratory validation study, or ring test, was performed, organized by the Dutch National Institute for Coastal and Marine Management (RIKZ) in cooperation with BioDetection Systems BV (BDS). The intralaboratory repeatability and reproducibility and the limit of detection (LOD) and quantification (LOQ) of the DR CALUX bioassay were determined by analyzing sediment extracts and dimethyl sulfoxide (DMSO) blanks. The highest observed repeatability was found to be 24.1%, whereas the highest observed reproducibility was calculated to be 19.9%. Based on the obtained results, the LOD and LOQ to be applied for the bioassay are 0.3 and 1.0 pM, respectively. The interlaboratory calibration study was divided into three phases, starting with analyzing pure chemicals. During the second phase, sediment extracts were analyzed, whereas in the third phase, whole sediments had to be extracted, cleaned, and analyzed. The average interlaboratory repeatability increased from 14.6% for the analysis of pure compound to 26.1% for the analysis of whole matrix. A similar increase in reproducibility with increasing complexity of handlings was observed with the interlaboratory reproducibility of 6.5% for pure compound and 27.9% for whole matrix. The results of this study are intended as a starting point for implementing the integrated chemical-biological assessment strategy and for systematic monitoring of dredged materials and related materials in the coming years.
    TIE-studie van dioxine-achtige stoffen in zwevend stof en sediment met behulp van de DR-CALUX assay en gas chromatografie met time-of-flight massaspectrometrie
    Leonards, P.E.G. ; Veen, I. van der; Hesselingen, J.M. van - \ 2004
    onbekend : RIVO Milieu en Voedselveiligheid (RIVO rapport C076/04) - 12
    dioxinen - gaschromatografie - massaspectrometrie - dioxins - gas chromatography - mass spectrometry
    In dit onderzoek werd de toxiciteit van dioxine-achtige stoffen met behulp van de DR-CALUX assay van zwevend stof en sediment monsters bepaald.
    Analyse van baggerslib met de DR-CALUX assay en een screening met gaschromatografie met time-of-flight massaspectrometrie
    Leonards, P.E.G. ; Hoek-van Nieuwenhuizen, M. van; Hesselingen, J.M. van - \ 2004
    onbekend : RIVO Milieu en Voedselveiligheid (RIVO rapport C066/04) - 17
    toxiciteit - dioxinen - mariene sedimenten - sediment - havens - anaërobe afbraak - verontreinigde sedimenten - toxicity - dioxins - marine sediments - sediment - harbours - anaerobic digestion - contaminated sediments
    In dit onderzoek werd de toxiciteit van dioxine-achtige stoffen met behulp van de DR-CALUX assay van sediment uit het Zeehavenkanaal van Delfzijl bepaald. De toxiciteit was vergelijkbaar met de resultaten uit het onderzoek van 2002. De activiteit van het sediment bewerkt met een niet-destructieve methode (GPC) was 100 maal hoger dan wanneer het sediment werd bewerkt met het standaard protocol (SPECIE-01) waarbij een chemisch agressieve methode wordt toegepast. Dit bevestigt de resultaten uit eerder onderzoek. Na 18 maanden van anaërobe degradatie van het sediment was de DR-CALUX activiteit van de totale hoeveelheid extraheerbare stoffen met een DR-CALUX activiteit onveranderd, maar een verhoging werd waargenomen voor de fractie waarin zich dioxinen, furanen en PCB’s bevonden. Onduidelijk is waardoor deze verhoging werd veroorzaakt. Echter een sterke afname in DRCALUX activiteit werd gevonden voor stoffen die biologisch beschikbaar zijn. In sediment werd een drietal stoffen (dichloroanthraceen, dichloro-lichexanthone, dichloorbenzidine) met gaschromatografie met time-of-flight massaspectrometrie geïdentificeerd. Deze stoffen bezitten mogelijk een DR-CALUX activiteit en kunnen daarom bijdragen in de dioxine-achtige toxiciteit. Uitgezocht zou moeten worden of deze stoffen inderdaad een activiteit bezitten en hoeveel van de toxiciteit verklaard kan worden.
    Overzicht dioxine proeven uitgevoerd in Nederland met koeien en schapen
    Kan, C.A. ; Meijer, G.A.L. - \ 2003
    Lelystad : ID-Lelystad (Rapport / ID-Lelystad 03/0000744)
    dioxinen - dierlijke producten - koeien - schapen - besmetting - toxische stoffen - dioxins - animal products - cows - sheep - contamination - toxic substances
    De problemen met dioxinen en dibenzofuranen in koeien en schapen in de omgeving van de Afvalverwerking Rijnmond (Lickebaert gebied 1985-1990) en de contaminatie van citruspulp (1998-1999) hebben aanleiding gegeven tot een aantal proeven. In deze notitie worden de belangrijkste gegevens van deze proeven samengevat. Doel van dit overzicht is om de huidige kennis en kennishiaten met betrekking tot risico's van overdracht van dioxine-achtige verbindingen naar het dierlijk product melk (en vlees) in kaart te brengen
    Steeds minder dioxinen, furanen en dioxineachtige PCB's in de voeding
    Boon, P.E. ; Klaveren, J.D. van; Bakker, M. ; Baumann, B. ; Hoogerbrugge, R. - \ 2003
    Voeding Nu 5 (2003)9. - ISSN 1389-7608 - p. 17 - 19.
    vissen - dioxinen - heterocyclische zuurstofverbindingen - herbicidenverontreinigingen - polychloorbifenylen - gechloreerde koolwaterstoffen - voedselveiligheid - voedselconsumptie - blootstelling - nederland - europa - fishes - dioxins - heterocyclic oxygen compounds - herbicide impurities - polychlorinated biphenyls - chlorinated hydrocarbons - food safety - food consumption - exposure - netherlands - europe
    Ondanks de steeds verder dalende dioxine- en PCB-gehalten in voedingsmiddelen verdienen deze stoffen ook in de toekomst blijvende aandacht. Dit geldt zeker voor PCB-gehalten in vis
    Voeding en gezondheid - toxische stoffen in de voeding
    Rietjens, I.M.C.M. ; Alink, G.M. - \ 2003
    Nederlands Tijdschrift voor Geneeskunde 147 (2003)48. - ISSN 0028-2162 - p. 2365 - 2370.
    voeding - toxinen - voedselbesmetting - verontreiniging - zware metalen - dioxinen - polychloorbifenylen - aromatische koolwaterstoffen - polycyclische koolwaterstoffen - aminen - acrylamiden - nutrition - toxins - food contamination - pollution - heavy metals - dioxins - polychlorinated biphenyls - aromatic hydrocarbons - polycyclic hydrocarbons - amines - acrylamides
    With respect to food, the most important factors causing adverse health effects are: an unbalanced diet, overconsumption of alcohol or fat, the presence of microbial contamination and the presence of natural toxines. Two additional factors, the presence of environmental contaminants and products formed on heating food, may also be of importance. It is generally assumed that, when combined, food-related factors contribute to around 35% of overall cancer incidence
    Effecten van hormoonverstorende stoffen op kikkers
    Lee-de Groot, M.B.E. ; Brink, N.W. van den; Hout, A. van der; Bie, P.A.F. de; Stumpel, A.H.P. ; Bosveld, A.T.C. - \ 2003
    Wageningen : Alterra (Alterra-rapport ) - 77
    amphibia - estradiol - dioxinen - toxicologie - voortplantingsorganen - mortaliteit - hormonen - biotesten - ecotoxicologie - hormoonverstoorders - amphibia - estradiol - dioxins - toxicology - reproductive organs - mortality - hormones - bioassays - ecotoxicology - endocrine disruptors
    Omdat de ontwikkeling van amfibieën sterk hormoon-gereguleerd is, is onderzocht in hoeverre de kikker een geschikte indicator is voor hormoonverstorende stoffen in het milieu. Hiertoe zijn in het laboratorium blootstellingstudies uitgevoerd met kikkerlarven en volwassen Rana kikkers, welke algemeen in Nederland voorkomen. Onderzocht is in hoeverre oestradiol (E2) en tetrachloordibenzo-p-dioxine (TCDD) de ontwikkeling, overleving, lichaams- en orgaangewichten, geslachtsorganen en -hormonen, en specifieke cytochroom P450 enzymen beïnvloeden. Ook is de onderlinge samenhang van deze ettectparameters bestudeerd. In een in-situ veldstudie zijn de overleving en ontwikkeling van larven van Rana Kikkers, die zijn uitgezet in de sterk verontreinigde Volgermeerpolder en een niet-verontreinigde referentielocatie, beschouwd. Naast dit alles zijn juveniele Rana kikkers gevangen uit beide locaties, waarin interne concentraties dioxine-achtige stoffen en activiteiten van specifieke cytochroom P450 enzymen zijn bepaald.
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