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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    A study of the 2013 Western European issue of aflatoxin contamination of maize from the Balkan area
    Rijk, T.C. de; Egmond, H.P. van; Fels-Klerx, H.J. van der; Herbes, R. ; Nijs, W.C.M. de; Samson, R.A. ; Slate, A.B. ; Spiegel, M. van der - \ 2015
    World Mycotoxin Journal 8 (2015)5. - ISSN 1875-0710 - p. 641 - 651.
    In March 2013 a large shipment of maize, intended for feed was subject of an alert in the Rapid Alert System for Food and Feed of the European Commission (EC) because the aflatoxin B1 (AFB1) level in the load exceeded the EC regulated maximum level of 20 µg/kg. Since the shipment had passed import controls and was already distributed (mainly to German farms), a massive recall followed. The aim of the current study was to investigate questions, raised by authorities and industry, related to the effectivity of EU sampling procedures, the influence of sample homogenisation procedures and sample storage conditions on the test results, and fungal identification as unexpected mycotoxins were identified during this study. The Netherlands Food and Consumer Product Safety Authority seized a shipload of maize in July 2013, suspected to be contaminated with AFB1. The shipload was sampled according to the 2009 and 2013 EC Sampling Regulations to compare the outcomes of both sampling protocols. Mycotoxin analysis of the incremental samples showed high mean levels of AFB1, aflatoxin G1 (AFG1), and ochratoxin A (OTA). Also an extreme inhomogeneous distribution of aflatoxins and OTA was proven. Analysis of samples homogenised according to the slurry method showed improved performance as compared to samples homogenised through dry homogenisation. Sampling and sample homogenisation according to the Regulation from 2013 showed a closer estimate of the ‘true’ AFB1 content as compared to sampling according to the Regulation from 2009. No influence of laboratory storage conditions on AFB1 concentration could be determined. Fungal identification revealed Aspergillus flavus as the main source of AFB1 in this shipment. Infrequent occurrence of Aspergillus parasiticus might have been the source of AFG1. The occurrence of sometimes large amounts of OTA could not be explained, however it was suggested that Aspergillus welwitschiae might have played a role.
    Carry-over of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in dairy cows fed smoke contaminated maize silage or sugar beet pulp
    Hoogenboom, L.A.P. ; Klop, A. ; Herbes, R. ; Eijkeren, J.C.H. van; Zeilmaker, M.J. ; Vuuren, A.M. van; Traag, W.A. - \ 2015
    Chemosphere 137 (2015). - ISSN 0045-6535 - p. 214 - 220.
    Fires and improper drying may result in contamination of feed with PCDD/Fs and PCBs. To predict the impact of elevated feed levels, it is important to understand the carry-over to edible products from food producing animals. Therefore, a carry-over study was performed with maize silage contaminated by a fire with PVC materials, and with sugar beet pulp contaminated by drying with coal, containing particles from a plastic roof. Levels of PCDD/Fs and dl-PCBs in the maize silage were 0.93 and 0.25ng TEQ kg(-1), those in beet pulp 1.90 and 0.15ng TEQ kg(-1) (both on 88% dry matter (DM)). Dairy cows (3 per treatment) received either 16.8kg DM per day of maize silage or 5.6kg DM per day of sugar beet pellets for a 33-d period, followed by clean feed for 33days. This resulted in a rapid increase of PCDD/F levels in milk within the first 10days with levels at day 33 of respectively 2.6 and 1.7pg TEQ g(-1) fat for maize silage and beet pulp. Levels of dl-PCBs at day 33 were lower, 1.0 and 0.5pg TEQ g(-1) fat. In the case of the maize silage, the carry-over rates (CORs) at the end of the exposure were calculated to be 25% and 32% for the PCDD/F- and dl-PCB-TEQ, respectively. For the dried beet pulp the CORs were 18% and 35%. This study shows that the carry-over of PCDD/Fs and dl-PCBs formed during drying processes or fires can be substantial.
    Sampling for heterogeneously distributed aflatoxins in maize lots from large shipments
    Spiegel, M. van der; Rijk, T.C. de; Fels-Klerx, H.J. van der; Nijs, W.C.M. de; Herbes, R. ; Egmond, H.P. van - \ 2014
    Follow-up of the 2013 aflatoxin issue in maize from the Balkan Area
    Spiegel, M. van der; Rijk, T.C. de; Fels-Klerx, H.J. van der; Herbes, R. ; Egmond, H.P. van - \ 2014
    Carry-over of veterinary drugs from medicated to non-medicated feeds in commercial feed manufacturing plants
    Stolker, A.A.M. ; Zuidema, T. ; Egmond, H.J. van; Deckers, E.R. ; Herbes, R. ; Hooglught, J. ; Olde Heuvel, E. ; Jong, J. de - \ 2013
    Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 30 (2013)6. - ISSN 1944-0049 - p. 1100 - 1107.
    feedingstuffs - residues - animals - agents - food
    Different compound feeds have to be manufactured in the same production line. As a consequence, traces of the first produced feed may remain in the production and get mixed with the next feed batches. This "carry-over" is unavoidable, and so non-medicated feed can be contaminated with veterinary drugs like antibiotics added to the previous batch of medicated feed. To monitor the carry-over of antibiotics in the Netherlands, 21 feed mills were visited and 140 samples of flushing feeds were collected and analysed for containing residues of antibiotics. Results show that 87% of all samples contain concentrations of antibiotics in the range of 0.1-154 mg/kg. It is expected that these levels - which are in the same range as previously found for the nowadays banned antimicrobial growth promoters (AMGPs) - have an effect on the occurrence of microbial resistance. Analysis of a second set of samples collected at four different feed mills directly after the production of oxytetracycline-medicated feed demonstrated that the first part of a flushing feed has much higher contamination than the last part of the batch. Furthermore, it was demonstrated that the carry-over percentage shows no correlation with the carry-over determined by one of the standard GMP+ procedures. These observations, unavoidable carry-over, inhomogeneous batches of feed with antibiotics and difficulties to predict the carry-over levels, together with the awareness of the increasing problem of microbial resistance, motivated the NEVEDI, association of Dutch Feed Producers, to announce that they will voluntarily stop the production of medicated feed in 2011. The alternatives for medicated feed are for example water or milk medication or the use of top-dressings at the farm. The consequences and possible new risks of carry-over at the farm are not completely clear yet
    Is there a future for medicated feed? The Dutch approach
    Stolker, A.A.M. ; Manti, Vicky ; Zuidema, T. ; Egmond, H.J. van; Deckers, E.R. ; Herbes, R. ; Hooglugt, J. ; Olde Heuvel, E. ; Jong, J. de - \ 2011
    In: International conference on responsible use of antibiotics in animals. - Bilthoven : Bastiaanse Communication - p. 55 - 57.
    Tracing and analytical results of the dioxin contamination incident in 2008 originating from the Republic of Ireland
    Heres, L. ; Hoogenboom, R. ; Herbes, R. ; Traag, W.A. ; Urlings, H.A.P. - \ 2010
    Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 27 (2010)12. - ISSN 1944-0049 - p. 1733 - 1744.
    long-evans rats - 2,3,7,8-tetrachlorodibenzo-p-dioxin tcdd - exposure
    High levels of dioxins (PCDD/Fs) in pork were discovered in France and the Netherlands at the end of 2008. The contamination was rapidly traced back to a feed stock in the Republic of Ireland (RoI). Burning oil, used for the drying of bakery waste, appeared to be contaminated with PCBs. Consequently, very high levels up to 500 pg TEQ g-1 fat were found in pork. The congener pattern clearly pointed to PCB-oil as a source, but the ratio between the non-dioxin-like indicator PCBs (PCBs 28, 52, 101, 138, 152 and 180) and PCDD/Fs was much lower than observed during the Belgian incident, thereby limiting the suitability of indicator PCBs as a marker for the presence of dioxins and dioxin-like PCBs. This paper describes the tracking and tracing of the incident, the public-private cooperation, the surveillance activities and its results. A major lesson to be learned from this incident is the importance of good private food safety systems. In this incident, it was the private surveillance systems that identified the origin of contamination within 10 days after the first signal of increased dioxin levels in a product. On the other hand, retrospective analyses showed that signals were missed that could have led to an earlier detection of the incident and the source. Above all, the incident would not have occurred when food safety assurance systems had been effectively implemented in the involved feed chain. It is discussed that besides primary responsibility for effective private food safety systems, the competent authorities have to supervise whether the food safety procedures are capable of coping with these kinds of complex food safety issues, while private food companies need to implement the law, and public authorities should supervise and enforce them. Finally, it is discussed whether the health risks derived from consumption of the contaminated batches of meat may have been underestimated during the incident due to the unusually high intake of dioxins. Keywords: traceability; risk assessment; screening assays; regulations; dioxins; TEQs; PCBs; meat; animal feed; animal products; ingredients
    A novel source for dioxins present in recycled fat from gelatin production
    Hoogenboom, L.A.P. ; Eijkeren, J.C.H. van; Zeilmaker, M.J. ; Mengelers, M.J.B. ; Herbes, R. ; Immerzeel, J. ; Traag, W.A. - \ 2007
    Chemosphere 68 (2007)5. - ISSN 0045-6535 - p. 814 - 823.
    chemical composition - growing pigs - contamination - pcbs - incident - growth - feed - food - tissue - health
    Within a survey on dioxins in animal fat used as feed ingredient, a sample originating from pigs offal was shown to contain 50 ng Toxic Equivalents (TEQ) PCDD/PCDFs kg(-1) fat. Further investigation revealed fat samples with levels as high as 440 ng TEQ kg(-1) fat and contaminated feed with a highest level of 8.4 ng TEQ kg(-1) feed. The congener pattern was dominated by 1,2,3,7,8-PeCDD and 2,3,7,8-TCDD, and was not recognized from any previous incident or known dioxin source. Remarkably, 2,3,7,8-substituted congeners were much more abundant than their non-2,3,7,8-substituted counterparts. The sampled fat was derived from a gelatin production W, plant. Broken filters, used to clean the hydrochloric acid (HCl) used in the process, caused the dioxin contamination. The fat was primarily used for pig feed. A new physiologically-based pharmacokinetic (PBPK) model for lipophilic contaminants in growing slaughter pigs predicted levels at slaughter varying between 40 pg TEQ g(-1) fat (worst-case) and 2.5-7 pg TEQ g(-1) fat under more realistic scenarios. Almost 300 farms were temporarily blocked. Many fat samples of pigs were analyzed using a combined approach of DR CALUXO and GC/HRMS. Levels in contaminated pig fat were around the EU-limit of 1 pg TEQ g(-1) fat, with some samples up to 2-3 pg TEQ g(-1) fat. Of 80 negative samples analyzed by DR CALIJX (R) and GC/HRMS no false-negatives were obtained, whereas 36 and 62 of the 80 samples classified suspected with the bioassay had GC/HRMS levels above respectively the tolerance and action limits. It is concluded that novel and unexpected dioxin sources remain a threat to the food chain and require the proper evaluation and monitoring of production processes, including chemicals used therein. (c) 2007 Elsevier Ltd. All rights reserved.
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