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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Bacillus cereus growth and biofilm formation: the impact of substratum, iron sources, and transcriptional regulator Sigma 54
Hayrapetyan, Hasmik - \ 2017
Wageningen University. Promotor(en): T. Abee, co-promotor(en): M.N. Nierop Groot. - Wageningen : Wageningen University - ISBN 9789463431194 - 181
microorganisms - bacillus cereus - food contamination - biofilms - foodborne pathogens - abiotic conditions - sporulation - micro-organismen - bacillus cereus - voedselbesmetting - biofilms - voedselpathogenen - abiotiek - sporulatie

Biofilms are surface-associated communities of microbial cells embedded in a matrix of extracellular polymers. It is generally accepted that the biofilm growth mode represents the most common lifestyle of microorganisms. Next to beneficial biofilms used in biotechnology applications, undesired biofilms can be formed by spoilage and pathogenic microorganisms in food production environments. Bacillus cereus is a foodborne human pathogen able to cause two types of food poisoning, emetic and diarrheal. B. cereus can persist in factory environments in the form of biofilms, which can become a source of food contamination. This thesis adds to the knowledge about (a)biotic factors and conditions that affect B. cereus biofilm formation, including the effect of type of substratum such as polystyrene and stainless steel, with the latter supporting the highest biofilm formation for all tested strains including two reference strains and 20 food isolates. The ability of B. cereus to use a variety of iron sources was subsequently studied in these 22 strains and linked to the genes encoding iron transport systems present in the respective genomes, revealing significant diversity in the capacity to use complex and non-complex iron sources for growth and biofilm formation. For spore forming Bacilli, biofilm formation and sporulation are two intertwined cellular processes and studies in wet and dry (air-exposed) biofilms revealed differences in sporulation rate and efficacy, with biofilm-derived spores showing higher heat resistance than their planktonic counterparts. Additionally, comparative phenotype and transcriptome analysis of B. cereus wild type and a Sigma 54 deletion mutant provided insight into the pleiotropic role of this transcriptional regulator in B. cereus biofilm formation and physiology in general. Taken together, this knowledge improves our understanding of the biofilm lifecycle of this notorious food-borne human pathogen and provides clues which can help to reduce the domestication of this microorganism in production environments.

Stakeholder interactions in nuclear emergency response for the Dutch food supply chain
Asselt, E.D. van; Brandhoff, P.N. ; Twenhöfel, C.J.W. - \ 2015
nuclear power stations - disasters - food industry - management - food contamination - multi-stakeholder processes - cooperation - kernenergiecentrales - rampen - voedselindustrie - bedrijfsvoering - voedselbesmetting - multi-stakeholder processen - samenwerking
In the Netherlands, EPAn (Unit Planning and Advice – Nuclear) assesses the radiological situation and advises the national and regional levels on protective actions. This advice is based on radiological and human health expertise provided by the Crisis Expert Team (CET) radiation. At the start of the project, CET lacked insight in the measures taken by food producers in case of a nuclear accident and communication with these stakeholders was limited. Furthermore, experience on recovery measures was primarily focused on the first stage after an incident.
Innovative mode of action based in vitro assays for detection of marine neurotoxins
Nicolas, J.A.Y. - \ 2015
Wageningen University. Promotor(en): Ivonne Rietjens, co-promotor(en): Peter Hendriksen; Toine Bovee. - Wageningen : Wageningen University - ISBN 9789462574724 - 214
fish toxins - fish consumption - neurotoxins - food safety - food contamination - animal testing alternatives - food analysis - vistoxinen - visconsumptie - neurotoxinen - voedselveiligheid - voedselbesmetting - alternatieven voor dierproeven - voedselanalyse

Innovative mode of action based in vitro assays for detection of marine neurotoxins

J. Nicolas, P.J.M. Hendriksen, T.F.H. Bovee, I.M.C.M. Rietjens

Marine biotoxins are naturally occurring compounds produced by particular phytoplankton species. These toxins often accumulate in seafood and thereby represent a threat to consumers. Regulatory limits have been set for lipophilic marine biotoxins (diarrhetic shellfish poisons (DSPs) and azaspiracids (AZPs)) and for most marine neurotoxins (amnesic (domoic acid (DA)), neurotoxic (NSPs), and paralytic shellfish poisons (PSPs)) and the detection of these biotoxins in seafood still heavily relies on the mouse bioassay (MBA). However, the MBA is forbidden since the 1st of January 2015, except for the periodic control of production areas, especially with regard to the detection of unknown marine biotoxins.

Although analytical methods are sensitive to many marine biotoxins and allow for their identification and quantification, their use still presents several major drawbacks (chapter 3). They do not allow the detection of unknown toxins for example and are quite expensive to be used as routine screening methods. Therefore, a screening assay that allows the broad detection of known and unknown marine biotoxins with great sensitivity at affordable costs is highly needed. Mode of action cell-based assays offer these possibilities.

This thesis describes a wide variety of innovative mode of action based assays that could be used for screening purposes and proposes an integrated testing strategy suitable for the current needs in terms of food safety associated with seafood consumption. In addition, the assays developed are in line with the 3R paradigm of Russel and Burch and therefore comply with the current European Regulation for the replacement of animal experiments in the field of marine neurotoxins detection in seafood.

Modelling the formation of heat-induced contaminants during thermal processing of food
Nguyen, H.T. - \ 2015
Wageningen University. Promotor(en): Tiny van Boekel, co-promotor(en): Ine van der Fels. - Wageningen : Wageningen University - ISBN 9789462574588 - 172
voedsel - maillard-reactie - voedselbereiding - acrylamiden - voedselbesmetting - gezondheidsgevaren - modellen - food - maillard reaction - food preparation - acrylamides - food contamination - health hazards - models

Many of our food products have undergone a heat-treatment before consumption, either at home or at the food industry. Heat treatments not only bring out desired characteristics of the food products such as flavour, texture, taste and safety aspects but also leads to the formation of undesired compounds that may have negative impacts for human health. Such undesired compounds that are generated from the Maillard reaction are neo-formed food contaminants (NFC). NFC are present in many common heat-processed foods, such as potatoes-based products, cereal-based products, baby foods, and dairy products. Therefore, effective mitigation measures are being developed to minimize the generation of such undesired compounds while maintaining the organoleptic attributes of the food products as consumer’s demands. This thesis aimed at understanding the mechanistic pathways for the formation of three neo-formed food contaminants: acrylamide, 5-hydroxymethylfurfural (HMF), and -(carboxymethyl)lysine (CML), using multireponse kinetic modelling.

First, the topic of the Maillard reaction, occurrence and human exposure to the three NFC in heated foods, and multiresponse kinetic modelling is introduced. Then, scientific literature on analytical methods, formation pathways, occurrence in processed foods, and health impacts of CML was reviewed. Based on the literature, an experiment was set up to understand the formation pathway for CML in caseinate-lactose/glucose solutions, each heated at 120oC and 130oC. According to the best fitting mechanistic model, the formation of CML in the two model solutions originated from the reaction between lactose/glucose and lysine residues via the Amadori rearrangement product formation. Moreover, glucose and lactose were degraded via Lobry de Bruyn-Alberda van Ekenstein (LA) arrangement. CML seems to be not thermally stable, and may thus not be an optimal indicator for heat damage of foods.

Another experiment was done for gaining insights into the formation of acrylamide and HMF in biscuits during baking at 200oC. Four biscuit recipes were prepared with three sugar types: (1) sucrose (35 g), (2) glucose (17.5 g) and fructose (17.5 g), (3) fructose (17.5 g), and (4) glucose. The molar ratio of total glucose and fructose to asparagine in each type of biscuit was higher than 1. The concentrations of acrylamide and HMF were lowest in the sucrose-prepared biscuits. Kinetic modelling results suggested that during baking of these four kinds of biscuits, acrylamide was formed via the specific amino acid route, i.e., a reducing sugar reacts with asparagine to form the Schiff base without the Amadori product formation (not via Strecker degradation), and that HMF was formed via caramelisation. Fructose played a key role in the formation of both acrylamide and HMF.

In a similar experiment, the effects of different types of wheat flour on acrylamide and HMF formation in sucrose-prepared biscuits during baking at 200oC were investigated. Four types of wheat flour, which had the most different concentrations of asparagine, and total glucose and fructose (the reducing sugar), were selected for the preparation of four kinds of biscuits. Out of four wheat flour types, two had the molar ratio of reducing sugars to asparagine lower than 1, and the other two had a ratio higher than 1. Results showed that those different molar ratios in wheat flour did not have effects on the pathways leading to the formation of acrylamide and HMF in all four types of biscuits. Acrylamide was formed via the specific amino acid route, and HMF was formed via caramelisation. No clear correlation was found between the concentration of either acrylamide or HMF in biscuits and the concentration of asparagine or the reducing sugars in wheat flour. Asparagine was not a limiting factor for acrylamide generation in biscuits.

The outcomes of this thesis give insights into the actual reaction pathways for the formation of acrylamide and HMF in biscuits during baking at 200oC and for the formation of CML in the model solutions. These modelling results may help to control the formation of these NFCs in a quantitative way.

Impact of climate change on microbial safety of leafy green vegetables
Liu, C. - \ 2015
Wageningen University. Promotor(en): Rik Leemans, co-promotor(en): Nynke Hofstra; Eelco Franz. - Wageningen : Wageningen University - ISBN 9789462574403 - 129
klimaatverandering - bladgroenten - groenten - voedselveiligheid - micro-organismen - besmetting - voedselbesmetting - escherichia coli - salmonella - climatic change - leafy vegetables - vegetables - food safety - microorganisms - contamination - food contamination - escherichia coli - salmonella


Climate change is generally recognized as a major threat to humans and the environment. With respect to food production, climate change does not only affect crop production or food security, but possibly also effects on food safety by affecting the prevalence and levels of bacteria, fungi or other pests and pesticides. Fresh-cut or ready-to-eat leafy vegetables (e.g. lettuce and spinach) are increasingly consumed because they are promoted as part of a healthy diet. Such leafy green vegetables (LGVs) are identified as the fresh produce commodity group of highest concern from a microbiological safety perspective, because they are often grown in the open field and therefore vulnerable to contamination and contact with (faeces of) wildlife. Moreover, they are grown and consumed in large volumes and often consumed raw. Bacteria, such as Salmonella spp. and pathogenic Escherichia coli strains are the main pathogens causing foodborne disease through LGVs. A major knowledge gap is understanding how climate change may directly or indirectly affect the contamination of LGVs. This primarily relates to the current lack of methods and tools to link climate data and climate change scenarios to food safety.

My thesis aims to quantify the impacts of climate change on microbial safety of pre-harvested LGVs. To achieve this, I reviewed the literature and synthesised major impacts of climate change on contamination sources and pathways of foodborne pathogens (focussing on Escherichia coli O157 and Salmonella spp.) on pre-harvested LGVs (Chapter 2). Subsequently, I developed a statistical model that identifies the weather and management variables that are associated with the LGVs contamination with generic E. coli using regression analysis (Chapter 3). To apply suitable climate data to this statistical model to assess future impacts, I have prepared a tool to downscale coarse climate and climate change data for local food safety scenario analysis (Chapter 4). Finally, I applied the downscaled data to the statistical model and used multi-criteria scenario analysis to explore future food safety (Chapter 5). E.coli is used as a hygienic indicator in this thesis to study microbial safety of LGVs. Its presence is indicative for an increased pathogen presence probability. E. coli and many foodborne bacteria share the same contamination pathways and climate change is expected to similarly impact on both bacteria. Hygienic status is therefore used in my thesis as a proxy for the microbial safety of LGVs.

The major result of the literature review in Chapter 2 is that the impact of climate change on LGV contamination depends on the resulting local balance of the positive and negative impacts. The review shows that the interactions between climate change and contamination are real but poorly understood. Therefore, integrative quantitative modelling approaches with scenario analyses and additional laboratory experiments are needed.

With this knowledge background, mixed effect logistic regression and linear regression models were developed to identify the climate and management variables that are associated with the presence and concentration of E. coli on LGVs (Chapter 3). These models used E. coli data of 562 lettuce and spinach samples taken between 2011 and 2013 from 23 open-field farms from Belgium, Brazil, Egypt, Norway and Spain. Weather and agriculture management practices together had a systematic influence on E.coli presence and concentration. Temperature explained most of the observed variation on E. coli prevalence and concentration on LGVs. Minimum temperature of the sampling day (odds ratio [OR] 1.47), region and application of inorganic fertilizer explained a significant amount of variation in E. coli prevalence. Maximum temperature on three days before sampling and region best explained the variation in E. coli concentration (R2= 0.75). Region is a variable masking many management variables including use of rain water, surface water, manure, inorganic fertilizer and spray irrigation. Climate variables and E. coli presence and concentration are positively related. The results indicate that climate change will have an impact on microbiological safety of LGVs. These impacts can be directly through an increasing temperature, but also indirectly through changes in irrigation water type, fertilizer type and irrigation method. Therefore, climate change and farm management should be considered more systematically in an integrated way in future studies on fresh produce safety.

To prepare climate data for local food safety scenario analysis, a climate data downscaling tool was presented and demonstrated (Chapter 4). Coarse gridded data from two general circulation models, HadGEM2-ES and CCSM4, were selected and downscaled using the ‘Delta method’ with quantile-quantile correction for the Belgium meteorological station in Ukkel. Observational daily temperature and precipitation data from 1981 to 2000 were used as a reference period for this downscaling. Data were provided for four future representative concentration pathways (RCPs) for the periods 2031–2050 and 2081–2100. These RCPs are radiative forcing scenarios for which future climate conditions are projected. The climate projections for these RCPs show that both temperature and precipitation will increase towards the end of the century in Ukkel. The climate change data were subsequently used with Ratkowsky's bacterial growth model to illustrate how projected climate data can be used for projecting bacterial growth in the future. In this example, the future growth rate of Lactobacillus plantarum and the number of days that the bacteria are able to grow are both projected to increase in Ukkel. This example illustrates that this downscaling method can be applied to assess future food safety. This downscaling tool is relatively straightforward compared to other more complex downscaling tools, so the food safety researchers can easily understand and apply it to their impact studies.

With the statistical model (Chapter 3) and downscaled climate data (Chapter 4), a multi-criteria scenario analysis tool was developed to explore future food safety using pre-harvest spinach in Spain as an example (Chapter 5). The future E. coli concentrations on spinach were projected to change in RCP 8.5 and RCP 2.6 by the end of the century in Spain. The E. coli concentration was projected to increase between 0.2 log10 CFU/g and 0.3 log10 CFU/g (depending on the climate scenarios and management options applied) due to higher temperature by the end of the century compared to the concentrations by the end of the last century. This comparison assumed no changes in agricultural management practices. This tool can be used to help selecting the best management practices considering climate change and other indicators.

The pioneering research presented in my thesis brought new methods and tools, and another mind set to food safety research. The climate-change data downscaling tool provides detailed temporal and spatial climate data for climate scenario analysis in food safety assessment studies. The multi-criteria scenario analysis tool provides a platform to study changes in weather or climate, and management impacts on future food safety. This tool also allows for inclusion of different stakeholders’ perspectives or interests and supports their decision making processes. Moreover, the thesis presents a statistical model that can be used to study the relationship between climate and E. coli contamination.

My thesis quantified the impacts of climate change on microbial safety of pre-harvested LGVs contaminated with generic E. coli for the first time. With one degree increase in minimum temperature of the sampling day, the odds of having E. coli presence on LGVs increase by a factor of 1.5. The mean E. coli concentrations are also expected to increase. Climate change should not be ignored in food safety management and research.

Resultaten melk- en grasmonitoring en kwaliteitscontroles 2014 : Landelijk Meetnet Radioactiviteit in Voedsel
Onstenk, C.G.M. ; Brandhoff, P.N. ; Vos van Avezathe, A. ; Bourgondien, M.J. van; Peters, R.J.B. - \ 2015
Wageningen : RIKILT Wageningen UR (RIKILT-rapport 2015.004) - 27
gewasmonitoring - melkkwaliteit - monitoring - radioactiviteit - melkveehouderij - radionucliden - weipoeder - gammaspectrometrie - voedselbesmetting - voedselveiligheid - volksgezondheid - crop monitoring - milk quality - radioactivity - dairy farming - radionuclides - dried whey - gamma spectrometry - food contamination - food safety - public health
Het Landelijk Meetnet Radioactiviteit in Voedsel (LMRV) dient als bewaking voor de voedselproductie en wordt ingezet in het nationale monitoringsprogramma, met name voor de monitoring van radioactiviteit in melk. In dit jaarrapport worden de resultaten van de melk- en grasmonitoring, en van de kwaliteitscontroles van de voedselmonitoren in 2014 gepresenteerd.
EU Food Law Handbook
Meulen, B.M.J. van der - \ 2014
Wageningen : Wageningen Academic Publishers (European Institute for Food Law series no. 9) - ISBN 9789086862467 - 692
voedingsmiddelenwetgeving - internationaal recht - voedselbesmetting - etiketteren - etiketteren van voedingsmiddelen - voedsel - voer - voedingsmiddelen - europese unie - food legislation - international law - food contamination - labelling - nutrition labeling - food - feeds - foods - european union
The twenty-first century has witnessed a fundamental reform of food law in the European Union, to the point where modern EU food law has now come of age. This book presents the most significant elements of these legal developments with contributions from a highly qualified team of academics and practitioners. Their analysis is based on a shared vision of the structure and content of EU food law. The book takes the perspective of food law embedded within general EU law. It highlights the consequences of this combination and provides insights into both substantive and procedural food law. Taking the General Food Law as a focal point, this handbook analyses and explains the institutional, substantive and procedural elements of EU food law. Principles are discussed as well as specific rules addressing food as a product, the processes related to food and communication about food to consumers through labelling. These rules define requirements on subjects like market authorisation for food additives, novel foods and genetically modified foods, food hygiene, tracking & tracing, withdrawal & recall. The powers of public authorities to enforce food law and to deal with incidents are outlined. Attention is given to the international context (WTO, Codex Alimentarius) as well as to private standards. In addition to the systematic analysis, the book includes selected topics such as nutrition and health policy, special foods, food import requirements, food contact materials, intellectual property and animal feed.
Method validation study on determination of melamine and cyanuric acid in food : CEN Collaborative Study 2014 : Melamine and cyanuric acid
Elbers, I.J.W. ; Traag, W.A. - \ 2014
Wageningen : RIKILT Wageningen UR (RIKILT report 2014.014) - 6
melamine - methodologie - triazinen - voedselveiligheid - geldigheid - standaardisering - voedselbesmetting - methodology - triazines - food safety - validity - standardization - food contamination
At the request of the European Committee for Standardization (CEN) by RIKILT a standard for the determination of melamine (MEL) and cyanuric acid (CYA) in food was described. In order to validate this new CEN method a ring trial was organized between February 2014 and July 2014. The objective is to assess the comparability of results of melamine and cyanuric acid obtained by the new draft CEN standard in seven samples of food.
Intervention methods to control the transmission of noroviruses and other enteric and respiratory viruses
Tuladhar, E. - \ 2014
Wageningen University. Promotor(en): Marcel Zwietering, co-promotor(en): E. Duizer; Rijkelt Beumer. - Wageningen : Wageningen University - ISBN 9789462571129 - 163
norovirus - gastro-enteritis - uitbraken (ziekten) - ziekteoverdracht - voedselbesmetting - ademhalingsziekten - voedselmicrobiologie - norovirus - gastroenteritis - outbreaks - disease transmission - food contamination - respiratory diseases - food microbiology

Intervention methods to control the transmission of noroviruses and other enteric and respiratory viruses

Era Tuladhar


Human noroviruses are the leading cause of acute and outbreak associated gastroenteritis worldwide. The outbreaks occur often in hospitals, nursing homes, health care centers as well as in individual homes. Due to the high number of outbreaks and frequency of infection, the burden of disease is high. The virus transmission takes place from person to person directly through the fecal oral route or indirectly through contaminated surfaces or consumption of contaminated food. This study aimed to investigate methods to reduce the burden of disease caused by norovirus and focuses on reducing the transmission through hands and contaminated surfaces. Besides human norovirus, other enteric and respiratory viruses are also transmitted through these routes and were included in the study. Enteric viruses included in the study were human norovirus GI.4 and GII.4, poliovirus Sabin1, rotavirus SA11, parechovirus 1 and murine norovirus 1 (MNV1). The respiratory viruses were adenovirus type 5 and influenza A (H1N1) virus. These viruses can contaminate food through food handler-related contamination. Heating and pasteurizing is a commonly used method for inactivation of microorganisms in food. Heating at commonly used temperatures of 56°C and 73°C showed that thermo-stability of parechovirus and influenza virus was found to be similar to that of proven foodborne viruses and heating at 73°C for 3 min is sufficient to reduce the infectivity of the tested viruses > 4 log10. Not only food, contaminated hands can also transfer viruses to different surfaces, which are then sources of further transmission of the viruses. Cleaning and disinfection of contaminated surfaces are common intervention methods used in health care and kitchen facilities. The enteric and respiratory viruses showed varying susceptibility to cleaning and disinfection procedures applied. Data on infectious doses and transfer efficiencies was used to estimate a target level to which the residual contamination should be reduced and it was found that a single wipe with liquid soap followed by a wipe with 250 ppm free chlorine solution was sufficient to reduce the residual contamination to below the target level for most of the pathogens tested. Spot disinfection by 1000 ppm chlorine solution after wiping with liquid soap was sufficient to reduce the genomic copies of human norovirus GI.4 and GII.4 (> 5 log10 PCRU) completely within 10 min. In addition to manual cleaning and disinfection, non-touch disinfection of contaminated surfaces by vaporized hydrogen peroxide disinfection at 127 ppm for 1 h, as approved disinfection in the Netherlands for hospitals and health care centers, is effective against poliovirus Sabin 1, rotavirus SA11, adenovirus type 5 and MNV1 on stainless steel, framing panel (> 4 log10 infectivity reduction) and gauze (> 2 log10 infectivity reduction). Beside non-touch disinfection, immobilized biocidals have been tested for disinfection of contaminated surfaces. Immobilized quaternary ammonium compound coatings were virucidal against the influenza virus within 2 min but no virucidal effect against poliovirus was found in 6 h. Thus the coating can be used against the influenza A virus to prevent the transmission through frequently touched sites but not for non-enveloped viruses. Our study demonstrated that a norovirus contaminated hand can transfer the viruses to different surfaces, including food, even after the virus is dried. As an intervention method to prevent the transmission of the virus, washing hands with soap and water (> 5 log10 PCRU reduction) is better than using alcohol based hand disinfectants in removing noroviruses from hands.

This research has delivered new insights in methods to reduce transmission of human norovirus and produced comparative quantitative data on intervention methods to control transmission of other enteric and respiratory viruses. The study has additionally contributed to a better understanding of human norovirus transmission intervention efficiency. The new insights allow for the development of science based guidelines to control norovirus and other enteric and respiratory viruses in outbreak settings and thus help to reduce the burden of illness caused by these viruses.

Nationale referentie laboratoria : RIKILT jaarrapport 2013
Traag, W.A. ; Mol, J.G.J. ; Lee, M.K. van der; Gersen, A. ; Leeuwen, S.P.J. van; Stolker, A.A.M. ; Sterk, S.S. ; Raamsdonk, L.W.D. van; Jong, J. de; Scholtens-Toma, I.M.J. ; Alewijn, A. ; Heenen, S. ; Ginkel, L.A. van; Noordam, M.Y. - \ 2014
Wageningen : RIKILT Wageningen UR (Rikilt rapport 2014-004) - 47
voedselveiligheid - voedselbesmetting - voederveiligheid - voedselanalyse - ringtest - laboratoria - eu regelingen - food safety - food contamination - feed safety - food analysis - ring test - laboratories - eu regulations
In deze jaarrapportage doet het RIKILT verslag van haar activiteiten als Nationaal Referentielaboratorium (NRL).
Interreg Safeguard - Food safety mapping of mussels and oysters (Crassostrea gigas) in the Dutch Wadden Sea
Glorius, S.T. ; Poelman, M. ; Zweeden, C. van; Gool, A.C.M. van - \ 2014
Den Helder : IMARES (Report / IMARES Wageningen UR C0104/14) - 71
waddenzee - oesters - crassostrea gigas - besmetting - pathogenen - verontreiniging - voedselveiligheid - mossels - voedselbesmetting - wadden sea - oysters - contamination - pathogens - pollution - food safety - mussels - food contamination
The areal coverage and biomass of the invasive Pacific oyster has increased in both the Dutch and German part of the Wadden Sea area since its introduction in the late seventies. In the Dutch part of the Wadden Sea oyster beds have increased in areal coverage in the period 2003 –2008. The Pacific oyster has relevance for commercial exploitation since 2009. This arises special interest for food safety aspects. A joint monitor program named ‘Interreg Safeguard’ has been set up with German partners to firstly identify oyster bed location and subsequently obtain insight in the temporal and areal variation in both the level of chemical contamination as well as contamination with pathogens. Measured levels were compared with legislation standards currently in force and it was also researched what the relation of pollution levels found in oysters were with those found in mussels collected in the near vicinity. This report describes the results of the work carried within the Dutch part of the Wadden Sea and include; results of the mapping effort of oyster beds, concentrations of chemical and microbiological parameters in oyster and mussel tissue and the comparison of the contaminant levels found in oyster with those found in mussels.
Contaminants in food supplements and associated health risks
Reeuwijk, N.M. - \ 2014
Wageningen University. Promotor(en): Ivonne Rietjens, co-promotor(en): Ron Hoogenboom; M.J. Martena. - Wageningen : Wageningen University - ISBN 9789461739438 - 160
voedselsupplementen - besmetters - voedselbesmetting - risicoschatting - food supplements - contaminants - food contamination - risk assessment


Through the increasing use and availability of food supplements on the market, safety Aconcerns relating to the safety of these food supplements are growing as well. The aim of the present PhD thesis was to investigate the presence and actual levels of contaminants of concern in selected food supplements on the Dutch market and to estimate the associated health risks.

First, in chapter 1, an overview is provided on the food supplements selected for the studies, which are clay products for oral use, herbal food supplements used to enhance sexual potency and herbal food supplements used for weight loss. Furthermore, an overview is given on the Dutch en European legal provisions for food supplements.

In the first study described in chapter 2 of this theses data are presented on the occurrence of metals such as lead, mercury and cadmium and the metalloid arsenic in clay products which are used via the oral route by pregnant and lactating women. For lead, the use of 34 of the 36 traditional clays and two of the 27 health clays would result in intake levels exceeding the selected health based guidance values, by up to 20-fold. In the case of inorganic arsenic, the use of 15 of the 35 traditional clays and 11 of the 27 health clays would result in intake levels exceeding the health based guidance values by up to 19-fold.

The second study, described in chapter 3 of the thesis, reports data on the presence of dioxins in 33 clay products, which were collected on the Dutch market and in some African countries. Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) were detected in clay products from the Dutch market, in concentrations ranging from 66 to 103 pg TEQ g-1, whereas PCDD/F concentrations in the suspected clay products from African countries varied from 24 to 75 pg TEQ g-1. Furthermore, in this study congener patterns in African clay products were compared with those of pooled human milk samples collected by WHO in eight African countries, to investigate a possible relation between PCDD/Fs in human milk with contaminated clay used for consumption. From the similarity between the patterns in clays and the human milk samples from the Democratic Republic of The Congo and Côte d’Ivoire, it can be concluded that there is probably a relationship with the consumption of contaminated clay.

The aim of the third study, described in chapter 4 of this thesis, was to determine whether herbal food supplements on the Dutch market contain active pharmacological ingredients (APIs) known to inhibit phosphodiesterase type 5 (PDE-5), such as sildenafil and other known analogous PDE-5 inhibitors. Therefore, herbal food supplements intended to enhance sexual potency (n=71), and two soft drinks, were analysed. In 23 herbal supplements, nine different PDE-5 inhibitors were identified, in a few cases (n=3) more than one. The presence of these APIs was however not stated on the label. Subsequently, it was estimated whether intake of the supplements with the detected PDE-5 inhibitors could result in pharmacological effects. It was concluded that 18 of the 23 herbal food supplements with PDE-5 inhibitors, when used as recommended, would have pharmacological effects due to the added APIs.

In the fourth study, described chapter 5 of in this thesis, another group of herbal food supplements, claiming to reduce weight, was investigated for the presence of APIs that can be used for the treatment of overweight and obesity. To this end, 30 herbal food supplements for weight loss on the Dutch market were collected and analysed for the presence of APIs with weight loss properties. In 24 samples the APIs sibutramine, desmethylsibutramine (DMS), didesmethylsibutramine (DDMS), rimonabant, sildenafil, and/or the laxative phenolphthalein were identified 41 times. The potential pharmacological effects of the detected APIs were estimated, and use of 20 of the 24 herbal food supplements, may result in potential pharmacological effects. Furthermore, a risk assessment of phenolphthalein regarding its carcinogenic effects, resulted in Margin of Exposure (MOE) values of 96-30,000. MOE values lower than the minimum required 10,000 (96-220) were calculated for the daily intake levels of four out of the ten supplements in which phenolphthalein was found. However, taking into account that weight loss preparations may be used for only a few weeks or months rather than during lifetime, MOE values may be two to three orders of magnitude higher. This study shows that the use of food supplements with sibutramine, DMS, DDMS, and/or phenolphthalein could result in both pharmacological but also other health effects.

From the studies described in this thesis it can be concluded (chapter 6) that, in addition to concerns over naturally occurring endogenous toxins present in herbal supplements, the presence of exogenous contaminants in herbal supplements can pose a health concern. Furthermore, the results of the present thesis also lead to the conclusion that in order to refine the risk assessment on the presence of contaminants such as metals, metalloids, dioxins and APIs in (herbal) food supplements more precise data are required on bioaccessibility of contaminants of concern from the food matrix. Also information on groups at increased risk may need to be increased. Additionally, the presence of APIs in herbal supplements, which may originate from drop outs in the drug development process, is of concern. In order to screen for unknown APIs the use of effect-based bioassays should be considered more often, as they have been shown to be successful in detecting unexpected and as yet unknown active ingredients. From the results obtained for the food supplements included in our studies it can be concluded that consumers should be aware that food supplements may not be without risks. The overall conclusion from the work described in this thesis is that for food supplements ‘natural’ does not equal ‘safe’.

Genetically modified organisms in food and feed : annual report 2012 of the Dutch National Reference Laboratory
Scholtens-Toma, I.M.J. ; Molenaar, B. ; Zaaijer, S. ; Prins, T.W. ; Kok, E.J. - \ 2013
Wageningen : RIKILT (Report / RIKILT 2013.006) - 25
genetisch gemanipuleerde organismen - voedselbesmetting - voedsel - voer - genetically engineered organisms - food contamination - food - feeds
This is the annual report of the Dutch Reference Laboratory (NRL) for Genetically Modified Food and Feed (RIKILT Wageningen UR). The report gives an overview of the NRL activities carried out in 2012. In 2012 the two Dutch Official Laboratories participated in several proficiency tests with good results. Furthermore RIKILT participated in two EURL/NRL meetings and the Working Group on Detection, Interpretation and Reporting. RIKILT advised the other Official Laboratory on the application of a 'SYBRGreen'detection method for unauthorized GM in rice in food from China. Also changes in the method were discussed. RIKILT has a flexible scope accreditation for real-time PCR GMO analysis in raw materials, food and feed.
Genetically modified organisms in food and feed : annual report of the Dutch National Reference Laboratory
Scholtens-Toma, I.M.J. ; Molenaar, B. ; Zaaijer, S. ; Voorhuijzen, M.M. ; Prins, T.W. ; Kok, E.J. - \ 2012
Wageningen : RIKILT (Report / RIKILT 2012.001) - 23
genetisch gemanipuleerde organismen - voedselbesmetting - genetically engineered organisms - food contamination
This is the annual report of the Dutch National Reference Laboratory (NRL) for Genetically Modified Food and Feed (RIKILT - Institute of Food Safety). The report gives an overview of the NRL activities carried out in 2011. In 2011 both RIKILT and the Routine Field Laboratory of the Netherlands Food and Consumer Product Safety Authority (NVWA) participated in several proficiency tests with good results. Also RIKILT participated in two EUR/NRL meetings and the Working Group on Method Verification, the Task Force 'New Techniques' NTTF and the Working Group Unauthorized GMOs. RIKILT has a flexible scope accreditation for real-time PCR GMO analysis in raw materials, food and feed.
Applicaties voor veilig voer en voedsel
Raamsdonk, L.W.D. van; Uiterwijk, M. - \ 2012
Kennis Online 9 (2012)april. - p. 16 - 16.
voedselveiligheid - diervoeding - kwaliteitscontroles - voedselbesmetting - modules - computertechnieken - food safety - animal nutrition - quality controls - food contamination - computer techniques
Voedsel en diervoeder worden steeds beter te onderzoeken op samenstelling en verontreinigingen. Dankzij computerapplicaties van Alterra en RIKILT, beide onderdeel van Wageningen UR, op basis van beeldmateriaal.
Trend analysis of mycotoxins in animal feed
Adamse, P. ; Egmond, H.J. van; Driessen, J.J.M. ; Rijk, T.C. de; Jong, J. de; Nijs, W.C.M. de - \ 2012
Wageningen : Rikilt-Institute for Food Safety (Rikilt report 2011.017)
mycotoxinen - voer - voedselbesmetting - mycotoxins - feeds - food contamination
Feed materials were analysed for the mycotoxins deoxynivalenol, ochratoxin A, zearalenone, aflatoxin B1, fumonisin B1 and B2, and HT-2- and T-2-toxins. In this report trends in the average content during the period 2001-2009 are reported for these mycotoxins. Monitoring data from the National Feed monitoring program and from the Commodity Board Animal Feed are used for this study.
Waardevermindering pluimveevlees besmet met Salmonella enteritidis en Salmonella typhymurium
Horne, P.L.M. van - \ 2011
Den Haag : LEI Wageningen UR - 6
salmonella enteritidis - salmonella typhimurium - pluimveevlees - voedselbesmetting - voedselveiligheid - vleeskuikens - pluimveehouderij - kosten - poultry meat - food contamination - food safety - broilers - poultry farming - costs
De doelstelling van het onderzoek is om de waardevermindering van met Salmonella enteritidis (S.e.) en Salmonella typhymurium (S.t.) besmet pluimveevlees van vleeskuikens te bepalen. Hoe hoog is de opbrengstenderving en hoe hoog zijn de extra kosten van maatregelen voor de slachterij of uitsnijderij? Wat is de waardevermindering van levende vleeskuikens in de situatie dat de slachterij de schade doorberekent aan de vleeskuikenhouder vanaf het moment dat dieren besmet zijn bij het stalonderzoek?
Listeria monocytogenes : nog steeds een probleem?
Beumer, R.R. - \ 2011
Gewasbescherming 42 (2011)4. - ISSN 0166-6495 - p. 183 - 183.
listeria monocytogenes - voedselveiligheid - voedselbesmetting - food safety - food contamination
Listeria monocytogenes is net als vele andere bacteriële voedselpathogenen al tientallen jaren bekend. De meeste grondstoffen voor voedingsmiddelen komen uit de akker- en tuinbouw, de veehouderij en de visserij. Besmetting vindt daar plaats met micro-organismen afkomstig uit grond, fecaliën, water, lucht en via ongedierte.
Microbiologische voedselveiligheid
Beumer, R.R. - \ 2010
In: 76 Voeding en Diëtetiek, Voedingsleer Houten : Bohn Stafleu van Loghum - p. 1 - 26.
voedselveiligheid - voedselmicrobiologie - voedselinspectie - infecties - voedselvergiftiging - voedselbesmetting - voeding en gezondheid - voedselbederf - food safety - food microbiology - food inspection - infections - food poisoning - food contamination - nutrition and health - food spoilage
Ondanks veel maatregelen op het gebied van hygiëne lukt het nog steeds niet om het aantal geregistreerde voedselinfecties drastisch te verminderen. Integendeel, het lijkt er zelfs op dat de incidentie toeneemt. Verschillende factoren spelen hierbij een rol: onvoldoende kennis bij producenten, bereiders en consumenten van levensmiddelen, en veranderingen in de commerciële voedselproductie (meer kant en klaar maaltijden die minimaal geconserveerd worden). Maar het kan ook (deels) veroorzaakt worden door een terugtrekkende overheid, bijvoorbeeld de Voedsel en Warenautoriteit die steeds meer taken overlaat aan de particuliere sector. Om het aantal voedselinfecties zoveel mogelijk terug te dringen moet er aan drie voorwaarden worden voldaan: 1) besmetting zoveel mogelijk voorkomen, 2) uitgroei van micro-organismen remmen, en 3) de consument, zo jong mogelijk, voldoende relevante kennis bijbrengen op dit gebied. Wordt aan al deze voorwaarden voldaan, dan zal het aantal voedselinfecties kunnen dalen. Men moet zich goed beseffen dat deze nooit geheel zullen verdwijnen.
Tropane alkaloids in food
Adamse, P. ; Egmond, H.P. van - \ 2010
Wageningen : RIKILT (Report / RIKILT 2010.011) - 24
tropaanalkaloïden - toxinen - voedselbesmetting - analytische methoden - voedselveiligheid - tropane alkaloids - toxins - food contamination - analytical methods - food safety
A large number of wild and cultured plants produce secondary metabolites that are toxic to humans and animals. Through accidental or intentional mixing of these plants with normal food and feed the consumers of these products will be exposed to the toxins. In this report tropane alkaloids will be discussed.
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