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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    Potatoes, pathogens and pests : effects of genetic modifi cation for plant resistance on non-target arthropods
    Lazebnik, Jenny - \ 2017
    Wageningen University. Promotor(en): J.J.A. Loon; M. Dicke. - Wageningen : Wageningen University - ISBN 9789463431620 - 151
    solanum tuberosum - potatoes - oomycetes - phytophthora infestans - genetic engineering - transgenic plants - disease resistance - risk assessment - nontarget organisms - arthropods - insect pests - herbivores - trophic levels - ecological risk assessment - greenhouse experiments - field experimentation - solanum tuberosum - aardappelen - oömyceten - phytophthora infestans - genetische modificatie - transgene planten - ziekteresistentie - risicoschatting - niet-doelorganismen - geleedpotigen - insectenplagen - herbivoren - trofische graden - ecologische risicoschatting - kasproeven - experimenteel veldonderzoek

    Currently, fungicides are necessary to protect potato crops against late blight, Phytophthora infestans, one of the world’s most damaging crop pathogens. The introgression of plant resistance genes from wild potato species targeted specifically to the late blight pathogen into susceptible potato varieties may alleviate the environmental impact of chemical control. Genetically modified plants are subject to an environmental risk assessment, and this includes testing for risks to the non-target arthropod community associated with the crop. The thesis begins with a review about the main plant defense responses and their role in influencing sequential interactions between herbivores and plant pathogens. The experimental chapters each focus on different aspects of the interaction between potato plants (both resistant and susceptible), the target pathogen (P. infestans) and several non-target insects. With each chapter, the scope widens: from the molecular gene expression in potato leaves in response to sequential attacks, to field scale biodiversity analyses. At the molecular level, one of the main findings was that the genomic position of the Rpi-vnt1 insertion conferring resistance to P. infestans influenced potato gene expression measured in leaves, when interacting with the non-target insect pests Myzus persicae (Green peach aphid) and Leptinotarsa decemlineata (Colorado potato beetle). Insect performance differed between the resistant GM and susceptible non-GM comparator. In the following chapter, the differences in insect performance were tested across a range of conventionally bred cultivars varying in resistance to P. infestans. Differences in M. persicae performance between several cultivars greatly outweighed the differences previously detected between the GM and non-GM comparator. These results are crucial in shaping the way risk is assessed in the context of GM crops, and these results are supported in our experiments assessing effects on biodiversity with pitfall traps in the field. The third trophic level was also addressed by comparing the performance of the parasitoid Aphidius colemani reared on GM and non-GM fed aphids, both with an without exposure to P. infestans. Differences in parasitoid performance were only found on the susceptible cultivar when inoculated with P. infestans. In the last experimental chapter the risk assessment is taken to the field comparing pitfall trap catches over two years and in two countries. Different methods for statistical analysis of biodiversity data were compared to arrive at recommendations for such analysis in the framework of environmental risk assessments. Drawing on these lessons, the discussion ends with ideas for the development of protocols for environmental risk assessments in the light of expected scientific progress in agricultural biotechnology.

    Integrated strategy for the assessment of kidney toxicity : the case of aristolochic acids
    Abdullah, Rozaini - \ 2017
    Wageningen University. Promotor(en): Ivonne Rietjens, co-promotor(en): Ans Punt; Sebas Wesseling; Jochem Louisse. - Wageningen : Wageningen University - ISBN 9789463430807 - 207
    animal testing alternatives - in vitro - toxicity - models - risk assessment - toxins - carboxylic acids - alternatieven voor dierproeven - in vitro - toxiciteit - modellen - risicoschatting - toxinen - carbonzuren

    This PhD thesis aimed to provide additional evidence to demonstrate the potential of an integrated testing strategy using in vitro assays with physiologically based kinetic (PBK) modeling based-reverse dosimetry to predict in vivo toxicity without animal testing. Kidney toxicity was chosen as the toxicity endpoint and aristolochic acids (AAs) were selected as model chemicals. AAs are natural nephrotoxic, genotoxic and carcinogenic chemicals present in Aristolochia species. PBK models for rat, mouse and human were developed for aristolochic acid I (AAI) based on kinetic parameter values derived from in vitro incubations using relevant tissue fractions. Then, in vitro concentration-response curves for cytotoxicity of AAI were obtained in kidney cell lines and translated to in vivo dose-response curves for kidney toxicity using PBK modeling-based reverse dosimetry. The points of departure (PODs) obtained from these predicted in vivo dose-response curves generally fell within the range of PODs derived from in vivo literature data on kidney toxicity of AAI. The same PBK models were subsequently used to translate the in vitro concentration-response curves for AAI-DNA adduct formation to in vivo dose-response curves for kidney AAI-DNA adduct formation. The predicted in vivo AAI-DNA adduct formation in the rat, mouse and human kidney varied within an order of magnitude compared to the in vivo values reported in the literature. The PBK models were also used to predict the dose level that would be required in humans to obtain the level of DNA adducts in rats at the BMD10 (the benchmark dose causing a 10% extra risk above background level) value for AAI-induced tumor formation in the rat kidney. This analysis revealed that the dose level required to induce the level of DNA adduct formation that equals the DNA adduct level at the BMD10 were similar to AA doses estimated to be taken in Belgian patients that developed urinary tract cancer. Given that the exposure to AAI is often accompanied by the presence of AAII, in a next study the relative formation of DNA adducts by these two major AA congeners was investigated. The results revealed that the relative higher formation of AAI-DNA adducts as compared to AAII-DNA adducts observed in vitro was not reflected in vivo where the levels formed upon exposure to equal dose levels were relatively similar. PBK model based translation of the in vitro data to the in vivo situation revealed that PBK model based prediction of in vivo DNA adduct formation is feasible. However, predicted AAI-DNA adduct levels were higher than predicted AAII-DNA adduct levels, indicating that the difference between the in vitro and in vivo AAI-/AAII-DNA adduct ratios could only in part be explained by differences in in vivo kinetics of AAI compared to AAII. The discrepancy between the difference in DNA adduct formation of AAI and AAII in the in vitro and the in vivo situation is an issue that needs further investigation to also adequately predict the relative differences between the two AAs. In a final chapter this thesis aimed to investigate the possible risks associated with exposure to AAs based on AA levels measured in plant food supplements (PFS) and herbal products. This is of interest given the restrictions on the presence of AAs in food, installed in various countries including The Netherlands, after the incidences with induction of Aristolochic Acid Nephropathy upon use of herbal weight loss preparations that accidentally contained AAs. The risk assessment of PFS and herbal products containing AAs purchased via online markets revealed that consumers can still be exposed to AA-containing PFS and herbal products and that the corresponding levels of exposure raise concern especially for people who frequently use the products. Altogether, this thesis presented further support for the use of combined in vitro-PBK modeling based alternative tools for risk assessment and revealed the continued risks posed by AAs present in PFS and herbal products.

    Risicobeoordeling van contaminanten in afval- en reststoffen bestemd voor gebruik als covergistingsmateriaal
    Ehlert, P.A.I. ; Wijnen, H.J. van; Struijs, J. ; Dijk, T.A. van; Schöll, L. van; Poorter, L.R.M. de - \ 2016
    Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-technical report 70) - 158
    biogas - co-vergisting - arsenicum - residuen - zware metalen - verontreinigende stoffen - pesticiden - biociden - mestbeleid - landbouwbeleid - organische verontreinigende stoffen - risicoschatting - biogas - co-fermentation - arsenic - residues - heavy metals - pollutants - pesticides - biocides - manure policy - agricultural policy - organic pollutants - risk assessment
    A number of wastes and by-products were reviewed for their suitability as substrates for co-digestion with animalmanure to produce biogas and a digestate for use as a fertiliser. The review included 21 substances proposed byLTO Noord (Dutch Farmers Union – Northern Netherlands) and Biogas Branche Organisatie (BBO, the Dutch BiogasIndustry Association) for inclusion in Annex Aa of the Fertiliser Act. At the request of the Ministry of EconomicAffairs a further 6 substances were added (21+6). In addition, 119 substances were re-reviewed in connection witha change to the reference composition for animal manure. The review focused on the possible adverseenvironmental effects of using the digestate as a fertiliser and followed the protocol for assessing the value andrisks of waste used as a fertiliser, version 2.1. The risk assessment included the inorganic contaminants (Cd, Cr, Cu,Hg, Ni, Pb, Zn, As) and organic contaminants (dioxine, PCBs, PAHs, mineral oil, residues of crop protectionproducts) as required by the Fertiliser Act. For all the wastes and by-products, data on composition were collectedfrom the literature and from analyses provided by stakeholders. Expert judgment was used where data were notavailable or were insufficient to conduct a risk assessment as prescribed by the protocol. Criteria for expertjudgment were developed for such situations. Two alternative risk assessment methods were developed for theresidues of pesticides and biocides, based partly on expert judgement. These methods were compared with themethod prescribed by the protocol. These three methods reflect different policy judgements; the protection level setby policymakers will determine which method should be used. The 21+6 substances were evaluated in accordancewith the protocol and using the three methods for evaluating the residues of pesticides and biocides. The resultswere compared with registered co-digestion materials in Flanders, Denmark and Germany. Recommendations aregiven to support policy decisions on the choice of alternative risk assessment method to be used to permit the codigestionof wastes and by-products in biogas production that produce an agronomically and environmentallyacceptable digestate for fertiliser use
    Statistical modelling of variability and uncertainty in risk assessment of nanoparticles
    Jacobs, R. - \ 2016
    Wageningen University. Promotor(en): Cajo ter Braak, co-promotor(en): Hilko van der Voet. - Wageningen : Wageningen University - ISBN 9789462578197 - 205
    modeling - statistics - particles - risk assessment - uncertainty - uncertainty analysis - nanotechnology - probabilistic models - modelleren - statistiek - deeltjes - risicoschatting - onzekerheid - onzekerheidsanalyse - nanotechnologie - waarschijnlijkheidsmodellen

    Engineered nanoparticles (ENPs) are used everywhere and have large technological and economic potential. Like all novel materials, however, ENPs have no history of safe use. Insight into risks of nanotechnology and the use of nanoparticles is an essential condition for the societal acceptance and safe use of nanotechnology.

    Risk assessment of ENPs has been hampered by lack of knowledge about ENPs, their environmental fate, toxicity, testing considerations, characterisation of nanoparticles and human and environmental exposures and routes. This lack of knowledge results in uncertainty in the risk assessment. Moreover, due to the novelty of nanotechnology, risk assessors are often confronted with small samples of data on which to perform a risk assessment. Dealing with this uncertainty and the small sample sizes are main challenges when it comes to risk assessment of ENPs. The objectives of this thesis are (i) to perform a transparent risk assessment of nanoparticles in the face of large uncertainty in such a way that it can guide future research to reduce the uncertainty and (ii) to evaluate empirical and parametric methods to estimate the risk probability in the case of small sample sizes.

    To address the first objective, I adapted an existing Integrated Probabilistic Risk Assessment (IPRA) method for use in nanoparticle risk assessment. In IPRA, statistical distributions and bootstrap methods are used to quantify uncertainty and variability in the risk assessment in a two-dimensional Monte Carlo algorithm. This method was applied in a human health (nanosilica in food) and an environmental (nanoTiO2 in water) risk context. I showed that IPRA leads to a more transparent risk assessment and can direct further environmental and toxicological research to the areas in which it is most needed.

    For the second objective, I addressed the problem of small sample size of the critical effect concentration (CEC) in the estimation of R = P(ExpC > CEC), where ExpC is the exposure concentration. First I assumed normality and investigated various parametric and non-parametric estimators. I found that, compared to the non-parametric estimators, the parametric estimators enable us to better estimate and bound the risk when sample sizes and/or small risks are small. Moreover, the Bayesian estimator outperformed the maximum likelihood estimators in terms of coverage and interval lengths. Second, I relaxed the normality assumption for the tails of the exposure and effect distributions. I developed a mixture model to estimate the risk, R = P(ExpC > CEC), with the assumption of a normal distribution for the bulk data and generalised Pareto distributions for the tails. A sensitivity analysis showed significant influence of the tail heaviness on the risk probability, R, especially for low risks.

    In conclusion, to really be able to focus the research into the risks of ENPs to the most needed areas, probabilistic methods as used and developed in this thesis need to be implemented on a larger scale. With these methods, it is possible to identify the greatest sources of uncertainty. Based on such identification, research can be focused on those areas that need it most, thereby making large leaps in reducing the uncertainty that is currently hampering risk assessment of ENPs.

    Environmental risk assessment of pesticides in Ethiopia : a case of surface water systems
    Teklu, B.M. - \ 2016
    Wageningen University. Promotor(en): Paul van den Brink. - Wageningen : Wageningen University - ISBN 9789462578104 - 152
    surface water - water systems - water pollution - risk assessment - ecological risk assessment - pesticides - aquatic ecology - aquatic organisms - irrigation systems - ethiopia - oppervlaktewater - watersystemen - waterverontreiniging - risicoschatting - ecologische risicoschatting - pesticiden - aquatische ecologie - waterorganismen - irrigatiesystemen - ethiopië

    The current increase in application rate and usage frequency of application of pesticides in Ethiopia pose direct risks to surface water aquatic organisms and humans and cattle using surface water as a source of drinking water in rural parts of the country. A model based risk assessment as currently being used in Europe and elsewhere in the world is tailored to the Ethiopian situation to quantify the risks. Suitability of toxicity data used as an input for risk assessment usually taken from the temperate world was checked through simple toxicity testing of Ethiopian aquatic macroinvertebrates. Subsequent monitoring activities to see the actual residue levels of pesticides in rivers and temporary ponds adjacent to extensive farming activities was also done and results compared with model prediction values. Combining all this knowledge is believed to bring the current pesticide registration system in Ethiopia one step closer to be a more reliable method, protecting non-target organisms as well as the health of humans at risk.

    Dermal absorption and toxicological risk assessment : pitfalls and promises
    Buist, H. - \ 2016
    Wageningen University. Promotor(en): Ruud Woutersen; Ivonne Rietjens, co-promotor(en): J.J.M. van de Sandt. - Wageningen : Wageningen University - ISBN 9789462577275 - 200
    skin - absorption - permeability - in vitro - experiments - exposure assessment - risk assessment - toxicology - biocides - rodenticides - preservatives - disinfection - huid - absorptie - permeabiliteit - in vitro - experimenten - blootstellingsbepaling - risicoschatting - toxicologie - biociden - rodenticiden - conserveermiddelen - desinfectie

    Absorption of toxic substances via the skin is an important phenomenon in the assessment of the risk of exposure to these substances. People are exposed to a variety of substances and products via the skin, either directly or indirectly, while at work, at home or in public space. Pesticides, organic solvents and metalworking fluids are seen to be important contributors to adverse health effects due to occupational exposure via the skin. In daily life, cosmetics, clothing and household products are the most relevant commodities with respect to exposure via the skin.

    Given the importance of skin exposure in the assessment of the risk of toxic substances, the objective of this thesis was to further develop, evaluate and improve methods for including skin absorption data this assessment.

    In this thesis, four factors influencing dermal absorption, namely dermal loading (chapters 3 and 6), irritative/corrosive potential (chapters 3 and 4), frequency of exposure (chapters 3, 4 and 5) and the vehicle used (chapter 5), were investigated in more detail. Furthermore, a model to extrapolate infinite dose absorption data to finite dose conditions, baptized Dermal Absorption Model for Extrapolation (DAME), was developed and tested.


    n chapter 2 of this thesis, the relationship between relative dermal absorption and dermal loading was investigated. Hundred-and-thirty-eight dermal publicly available absorption experiments with 98 substances were evaluated. The results obtained revealed that dermal loading ranged mostly between 0.001 and 10 mg/cm2. In 87 experiments (63%), an inverse relationship was observed between relative dermal absorption and dermal loading. On average, relative absorption at high dermal loading was 33 times lower than at low dermal loading. Known skin irritating and volatile substances less frequently showed an inverse relationship between dermal loading and relative absorption. It was concluded that when using relative dermal absorption in regulatory risk assessment, its value should be determined at or extrapolated to dermal loadings relevant for the exposure conditions being evaluated.


    n chapter 3 of this thesis, a literature search was presented with the aim to investigate whether neglecting the effects of repeated exposure may lead to an incorrect estimate of dermal absorption. The results demonstrated that the effect of repeated versus single exposure does not demonstrate a unique trend. Nevertheless, an increase in daily absorption was frequently observed upon repeated daily exposure. The little information available mostly concerned pharmaceuticals. However, consumers and workers may be repeatedly exposed to other types of chemicals, like disinfectants and cleaning products, which often contain biocidal active substances that may decrease the barrier function of the skin, especially after repeated exposure. These biocidal products, therefore, may present a safety risk that is not covered by the current risk assessment practice since absorption data are usually obtained by single exposure experiments. Consequently, it was decided to investigate the importance of this issue for biocide safety evaluation. As the literature search revealed that hardly any data on absorption upon repeated dermal exposure to biocides are available, it was concluded that data need to be generated by testing.

    To cover the entire range of biocidal products in such testing, a representative series of biocidal substances should be tested, making in vitro testing of dermal absorption the preferred choice over in vivo testing. Based on an inventory made, it appeared that the 16 product types represented among the biocidal products authorised in the Netherlands could be clustered into 6 more or less homogeneous categories based on similarity in active substances. This result could facilitate experimental testing by providing a basis for selection of a limited number of representative compounds to be evaluated.


    n chapter 4 of this thesis, the importance of the effect of repeated dermal exposure on skin permeability for biocide safety evaluation was investigated, using a selection of nine representative biocides from the inventory made in chapter 3. The in vitro dermal penetration of tritiated water and [14C]propoxur was chosen as a measure of the permeability and integrity of human abdominal skin after single and repeated exposure. The results indicated that single and repeated exposure to specific biocidal products (e.g. the quaternary ammonium chlorides DDAC and ADBAC) may significantly increase skin permeability, especially when the compounds are applied at high concentrations, while a substance like formaldehyde may reduce skin permeability under specific conditions.


    n chapter 5 of this thesis, the in vitro dermal absorption kinetics of the quaternary ammonium compound didecyldimethylammonium chloride (DDAC) during single and repeated exposure was studied in more detail. In addition, the influence of biocidal formulations on the absorption of DDAC was investigated, because it was expected that formulation characteristics may be another factor influencing its dermal absorption. The analysis of biocidal products on the Dutch market, reported in chapter 3, indicated that DDAC is often used in combination with other active ingredients. DDAC was most frequently combined with formaldehyde, glutaraldehyde and/or alkyldimethylbenzyl­ammo­nium chloride (ADBAC). Consequently, commercial formulations containing one or more of these additional active ingredients were selected, in addition to one formulation containing only DDAC as an active ingredient. The selected commercial formulations tended to reduce skin penetration of DDAC. This was most pronounced with the formulation containing the highest concentration of formaldehyde (196 mg/mL) and glutaraldehyde (106 mg/mL), which reduced the flux of DDAC across the skin by 95%. The reduction caused by the only tested formulation containing no other active ingredients than DDAC, and thus incorporating no aldehydes, was smallest, and did not reach statistical significance.


    n chapter 6 of this thesis, a simple in silico model to predict finite dose dermal absorption from infinite dose data (kp and lag time) and the stratum corneum/water partition coefficient (KSC,W) was developed. This model was tentatively called Dermal Absorption Model for Extrapolation (DAME). As dermal exposure may occur under a large variety of conditions leading to quite different rates of absorption, such a predictive model using simple experimental or physicochemical inputs provides a cost-effective means to estimate dermal absorption under different conditions.

    To evaluate the DAME, a series of in vitro dermal absorption experiments was performed under both infinite and finite dose conditions using a variety of different substances. The kp’s and lag times determined in the infinite dose experiments were entered into DAME to predict relative dermal absorption value under finite dose conditions. For six substances, the predicted relative dermal absorption under finite dose conditions was not statistically different from the measured value. For all other substances, measured absorption was overpredicted by DAME, but most of the overpredicted values were still lower than 100%, the European default absorption value for the tested compounds.

    In conclusion, our finite dose prediction model (DAME) provides a useful and cost-effective estimate of in vitro dermal absorption, to be used in risk assessment for non-volatile substances dissolved in water at non-irritating concentrations.


    n chapter 7 of this thesis, the results of the research reported in chapters 2 to 6 were put into perspective, the pitfalls and promises emanating from them discussed and general conclusions drawn. The possible influence of vehicles on absorption and the possible impact of irritative or corrosive vehicles or chemicals on the skin barrier have been demonstrated in this thesis. An in silico predictive model tentatively called DAME was developed, which enables the user to evaluate a variety of dermal exposure scenarios with limited experimental data (kp and lag time) and easy to obtain physicochemical properties (MW and log KOW). The predictions of our experiments reported in chapter 6 were compared to those of the Finite Dose Skin Permeation (FDSP) model published on the internet by the US Centers for Disease Control and Prevention (CDC). DAME outperformed FDSP (R2 of the correlation predicted/measured potential absorption 0.64 and 0.12, respectively). At present, the applicability domain of DAME is limited to non-volatile substances dissolved in aqueous solvents. However, in future the model will be adapted to include volatile substances as well.

    Altogether, it is concluded that dermal exposure can be an important factor in risks posed by chemicals and should be taken into account in risk assessment. The methods to actually do this are still open for further improvement to better account for the various factors influencing skin penetration and to develop adequate combinations of in vitro and in silico models that can accurately predict human dermal absorption.

    Pesticide use and off-site risk assessment : a case study of glyphosate fate in Chinese Loess soil
    Yang, X. - \ 2016
    Wageningen University. Promotor(en): Coen Ritsema; Violette Geissen, co-promotor(en): Hans Mol; Fei Wang. - Wageningen : Wageningen University - ISBN 9789462576759 - 152
    pesticides - risk assessment - pesticide residues - glyphosate - loess soils - soil pollution - erosion - china - pesticiden - risicoschatting - pesticidenresiduen - glyfosaat - lössgronden - bodemverontreiniging - erosie - china

    Pesticide use and off-site risk assessment: a case study of glyphosate fate in Chinese Loess soil

    Xiaomei Yang

    Abstract: Repeated applications of pesticide may contaminate the soil and water, threatening their quality within the environmental system and beyond it through water erosion related processes and leaching. Taking into account the situation of intense farming, pesticide use and erosion in China, and in the loess area in particular, this study aims to further the science of pesticide risk assessment by increasing the understanding of the fate of glyphosate and its main metabolite AMPA while also assessing their risks related to soil erosion in Chinese loess soil. Four main objectives are conducted:

    1) Assessment of farmers’ knowledge and awareness of pesticide use in the Wei River catchment

    In this study, we presented the information for the knowledge and awareness of pesticide risks via face-to-face interview among farmers (209) and retailers (20) in two rural regions (Qianyang County (S1) and Chencang County (S2)) of the Wei River catchment in China where the modes of farming and the state of erosion are very different. The results showed that farmers learned about the use and risk related to of pesticide use mainly by oral communication (p<0.01), rather than by introduction labelled on pesticide package bag/bottle and media tools (TV/newspaper/Internet/books). Protective measures were inadequate and washing hands (>70%) was the most common mode of personal hygiene after spraying, comparing to wearing masks, showering, and changing clothes. Regarding to dealing with the packages or containers of pesticide, farmers dumped them directly onto the land or into water, and over 85% of farmers claimed to use illegal pesticides. Compared to farmers, pesticide retailers were well-informed and highly conscious of their responsibility for the safe use of pesticides. Educational programmes targeted to age groups, proper disposal of pesticide waste, and sufficient supervision from authorities should consequently be considered for improving the levels of knowledge and awareness of the dangers of pesticides to human health and environmental pollution in the Wei River catchment, China.

    2) Investigation of off-site transport of glyphosate and AMPA by runoff and erosion in Chinese loess soil

    In this study, we assessed the short-term transport (1h duration, 1 mm min-1 rainfall) of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) related to erosion and runoff on bare loess soil with different slopes (10° and 20°)and application rates (3.6 kg ha-1 and 7.2 kg ha-1) in hydraulic flumes. Significant power and exponent function described a significantly negative relation between rainfall duration and the content of glyphosate and AMPA (p<0.01) in runoff and suspended load, respectively. The transport rate of glyphosate (including AMPA) by runoff and suspended load was approximately 4% and 10% of the applied amount, respectively indicating that it mainly underlies particulate transport. The glyphosate and AMPA content in the flume soil at the end of the experiment (after 1h) decreased significantly with depth (p<0.05), and 72, 2, and 3% of the applied glyphosate (including AMPA) remained in the 0-2, 2-5, and 5-10 cm soil layers, respectively. Thus, the risk of leaching was low. In view of loss of 14 % of the initially applied glyphosate after 1 h, “buffer zone”, referred as the protection area for ecosystem discharge between farming land and public rivers, is strongly recommended, especially in regions where rain-induced soil erosion is common.

    3) Investigation of the on-site fate of glyphosate and AMPA formation in Chinese loess soil

    In this study, we observed glyphosate decay, erosion and runoff related transport of glyphosate and AMPA at different slopes (10° and 20°) and application rates (3.6 kg ha-1 and 7.2 kg ha-1) under field condition during 35 d, September-October in 2012 (16.8±2.1°C with 35 mm rainfall in total) and July-August in 2013 (27 ± 2.3°C with 74 mm rainfall in total). The initial glyphosate decayed rapidly (half-life of 3.5 d) in the upper 2 cm of soil following a first-order rate of decay. AMPA content in the 0-2 cm soil layer correspondingly peaked 3 d after glyphosate application and then gradually decreased. The residues of glyphosate and AMPA decreased significantly with soil depth (p<0.05) independently of the slope inclination and application rate. About 0.36% of the glyphosate initially applied was transported off-site plots after one erosive rain 2 days after the application. Glyphosate and AMPA concentration in runoff were low while the contents in the sediment was much higher than in the upper 2 cm of the soil. This suggested that even though the transported glyphosate is limited, the off-site risk of glyphosate and AMPA is high. Consequently, a realistic erosion-pesticide model should be developed that can simulate the particulate-facilitated transport of glyphosate and its off-site risks involving decay processes.

    4) Off-site risk assessment of particle-facilitated pesticide transport related to erosion

    In this study, we have developed a parsimonious integrative model of pesticide displacement by runoff and erosion that explicitly accounts for water infiltration, erosion, runoff, and pesticide transport and degradation in soil. The conceptual framework was based on broadly accepted assumptions such as the convection-dispersion equation and lognormal distributions of soil properties associated with transport, sorption, degradation, and erosion. To illustrate the concept, a few assumptions are made with regard to runoff in relatively flat agricultural fields: dispersion is ignored and erosion is modelled by a functional relationship. A sensitivity analysis indicated that the total mass of pesticide associated with soil eroded by water scouring increased with slope, rain intensity, and water field capacity of the soil. The mass of transported pesticide decreased as the micro-topography of the soil surface became more distinct. The timing of pesticide spraying and rate of degradation before erosion negatively affected the total amount of transported pesticide. The mechanisms involved in pesticide displacement, such as runoff, infiltration, soil erosion, and pesticide transport and decay in the topsoil, were all explicitly accounted for, so the mathematical complexity of their description can be high, depending on the situation.

    Overall, the outcome of this study indicates that it is urgent to improve farmers knowledge and awareness on pesticide use in order to reduce pesticide risks before they are applied in environmental system. The rapid decay of glyphosate to AMPA in loess soil suggests that on-site risks of glyphosate is mainly related to AMPA, especially under warmer climatic conditions. The off-site transport of glyphosate in our study was about 14% of the applied dose after 1 h of rainfall indicating that the off-site risks of glyphosate should be taken into account in regions highly prone to soil erosion. The concept of particulate transport elaborated in objective 4 should be incorporated in existing erosion models, such as LISEM, to predict off-site effects of glyphosate applications.

    Alternative testing strategies for predicting developmental toxicity of antifungal compound
    Li, H. - \ 2016
    Wageningen University. Promotor(en): Ivonne Rietjens; Bennard van Ravenzwaay, co-promotor(en): Jochem Louisse. - Wageningen : Wageningen University - ISBN 9789462576780 - 197
    toxicity - fetal development - transfer - infant development - adolescent development - child development - pregnancy - in vivo experimentation - modeling - placenta - in vitro - risk assessment - tebuconazole - conazole fungicides - antifungal agents - alternative methods - toxiciteit - foetale ontwikkeling - overdracht - zuigelingenontwikkeling - adolescentenontwikkeling - kinderontwikkeling - zwangerschap - in vivo experimenten - modelleren - placenta - in vitro - risicoschatting - tebuconazool - conazoolfungiciden - antimycotica - alternatieve methoden

    Determination of safe human exposure levels of chemicals in toxicological risk assessments largely relies on animal toxicity data. In these toxicity studies, the highest number of animals are used for reproductive and developmental toxicity testing. Because of economic and ethical reasons, there is large interest in the development of in vitro and/or in silico test systems as alternatives for the animal studies. The aim of the present thesis was to evaluate the applicability of combined in vitro approaches taking toxicokinetic and toxicodynamic aspects into account, as well as of an integrated in vitro and in silico approach for prediction of developmental toxicity using a series of antifungal compounds as the model compounds.

    Transplacental transfer of compounds is highly likely to play an important role in developmental toxicity, so we developed and validated an in vitro placental barrier model using BeWo b30 cells to predict placental transfer. Then we investigated the applicability of the ES-D3 cell differentiation assay combined with the in vitro BeWo transport model to predict the relative in vivo developmental toxicity potencies of two sets of selected antifungal compounds. The data obtained show that the combined in vitro approach provided a correct prediction for the relative in vivo developmental toxicity, whereas the ES-D3 cell differentiation assay as stand-alone did not. In order to detect specific structural alterations induced by chemicals, we investigated the applicability of the ex ovo assay of chicken embryos to predict the specific alterations induced by the antifungal compounds. Data revealed that the ex ovo assay of chicken embryos is able to assess the teratogenic potential of antifungal compounds, and, when combined with the in vitro BeWo transport model, is able to better predict relative in vivo prenatal developmental toxicity potencies.

    Subsequently, we translated in vitro concentration–response data of the antifungal compound tebuconazole, obtained in the ES-D3 cell differentiation assay and the ex ovo assay of chicken embryos, into predicted in vivo dose–response data using physiologically based kinetic (PBK) modelling-facilitated reverse dosimetry. The results show that the BMD10 values from predicted dose–response data from both assays are in concordance with BMD10 values derived from in vivo data (within 5-fold difference). This revealed that PBK modeling is a promising tool to predict in vivo dose-response curves based on the results of in vitro toxicity assays, and may therefore be used to set a point of departure for deriving safe exposure limits in risk assessment.

    It is concluded the combined in vitro approaches and the integrated in vitro-in silico approaches appear to be promising for the screening and prioritization of chemicals and to provide reference values, such as BMD10 values, without using animals, therefore contributing to the 3R principle of animal testing.

    Scenarios for exposure of aquatic organisms to plant protection products in the Netherlands : soilless cultivations in greenhouses
    Linden, A.M.A. van der; Os, E.A. van; Wipfler, E.L. ; Cornelese, A.A. ; Ludeking, Daniel ; Vermeulen, T. - \ 2015
    Bilthoven : RIVM (RIVM report 2015-0128) - 78
    greenhouse horticulture - pesticides - water pollution - authorisation of pesticides - leaching - risk assessment - protected cultivation - emission - surface water - glastuinbouw - pesticiden - waterverontreiniging - toelating van bestrijdingsmiddelen - uitspoelen - risicoschatting - teelt onder bescherming - emissie - oppervlaktewater
    Als door het gebruik van gewasbeschermingsmiddelen in kassen restanten van deze middelen in het nabijgelegen oppervlaktewater terechtkomen, kan dat het waterleven aantasten. Hiermee wordt te weinig rekening gehouden bij de huidige risicobeoordeling van het gebruik van een gewasbeschermingsmiddel voor gewassen die in kassen op substraat, bijvoorbeeld steenwol, worden geteeld. Daarom zijn voor deze toepassingen nieuwe methoden voor de risicobeoordeling ontwikkeld waarin dat wel is ingecalculeerd.
    Evaluation of the Dutch leaching decision tree with the substances bentazone, MCPA and mecoprop
    Linden, A.M.A. van der; Beltman, W.H.J. ; Boesten, J.J.T.I. ; Pol, J.W. - \ 2015
    Bilthoven : RIVM (RIVM report 2015-0095) - 78
    pesticides - groundwater - drinking water - water quality - water pollution - degradation - risk assessment - sorption - decision models - leaching - bentazone - mcpa - pesticiden - grondwater - drinkwater - waterkwaliteit - waterverontreiniging - degradatie - risicoschatting - sorptie - beslissingsmodellen - uitspoelen - bentazon - mcpa
    Sinds 2004 wordt een beslismodel (beslisboom) gebruikt om te beoordelen in welke mate een gewasbeschermingsmiddel uitspoelt naar het grondwater. Uit een evaluatie van het RIVM, het College voor de toelating van gewasbeschermingsmiddelen en biociden (Ctgb) en onderzoekinstituut Alterra blijkt dat de beslisboom goed werkt en state of the art is. Wel laten de stofgegevens waarmee wordt gerekend te wensen over. Om de kwaliteit van het grondwater te waarborgen moeten deze gegevens zorgvuldiger worden afgeleid.
    Sediment toxicity testing and prospective risk assessment of organic chemicals
    Diepens, N.J. - \ 2015
    Wageningen University. Promotor(en): Bart Koelmans, co-promotor(en): Paul van den Brink. - Wageningen : Wageningen University - ISBN 9789462574991 - 346
    sediment - toxiciteit - testen - sedimenttest - verontreinigde sedimenten - chemicaliën - risicoschatting - ecotoxicologie - sediment - toxicity - testing - sediment test - contaminated sediments - chemicals - risk assessment - ecotoxicology

    While providing an option for development in coastal areas, shrimp farming is usually associated with high environmental cost due to the loss of mangrove forest and high social cost as farmers suffer heavy financial losses due to disease outbreaks. Planning shrimp farming requires to integrate risk as well as social and environmental cost. This thesis, using the Mekong Delta as a case, presents an approach to investigate, with local stakeholders, options to plan a resilient and sustainable shrimp farming sector. First, Olivier Joffre analyzed the different shrimp production systems from economic point of view before analyzing farmer’s strategies and providing insights on drivers that will push or, at the opposite, constraint farmers to choose integrated mangrove shrimp systems. This knowledge was integrated in an Agent Based Model (ABM) that was calibrated using Role Playing Games (RPG).

    The effect of future scenarios and different policies on the farmers’ decisions was tested using a combination of RPG and ABM. For one coastal district of the Mekong Delta, the results showed that promotion of intensification of shrimp production has a high social cost and decreases the total production in the study area after 10 years. Policies for supporting the spread of integrated mangrove-shrimp systems, such as Payment for Ecosystem Services, or access to an organic value chain, are not strong enough to influence farmers’ decision toward adopting these systems. Without any adaptation to climate change a sharp decrease of the production is expected. The approach brought local farmers’ knowledge to the attention of decision makers.

    Development of probabilistic models for quantitative pathway analysis of plant pests introduction for the EU territory
    Douma, J.C. ; Robinet, C. ; Hemerik, L. ; Mourits, M.C.M. ; Roques, A. ; Werf, W. van der - \ 2015
    European Food Safety Authority - 435
    gewasbescherming - landen van de europese unie - plantgezondheid - siergewassen - stochastische modellen - bouwhout - vermeerderingsmateriaal - invasieve exoten - plantaardige producten - waarschijnlijkheid - risicoschatting - risicovermindering - plantenplagen - plant protection - european union countries - plant health - ornamental crops - stochastic models - building timbers - propagation materials - invasive alien species - plant products - probability - risk assessment - risk reduction - plant pests
    The aim of this report is to provide EFSA with probabilistic models for quantitative pathway analysis of plant pest introduction for the EU territory through non-edible plant products or plants. We first provide a conceptualization of two types of pathway models. The individual based PM simulates an individual consignment (or a population of such consignment) by describing the stochastic change in the state of the individual consignment over time and space. The flow-based PM, simulates the flow of infested product over time and space, without distinguishing individual consignments. We show how these two conceptualisations are mathematically related, and present, as a show case, both models for cut flowers. Second, we developed PMs for five product groups: round wood, sawn wood, cut flowers, plants for planting and seeds. For each product group we have developed a case-study (combination of product, origin and pest) to illustrate the use of the pathway models: (1) oak wood from the USA and Ceratocystis fagacearum, (2) Coniferous sawn wood from China and Bursaphelenchus xylophilus, (3) Cut orchids from Thailand and Thrips palmi, (4) Pot orchids from Thailand and Thrips palmi, and (5) Tomato seeds and Clavibacter michiganensis subsp. michiganensis from outside the European Union. An uncertainty analysis on the models shows that the pest species-specific parameters appear to be sensitive and uncertain. Third, a practical guidance is provided on i) how to develop a PM, ii) the application of PMs in @Risk (a plugin for MS Excel), and iii) application in R. Finally, future research topics are defined. Further work is needed on interpretation of results, linking quantitative outcomes of pathway modelling to pest risk scoring guidance, and evaluation of management options using pathway models.
    Ontwikkeling emissietoetswaarden voor het beoordelen van duurzaam stortbeheer op pilotstortplaatsen : fase 2: Voorstellen voor emissietoetswaarden (Nederlandstalige verkorte versie van RIVM-rapport 607710002)
    Brand, E. ; Nijs, T. de; Claessens, J. ; Dijkstra, J. ; Comans, R.N.J. ; Lieste, R. - \ 2015
    Bilthoven : Rijksinstituut voor Volksgezondheid en Milieu - 105
    dumping - afvalstortplaatsen - emissie - grondwater - risicoschatting - diffusiemodellen - waterverontreiniging - grondwaterverontreiniging - modelleren - waterkwaliteit - dumping - waste disposal sites - emission - groundwater - risk assessment - diffusion models - water pollution - groundwater pollution - modeling - water quality
    Sinds de jaren negentig wordt internationaal onderzoek verricht naar ‘duurzaam stortbeheer’. Het idee hierachter is dat de bron, de stortplaats zelf, schoner wordt, zodat er minder verontreinigingen uit de stortplaatsen kunnen weglekken. Op deze manier worden de bodem en het nabijgelegen grondwater beschermd. Tot nu toe zijn er nog geen technieken beschikbaar waarvan het effect op grote schaal bewezen is. In dat verband heeft het RIVM, in samenwerking met het Energieonderzoek Centrum Nederland (ECN), onderzoek gedaan voor drie vuilstortlocaties in Nederland. Voor deze locaties zijn ‘emissietoetswaarden’ afgeleid, waarmee kan worden vastgesteld hoeveel schadelijke stoffen er maximaal in het water afkomstig van de stortplaats mag zitten.
    Overweight and obesity in primary-school children: a surveillance system for policy-making in Europe from 2007 onwards
    Wijnhoven, T.M.A. - \ 2015
    Wageningen University. Promotor(en): Pieter van 't Veer, co-promotor(en): Joop van Raaij. - Wageningen - ISBN 9789462574656 - 265
    overgewicht - obesitas - quetelet index - lichaamsgewicht - schoolkinderen - kinderen - kwantitatieve analyse - who - gezondheid van kinderen - risicoschatting - kindervoeding - lichamelijke activiteit - kleding - overweight - obesity - body mass index - body weight - school children - children - quantitative analysis - who - child health - risk assessment - child nutrition - physical activity - clothing

    Trudy M.A. Wijnhoven

    Overweight and obesity in primary-school children: a surveillance system for policy-making in Europe from 2007 onwards.


    As a follow-up to the European Ministerial Conference on Counteracting Obesity convened in 2006 in Turkey, the European Childhood Obesity Surveillance Initiative (COSI) was launched by the Regional Office for Europe of the World Health Organization (WHO). COSI, a collaboration between WHO and interested Member States, aims to monitor the magnitude of overweight and obesity among primary-school children in European countries, to allow intercountry comparisons and to identify regional differences for informed policy-making. It collects at regular intervals data on weight and height of primary-school children and on their nutrition and physical activity behaviours, as well as on school environmental characteristics supportive to healthy nutrition and physical activity.


    The research described in this PhD thesis is based on the data collected in the first two COSI rounds by 12 European countries in school year 2007/2008 and by 13 European countries in school year 2009/2010. Nationally representative samples of children aged 6–9 years were drawn, whereby a majority of the countries applied a two-stage school-based cluster sampling approach.

    A total of 168 832 children in school year 2007/2008 and 224 920 children in school year 2009/2010 were included in the anthropometric intercountry data analyses. Children's weight and height were measured by trained examiners using standardized procedures. Participating countries were allowed to adhere to their local legal requirements by specified deviations from standardized procedures, such as in types of clothing worn by the children during weight and height measurements. For each country, the prevalence of overweight and obesity, as well as mean Z-scores of anthropometric indices of height, weight and body mass index (BMI) were computed.

    The characteristics included in the analyses on the school environment referred to the frequency of physical education lessons, the availability of school playgrounds, the possibility to obtain food items and beverages on the school premises, and the organization of school initiatives to promote a healthy lifestyle. The school form was usually completed by the school principal or the teachers involved with the sampled classes. Data from 1831 schools in school year 2007/2008 and from 2045 schools in school year 2009/2010 were used. For each school, a school nutrition environment score (range: 0–1) was determined whereby higher scores correspond to higher support for a healthy school nutrition environment and the mean of the children's BMI-for-age Z-scores calculated.

    Five countries in school year 2007/2008 provided children's data on 13 health-risk behaviours related to breakfast and food consumption frequency, physical activity, screen time and sleep duration (n = 15 643). These data were reported by the caregivers alone or jointly with their child. For each country, the prevalence of the risk behaviours was estimated, and associations between them and overweight and obesity examined by multilevel logistic regression analyses.


    In both school years, a wide range in overweight and obesity prevalence estimates was found that differed significantly by country, as well as by European region. In all countries, the percentage of overweight children was about 20% or more (range: 18–57%), and the percentage of obese children was 5% or more (range: 5–31%). The findings suggest the presence of a north–south gradient with the highest overweight and obesity prevalence estimates found in southern European countries. Furthermore, changes in mean BMI-for-age Z-scores (range: from –0.21 to +0.14) and prevalence of overweight (range: from –9.0% to +6.2%) from school year 2007/2008 to school year 2009/2010 varied significantly among countries, whereas a period of two years is considered too short to identify these developments. The clothes-adjusted overweight prevalence estimates were lower by as much as 12% than the unadjusted estimates. Monthly BMI-for-age Z-score values within countries did not show systematic seasonal effects.

    Large between-country differences were observed in both school years in the availability of food items or beverages on the school premises (e.g., fresh fruit could be obtained in 12–95% of schools) and in the organization of initiatives to promote a healthy lifestyle in the selected classes (range: 42–97%). The provision of physical education lessons and the availability of school playgrounds were more uniformly present across the countries (range: 76–100%). A large variation was also seen in school nutrition environment scores (range: 0.30–0.93) whereby countries with a low score (< 0.70) graded less than three out of five characteristics as supportive. High-score countries showed more often than low-score countries a combined absence of cold drinks containing sugar, sweet snacks and salted snacks on the school premises.

    The prevalence of all 13 health-risk behaviours differed significantly across countries. For instance, the percentage of children who ate ‘foods like candy bars or chocolate’ > 3 days/week ranged from 2.2% to 63.4%; this figure ranged from 1.1% to 46.5% for those who ate ‘foods like potato chips (crisps), corn chips, popcorn or peanuts’ > 3 days/week. The range for children who did not have breakfast every day was between 4.4% and 32.5%, and from 4.8% to 35.0% for those who did not play outside ≥ 1 hour/day. Not having breakfast daily and spending screen time ≥ 2 hours/day were clearly positively associated with obesity. The same was true for eating ‘foods like pizza, French fries, hamburgers, sausages or meat pies’ > 3 days/week and playing outside < 1 hour/day. While a combination of multiple less favourable physical activity behaviours was clearly positively associated with obesity, a combination of the presence of multiple unhealthy eating behaviours did not lead to higher odds of obesity.


    The results found in both COSI school years show that overweight and obesity among 6–9-year-old children are a serious public health concern, especially in southern European countries, and show the need for accelerated efforts to prevent excess body weight early in life by all participating countries. It was possible to detect relevant changes within a period of two years but to identify clear trends within countries, a longer time interval is necessary. The data on the school nutrition environment and the children's health-risk behaviours may assist policy-makers in monitoring their national policies targeting school settings and childhood obesity. In particular, promoting physical activity-related and discouraging sedentary behaviours among schoolchildren in the context of obesity preventive interventions seem to be essential.

    Omgaan met bodemverontreiniging in het landelijk gebied
    Waarde, J.J. van der; Boels, D. ; Hopman, M. - \ 2015
    De Levende Natuur 105 (2015)3. - ISSN 0024-1520 - p. 110 - 114.
    bodemverontreiniging - bodembiologie - herstel - natuurbescherming - ecologie - risicoschatting - bodemkwaliteit - soil pollution - soil biology - rehabilitation - nature conservation - ecology - risk assessment - soil quality
    Bodemverontreiniging kan leiden tot ecologische effecten en risico's voor plant en dier. Soms moeten er daarom maatregelen worden getroffen. In de praktijk van natuurbeheer en natuurontwikkeling is er nog veel onduidelijkheid over hoe deze effecten bepaald moeten worden. Daartoe is door VROM, LNV, RIZA, RIVM en Bioclear (mede gefinancierd door SKB) PERISCOOP opgezet (Platform Ecologische Risicobeoordeling)
    Phosphorus leaching from soils: process description, risk assessment and mitigation
    Schoumans, O.F. - \ 2015
    Wageningen : Alterra, Wageningen-UR (Alterra scientific contributions 46) - ISBN 9789462573666 - 261
    nutrient leaching - leaching - soil chemistry - adsorption - phosphorus - phosphate leaching - risk assessment - water quality - eutrophication - nutriëntenuitspoeling - uitspoelen - bodemchemie - adsorptie - fosfor - fosfaatuitspoeling - risicoschatting - waterkwaliteit - eutrofiëring
    Extensive literature searches soil and growing media inventories : (RC/EFSA/PLH/2013/01-SC1)
    Bremmer, J. ; Holeva, M. ; Breukers, M.L.H. ; Brouwer, J.H.D. - \ 2015
    Brussels : IBF International Consulting (EFSA supporting publication 2015- EN-834) - 49
    bodem - groeimedia - basisproducten - plantenziekteverwekkers - plantenplagen - onkruiden - gastheerreeks - inventarisaties - risicoschatting - soil - growing media - commodities - plant pathogens - plant pests - weeds - host range - inventories - risk assessment
    In this project two inventories by means of extensive literature searches have been executed: Inventory 1 of all types of soil and growing media (if relevant components thereof) to be elaborated considering (i) the soil and growing medium imported as commodities (i.e. not in association with plants intended for planting), (ii) the soil and growing medium attached to plants for planting, and (iii) the soil and growing medium attached as a contaminant to imported goods (ranging from ware potatoes to agricultural machinery). Inventory 2, based on interceptions data and scientific and technical literature, of plant pests, plant diseases and weeds that can be associated with soil and growing medium (if relevant components thereof). Execution of Inventory 1 resulted in a list of 956 soils and growing media. Execution of Inventory 2 resulted in Excel tables for each taxonomic group separately in which the pests and diseases are linked to the soil and growing media. Additional information has been provided for processes applied to produce growing media and the impact on harmful organisms and private certification schemes applied in Europe to control the trade and use of growing media.
    Phosphorus leaching from soils: process description, risk assessment and mitigation
    Schoumans, O.F. - \ 2015
    Wageningen University. Promotor(en): Sjoerd van der Zee, co-promotor(en): Wim Chardon. - Wageningen : Wageningen University - ISBN 9789462572997 - 261
    nutriëntenuitspoeling - uitspoelen - bodemchemie - adsorptie - fosfor - fosfaatuitspoeling - risicoschatting - waterkwaliteit - eutrofiëring - nutrient leaching - leaching - soil chemistry - adsorption - phosphorus - phosphate leaching - risk assessment - water quality - eutrophication
    Er zijn succesvolle management strategieën voor P nodig om de waterkwaliteit te verbeteren en daarvoor is allereerst kwantitatieve informatieve nodig over de ruimtelijke verdeling van de fosfaatbelasting van het oppervlaktewater vanuit landbouwgronden. In Nederland is een protocol fosfaatverzadigde gronden ontwikkeld om het potentiële risico van verhoogde fosfaatconcentraties in het bovenste grondwater (op termijn) te voorspellen voor kalkarme zandgronden, omdat in deze gebieden veel intensieve veehouderij voorkomt. Voor deze grondsoort zijn de parameters voor het protocol vastgesteld. Echter, voor de overige grondsoorten is geen informatie verzameld, waardoor er voor Nederland als geheel geen ruimtelijke beeld bestaat van de mate van fosfaatverzadiging en van het potentiële risico van verhoogde fosfaatconcentraties in het bovenste grondwater. Daarnaast is er behoefte aan eenvoudige methoden om het (huidige) actuele risico van de fosfaatbelasting van het oppervlaktewater in kaart te brengen, zodat inzichtelijk gemaakt kan worden welke gebieden nu al substantieel de oppervlaktewaterkwaliteit en de eutrofiestatus beïnvloeden.
    Crop protection and pesticide risk assessment Myanmar : towards sustainable agricultural and export of high value crops
    Peeters, F.M. ; Meggelen, J. van; Schepers, H.T.A.M. - \ 2015
    Wageningen : Alterra, Wageningen-UR (Alterra-report 2621) - 81
    gewasbescherming - pesticiden - risicoschatting - myanmar - plant protection - pesticides - risk assessment - myanmar
    Development of an integrated in vitro model for the prediction of oral bioavailability of nanoparticles
    Walczak, A.P. - \ 2015
    Wageningen University. Promotor(en): Ivonne Rietjens, co-promotor(en): Hans Bouwmeester; Peter Hendriksen. - Wageningen : Wageningen University - ISBN 9789462572201 - 153
    nanotechnologie - deeltjes - in vitro - inname - biologische beschikbaarheid - voedingsonderzoek bij de mens - risicoschatting - nanotechnology - particles - in vitro - ingestion - bioavailability - human nutrition research - risk assessment

    Title of the PhD thesis: Development of an integrated in vitro model for the prediction of oral bioavailability of nanoparticles

    The number of food-related products containing nanoparticles (NPs) increases. To understand the safety of such products, the potential uptake of these NPs following consumption needs to be assessed. In normal safety assessment studies this is investigated using animal models. For scientific, ethical and economical reasons, there is a demand to refine, reduce and replace animal testing by developing in vitro alternatives for hazard characterization. In this thesis an in vitro model for the prediction of the uptake of NPs in the human body after consumption was developed. The model consists of two parts. The first part is a laboratory incubation model mimicking human digestion in mouth, stomach and intestine. For the second part, human intestinal wall cells are used to assess the uptake of nanoparticles. The two models were combined into the integrated in vitro model to take into consideration the potential effect of digestion on nanoparticle uptake in the gut. The main outcome of the work is that the cell-based integrated in vitro model can be used to evaluate which NPs are likely taken up by the body at the highest rate. The size of NPs and the type of chemical groups on their surface greatly influenced the uptake of NPs. The developed model can be used to prioritize the NPs for additional investigations. Using this model in the safety assessment of NPs would reduce the number of animals used in safety assessment.

    Ecological and experimental constraints for field trials to study potential effects of transgenic Bt-crops on non-target insects and spiders
    Booij, C.J.H. - \ 2014
    Bilthoven : Cogem (Report / Plant Research International, Business Unit Biointeractions and Plant Health 592) - 58
    transgene planten - schade - risicoschatting - onbedoelde effecten - veldproeven - nadelige gevolgen - niet-doelorganismen - akkerbouw - gewasbescherming - transgenic plants - damage - risk assessment - nontarget effects - field tests - adverse effects - nontarget organisms - arable farming - plant protection
    Veldproeven zijn een belangrijk onderdeel van de milieurisicobeoordeling bij de toelatingsprocedure voor teelt van genetisch gemodificeerde gewassen , met name om eventuele nadelige effecten op zogenaamde niet-doelwitorganismen te onderkennen.
    Extensive literature search for preparatory work to support pan European pest risk assessment: Trichilogaster acaciaelongifoliae RC/EFS/ALPHA/2014/07
    Derkx, M.P.M. ; Brouwer, J.H.D. ; Breda, P.J.M. van; Helsen, H.H.M. ; Hoffman, M.H.A. ; Hop, M.E.C.M. - \ 2014
    Parma, It. : EFSA (EFSA supporting publication 2015- EN-764) - 71
    acacia - acacia longifolia - houtachtige planten als sierplanten - distributie - onkruiden - invasieve exoten - geïntroduceerde soorten - biologische bestrijding - organismen ingezet bij biologische bestrijding - hymenoptera - risicoschatting - europa - acacia - acacia longifolia - ornamental woody plants - distribution - weeds - invasive alien species - introduced species - biological control - biological control agents - hymenoptera - risk assessment - europe
    The European Commission is currently seeking advice from EFSA (Mandate M-2012-0272) to assess for Arabis mosaic virus, Raspberry ringspot virus, Strawberry latent ringspot virus, Tomato black ring virus, Strawberry mild yellow edge virus, Strawberry crinkle virus, Daktulosphaira vitifoliae, Eutetranychus orientalis, Parasaissetia nigra, Clavibacter michiganensis spp. michiganensis, Xanthomonas campestris pv. vesicatoria, Didymella ligulicola and Phytophthora fragariae the risk to plant health for the EU territory and to evaluate the effectiveness of risk reduction options in reducing the level of risk. In addition, the Panel is requested to provide an opinion on the effectiveness of the present EU requirements against these organisms laid down in Council Directive 2000/29/EC. As a consequence EFSA needs insight in the cropping practices of Citrus spp., Fragaria x ananassa, Ribes spp., Rubus spp., Vaccinium spp., Humulus lupulus, Vitis vinifera, Prunus armeniaca, P. avium, P. cerasus, P. domestica and P. persica, which are host plants for these pests. An extensive and systematic literature search was done in which scientific and grey/technical literature was retrieved from the 28 EU Member States, Iceland and Norway. All references were stored in EndNote libraries, separately for scientific literature and grey/technical literature. For each reference information is provided on the source/search strategy, the crop, the country, the topic (cropping practice, propagation, protection or irrigation (only for Citrus)) and protected cultivation vs. field production. Yields of references depended on the crop and on the country. Over 27,000 references were provided to EFSA. This allows EFSA to quickly find information on crop production, both indoors and outdoors, of all crops that were studied in this extensive literature search. The data can be used by EFSA for the present mandate, but are also an excellent basis for other current and future mandates.
    PRIMET_registration_Ethiopia_1.1, technical description and manual : a decision support system for assessing pesticide risks in the tropics to man, environment and trade, for pesticide registration in Europe
    Wipfler, E.L. ; Adriaanse, P.I. ; Horst, M.M.S. ter; Vlaming, J. ; Brink, P.J. van den; Peeters, F.M. ; Deneer, J.W. ; Boesten, J.J.T.I. ; Groenwold, J.G. - \ 2014
    Wageningen : Alterra, Wageningen-UR (Alterra report 2573) - 133
    pesticiden - risicoschatting - ecologische risicoschatting - gezondheid - registratie - blootstelling - ethiopië - pesticides - risk assessment - ecological risk assessment - health - registration - exposure - ethiopia
    Inventarisatie zoönosen bij het paard in Nederland
    Swanenburg, M. ; Vos, C.J. de; Visser, E.K. ; Nodelijk, G. - \ 2014
    Lelystad : CVI Wageningen UR (CVI report 14/CVI0155) - 62
    dierenwelzijn - paarden - ziekten - diergezondheid - zoönosen - volksgezondheid - risicoschatting - inventarisaties - ziekteoverdracht - animal welfare - horses - diseases - animal health - zoonoses - public health - risk assessment - inventories - disease transmission
    Het ministerie van EZ heeft laten onderzoeken of het paard in Nederland een rol speelt bij het ontstaan van infectieziekten die kunnen worden overgedragen van dieren op mensen (zoönosen).
    Ten building blocks for sustainable water governance: an integrated method to assess the governance of water
    Rijswick, M. ; Edelenbos, J. ; Hellegers, P.J.G.J. ; Kok, M. ; Kuks, S.M.M. - \ 2014
    Water International 39 (2014)5. - ISSN 0250-8060 - p. 725 - 742.
    watersystemen - waterbeheer - oppervlaktewaterkwaliteit - overstromingen - risicoschatting - infrastructuur - governance - watervoorraden - beoordeling - hoogwaterbeheersing - water systems - water management - surface water quality - floods - risk assessment - infrastructure - governance - water resources - assessment - flood control - research agenda - management - climate
    A three-step interdisciplinary method to assess approaches to water shortage, water quality and flood risks is presented. This method, based on water system analysis, economics, law and public administration, seeks to create common understanding based on newly developed concepts and definitions. First, generating content knowledge about the water system and about values, principles and policy discourses. Second, providing an organizational process with sufficient stakeholder involvement, insight into the trade-off between social objectives, and attribution of responsibilities in addition to regulations and agreements. Finally, implementing the agreed service level through adequate infrastructure, enforcement and conflict resolution.
    Sedimentatiemodel kwelders Ameland Fase 1: ontwerp en haalbaarheid
    Groot, A.V. de; Duin, W.E. van; Brinkman, A.G. ; Vries, P. de - \ 2014
    Den Helder : IMARES (Rapport / IMARES Wageningen UR C025/14) - 47
    kweldergronden - waterstand - bodemdaling - aardgas - overstromingen - risicoschatting - fauna - watervogels - nederlandse waddeneilanden - salt marsh soils - water level - subsidence - natural gas - floods - risk assessment - fauna - waterfowl - dutch wadden islands
    Op Ameland vindt bodemdaling plaats als gevolg van gaswinning. Dit heeft consequenties voor de opslibbingsbalans en daarmee de maaiveldhoogte van de oostelijke kwelders Neerlands Reid en De Hon, vergeleken met wanneer er geen bodemdaling zou hebben plaatsgevonden. Dit kan weer gevolgen hebben voor het broedsucces van grondbroedende vogels, dat mede afhankelijk is van het overstromingsrisico. Om de impact van gaswinning op het ecosysteem te bepalen, is het dus mede van belang om inzicht te krijgen in hoe het overstromingsrisico op de kwelders op Ameland zou zijn geweest vanaf 1986 zónder de opgetreden bodemdaling. Daarvoor is het nodig de hoogteligging zonder bodemdaling te reconstrueren.
    Toepassing ODEMM - methodiek voor het Nederlandse KRM Programma van Maatregelen
    Piet, G.J. ; Sluis, M.T. van der; Paijmans, A.J. - \ 2014
    IJmuiden : IMARES (Rapport / IMARES Wageningen UR C162/14) - 61
    evaluatie - risicoschatting - ecologische risicoschatting - maatregelen - milieueffect - menselijke invloed - ecosysteembeheer - mariene ecologie - natuurbeheer - evaluation - risk assessment - ecological risk assessment - measures - environmental impact - human impact - ecosystem management - marine ecology - nature management
    Het Nederlandse Kaderrichtlijn Mariene strategie Programma van Maatregelen (PvM) is geëvalueerd met behulp van de ODEMM methodiek. Deze methodiek is ontwikkeld binnen het door de EU gesubsidieerde FP7 project ODEMM (Options for Delivering Ecosystem-based Marine Management). Met deze methodiek kan worden vastgesteld in hoeverre het PvM de menselijke activiteiten die hun invloed op het mariene ecosysteem hebben, in potentie kan mitigeren, zodat een goede milieutoestand behaald kan worden.
    Ecologische gevolgen van bollenteelt op de Veluwe : bureaustudie naar omvang bollenteelt, bestrijdingsmiddelengebruik en mogelijke effecten op natuur
    Lahr, J. ; Smidt, R.A. ; Vink, C. ; Lange, M. de; Deneer, J.W. - \ 2014
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 4542)
    landbouw bedrijven - bloembollen - oppervlakte (areaal) - landbouw en milieu - pesticiden - drift - emissie - natura 2000 - risicoschatting - nadelige gevolgen - veluwe - farming - ornamental bulbs - acreage - agriculture and environment - pesticides - drift - emission - natura 2000 - risk assessment - adverse effects - veluwe
    Naar aanleiding van een vraag van de Partij voor de Dieren in de Provinciale Staten van Gelderland is een korte bureaustudie uitgevoerd naar de mogelijke ecologische gevolgen van bollenteelt op de Veluwe voor Natura 2000-doelen. De vraagstelling spitste zich toe op een aantal onderdelen: omvang van de bollenteelt op de Veluwe, ontwikkelingstrend van bollenteelt op de Veluwe, verschillen in bestrijdingsmiddelengebruik tussen 'normale' akkerbouw (maïs, aardappelen, graan) en bollenteelt en mogelijke nadelige effecten op aangrenzende natuur via verwaaiing, uitspoeling of anderszins.
    Environmental risk assessment : handbook for pesticide registration in China
    Peeters, F.M. ; Qu, M. ; Piao, X. ; Valk, H. van de; Tao, C. - \ 2014
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2558) - 148
    pesticiden - risicoschatting - milieu - registratie - grondwater - china - pesticides - risk assessment - environment - registration - groundwater - china
    The handbook focusses on environmental and beneficial animals. Aquatic ecosystems, birds, honeybees, silkworms end groundwater are selected as protection goals and for each of the protection the following three questions were answered: What do we want to protect? Where do we want to protect? How strict do we want to protect? For each protection goal risk assessment procedures are described.
    Chinese scenarios for groundwater leaching and aquatice exposure : development of scenarios for environmental risk assessment procedures of pesticides in China
    Horst, M.M.S. ter; Wipfler, E.L. ; Adriaanse, P.I. ; Boesten, J.J.T.I. ; Fait, G. ; Li, W. ; Tao, C. - \ 2014
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2559) - 164
    grondwater - pesticiden - uitspoelen - risicoschatting - modellen - oppervlaktewater - blootstelling - rijstvelden - rijst - china - groundwater - pesticides - leaching - risk assessment - models - surface water - exposure - rice fields - rice - china
    Within the frame work of the Sino-Dutch Pesticide Environment Risk Assessment Project (PERAP) and as part of the Chinese environmental ris assessment procedures models and scenarions were developed to estimate concentrations of Plant Protection Product (PPP) leaching to the groundwater and to estimate PPP concentrations in Chinese small surface waters. Protection goals considering groundwater and surface water were defined in detail. Realistic worst-case groundwater scenario's and surface water scenarios were defined to be used in respectively a Tier 1 leaching assessment of PPP a Tier 1 assesment of the risks of PPP to aquatic ecosystems in China. Data on soil, weather, crops, irrigation and Agricultural practices were gathered for both scenario definitions. Existing models PEARL and TOXSWA were modified and parameterised for the scenarions defined.
    Setting environmental criteria for risk assessment : evaluation of Chinese environmental risk assessment procedures
    Valk, H. ; Tao, C. ; Geng, Y. ; Ma, J. ; Zhou, R. ; Jia, R. ; Liu, Y. ; Li, C. ; Li, W. ; Yan, L. ; Ma, X. ; Qu, M. ; Piao, X. ; Horst, M.M.S. ter; Pol, W. - \ 2014
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2560) - 85
    risicoschatting - pesticiden - registratie - grondwater - china - risk assessment - pesticides - registration - groundwater - china
    Molecular effects of isoflavone supplementation : human intervention studies and quantitative models for risk assessment
    Velpen, V. van der - \ 2014
    Wageningen University. Promotor(en): Pieter van 't Veer; Evert Schouten, co-promotor(en): Anouk Geelen; Lydia Afman. - Wageningen : Wageningen UR - ISBN 9789461739520 - 153
    isoflavonen - voedselsupplementen - risicoschatting - genexpressie - blootstellingsbepaling - menopauze - isoflavones - food supplements - risk assessment - gene expression - exposure assessment - menopause

    Background: Risk assessment can potentially be improved by closely linked experiments in the disciplines of epidemiology and toxicology. This was explored for isoflavones in a case study. For isoflavones potential beneficial health effects have been suggested, but discussions on their safety are ongoing as well.

    Aims and methods: Effects of isoflavone supplements on gene expression were studied in white blood cells (PBMCs) and adipose tissue, among postmenopausal women in two human intervention studies. To advance risk assessment, the dose response relation between intake and blood levels was studied with a log-linear regression model as well as the comparability of the human gene expression profiles with results from a rat experiment using multivariate analysis.

    Results: In both PBMCs and adipose tissue, changes in gene expression profiles pointed at effects of isoflavones on energy metabolism, inflammation and cell cycle; these effects were modified by supplement composition and equol-producing phenotype. Hypothesized estrogen-responsive effects were not observed. For the intake range of 0-100mg/day, the plasma concentrations of daidzein, equol, genistein and total isoflavones were quantified, interindividual variation. Expression of estrogen-responsive gene profiles and other biological pathways could be quantitatively compared between PBMCs and adipose tissue, as well as between humans and rats. en nog iets

    Conclusion: Effects of isoflavone supplementation on gene expression in PBMCs and adipose tissue of postmenopausal women suggest mainly beneficial effects of a dose of ~100mg/day. The absence of a clear estrogen-like response suggested a limited role of the estrogen receptor in isoflavone induced gene expression in postmenopausal women. The trials and quantitative models provide important tools[AG1] that enable further exploration of intertissue and interspecies comparability and advancing the use of transcriptomics in assessing risks and benefits.

    Modelling data from human and animal studies provide important possibilities for further exploration of intertissue and interspecies similarities and for the use of transcriptomics in improving risk assessment.

    New concepts for risk and safety assessment of botanicals and botanical preparations including plant food supplements (PFS)
    Berg, S.J.P.L. van den - \ 2014
    Wageningen University. Promotor(en): Ivonne Rietjens, co-promotor(en): Ans Punt. - Wageningen : Wageningen University - ISBN 9789461739377 - 253
    voedselsupplementen - plantaardige producten - plantextracten - risicoschatting - genotoxiciteit - carcinogenese - ocimum basilicum - venkel - food supplements - plant products - plant extracts - risk assessment - genotoxicity - carcinogenesis - ocimum basilicum - fennel
    Microbïele risico's bij hergebruik van drankenkartons : rapportage naar aanleiding van een vergadering gehouden op 24 februari 2014 in aanwezigheid van experts op het gebied van microbiologie
    Bokhorst-van de Veen, H. van; Brouwer, M.T. - \ 2014
    Wageningen : Wageningen UR - Food & Biobased Research (Rapport / Wageningen UR Food & Biobased Research nr. 1472) - ISBN 9789461739919 - 20
    flessen - verpakkingsmaterialen - risicoschatting - microbiële besmetting - bordpapier - bottles - packaging materials - risk assessment - microbial contamination - cardboard
    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’.

    Safety and efficacy of iron supplementation in pregnant Kenyan women
    Mwangi, M.N. - \ 2014
    Wageningen University. Promotor(en): Huub Savelkoul; A.M. Prentice, co-promotor(en): Hans Verhoef. - Wageningen : Wageningen University - ISBN 9789461739209 - 220
    ijzer - minerale supplementen - veiligheid - risicoschatting - werkzaamheid - zwangerschap - kenya - iron - mineral supplements - safety - risk assessment - efficacy - pregnancy - kenya

    Since the British doctor Ronald Ross received the 1902 Nobel Prize in medicine for his work on malaria, more people have died from the disease than all world wars combined. This is in spite of the fact that the French chemists Pierre Joseph Pelletier and Joseph Bienaimé Caventou made quinine available from as early as 1820. According to the World Health Organisation (WHO), there were about 219 million cases of malaria in 2010 and an estimated 660,000 deaths majority of which (80% of cases and 90% of deaths) were in Africa.

    Of almost two billion people who are anaemic globally, 41.8% are pregnant women. Iron supplements are used to prevent anaemia. There are concerns that iron given in high doses may increase malaria rates. Uncertainties regarding the safety of iron supplementation in malaria endemic regions were propelled by a randomized controlled trial that evaluated the effects of iron and folic acid supplementation in 32,155 children in Pemba, Tanzania. This study found that children who received iron and folic acid supplements were more likely to die or to need hospitalisation for an adverse event. At the same time, malaria is known to exacerbate anaemia; an almost inevitable consequence of malarial infection. As such, the safety of daily oral use of iron supplements by pregnant women, as a public health intervention is still not clearly established; at least not until publication of our main findings.

    This thesis assessed the effects of iron supplementation on safety indicators, and on iron status, in pregnant women and their neonates. Several preparatory activities were carried out, including a census of the population in the study area and a pilot study to check the operability of the study protocols. A main study was designed with the hypothesis that consumption of food products fortified with iron combined with intake of iron supplements especially in pregnancy, would be detrimental to the health of pregnant women and their neonates.

    The objectives of the study were: 1) to compare the presence of malarial infection in parturient women who received a combination of iron-fortified foods with iron supplements versus iron-fortified foods only; 2) to assess intervention effects on the maternal prevalence of iron deficiency anaemia at 1 month after delivery; 3) to assess intervention effects on neonatal iron stores at 1 month of age; 4) to assess the diagnostic utility of Zinc protoporphyrin (ZPP) in diagnosing iron deficiency in malaria endemic regions; 5) to identify baseline factors that are prognostic for the Non-Transferrin Bound Iron (NTBI) response to consumption of a single iron supplement; 6) to determine the factors that predict Plasmodium infection in pregnancy; 7) to identify factors associated with birth weight; 8) to develop a methodology to predict cases of low birth weight, using a single prognostic score that is based on prognostic variables collected at the second trimester of pregnancy; and 9) to develop methods for community-based flour fortification with iron.

    Most countries have enacted, or are in the process of enacting legislation for mandatory fortification of flour with iron. Thus pregnant women may receive iron from fortified foods and from universal iron supplementation programmes. This thesis provides answers to pertinent questions regarding the safety and efficacy of iron supplementation by comparing daily high-dose iron (i.e. iron-fortified foods plus iron supplements) versus low-dose iron (i.e. iron-fortified foods only) during pregnancy. The main outcome measure was the presence of maternal Plasmodium infection at birth, regardless of species. Chapter 1 is a detailed introduction of the background to the study and the design of the study.

    This thesis presents concrete evidence that iron supplementation to pregnant women in a highly malaria endemic region does not result in increased risk of malarial infection; percent difference (95%CI) = 0.0% (─9.3% to 9.3%). Programme implementers and governments in malaria endemic regions should not be held back by previous recommendations that cautioned against issuing iron supplements to pregnant women. In light of these findings, there is no need to first screen for malaria before giving iron supplements.

    Iron supplementation had major benefits for mothers and their neonates (chapter 2). The findings reported in this thesis showed a mean increase in birth weight of 143 g relative to the low-dose iron group. The effects of iron were influenced by the participants initial iron status. Correction of iron deficiency increased birth weight by 249 g, even though we cannot exclude the possibility that this may have increased malarial infection by 10%. There was no evidence that effects of iron on birth weight were influenced by intermittent preventive treatment against malaria. Iron supplementation also increased fetal growth by 0.27 SD, 95%CI: (0.04 to 0.50) probably as a result of gains in length and weight for gestation age.

    We also showed improved neonatal iron stores one month post-partum as indicated by a 17.1 % (95% CI: 2.0% to 34.3%) increase in plasma ferritin concentration in neonates of mothers who received high-dose iron compared to those who received low-dose iron. This provides more impetus to the need to offer iron supplements to pregnant women with the aim of boosting infant iron stores (chapter 2).

    ZPP was found to be of unreliable diagnostic utility when discriminating between pregnant women with and without iron deficiency in regions where chronic diseases are prevalent (chapter 3). The current conventional cut off points for whole blood ZPP e.g. >70 μmol/mol heme, can result in gross estimates of the prevalence of iron deficiency especially if the true prevalence is low.

    The appearance of non-transferrin bound iron (NTBI) in circulation after oral ingestion of iron supplements has been thought to aid the growth and multiplication of Plasmodium parasites thereby increasing malaria induced morbidity and mortality. We did not observe any increase in NTBI concentrations three hours after oral ingestion of 60 mg of ferrous fumarate (Chapter 4). We cannot exclude the possibility that iron supplementation leads to NTBI production when supplements are not consumed with food, because the lunch meal consumed by majority of our participants during the 3-hour waiting period probably contained natural compounds (phytates) that may have limited an NTBI response.

    In chapter 5 of this thesis, we aimed to develop a field friendly tool that can be used to predict asymptomatic Plasmodium infection. This was motivated by the fact that most point-of-care dipstick tests used to detect Plasmodium infection are not able to detect 100% of all the infection present yet asymptomatic infections are increasingly associated with adverse maternal and neonatal outcomes. Although many likely predictive factors were assessed individually or in combination with others, we did not succeed in developing a reliable tool that is easy to apply in resource-poor malaria endemic settings.

    In Chapter 6, we aimed to identify factors associated with birth weight and to develop a methodology to predict cases of low birth weight using a single prognostic score that is based on prognostic variables collected at the second trimester of pregnancy. Factors that were found to be independently associated with reduced birth weight were being never married, inflammation, being a girl, and iron deficiency. Being overweight was associated with increased birth weight. The results indicate that we can use variables collected rapidly and at relatively low cost and ease to identify with fair accuracy women in the second trimester of pregnancy who are at high risk of giving birth to a neonate with low birth weight.

    The various aspects of the work presented in this thesis including the implications for policy makers are discussed in chapter 7. For policy makers, the findings of this thesis are a welcome relief. The findings therein eliminate all doubt that has hitherto been associated with antenatal iron supplementation in malaria endemic areas. Most countries already have iron supplementation policies that are well aligned to the World Health Organisation policies. Efforts to widen the coverage of antenatal iron supplementation especially in malaria endemic regions should be urgently scaled up. However, the evidence provided in this thesis is only applicable to pregnant women and cannot be extrapolated to children in malaria endemic regions. For this population, the current WHO policy must be used thus before iron supplementation, children must first be screened for malaria.

    Although this thesis provides answers to key scientific questions that have hitherto baffled the scientific community, there are still research questions that can be clarified further. The effects of a high iron dose in pregnancy (as per national and international guidelines, the daily supplementation dose for pregnant women should be doubled to 120 mg iron if they are anaemic or if 6 months duration cannot be achieved in pregnancy (Chapter 2)) on maternal and neonatal outcomes need to be elucidated. Further research is needed in order to describe fully, the NTBI response to consumption different types and amounts of oral iron supplements. There is urgent need for diagnostic tools that can be used in resource-poor settings to diagnose asymptomatic infections. Further research in children is needed to provide evidence of the safety and efficacy of iron supplementation in malaria endemic regions and to assess the diagnostic performance of zinc protoporphyrin in children. In addition, since our studies suggest that screening based on Hb concentration as now practiced in many countries, is inaccurate in discriminating between women at high and low risk of delivering neonates with low birth weight, further studies are needed to identify appropriate markers and cut-off points that are suited to this purpose.

    In conclusion, this thesis has shown that there is no evidence that antenatal iron supplementation increases Plasmodium infection. Antenatal iron supplementation leads to large improvements in birth weight, fetal growth and infant iron stores, with potentially immense benefits for infant survival and health that should outweigh any possible concerns about risks of malaria. Epidemiological calculations indicate that if our results are applied to all women in developing countries in order to eliminate iron deficiency, we could avoid 3 million births with low birth weight annually and save the lives of more than half a million neonates. Scaling up universal iron supplementation in pregnancy in developing countries will generate major public health gains.

    Manual to proposed Dutch implementation of OSPAR's risk-based approach to the management of produced water discharges
    Vries, P. de; Tamis, J.E. - \ 2014
    Den Helder : IMARES (Report / IMARES Wageningen UR C057.14 A) - 48
    mijnbouw - aardgas - aardolie - afvoerwater - offshore - ecotoxicologie - risicoschatting - noordzee - mariene gebieden - mining - natural gas - petroleum - effluents - offshore - ecotoxicology - risk assessment - north sea - marine areas
    This manual is intended to assist operators on the Dutch Continental Shelf in the application of the Dutch implementation of the risk-based approach (RBA). In essence all oil and gas platforms on the Dutch Continental Shelf (DCS) have to go through the risk management cycle at least once, where the pre-screening determines in which order the platforms enter the cycle. The risk management cycle follows all steps required for the RBA, which are all individually addressed in the following chapters: chapter 3 (sampling); chapter 4 (whole effluent toxicity risk assessment, including ecotoxicological testing of the effluent and risk characterisation); chapter 5 (substance-based risk assessment, including chemical analysis and risk characterisation); chapter 6 (measures) and chapter 7 (reporting).
    Optimal dike investments under uncertainty and learning about increasing water levels
    Pol, T.D. van der; Ierland, E.C. van; Weikard, H.P. - \ 2014
    Journal of Flood Risk Management 7 (2014)4. - ISSN 1753-318X - p. 308 - 318.
    dijken - versterking - investeringsvereisten - risicoschatting - waterstand - klimaatverandering - dykes - reinforcement - investment requirements - risk assessment - water level - climatic change - flood risk-assessment - climate-change - maintenance - netherlands - decisions - framework
    Water level extremes for seas and rivers are crucial to determine optimal dike heights. Future development in extremes under climate change is, however, uncertain. In this paper, we explore impacts of uncertainty and learning about increasing water levels on dike investment. We extend previous work in which a constant rate of structural water level increase is assumed. We introduce a probability distribution for this rate and study the impact of learning about this rate. We model learning as a single stochastic event where full information becomes available. Numerical solutions are obtained with dynamic programming. We find that the expected value of information can be substantial. Before information arrives, investment size is reduced as compared with the benchmark without learning, but investment frequency may be increased. The impact of learning on the initial investment strategy, however, is small as compared with the impact of uncertainty about increasing water levels by itself
    Risk assessment of alien species found in and around the oyster basins of Yerseke
    Foekema, E.M. ; Cuperus, J. ; Weide, B.E. van der - \ 2014
    Den Helder : IMARES (Rapport / IMARES Wageningen UR C014/14) - 38
    schaal- en schelpdierenteelt - oesterteelt - invasieve exoten - geïntroduceerde soorten - risicoschatting - ecologische risicoschatting - oosterschelde - shellfish culture - oyster culture - invasive alien species - introduced species - risk assessment - ecological risk assessment - eastern scheldt
    On behalf of the Office of Research and Risk Assessments (BuRO) of the Netherlands Food and Consumer Product Safey Authority (NVWA), IMARES conducted a species inventory in the Oyster basins in Yerseke and the surrounding area in the Eastern Scheldt, known to be subject to shellfish related activities. This inventory that was performed in September/October 2013 revealed 21 macro invertebrate species that are regarded as alien species. Five of these are assumed not to be present in the Wadden Sea and one species was discovered there once very recently. For all six alien species an assessment was performed to define the potential risk that they will reach the Wadden Sea and affect the local native ecosystem, which is described in this report.
    Governing nano foods : Principles-Based Responsive Regulation
    Meulen, B.M.J. van der; Bremmers, H.J. ; Purnhagen, K. ; Gupta, N. ; Bouwmeester, H. ; Geyer, L. - \ 2014
    Amsterdam, Boston, Heidelberg, London, New York, Oxford, Paris, San Diego, San Francisco, Singapore, Sydney, Tokyo : Academic Press (EFFoST Critical Reviews 3) - ISBN 9780124201569 - 100
    nanotechnologie - voedselvoorziening - voedingsmiddelenwetgeving - wetgeving - risicoschatting - regelingen - nanotechnology - food supply - food legislation - legislation - risk assessment - regulations
    Food which nanotechnology has impacted or to which nanotechnology is applied is referred to as nanofood. From treatment of the soil in which a crop plant is grown to the caring of a food, nanotechnology is a growing factor in the food supply. At this point, however, there is no definitive, effective global method for regulating the use of nanotechnology as it relates to the food suply. Legislation on nanotechnologies is still evolving, as is understanding what data is needed for effective, efficient and appropriate risk assessment associated with nanotechnology impacted foods. Due to the emerging nature of nanotechnology and its role in the food supply, case-by-case studies are the current norm, but the need for wide-scale testing and broad-based regulatory standards is urgent. This project is based on an EFFoST study designed to provide a comparative study of nanofood regulations in order to guide regulation development in this rapidly expanding market.
    Assessing and communicating climate change uncertainties : case of the Rhine basin
    Pelt, S.C. van - \ 2014
    Wageningen University. Promotor(en): Pavel Kabat; Bas Arts; B.J.J.M. van den Hurk. - Wageningen : Wageningen University - ISBN 9789461738332 - 200
    waterbeheer - klimaatverandering - onzekerheid - communicatie - risicobeheersing - simulatiemodellen - neerslag - hoogwaterbeheersing - risicoschatting - stroomgebieden - rijn - water management - climatic change - uncertainty - communication - risk management - simulation models - precipitation - flood control - risk assessment - watersheds - river rhine
    The main aim of this thesis is to analyse the climate change uncertainties that are important to take into account for long term water management and to explore the communication of these uncertainties. The study design combines natural and social scientific theories and methods and consists of three different elements: 1) an assessment of the dominant uncertainty for changes in mean and extreme precipitation over the Rhine basin; 2) an assessment of the impact of the main uncertainties on changes in flood risk and associated damage in the Rhine basin and 3) an exploration of the use of simulation gaming to communicate about climate change uncertainties to water managers.
    Including climate change projections in probabilistic flood risk assessment
    Ward, P.J. ; Pelt, S.C. van; Keizer, O. de; Aerts, J.C.J.H. ; Beersma, J.J. ; Hurk, B.J.J.M. van den - \ 2014
    Journal of Flood Risk Management 7 (2014)2. - ISSN 1753-318X - p. 141 - 151.
    klimaatverandering - overstromingen - risicoschatting - modellen - climatic change - floods - risk assessment - models - rhine basin - model - precipitation - uncertainty - simulations - decisions
    This paper demonstrates a framework for producing probabilistic flood risk estimates, focusing on two sections of the Rhine River. We used an ensemble of six (bias-corrected) regional climate model (RCM) future simulations to create a 3000-year time-series through resampling. This was complemented with 12 global climate model (GCM)-based future time-series, constructed by resampling observed time-series of daily precipitation and temperature and modifying these to represent future climate conditions using an advanced delta change approach. We used the resampled time-series as input in the hydrological model Hydrologiska Byråns Vattenbalansavdelning (HBV)-96 to simulate daily discharge and extreme discharge quantiles for return periods up to 3000 years. To convert extreme discharges to estimates of flood damage and risk, we coupled a simple inundation model with a damage model. We then fitted probability density functions (PDFs) for the RCM, GCM, and combined ensembles. The framework allows for the assessment of the probability distribution of flood risk under future climate scenario conditions. Because this paper represents a demonstration of a methodological framework, the absolute figures should not be used in decision making at this time.
    Wolven en zwijnen, acceptabel risico?
    Stikvoort, B.T. ; Poortvliet, P.M. ; Elands, B.H.M. - \ 2013
    Landschap : tijdschrift voor landschapsecologie en milieukunde 30 (2013)3. - ISSN 0169-6300 - p. 109 - 117.
    wolven - migratie - fauna - wildbeheer - risicoschatting - wolves - migration - fauna - wildlife management - risk assessment
    Wolven keren terug naar Nederland. De vraag is niet of, maar wanneer ze vanuit Duitsland hier naartoe migreren. In die context is het belangrijk om te weten hoe Nederlanders reageren op het risico van grote wilde dieren. Zien we de aanwezigheid van de wolf als een groot risico, of valt er wel mee te leven? En hoe zit dat voor het eveneens gevaarlijke wilde zwijn. Welke factoren spelen een rol bij risicoperceptie en -acceptatie van groot wild?
    Living with storm damage to forests
    Gardiner, B. ; Schuck, A. ; Schelhaas, M.J. ; Orazio, C. ; Blennow, K. ; Nicoll, B. - \ 2013
    Joensuu, Finland : European Forest Institute (What science can tell us 3) - 132
    bossen - windschade - risicoschatting - klimaatverandering - inventarisaties - europa - forests - wind damage - risk assessment - climatic change - inventories - europe
    Windstorms are a major disturbance factor for European forests. In the past six decades wind storms have damaged standing forest volume, which on a yearly average equals about the size of Poland's annual fellings. The evedence also indicates that the actual severity of storms in the wake of climatic changes may increase during next decades.Windstorms damages have many environmental, economic and social implications.
    Sanitation in unsewered urban poor areas: technology section, quantitative microbial risk assessment and grey water treatment
    Katukiza, A.Y. - \ 2013
    Wageningen University. Promotor(en): Piet Lens, co-promotor(en): M. Ronteltap. - Leiden : CRC Press/Balkema - ISBN 9781138015555 - 256
    afvalwaterbehandeling - waterzuivering - volksgezondheidsbevordering - stedelijke gebieden - stedelijk afvalwater - risicoschatting - volksgezondheid - waste water treatment - water treatment - sanitation - urban areas - municipal wastewater - risk assessment - public health
    Towards a realistic risk characterization of complex mixtures using in vitro bioassays
    Montano Garces, M. - \ 2013
    Wageningen University. Promotor(en): Tinka Murk, co-promotor(en): A.C. Gutleb. - [S.l.] : s.n. - ISBN 9789461736598
    risicoschatting - persistente organische verontreinigende stoffen - verontreinigde sedimenten - mengsels - biotesten - in vitro - toxiciteit - schildklierhormonen - risk assessment - persistent organic pollutants - contaminated sediments - mixtures - bioassays - in vitro - toxicity - thyroid hormones

    This thesis aims to better understand and further improve the relevance and reliabilityof in vitro bioassaysfor a biobased risk characterisation of complex mixtures, with special focus on persistent organic pollutants (POPs) in sediments.

    In Chapter 1 the importance of complex mixture characterization in modern society is introduced. The methods available, their current advantages and their disadvantages for complex mixture testing are described. With the shift from policy oriented chemical testing towards the inclusion of in vitro bioanalysis, important challenges have to be overcome to ensure a relevant and reliable quantification of the toxic potency of complex mixtures. These challenges are explained in the introduction, including the status of development and validation of those aspects for reliable testing. One of the main advantages that in vitro bioanalysis has to offer is the possibility to quantify the toxic potency of compounds for which chemical analytical methods have not or hardly been developed, for example because standards do not yet exist. Hydroxylated metabolites of POPs are an example of a toxicologically relevant group of compounds that can exert endocrine disrupting effects, but they cannot yet be routinely analysed. A selection of yet unsolved issues are further studied and discussed in this thesis, as outlined in the “approach and structure of the thesis”.

    In Chapter 2 a meta-analysis is performed to study the occurrence and relevance of hydroxylated (OH) compounds in humans and wildlife. Reported body burdens of halogenated phenolic contaminants (HPCs), including OH-POP in different tissues from humans and wildlife species, are reviewed in relation to the concentration of their putative parent compounds to be able to reveal relevant exposure routes and sub-populations at risk. Highest OH-POP levels were found in blood plasma, and highly perfused and fetal tissues. Plasma concentrations of analysed known HPCs ranged from 0.1-100 nM in humans and up to 240, 454, 800 and 7650 nM for birds, fish, cetaceans and other mammals, respectively. Reported metabolite blood plasma levels also are compared with relevant toxicological threshold concentrations from toxicological studies, and appeared to fully fall within the in vitro (0.05–10000 nM) and in vivo (3-940 nM) effect concentrations reported for OH-POPs. Given the sensitivity of early developmental stages, and information lacking about the general population, it is advisable to determine HPC background blood levels in children and fetal tissue .

    Given the toxicological relevance of the OH-POPs, Chapter 3 aims at providing solutions to the long standing problem of the in vitro production and analysis of OH-POP metabolite thyroid hormone disrupting (THD) potency via binding to plasma thyroid hormone binding proteins (THBPs). In sediments and for example seafood, the POPs occur as parent compounds that would only become THD after metabolisation (hydroxylation). Several methods have shown the competitive thyroxine (T4) T4 displacement potency of pure metabolites. However, in vitro metabolization of, among others, polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers(PBDEs) followed by in vitro quantification of their potency has encountered drawbacks related to the co-extraction of compounds disturbing the T4-TTR competitive binding assay. The present study identifies and quantifies the major co-extractants, cholesterol and saturated and non-saturated fatty acids (SFA and NSFA), at levels above 20 μM (20 nmol per mg protein in the incubation mixture) following various extraction methods. A new method is presented to in vitro metabolise parent compounds into OH-metabolites followed by selective extraction of metabolites while four-fold reducing co-extraction of the disturbing compounds. In addition a microplate-format non-radioactive fluorescence displacement assay was developed to quantify the TTR binding potency of the metabolites formed. The effectiveness of the in vitro metabolism and extraction of the OH-metabolites of the model compounds CB 77 and BDE 47 was chemically quantified with a newly developed chromatographic method analyzing silylated derivatives of the OH-metabolites and co-extractants. Due to the mentioned improvements, it is now possible to make a dose-response curve up to 50% inhibition with OH-metabolites extracted from bioactivated CB 77 and BDE 47. Without taking the toxic potencies of bio-activated POPs into account with bioanalysis, the hazard and risk posed by POPs will be seriously underestimated.

    The chapters 4 and 5 are committed to tackle the issues of supramaximal (SPMX) responses and sample extract concentration which are crucial to reliably quantify of the toxic potencies of complex mixtures with in vitro bioassays.

    A SPMX effect is the phenomenon that compounds induce a maximum response in an assay that is significantly higher than that of the positive control. As the positive control is used to quantify the toxic potency of a sample, this could result in over-estimation of its toxic potency. As this has been most elaborately reported for in vitro estrogenicity assays, a meta-analysis was performed of such assays, compounds and conditions in which the effect is observed (Chapter 4a).For the 21 natural and industrial chemicals that could be identified as SPMX inducers, the culture and exposure conditions varied greatly among and between the assays. Relevant information on assay characteristics, however, sometimes lacked. Diethylstilbestrol (DES), genistein (GEN) and bisphenol A (BPA) were selected to build a database. The meta-analysis revealed that the occurrence of SPMX effects, could be related to a number of specific assay characteristics: 1) the type and concentration of the serum used to supplement the exposure medium; 2) the endpoint used to quantify the estrogenic potency (endogenous or transfected reporter gene), 3) the number of EREs (estrogen responsive elements) used before the reporter gene, and 4) the nature of the promoter’s. There were no indications that solvent concentration in culture, exposure period or cell model influenced the occurrence of SPMX. It is important to understand the mechanism behind this phenomenon because in vitro assays for estrogenicity are used extensively to characterize and quantify the estrogenic potency of compounds, mixtures and environmental extracts.

    Several SPMX inducers also have been reported to block cellular efflux pumps in vivo and in vitro (Anselmo et al. 2012; Georgantzopoulou et al. 2013). Therefore it was hypothesized that efflux pump blockers present in environmental matrices could increase the internal concentration of bioassay agonists and thus cause the SPMX. In Chapter 4b this hypothesis was tested by adapting a 96-well plate cellular efflux pump inhibition assay (CEPIA) to the H4IIE rat hepatoma cell line used for the DR.Luc reporter gene assay for dioxin-like compounds. The influence of various environmentally relevant efflux pump inhibitors on the 2,3,7,8-tetrachlorodibenzo-p-dioxine (TCDD) response was tested. Under the DR.Luc assay conditions there was no evidence that P-gp efflux pump inhibitors modified or potentiated the activity of TCDD. Neither genistein nor quercetin, two potent SPMX inducers on ER-mediated assays, induced any signal on the DR.Luc assay, nor influenced the luciferase induction by TCDD. Future work should be focused on testing the consequences of efflux pump inhibition with an AhR-agonist which is a P-gp substrate, as this could result in intracellular accumulation of this AhR-agonist.

    It is standard practice to use a high single stock concentration of extracts to further dilute test concentrations from and perform the analysis. However, a high contaminant load in an extract may oversaturate the solubility of the extracted compounds in carrier solvents and overload the clean-up columns which may reduce the efficiency of polyaromatic hydrocarbons (PAHs) elimination from the extract. These problems may cause respectively under- or over-estimation of the quantified dioxin-like toxic potency. Therefore Chapter 5 focuses on the effects of initial stock concentrations, including sonication assisted dissolution and exposure time, on the quantified dioxin-like potency of cleaned nonpolar sediment extracts. Indeed, more than 20 g sediment equivalents (SEQ)/mL DMSO) as initial stock concentrations resulted in underestimation of bio-TEQ levels in the sediments as observed for cleaned nonpolar sediment extracts from various locations in Luxembourg. An overload of extract on clean-up columns caused an over-estimation of the dioxin-like potency at 24 hours of exposure, probably due to limited removal of PAHs that can induce false positive responses in the in vitro assays. Sonication assisted dissolution of the stock before serial dilution strongly reduced the standard variation of the outcomes. Taking into account the aspects revealed in this study, in addition to already described important issues for quality control, the in vitro bioassays based bio-TEQs can be applied in a comprehensive monitoring program to determine whether sediments comply with health and safety standards for humans and the environment. For the generally applied sediment quality criteria, advices are given about maximum initial stock concentrations to achieve reliable bioassay outcomes.

    The methods and concepts developed for metabolic activation of compounds in non-polar sediment extracts and in in vitro analysis of the TTR-competitive binding are applied in Chapter 6 to extracts from highly or less contaminated sediments collected in Luxembourg. Nonpolar fractions of sediment extracts were incubated with S9 rat microsomes, and the metabolites were extracted with a newly developed method that excludes most of the lipids to avoid interference in the non-radioactive 96-well plate transthyretin (TTR) competitive binding assay. Metabolic activation increased the TTR binding potency of nonpolar fractions of POP-polluted sediments up to 100 times, resulting in potencies up to 240 nmol T4 equivalents/g sediment equivalent (nmol T4-Eq/g SEQ). Without bioactivation, medium polar and polar fractions also contained potent TTR-binding compounds with potencies from 1.6 to 17 nmol T4-Eq/g SEQ. This demonstrates that a more realistic in vitro sediment THD risk characterization should also include testing ofboth polar and medium polar sediment extracts for THD, as well as bioactivated nonpolar sediment fractions. Without bioactivation THD potency is not observed in nonpolar sediment extracts, although in in vivo experiments PCBs and PBDEs, and not with dioxins or PAHs, have shown to be thyroid hormone disrupting (THD), demonstrating this bio-activation is toxicologically relevant and therefore required for sediment hazard characterisation.

    Chapter 7 discusses the implications of our results to improve the relevance and reliability of in vitro bioassay applied for risk characterisation of complex mixtures from sediments and other matrices. The evidence obtained to support the relevance of POP bio-activation is considered both from the exposure perspective as well as the toxicity perspective. Various features of the newly developed methods and knowledge acquired within this PhD project are discussed in relation to in vitro bioassay risk characterization of sediments towards a realistic in vitro bioassay-based risk characterization of complex mixtures. Some important aspects for the inclusion of metabolizing systems within in vitro bioassay are discussed. In addition, alternatives to deal with the SPMX effect and the definition of suitable sample amounts to improve in vitro bioassay reliability are offered. The suitability of the developed approach application is considered for the risk characterization of sediments. Furthermore, an analysis is made to decide whether this thesis have made in vitro bioassays more reliable and relevant for risk characterization of complex mixtures. Finally, it provides some concluding remarks and aspects for further applications and research.

    AGRIVIS: de economische haalbaarheid van het kweken van vis in open poldersystemen en het effect op de veenbodemdaling en overige risico's
    Ottburg, F.G.W.A. ; Maas, G. ; Schrijver, R. ; Kranenbarg, J. ; Schiphouwer, M. ; Haenen, O.L.M. ; Blonk, R.J.W. ; Kotterman, M.J.J. ; Graaf, M. de - \ 2013
    Wageningen : Alterra (Alterra-rapport 2398) - 60
    multifunctionele landbouw - landgebruik - visteelt - polders - haalbaarheidsstudies - bodemdaling - economische analyse - aquatische ecosystemen - visziekten - risicoschatting - zoetwatervissen - multifunctional agriculture - land use - fish culture - polders - feasibility studies - subsidence - economic analysis - aquatic ecosystems - fish diseases - risk assessment - freshwater fishes
    In de agrarische sector is men op zoek naar mogelijkheden om de agrarische activiteiten te verbreden. Eén van deze verbrede activiteiten wordt ontwikkeld door het bedrijf AGRIVIS. AGRIVIS wil door gebruik te maken van open poldersystemen zoetwatervissen uitzetten, verzorgen en oogsten om een commerciële markt te bedienen. In opdracht van het ministerie van Economische Zaken, directie Regio en Ruimtelijke Economie wordt dit onderzoek door Alterra Wageningen UR in samenwerking met Stichting RAVON, CVI Wageningen UR en IMARES Wageningen UR uitgevoerd. De twee hoofdvragen in dit onderzoek zijn: 1) Kan het opkweken en oogsten van consumptievis in een open poldersysteem een nieuwe economische pijler vormen voor de landbouw sector? en 2) Welke risico's zijn er voor veenbodemdaling en de aanwezige inheemse visfauna. Dit laatste aspect wordt beoordeeld aan de hand van visziekten, genetica, ecologie en contaminanten.
    Risico op ondergrondverdichting in kaart : resultaten PRISMA-project 'gevoeligheid voor verdichting'
    Akker, J.J.H. van den; Vries, F. de; Hack-ten Broeke, M.J.D. - \ 2013
    Bodem 23 (2013)1. - ISSN 0925-1650 - p. 14 - 15.
    bodemverdichting - ondergrond - landgebruik - risicoschatting - kaarten - soil compaction - subsoil - land use - risk assessment - maps
    Zowel in Europa als in Nederland wordt steeds meer onderkend dat ondergrondverdichting een serieuze bodembedreiging is. Het is echter niet bekend waar en in welke mate ondergrondverdichting nu al optreedt. Het is ook onvoldoende bekend welke gronden en gebieden het meest gevoelig zijn voor verdichting. Daarom is voor heel Nederland in kaart gebracht wat het risico is op ondergrondverdichting. Deze kaarten kunnen door de provincies worden gebruikt om na te gaan waar mogelijke maatregelen nodig zijn en waar maatregelen het meeste effect zullen hebben om te komen tot duurzaam bodembeheer.
    Antibiotica in grond en water : via plant weer in mens en dier
    Verwer, C.M. ; Smolders, E.A.A. ; Vijver, L.P.L. van de; Eekeren, N.J.M. van; Hospers-Brands, A.J.T.M. ; Marel, A. van der - \ 2013
    V-focus 10 (2013)1. - ISSN 1574-1575 - p. 34 - 35.
    veevoeder - bijproducten - dierlijke meststoffen - antibioticumresiduen - antibioticaresistentie - risicoschatting - voedselketens - kennisniveau - dierenwelzijn - fodder - byproducts - animal manures - antibiotic residues - antibiotic resistance - risk assessment - food chains - knowledge level - animal welfare
    Residuen van antibiotica en resistente bacteriën zijn niet alleen rechtstreeks een risico voor mens en dier, maar kunnen ook via de grond en het oppervlaktewater in planten terechtkomen. Zo kunnen ze indirect ook een risico vormen voor mens en dier. Dit spoor in de voedselketen is in de discussie over het gebruik van antibiotica en de gevolgen hiervan tot nu toe onderbelicht. Bij het Louis Bolk Instituut is een project gestart, waarin de verschillende sporen van overdracht in de voedselketen in kaart gebracht worden en waarin nog aanwezige hiaten in de kennis opgespoord en mogelijk gedicht kunnen worden.
    Attention to safety 2
    Ward, P.J. ; Aerts, J.C.J.H. ; Pelt, S.C. van; Keizer, O. de; Hurk, B.J.J.M. van den; Beersma, J.J. ; Buishand, T.A. - \ 2012
    Nieuwegein : Programme Office Climate changes Spatial Planning (KvR 051/12) - ISBN 9789088150449 - 44
    klimaatverandering - risicoschatting - overstromingen - modellen - rijn - stroomgebieden - climatic change - risk assessment - floods - models - river rhine - watersheds
    Tot op heden heeft onderzoek naar toekomstig overstromingsrisico vooral gebruik gemaakt van de scenarioaanpak. Het belangrijkste doel van deze studie is om een demonstratie te geven van een methode voor het produceren van probabilistische schattingen van overstromingsrisico’s als gevolg van klimaatverandering. Het onderzoek richt zich op twee casestudy trajecten langs de Rijn: Bonn-Duisburg en Mainz-Koblenz.
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