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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    Quantifying ecological risks of aquatic micro- and nanoplastic
    Besseling, Ellen ; Redondo-Hasselerharm, Paula ; Foekema, Edwin M. ; Koelmans, Albert A. - \ 2019
    Critical Reviews in Environmental Science and Technology 49 (2019)1. - ISSN 1064-3389 - p. 32 - 80.
    Microplastic - Nanoplastics - exposure - risk assesment - Species sensitivity distributions
    Diverse effects of nano- and microplastic (NMP) have been demonstrated in the laboratory. We provide a broad review of current knowledge on occurrence, measurement, modeling approaches, fate, exposure, effects, and effect thresholds as regard to microplastics in the aquatic environment. Using this
    information, we perform a ‘proof of concept’ risk assessment for NMP, accounting for the diversity of the material. New data is included showing how bioturbation affects exposure, and exposure is evaluated based on literature data and model analyses. We review exposure and effect data and provide a
    worst case risk characterization, by comparing HC5 effect thresholds from ‘all inclusive’ Species Sensitivity Distributions (SSDs) with the highest environmental concentrations reported. HC5 values show wide confidence intervals yet suggest that sensitive aquatic organisms in near-shore surface waters might be at risk.
    Opportunities and barriers to effective operation and maintenance of public toilets in informal settlements: perspectives from toilet operators in Kampala
    Ssekamatte, Tonny ; Bosco Isunju, John ; Enock Balugaba, Bonny ; Nakirya, Doreen ; Osuret, Jimmy ; Mguni, P. ; Mugambe, Richard ; Vliet, B.J.M. van - \ 2018
    International Journal of Environmental Health Research 29 (2018)4. - ISSN 0960-3123 - p. 359 - 370.
    sanitation - occupational hazards - exposure - risk - hygiene
    Although classified by the Joint Monitoring Programme (JMP) as unimproved sanitation facilities, public toilets still play a critical role in eliminating open defecation in informal settlements. We explored perspectives of toilet operators on opportunities and barriers to operation and maintenance (O&M) of public toilets in informal settlements. A cross-sectional study design was used. Up to 20 in-depth interviews were used to obtain data on the experiences of public toilet operators. Thematic content analysis was used. Ressults show that opportunities for improving O&M include; operation of public toilets is a source of livelihood; operators are knowledgeable on occupational risks, and the community is involvedin sanitation activities. Barriers to effective O&M include; high operation costs, failure to break even and a lack of investments in occupational health Therefore, there is need to recognise the significance of public toilets as a viable alternative to open defecation in areas where ownership of private sanitation facilities is difficult. Failure to observe the health and safety of toilet operators may further compromise O&M.
    Sweet taste exposure and the subsequent acceptance and preference for sweet taste in the diet : Systematic review of the published literature
    Appleton, Km ; Tuorila, H. ; Bertenshaw, Ej ; Graaf, C. De; Mela, Dj - \ 2018
    American Journal of Clinical Nutrition 107 (2018)3. - ISSN 0002-9165 - p. 405 - 419.
    exposure - food choice - food intake - food preferences - sweet taste
    Background There are consistent, evidence-based global public health recommendations to reduce intakes of free sugars. However, the corresponding evidence for recommending reduced exposure to sweetness is less clear. Objective Our aim was to identify and review the published evidence investigating the impact of dietary exposure to sweet-tasting foods or beverages on the subsequent generalized acceptance, preference, or choice of sweet foods and beverages in the diet. Design Systematic searches were conducted to identify all studies testing relations of variation in exposure to sweetness through foods and beverages with subsequent variation in the generalized acceptance, preference, or choice of sweetened foods or beverages, in humans aged >6 mo. Results Twenty-one studies met our inclusion criteria, comprising 7 population cohort studies involving 2320 children and 14 controlled trials involving 1113 individuals. These studies were heterogeneous in study design, population, exposure, and outcomes measured, and few were explicitly designed to address our research question. The findings from these were inconsistent. We found equivocal evidence from population cohort studies. The evidence from controlled studies suggests that a higher sweet taste exposure tends to lead to reduced preferences for sweetness in the shorter term, but very limited effects were found in the longer term. Conclusions A small and heterogeneous body of research currently has considered the impact of varying exposure to sweet taste on subsequent generalized sweet taste preferences, and this evidence is equivocal regarding the presence and possible direction of a relation. Future work should focus on adequately powered studies with well-characterized exposures of sufficient duration. This review was registered with PROSPERO as CRD42016051840, 24 November 2016.
    Including multistress in the risk assessment of plant protection products : current state of knowledge, based on a literature review and an evaluation of tank mixture applications in a spraying schedule for strawberries
    Arts, G.H.P. ; Beltman, W.H.J. ; Holterman, H.J. ; Vliet, P.J.M. van; Wipfler, E.L. ; Zande, J.C. van de - \ 2017
    Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2793) - 51
    pesticides - environmental impact - risk - exposure - drift - pesticiden - milieueffect - risico - blootstelling - drift
    Fluctuations of input and output prices are major reasons causing volatile gross margins in livestock production. There are large historic differences in the period 2001-2015 between the dairy sector and fattening pig sector in volatility. Relatively large fluctuations in gross margins were observed in the fattening pig sector (median coefficient of variation (CV) value of 32%). In the dairy sector gross margin between years was more smooth (median CV values of 12%), but projections are that after the gradual reduction of EU milk price support and following the abolishment of the EU milk quota system dairy farmers will become more exposed to the world market for dairy products and are becoming more vulnerable to (supply and demand) shocks affecting world dairy markets and prices.
    Cadmium in soil, crops and resultant dietary exposure
    Rietra, R.P.J.J. ; Mol, G. ; Rietjens, I.M.C.M. ; Römkens, P.F.A.M. - \ 2017
    Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2784) - 39
    cadmium - soil - food intake - crops - exposure - fertilizers - food safety - toxicology - cadmium - bodem - voedselopname - gewassen - blootstelling - kunstmeststoffen - voedselveiligheid - toxicologie
    Calculation of exposure concentrations for NL standard scenarios by the TOXSWA model : use of FOCUS_TOXSWA 4.4.3 software for plant protection products and their metabolitesin Dutch risk assessment for aquatic ecosystems
    Beltman, W.H.J. ; Vink, C. ; Poot, A. - \ 2016
    Wageningen : Statutory Research Tasks Unit for Nature & the Environment (WOT Natuur & Milieu) (WOt-technical report 77) - 46
    pesticides - models - exposure - exposure assessment - surface water - netherlands - pesticiden - modellen - blootstelling - blootstellingsbepaling - oppervlaktewater - nederland
    TOXSWA calculates exposure concentrations of plant protection products in water and in sediment and is
    used in risk assessment studies of aquatic organisms. Replacement of the TOXSWA 1.2 software by the more
    recent FOCUS_TOXSWA software for use with the NL standard scenarios was investigated. The impact of the
    replacement on the calculated exposure concentrations of parent compounds and of metabolites was
    determined. For parent substances the calculated exposure concentrations of the two TOXSWA versions were
    equivalent. Due to a different way to simulate metabolites, the differences in exposure concentrations
    calculated by the two versions can be large. For the simulation of metabolite substances two approaches are
    given to handle situations where the formation fraction is not known.
    Training Manual Occupational Pesticide Exposure & Health and Safe & Responsible Handling of Pesticides : With courtesy of vegIMPACT a program financed by The Netherlands’ Government
    Maden, E.C.L.J. van der; Koomen, I. - \ 2016
    Centre for Development Innovation (Report CDI-16-029 ) - 40
    pesticides - exposure - occupational health - safety at work - horticulture - farmers - training - handbooks - kenya - pesticiden - blootstelling - gezondheid op het werk - veiligheid op het werk - tuinbouw - boeren - opleiding - handboeken - kenya
    Pesticides are commonly used in the horticulture sector. While emphasis is often on the correct and efficient application of pesticides, the risk associated with application of pesticides receives less attention. Those working with pesticides need to know about occupational pesticide exposure and health risks, both for themselves as well as people living in the vicinity of places where pesticides are used. The Practical Training Centre Horticulture Kenya (PTC Horticulture) offers hands-on trainings to the horticultural sector. This manual is developed for PTC Horticulture and is about the safe and responsible use of pesticides – a guide for trainers who have to deliver trainings on ‘Occupational Pesticide Exposure & Health’ and ‘Safe & Responsible Handling of Pesticides’. This manual guides the trainers through the material, provides background and tips to the content and gives suggestions for practical assignments.
    Transmission through air as a possible route of exposure for MRSA
    Bos, Marian E.H. ; Verstappen, Koen M. ; Cleef, Brigitte A.G.L. Van; Dohmen, Wietske ; Dorado-García, Alejandro ; Graveland, Haitske ; Duim, Birgitta ; Wagenaar, Jaap A. ; Kluytmans, Jan A.J.W. ; Heederik, Dick J.J. - \ 2016
    Journal of Exposure Science and Environmental Epidemiology 26 (2016)3. - ISSN 1559-0631 - p. 263 - 269.
    air - exposure - livestock - MRSA - transmission

    Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is highly prevalent in pigs and veal calves. The environment and air in pig and veal calf barns is often contaminated with LA-MRSA, and can act as a transmission source for humans. This study explores exposure-response relationships between sequence type 398 (ST398) MRSA air exposure level and nasal ST398 MRSA carriage in people working and/or living on farms. Samples and data were used from three longitudinal field studies in pig and veal calf farm populations. Samples consisted of nasal swabs from the human participants and electrostatic dust fall collectors capturing airborne settled dust in barns. In both multivariate and mutually adjusted analyses, a strong association was found between nasal ST398 MRSA carriage in people working in the barns for >20 h per week and MRSA air levels. In people working in the barns <20 h per week there was a strong association between nasal carriage and number of working hours. Exposure to ST398 MRSA in barn air seems to be an important determinant for nasal carriage, especially in the highly exposed group of farmers, next to duration of contact with animals. Intervention measures should therefore probably also target reduction of ST398 MRSA air levels.

    Probabilistic dietary exposure models : relevant for acute and chronic exposure assessment of adverse chemicals via food
    Boon, Polly E. ; Voet, H. van der - \ 2015
    Bilthoven : RIVM (RIVM letter report 2015-0191) - 41
    exposure assessment - exposure - models - chemicals - toxic substances - intake - food consumption - food safety - probabilistic models - blootstellingsbepaling - blootstelling - modellen - chemicaliën - toxische stoffen - opname (intake) - voedselconsumptie - voedselveiligheid - waarschijnlijkheidsmodellen
    Exposure models are used to calculate the amount of potential harmful chemicals ingested by a human population. Examples of harmful chemicals are residues of pesticides, chemicals entering food from the environment (such as dioxins, cadmium, lead, mercury), and chemicals that are generated via heating (such as acrylamide and furans). In this report we describe the characteristics of two types of models: the first for calculating the short term-intake, and the second for calculating long-term intake. These models currently result in the most realistic estimation of chemical intake via food.
    Training Manual Occupational Pesticide Exposure & Health
    Maden, E.C.L.J. van der; Gordijn, F. ; Wulansari, M. ; Koomen, I. - \ 2015
    Wageningen UR (vegIMPACT report 11) - 61
    pesticiden - toepassing - blootstelling - gezondheid op het werk - opleiding - handleidingen - pesticides - application - exposure - occupational health - training - guide books
    The VegIMPACT project, short for ‘vegetable production and marketing with impact’, aims to improve vegetable production and marketing of small farmers in Indonesia. VegIMPACT contributes to increased food security and private sector development in Indonesia and is financed by the Netherlands Government. The program (2013-2016) is carried out by Wageningen University and Research Centre, together with local partners and national and international companies involved in the vegetable production and marketing chain. One of the work packages of the vegIMPACT project is Occupational Health. This work package intends to reduce pesticide related occupational health hazards, with specific attention to women. At the moment there is limited awareness about the chronic negative health effects of exposure to pesticides such as e.g. cancer, infertility and miscarriages. Especially women receive no or limited information on pesticides. In order to reduce pesticide related occupational health risks in Indonesian agriculture major steps must be taken with regard to the reduction of pesticide exposure and improvement of handling and application practices. This training manual is developed as a supplement to the vegIMPACT ‘Occupational Pesticide Exposure & Health’ PowerPoint presentation and is designed for trainers facilitating the vegIMPACT ‘Occupational Pesticide Exposure & Health’ training.
    Species interactions and chemical stress combined effects of intraspecific and interspecific interactions and pyrene n Daphnia magna populations dynamics
    Viaene, K.P.J. ; Laender, F. de; Rico, A. ; Brink, P.J. van den; Guardo, A. Di; Morselli, M. ; Janssen, C.R. - \ 2015
    Environmental Toxicology and Chemistry 34 (2015)8. - ISSN 0730-7268 - p. 1751 - 1759.
    ecological risk-assessment - competition delays recovery - dry-weight estimate - modeling approach - exposure - sensitivity - water - ecotoxicology - contaminants - zooplankton
    Species interactions are often suggested as an important factor when assessing the effects of chemicals on higher levels of biological organization. Nevertheless, the contribution of intraspecific and interspecific interactions to chemical effects on populations is often overlooked. In the present study, Daphnia magna populations were initiated with different levels of intraspecific competition, interspecific competition, and predation and exposed to pyrene pulses. Generalized linear models were used to test which of these factors significantly explained population size and structure at different time points. Pyrene had a negative effect on total population densities, with effects being more pronounced on smaller D. magna individuals. Among all species interactions tested, predation had the largest negative effect on population densities. Predation and high initial intraspecific competition were shown to interact antagonistically with pyrene exposure. This was attributed to differences in population structure before pyrene exposure and pyrene-induced reductions in predation pressure by Chaoborus sp. larvae. The present study provides empirical evidence that species interactions within and between populations can alter the response of aquatic populations to chemical exposure. Therefore, such interactions are important factors to be considered in ecological risk assessments. Environ Toxicol Chem 2015;34:1751-1759. (c) 2015 SETAC
    Waves of change: immunomodulation of the innate immune response by low frequency electromagnetic field exposure
    Golbach, L.A. - \ 2015
    Wageningen University. Promotor(en): Huub Savelkoul, co-promotor(en): Lidy van Kemenade. - Wageningen : Wageningen University - ISBN 9789462574090 - 172
    immuniteitsreactie - elektromagnetisch veld - cellen - celbiologie - blootstelling - immune response - electromagnetic field - cells - cellular biology - exposure

    In this thesis we investigated possible modulatory roles of low frequency electromagnetic fields (LF EMFs) exposure on the innate immune system. Recent decades have seen a huge increase in the use of electronic devices that nowadays enable us to communicate with distant family, enjoy music everywhere or order food without leaving the house. However besides the benefits, this evolution has also resulted in increased public concern about the potential adverse health effects of non-ionizing radiation. Every power line or electronic device emits a wide range of electromagnetic waves, which can pass through our bodies or damage our skin, depending on the characteristics of the waves. The symptoms attributed to continuous EMF exposure range from non-specific physical symptoms, such as fatigue 1, headaches 2, and redness of the skin to increased prevalence of childhood leukaemia 3. Although many theories regarding a potential mechanism of induction are put forward, to date no clear mechanism of action has been elucidated. Experimental evidence that could support an association between exposure and health status appears to be insufficient and inconsistent 4,5. We investigated the potential effect of LF EMF exposure on neutrophils, one of the key players of the innate immune response. We tried to elucidate a possible mechanism of interaction between intracellular signalling pathways and LF EMF exposure. We aimed to investigate calcium signalling, actin reorganization, cell migration and antimicrobial activity during exposure with different in vitro approaches.

    Cumulative ozone effect on canopy stomatal resistance and the impact on boundary layer dynamics and CO2 assimilation at the diurnal scale: A case study for grassland in the Netherlands
    Super, I. ; Vilà-Guerau De Arellano, J. ; Krol, M.C. - \ 2015
    Journal of Geophysical Research: Biogeosciences 120 (2015). - ISSN 2169-8953 - p. 1348 - 1365.
    climate-change - soil-moisture - vegetation - exposure - drought - yield - l. - conductance - sensitivity - atmosphere
    Biological, chemical, and dynamical processes occurring at the surface strongly interact at diurnal scales. Therefore, this study examines the seasonal ozone impact on stomatal resistance, surface energy balance, boundary layer dynamics, and CO2 assimilation at this (sub)diurnal scale under changing conditions. We combine a seasonal canopy resistance module with a surface-boundary layer model that solves the diurnal evolution of dynamical and chemical variables in a well-mixed, convective boundary layer. The model is constrained with observations from Cabauw (Netherlands) for the dry year 2003, representing a well-mixed boundary layer at midlatitudes over water-stressed grassland. To quantify the ozone impact, the Cumulative Uptake of Ozone is calculated over a growing season, which gives an estimate of the reduction in stomatal aperture and photosynthesis. From a sensitivity analysis with mixed-layer temperature and soil moisture content we conclude that drought is the dominant factor that determines the surface energy partitioning and limits CO2 assimilation. Although drought causes stomatal closure, the results indicate that ozone damage, nevertheless, occurs. A second sensitivity analysis with CO2 and ozone shows that ozone damage causes an increase in stomatal resistance of up to 40% under high ozone levels and that CO2-induced stomatal closure limits ozone damage. The impact on boundary layer development through the effect of CO2 and ozone on the stomatal resistance is much smaller. At the diurnal scale soil moisture influences the surface energy partitioning, which affects the entrainment of ozone-rich air. Due to ozone damage, the CO2 assimilation flux is reduced by about 15%.
    Dioxins, PCBs and heavy metals in Chinese mitten crabs from Dutch rivers and lakes
    Hoogenboom, L.A.P. ; Kotterman, M.J.J. ; Hoek - van Nieuwenhuizen, M. ; Lee, M.K. van der; Mennes, W.C. ; Jeurissen, S.M.F. ; Leeuwen, S.P.J. van - \ 2015
    Chemosphere 123 (2015). - ISSN 0045-6535 - p. 1 - 8.
    dr-calux(r) bioassay - netherlands - biphenyls - exposure - eel
    Chinese mitten crab is an invasive species in many European rivers and lakes. Data from the UK indicated high levels of dioxins and PCBs, in particular in the brown meat in the body. This was confirmed by studies in the Netherlands, showing average levels of dioxins and PCBs in the meat in the body of 43 pg TEQ g-1 ww in crabs caught in the large rivers. Levels in crab of lakes in the Northern part of the Netherlands were on average 3.7-fold lower. Consumption of crabs from polluted areas results in a relatively high dose of dioxins and dl-PCBs and could significantly increase the intake above the TWI. However, in general consumption of these crabs is low, even in the Asian sub-population in the Netherlands. Cadmium and lead levels were higher in crabs from contaminated areas, but for mercury and arsenic there was no clear difference. Consumption of crabs would not result in significant risks for cadmium and mercury. For lead the daily intake could be raised above the BMDL01 for neurodevelopmental toxicity, but this would only occur on a limited number of days. For arsenic the exposure would exceed the lower end of the BMDL01 values for certain cancers, but again, the infrequent consumption by most consumers reduces this risk. Furthermore, speciation showed that most arsenic in crabs was probably not a toxic inorganic form, but likely to be in an organic form.
    Spatially explicit fate modelling of nanomaterials in natural waters
    Quik, J.T.K. ; Klein, J.J.M. de; Koelmans, A.A. - \ 2015
    Water Research 80 (2015). - ISSN 0043-1354 - p. 200 - 208.
    engineered nanomaterials - aquatic environments - nanoparticles - aggregation - systems - exposure - sedimentation - calibration - matrices - silver
    Site specific exposure assessments for engineered nanoparticles (ENPs) require spatially explicit fate models, which however are not yet available. Here we present an ENP fate model (NanoDUFLOW) that links ENP specific process descriptions to a spatially explicit hydrological model. The link enables the realistic modelling of feedbacks between local flow conditions and ENP fate processes, such as homo- and heteroaggregation, resuspension and sedimentation. Spatially explicit simulations using five size classes of ENPs and five size classes of natural solids showed how ENP sediment contamination ‘hot spots’ and ENP speciation can be predicted as a function of place and time. For the catchment modelled, neglect of spatial heterogeneity caused relatively small differences in ENP retention. However, simplification of the number of size classes to one average class, resulted in up to 3.3 times lower values of retention compared to scenarios that used detailed size distributions. Local concentrations in sediment were underestimated up to 20 fold upon simplification of spatial heterogeneity or particle size distribution. We conclude that spatial heterogeneity should not be neglected when assessing the risks of ENPs.
    Mesocosm validation of the marine No Effect Concentration of dissolved copper derived from a species sensivity distribution
    Foekema, E.M. ; Kaag, N.H.B.M. ; Kramer, K.J.M. ; Long, K. - \ 2015
    Science of the Total Environment 521-522 (2015). - ISSN 0048-9697 - p. 173 - 182.
    principal response curves - organic-matter - toxicity - water - carbon - speciation - exposure - ph
    The Predicted No Effect Concentration (PNEC) for dissolved copper based on the species sensitivity distribution (SSD) of 24 marine single species tests was validated in marine mesocosms. To achieve this, the impact of actively maintained concentrations of dissolved copper on a marine benthic and planktonic community was studied in 18 outdoor 4.6 m3 mesocosms. Five treatment levels, ranging from 2.9 to 31 µg dissolved Cu/L, were created in triplicate and maintained for 82 days. Clear effects were observed on gastropod and bivalve molluscs, phytoplankton, zooplankton, sponges and sessile algae. The most sensitive biological endpoints; reproduction success of the bivalve Cerastoderma edule, copepod population development and periphyton growth were significantly affected at concentrations of 9.9 µg Cu/L and higher. The No Observed Effect Concentration (NOEC) derived from this study was 5.7 µg dissolved Cu/L. Taking into account the DOC concentration of the mesocosm water this NOEC is comparable to the PNEC derived from the SSD.
    Successful validation of genomic biomarkers for human immunotoxicity in Jurkat T cells in vitro
    Schmeits, P.C.J. ; Shao, J. ; Krieken, D.A. van der; Volger, O.L. ; Loveren, H. van; Peijnenburg, A.A.C.M. ; Hendriksen, P.J.M. - \ 2015
    Journal of Applied Toxicology 35 (2015)7. - ISSN 0260-437X - p. 831 - 841.
    polycyclic aromatic-hydrocarbons - brominated flame retardants - tetrabromobisphenol-a - balb/c mice - vitamin-c - chlorpyrifos - activation - exposure - rats - kinase
    Previously, we identified 25 classifier genes that were able to assess immunotoxicity using human Jurkat T cells. The present study aimed to validate these classifiers. For that purpose, Jurkat cells were exposed for 6¿h to subcytotoxic doses of nine immunotoxicants, five non-immunotoxicants and four compounds for which human immunotoxicity has not yet been fully established. RNA was isolated and subjected to Fluidigm quantitative real time (qRT)–PCR analysis. The sensitivity, specificity and accuracy of the screening assay as based on the nine immunotoxicants and five non-immunotoxicants used in this study were 100%, 80% and 93%, respectively, which is better than the performance in our previous study. Only one compound was classified as false positive (benzo-e-pyrene). Of the four potential (non-)immunotoxicants, chlorantraniliprole and Hidrasec were classified immunotoxic and Sunset yellow and imidacloprid as non-immunotoxic. ToxPi analysis of the PCR data provided insight in the molecular pathways that were affected by the compounds. The immunotoxicants 2,3-dichloro-propanol and cypermethrin, although structurally different, affected protein metabolism and cholesterol biosynthesis and transport. In addition, four compounds, i.e.¿chlorpyrifos, aldicarb, benzo-e-pyrene and anti-CD3, affected genes in cholesterol metabolism and transport, protein metabolism and transcription regulation. qRT–PCR on eight additional genes coding for similar processes as defined in ToxPi analyzes, supported these results. In conclusion, the 25 immunotoxic classifiers performed very well in a screening with new non-immunotoxic and immunotoxic compounds. Therefore, the Jurkat screening assay has great promise to be applied within a tiered approach for animal free testing of human immunotoxicity.
    Surface water risk assessment of pesticides in Ethiopia
    Teklu, B.M. ; Adriaanse, P.I. ; Horst, M.M.S. ter; Deneer, J.W. ; Brink, P.J. van den - \ 2015
    Science of the Total Environment 508 (2015). - ISSN 0048-9697 - p. 566 - 574.
    predict insecticide concentrations - models fail - field - validation - exposure
    Scenarios for future use in the pesticide registration procedure in Ethiopia were designed for 3 separate Ethiopian locations, which are aimed to be protective for the whole of Ethiopia. The scenarios estimate concentrations in surface water resulting from agricultural use of pesticides for a small stream and for two types of small ponds. Seven selected pesticides were selected since they were estimated to bear the highest risk to humans on the basis of volume of use, application rate and acute and chronic human toxicity, assuming exposure as a result of the consumption of surface water. Potential ecotoxicological risks were not considered as a selection criterion at this stage. Estimates of exposure concentrations in surface water were established using modelling software also applied in the EU registration procedure (PRZM and TOXSWA). Input variables included physico-chemical properties, and data such as crop calendars, irrigation schedules, meteorological information and detailed application data which were specifically tailored to the Ethiopian situation. The results indicate that for all the pesticides investigated the acute human risk resulting from the consumption of surface water is low to negligible, whereas agricultural use of chlorothalonil, deltamethrin, endosulfan and malathion in some crops may result in medium to high risk to aquatic species. The predicted environmental concentration estimates are based on procedures similar to procedures used at the EU level and in the USA. Addition of aquatic macrophytes as an ecotoxicological endpoint may constitute a welcome future addition to the risk assessment procedure. Implementation of the methods used for risk characterization constitutes a good step forward in the pesticide registration procedure in Ethiopia. KEYWORDS: Aquatic ecosystems; Drinking water; Ecological risk assessment; Ethiopia; Exposure modelling; Pesticides; Tropics
    Short communication: Effect of straw inclusion rate in a dry total mixed ration on the behavior of weaned dairy calves
    Groen, M.J. ; Steele, M.A. ; DeVries, T.J. - \ 2015
    Journal of Dairy Science 98 (2015). - ISSN 0022-0302 - p. 2693 - 2700.
    feed delivery method - heifers - cows - management - patterns - exposure - fiber
    The primary objective of this study was to determine the effect of straw inclusion levels on the feeding behavior of young, weaned calves adapted to a dry total mixed ration (TMR) composed of a multitextured concentrate and chopped straw. A secondary objective was to determine how developed feeding patterns persist after calves were switched to a conventional silage-based diet. Ten Holstein bull calves (91 ± 2.4 d of age, weighing 136 ± 12.3 kg) were assigned to 1 of 2 treatments: a TMR containing [dry matter (DM) basis] either (1) 85% concentrate and 15% chopped straw for 10 wk (wk 1 to 10) or (2) 85% concentrate and 15% chopped straw for 5 wk (wk 1 to 5), then 70% concentrate and 30% chopped straw for 5 wk (wk 6 to 10). After 10 wk, all animals were transitioned to a TMR containing (DM basis) 42.3% corn silage and 57.7% haylage for 2 wk (wk 11 to 12). During wk 1 to 5, all calves had similar DMI (5.5 kg/d), average daily gain (1.7 kg/d), feed efficiency (3.5 kg of DM/kg of gain), and eating time (151.9 min/d). During wk 6 to 10, calves transitioned to the 70% diet ate less DM (5.5 vs. 7.4 kg/d), grew more slowly (1.3 vs. 1.6 kg/d), sorted more against long forage particles (62.8 vs. 103.8%), and had greater feeding times (194.9 vs. 102.6 min/d). The difference in feeding time occurred only during the first 8 h after feed delivery. Despite similar DMI (5.2 kg/d) and average daily gain (1.1 kg/d) in wk 11 to 12, differences in behavior were observed resulting from previous diets. In wk 11 to 12, calves previously fed the 70% diet continued to have a longer meal immediately after feed delivery. Overall, the results indicate that diluting a dry TMR containing a multitextured concentrate and chopped straw with more straw resulted in calves spending more time feeding and having longer meals immediately after feed delivery; this feeding pattern carried over after calves were transitioned to a silage-based ration.
    Vaccination of cattle only is sufficient to stop FMDV transmission in mixed populations of sheep and cattle
    Bravo De Rueda, C. ; Dekker, A. ; Eblé, P.L. ; Jong, M. de - \ 2015
    Epidemiology and Infection 143 (2015)11. - ISSN 0950-2688 - p. 2279 - 2286.
    mouth-disease virus - basic reproduction ratio - between-pen transmission - emergency vaccination - infectious-diseases - quantification - eradication - protection - reduction - exposure
    We quantified the transmission of foot-and-mouth disease virus in mixed cattle-sheep populations and the effect of different vaccination strategies. The (partial) reproduction ratios (R) in groups of non-vaccinated and vaccinated cattle and/or sheep were estimated from (published) transmission experiments. A 4 × 4 next-generation matrix (NGM) was constructed using these estimates. The dominant eigenvalue of the NGM, the R for a mixed population, was determined for populations with different proportions of cattle and sheep and for three different vaccination strategies. The higher the proportion of cattle in a mixed cattle-sheep population, the higher the R for the mixed population. Therefore the impact of vaccination of the cattle is higher. After vaccination of all animals R = 0·1 independent of population composition. In mixed cattle-sheep populations with at least 14% of cattle, vaccination of cattle only is sufficient to reduce R to <1.
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