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.

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    Cost-effective monitoring of dioxins in agri-production chains
    Lascano Alcóser, Víctor Hugo - \ 2018
    Wageningen University. Promotor(en): A.G.J.M. Oude Lansink, co-promotor(en): M.C.M. Mourits; H.J. van der Fels-Klerx. - Wageningen : Wageningen University - ISBN 9789463433600 - 214

    Dioxins are important chemical pollutants due to their high toxicity to human health even at very low concentrations. From all possible human exposure pathways, food ingestion is the major route with food products of animal origin as the main contributors. Feed ingredients and/or additives used in compound feed for livestock production have been a main cause of various food dioxin incidents in recent decades. These incidents resulted into large financial implications due to recalls and trade disruptions. Monitoring dioxins in feed and food products is deemed crucial when aiming at reducing human dioxin exposure with time as well as when preventing and diminishing the salient financial impact of dioxin incidents in agribusiness along the food chain. However, economic aspects embedded in the practical assessment and implementation of dioxin monitoring schemes along the food chain have not yet been analysed in the scientific literature. Hence this dissertation aims to analyse the cost-effectiveness of schemes for monitoring dioxins along the food chain by 1) assessing the financial impact of a dioxin incident in the food chain, 2) determining the cost-effectiveness of monitoring dioxins at a single control point along the food chain 3) determining the cost-effective allocation of resources for monitoring dioxins at different stages of the food chain, and 4) determining the cost-effective allocation of resources at one stage of the food chain considering incoming ingredients and final products.

    Chapter 2 aimed to quantify the financial consequences of a milk-dioxin crisis on the stages of the dairy chain involved. Results obtained based on the assumption of the worst-case scenario in which the entire daily production of each business unit from feed supplier to milk processor is contaminated, show that the financial impact of a dioxin incident would be €141.2 million. The stages of the chain that contributed most to the total net costs are the milk processor (76.9%) and the dairy farm (20.5%). In case the moment of detection was reduced from 2 weeks to 3 days after initial contamination, the estimated total financial impact decreased to €10.9 million. This result emphasizes the importance of an early detection of the contamination in decreasing the number of food businesses involved and lowering the total financial impact value.

    Chapter 3 assessed the costs and effectiveness of bulk milk dioxin monitoring in milk trucks to optimize the sampling and pooling monitoring strategies aimed at detecting at least one contaminated farm out of 20,000 at a target dioxin concentration level. Two optimization models were built using linear programming. The first model aimed to minimize monitoring costs subject to a minimum required effectiveness of finding an incident, whereas the second model aimed to maximize the effectiveness for a given monitoring budget. Incidents with different numbers of contaminated farms and concentrations were simulated. The results show that monitoring with 95% probability of detecting one contaminated farm with 2 pg TEQ/g fat costs €2.6 million per month. At the same level of effectiveness, a 73% cost reduction is possible when aiming to detect an incident where 2 farms are contaminated at a dioxin concentration of 3 pg of toxic equivalents/g of fat (EC maximum level). With a fixed budget of €40,000 per month, the probability of detecting an incident with a single contaminated farm at a dioxin concentration equal to the EC action level is 4.4%. This probability almost doubled (8.0%) when aiming to detect the same incident but with a dioxin concentration equal to the EC maximum level.

    In Chapter 4 a decision support tool (optimization model) is developed to determine cost-effective monitoring schemes for detecting and tracing a dioxin contamination over four control points (i.e. at the supplier of fatty feed ingredients, the feed mill, the slaughterhouse and the fat melting facility) along the pork chain. The cost-effective allocation of resources for detecting and tracing the dioxin contamination from an integrated chain approach (i.e. considering all control points) focuses on monitoring at the feed mill, followed by the supplier of fatty feed ingredients and - to a lesser extent - by the slaughterhouse. The number of contaminated feed mills, the frequency of dioxin contaminations, the required level of effectiveness, and the cost of screening are main factors driving the total monitoring costs. Sharing the responsibility of monitoring dioxins within control points along the chain largely reduces the total monitoring costs. In each of the evaluated scenarios, the total costs of monitoring dioxins at individual control points are larger than the costs resulting from an optimal allocation of resources among all control points integrated in one overarching chain monitoring scheme. These results elicit the economic benefits of a chain approach to monitoring dioxins over an approach where each chain actor independently monitors dioxins.

    Chapter 5 determined cost-effective strategies for monitoring dioxins at the feed mill, in order to prevent dioxin contaminations in compound feed entering the poultry production chain. Results showed that monitoring dioxins in a combination of feed ingredients (i.e., Wheat and Corn) results into a high level of effectiveness of preventing elevated levels of dioxins in the compound feed (96.2%) at lower total costs (20% less) compared to the costs related to the 100% effective monitoring in charges of compound feed. Ingredients with dioxin concentrations above ML dioxins levels but with a low inclusion rate in the feed formulation are not detected by monitoring dioxins in compound feed as a result of the dilution effect.

    Chapter 6 provides a synthesis of the results obtained in the previous Chapters and discusses these findings with respect to existing literature. This chapter also presents a critical discussion of methodological issues regarding data availability and modelling approaches used to analyse the data. This is followed by a discussion about the implications of the findings for policy makers as well as for food safety managers in agri-food business, and topics for further research that go in line with this dissertation. The main conclusions of this dissertation are the following:

    • There is financial room for monitoring dioxins along the Dutch dairy chain (between €500.4 thousand and €28.8 million per year) suggested by the size of the direct financial losses of a dioxin incident in the dairy chain (Chapter 2).

    • Monitoring bulk milk with 95% probability of detecting contamination levels as low as 2 pg TEQ/g fat requires resources of approximately €2.6 million/month (Chapter 3).

    • Testing dioxins levels in aggregate samples rather than in individual samples is a valid strategy for reducing monitoring costs. However, pooling strategies must take into account the target dioxin concentration in individual samples, in order to avoid dilution of dioxin levels and to ensure the proper detection of dioxin contamination (Chapter 3).

    • Focusing monitoring efforts at feed mills to tackle a dioxin contamination in the food chain is the cost-effective solution of monitoring dioxins for the whole pork chain (Chapter 4).

    • Monitoring dioxins in an integrated chain approach rather than in an independent chain actor approach has large economic benefits for the whole pork chain (Chapter 4).

    • For all evaluated contamination scenarios, monitoring dioxins at the feed mill stage contributes, on average, 90% to the total effectiveness of the optimal monitoring schemes (Chapter 4).

    • It is cost effective to focus dioxin monitoring efforts in earlier rather than later stages of the pork and poultry chain, when a dioxin contamination originates from a source early in the chain (Chapter 4 and 5).

    • Elevated levels of dioxins in compound feed not only depend on the concentration of dioxins in feed ingredients but also on the inclusion rate of the ingredients in the compound feed (Chapter 5).

    Cost-effective allocation of resources for monitoring dioxins along the pork production chain
    Lascano Alcoser, V. ; Mourits, M.C.M. ; Fels-Klerx, H.J. van der; Heres, L. ; Velthuis, A.G.J. ; Hoogenboom, L.A.P. ; Oude Lansink, A.G.J.M. - \ 2014
    Food Research International 62 (2014). - ISSN 0963-9969 - p. 618 - 627.
    critical control points - dibenzo-p-dioxins - polychlorinated-biphenyls - contaminated feed - food-chain - incident - pcbs - pigs - perspective - pcdd/fs
    The pork chain has been seriously affected by dioxin incidents in recent decades. Hence, monitoring dioxins is crucial for detecting contaminations in the pork chain. This study aims to develop a decision support tool (optimization model) to determine cost-effective monitoring schemes for detecting and tracing a dioxin contamination over multiple control points along the pork production chain. The optimization model considers four control points (i.e. at the supplier of fatty feed ingredients, the feed mill, the slaughterhouse and the fat melting facility). It was applied to several hypothetical contamination scenarios involving contaminated animal fatty feed ingredients. The cost-effective allocation of resources for detecting and tracing the dioxin contamination from an integrated chain approach (i.e. considering all control points) focuses on monitoring at the feed mill, followed by the supplier of fatty feed ingredients and - to a lesser extent - by the slaughterhouse. The number of contaminated feed mills, the frequency of dioxin contaminations, the required level of effectiveness, and the cost of screening are main factors driving the total monitoring costs. Sharing the responsibility of monitoring dioxins within control points along the chain largely reduces the total monitoring costs. In each of the evaluated scenarios, the total costs of monitoring dioxins at individual control points are larger than the costs resulting from an optimal allocation of resources among all control points integrated in one overarching chain monitoring scheme. These results elicit the economic benefits of a chain approach to monitoring dioxins over an approach where each chain actor independently monitors dioxins. The developed model can be used by decision makers in the feed and food industry for determining optimal schemes for monitoring dioxins in the pork chain focusing on preventing specific contaminations
    Optimizing bulk milk dioxin monitoring based on costs and effectiveness
    Lascano Alcoser, V. ; Velthuis, A.G.J. ; Fels-Klerx, H.J. van der; Hoogenboom, L.A.P. ; Oude Lansink, A.G.J.M. - \ 2013
    Journal of Dairy Science 96 (2013)7. - ISSN 0022-0302 - p. 4125 - 4141.
    food - contamination - incident - chain - inspection - risk - feed
    Dioxins are environmental pollutants, potentially present in milk products, which have negative consequences for human health and for the firms and farms involved in the dairy chain. Dioxin monitoring in feed and food has been implemented to detect their presence and estimate their levels in food chains. However, the costs and effectiveness of such programs have not been evaluated. In this study, the costs and effectiveness of bulk milk dioxin monitoring in milk trucks were estimated to optimize the sampling and pooling monitoring strategies aimed at detecting at least 1 contaminated dairy farm out of 20,000 at a target dioxin concentration level. Incidents of different proportions, in terms of the number of contaminated farms, and concentrations were simulated. A combined testing strategy, consisting of screening and confirmatory methods, was assumed as well as testing of pooled samples. Two optimization models were built using linear programming. The first model aimed to minimize monitoring costs subject to a minimum required effectiveness of finding an incident, whereas the second model aimed to maximize the effectiveness for a given monitoring budget. Our results show that a high level of effectiveness is possible, but at high costs. Given specific assumptions, monitoring with 95% effectiveness to detect an incident of 1 contaminated farm at a dioxin concentration of 2 pg of toxic equivalents/g of fat [European Commission's (EC) action level] costs €2.6 million per month. At the same level of effectiveness, a 73% cost reduction is possible when aiming to detect an incident where 2 farms are contaminated at a dioxin concentration of 3 pg of toxic equivalents/g of fat (EC maximum level). With a fixed budget of €40,000 per month, the probability of detecting an incident with a single contaminated farm at a dioxin concentration equal to the EC action level is 4.4%. This probability almost doubled (8.0%) when aiming to detect the same incident but with a dioxin concentration equal to the EC maximum level. This study shows that the effectiveness of finding an incident depends not only on the ratio at which, for testing, collected truck samples are mixed into a pooled sample (aiming at detecting certain concentration), but also the number of collected truck samples. In conclusion, the optimal cost-effective monitoring depends on the number of contaminated farms and the concentration aimed at detection. The models and study results offer quantitative support to risk managers of food industries and food safety authorities
    Estimating the financial consequences of a milk dioxin contamination in the Dutch dairy chain
    Lascano Alcoser, V. ; Velthuis, A.G.J. ; Hoogenboom, L.A.P. ; Fels-Klerx, H.J. van der - \ 2012
    In: Book of Abstracts of the 13th International Symposium on Veterinary Epidemiology and Economics. - - p. 309 - 309.
    The aim of this study was to quantify the financial consequences of a milk-dioxin crisis on the stages of the dairy chain involved. The milk dioxin contamination impact model was designed for this purpose and also was used to estimate the net costs of control measures limiting the impact. Results obtained based on the assumption of the worst-case scenario in which the entire daily production of each business unit from feed supplier to milk processor is contaminated suggested that the financial impact of one dioxin incident would be J141.2 million. Another assumption was that the dioxin contamination started at one feed processing plant and was detected 2 weeks after initial contamination (the high-risk period), which would result in the involvement of 714 dairy farms, 26 milk processors, and 2,664 retailers. The stages of the chain that contributed most to the total net costs were the milk processor (76.9%) and the dairy farm (20.5%). If the high-risk period were shorter, i.e. 3 days, the estimated total financial impact decreases to J10.9 million. Thus, early detection of the contamination is crucial for decreasing the number of food businesses involved and lowering the total financial impact. The most influential inputs of the model were the sale price of milk at the processing stage, the daily amount of milk processed per processing plant, the farm-blocking period, and the daily amount of milk produced per farm. However, the effect of these inputs on the total financial impact was less than 10.0%. These results can be used to establish priorities in the application of control measures to limit the financial and public health impacts of a possible food safety incident.
    Assessing the costs versus the effectiveness of dioxin monitoring in bulk milk
    Lascano Alcoser, V. ; Velthuis, A.G.J. ; Fels-Klerx, H.J. van der; Hoogenboom, L.A.P. ; Oude Lansink, A.G.J.M. - \ 2012
    In: Book of Abstracts of the 13th International Symposium on Veterinary Epidemiology and Economics. - - p. 130 - 130.
    Dioxins are environmental pollutants present in the agri-food chains. The negative consequences associated with their presence in food are not only related to human health but also to the food businesses operators embedded in the food chains. Food and feed dioxin-monitoring programs aiming to detect, control and reduce the presence of dioxins in food chains have been implemented. However, to date, the costs and effectiveness of such programs have not been assessed. This study aims to quantify the costs and effectiveness of bulk milk dioxin monitoring to optimize the sampling and pooling strategies for a selected set of contamination scenarios. Two different optimization models were built using a linear programming methodology. The first model aims to minimize the monitoring costs subject to a minimum required effectiveness, while the second model aims to maximize the effectiveness of monitoring for a given monitoring budget. This study shows that a higher level of effectiveness is possible but at higher costs. Monitoring with 95% effectiveness aiming to detect a single contaminated farm with a tank milk concentration equal to the EC legal action level (i.e. 2 pg TEQ/g fat) would cost €2.6 million per month. A large reduction in monitoring costs (at the same level of effectiveness) is possible at intermediate incident sizes (i.e. 73% reduction when two farms are contaminated at 3 pg TEQ/g fat), which is close to the smallest incident aimed to be detected. Both models enable the analysis of the costs and the effectiveness of bulk milk dioxin monitoring programs, offering quantitative support to risk managers of the food industry and the food safety authority. Additionally, this study proves that the effectiveness of monitoring depends not only on the performance of the detection tests but also on the number of samples collected.
    Test of the rosetta pedotransfer function for saturated hydraulic conductivity
    Alvarez-Acosta, C. ; Lascano, R.J. ; Stroosnijder, L. - \ 2012
    Open Journal of Soil Science 2 (2012)3. - ISSN 2162-5379 - p. 203 - 212.
    Simulation models are tools that can be used to explore, for example, effects of cultural practices on soil erosion and irrigation on crop yield. However, often these models require many soil related input data of which the saturated hy- draulic conductivity (Ks) is one of the most important ones. These data are usually not available and experimental de- termination is both expensive and time consuming. Therefore, pedotransfer functions are often used, which make use of simple and often readily available soil information to calculate required input values for models, such as soil hydraulic values. Our objective was to test the Rosetta pedotransfer function to calculate Ks. Research was conducted in a 64-ha field near Lamesa, Texas, USA. Field measurements of soil texture and bulk density, and laboratory measurements of soil water retention at field capacity (–33 kPa) and permanent wilting point (–1500 kPa), were taken to implement Rosetta. Calculated values of Ks were then compared to measured Ks on undisturbed soil samples. Results showed that Rosetta could be used to obtain values of Ks for a field with different textures. The Root Mean Square Difference (RMSD) of Ks at 0.15 m soil depth was 7.81 ¿ 10–7 m·s–1. Further, for a given soil texture the variability, from 2.30 ¿ 10–7 to 2.66 ¿ 10–6 m·s-1, of measured Ks was larger than the corresponding RMSD. We conclude that Rosetta is a tool that can be used to calculate Ks in the absence of measured values, for this particular soil. Level H5 of Rosetta yielded the best results when using the measured input data and thus calculated values of Ks can be used as input in simulation models
    Financial Impact of a Dioxin Incident in the Dutch Dairy Chain
    Lascano Alcoser, V. ; Velthuis, A.G.J. ; Hoogenboom, L.A.P. ; Fels-Klerx, H.J. van der - \ 2011
    Journal of Food Protection 74 (2011)6. - ISSN 0362-028X - p. 967 - 979.
    recall costs - netherlands - food - contamination - pcbs - farm - feed - milk
    The aim of this study was to quantify the financial consequences of a milk-dioxin crisis on the stages of the dairy chain involved. The milk dioxin contamination impact model was designed for this purpose and also was used to estimate the net costs of control measures limiting the impact. Results obtained based on the assumption of the worst-case scenario in which the entire daily production of each business unit from feed supplier to milk processor is contaminated suggested that the financial impact of one dioxin incident would be J141.2 million. Another assumption was that the dioxin contamination started at one feed processing plant and was detected 2 weeks after initial contamination (the high-risk period), which would result in the involvement of 714 dairy farms, 26 milk processors, and 2,664 retailers. The stages of the chain that contributed most to the total net costs were the milk processor (76.9%) and the dairy farm (20.5%). If the high-risk period were shorter, i.e., 3 days, the estimated total financial impact decreases to J10.9 million. Thus, early detection of the contamination is crucial for decreasing the number of food businesses involved and lowering the total financial impact. The most influential inputs of the model were the sale price of milk at the processing stage, the daily amount of milk processed per processing plant, the farm-blocking period, and the daily amount of milk produced per farm. However, the effect of these inputs on the total financial impact was less than 10.0%. These results can be used to establish priorities in the application of control measures to limit the financial and public health impacts of a possible food safety incident
    Loss of water through terminated wheat plants: a wick effect.
    Koekkoek, E.J.W. ; Lascano, R.J. ; Hicks, S.K. ; Krieg, D.R. ; Stroosnijder, L. - \ 1995
    In: Annual Meeting 1995, Agronomy Abstracts, St.Louis, Missouri. - p. 15 - 15.
    A simple method for measuring the spatial distribution of soil hydraulic properties.
    Lascano, R.J. ; Stroosnijder, L. - \ 1993
    Soil Science Society of America Journal 57 (1993)6. - ISSN 0361-5995 - p. 1479 - 1484.
    capillaire opstijging - hysterese - vocht - deeltjesgrootteverdeling - permeabiliteit - retentie - bodem - grondmechanica - bodemstructuur - bodemtextuur - zuiging - spanning - geostatistiek - pf-curve - capillary rise - hysteresis - moisture - particle size distribution - permeability - retention - soil - soil mechanics - soil structure - soil texture - suction - tension - geostatistics - pf-curve
    A method to calculate the statistical distribution of a scaling factor from soil-water retention curves consists of measuring the particle-size distribution by laser scattering, computing soil water retention curves using the Arya and Paris model, and calculating a scale factor for each function. The method was tested by comparing measured and predicted soil-water retention curves. The advantage of this method is in its simplicity and ease of use. The applicability of the method to a given soil texture depends on the verification of the calculated soil-water retention functions.
    Test and analysis of a model of water use by sorghum
    Bavel, C.H.M. van; Lascano, R.J. ; Stroosnijder, L. - \ 1984
    Soil Science 137 (1984)6. - ISSN 0038-075X - p. 443 - 456.
    We carried out a field experiment with a well-developed sorghum crop to validate a water use and uptake model. The calculated evapotranspiration over a 50-d period was not significantly different from the experimental values. Soil water content profiles calculated with the model showed some systematic deviation from the measured values, possibly because the physical nature of the profile was assumed to be homogeneous. The spread of the simulated results reflects the field variation of hydraulic soil properties.-
    Estimating net rainfall, evaporation and water storage of a bare soil from sequential L-band sensitivities
    Stroosnijder, L. ; Lascano, R.J. ; Newton, R.W. ; Bavel, C.H.M. van - \ 1984
    In: Proc. IGARSS'84, ESA, Noordwijkerhout - p. 197 - 202.
    A simple method to scale soil hydraulic properties
    Lascano, R.J. ; Stroosnijder, L. - \ 1984
    Agronomy Abstracts (1984). - ISSN 0375-5495 - p. 169 - 169.
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