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We propose new models for dealing with various sources of variability and uncertainty that influence risk assessments for dietary exposure. The uncertain or random variables involved can interact in complex ways, and the focus is on methodology for integrating their effects and on assessing the relative importance of including different uncertainty model components in the calculation of dietary exposures to contaminants, such as pesticide residues. The combined effect is reflected in the final inferences about the population of residues and subsequent exposure assessments. In particular, we show how measurement uncertainty can have a significant impact on results and discuss novel statistical options for modeling this uncertainty. The effect of measurement error is often ignored, perhaps due to the laboratory process conforming to the relevant international standards, for example, or is treated in an ad hoc way. These issues are common to many dietary risk analysis problems, and the methods could be applied to any food and chemical of interest. An example is presented using data on carbendazim in apples and consumption surveys of toddlers.

International audience ; A computer-based decision support tool (p-EMA) has been developed to support UK Government policy of optimising agricultural pesticide use. The system estimates risks to a wide range of taxonomic groups and environmental compartments using methods consistent with current regulatory assessments, but also allows adjustments to reflect formulation, the local conditions and the environmental costs and benefits of varying management practices. Simple models of the dispersion pathways of the pesticide in the local environment are used to estimate predicted environmental concentrations in the field and margin soil, surface water and groundwater. Exposure estimates are then combined with the toxicological properties of the pesticide in the form of toxicity:exposure ratios. Concentrations in groundwater are calculated on the basis of a meta-version of the MACRO model linked to environmental and pesticide databases. Surface water concentrations are taken as the maximum of those arising from inputs via spray drift and drainflow. ; p-EMA : Simulation de l'évolution des pesticides dans l'environnement pour un système d'évaluation du risque au niveau de l'exploitation. Un système expert d'aide à la décision (p-EMA) a été développé afin d'assister la démarche britannique d'optimisation de l'utilisation agricole de pesticides. Le système estime le risque d'impact environnemental sur un grand nombre d'organismes sur la base des mêmes méthodes utilisées dans l'homologation des produits de protection des plantes. Le système tient compte du type de formulation utilisé, des conditions environnementales locales et applique une approche perte-bénéfice vis-à-vis de l'environnement dans l'application de différentes alternatives de gestion de traitement. Des modèles simples de transfert de pesticides dans l'environnement sont utilisés pour estimer les concentrations dans le sol et les eaux de surface et souterraines. Ces concentrations sont comparées aux données écotoxicologiques sur la base d'un quotient ...

International audience ; This paper reports the development of methods for assessing the environmental risks of pesticide use in a farm-level evaluation tool. The basic risk indices that were used, and the criteria used to define different levels of risk, were designed to be consistent with national and EU regulatory risk assessment procedures. They took account of both toxicity and exposure and were responsive to the influence of local conditions and practices, such as pesticide application methods and habitat structure. They also took account of 'higher tier' risk assessments carried out for pesticide approvals. The outputs of the system were designed to provide clear and meaningful information for users at various levels of detail, from the individual pesticide application to an overall farm eco-rating. It is recommended that the principle of consistency with regulatory risk assessment should also be applied to the development of other policy instruments such as consumer labels and pesticide taxes. ; p-EMA : Évaluation des risques écologiques des pesticides pour un système d'évaluation du risque au niveau de l'exploitation agricole. Cet article rapporte le développement de méthodes d'évaluation des risques environnementaux liés à l'emploi des pesticides avec un outil d'évaluation à l'échelle de l'exploitation. Les indices de risque fondamentaux utilisés et les critères de définition des différents niveaux de risque, ont été mis au point pour être compatibles avec les procédures nationales et européennes. Ils tiennent compte de la toxicité et de l'exposition, et sont sensibles aux conditions et pratiques locales (méthodes d'application des pesticides, structure de l'habitat). Ils tiennent également compte des évaluations des risques " de haut niveau " conduites pour les agréments des pesticides. Les sorties du système fournissent des informations claires et significatives aux utilisateurs, à divers niveaux de détail, de l'application du pesticide à l'éco-évaluation globale au niveau de l'exploitation. Le ...

Since the foot‐and‐mouth disease outbreak of 2001 in the United Kingdom, there has been debate about the sharing, between government and industry, both the costs of livestock disease outbreaks and responsibility for the decisions that give rise to them. As part of a consultation into the formation of a new body to manage livestock diseases, government veterinarians and economists produced estimates of the average annual costs for a number of exotic infectious diseases. In this article, we demonstrate how the government experts were helped to quantify their uncertainties about the cost estimates using formal expert elicitation techniques. This has enabled the decisionmakers to have a greater appreciation of government experts' uncertainty in this policy area.