Jos Boesten is an expert in the field of fate of pesticides in the environment (both modelling and experimental assessment). He is specialised in developing exposure assessment methodologies for pesticide registration based on clearly defined goals to be agreed at the political level. These methodologies include leaching to groundwater and exposure of soil and aquatic organisms and of honey bees. Most of his work was for EU and Dutch pesticide registration but he has also been active in projects related to pesticide registration in Slovenia, Hungary and China. Jos has a drive for improving the interaction between the exposure and effect assessments because he considers this the limiting factor for the quality of methodologies for assessing the risk to organisms. He is first author of some 20 papers in peer-reviewed journals and works in the team ‘Environmental Risk Assessment’ of Alterra (part of Wageningen University and Research Centre, Netherlands).