Leo Posthuma is senior researcher at the Dutch National Institute for Public Health and the Environment (RIVM) and professor of Sustainability and Environmental Risks at Radboud University. He is European Registered Toxicologist (ERT) accorded by EUROTOX and a SETAC Registered Environmental Risk Assessor (CRA). He was lead editor on the 2002-book on the use of species sensitivity distributions modeling in ecotoxicology, which described the principles, data, approaches and utility of this modeling for environmental protection, environmental quality assessment and life cycle impact assessment. With such broad use of a model, he contributed to operationalization for vast numbers of chemicals, uncertainty analyses, solution-focused uses to address environmental problems from the local to the global scale, and intensive validation studies. He is member of the scientific advisory board of the Gothenburg Centre for Future Risk Assessment and Management (FRAM) and advisor of governments from the local to the global scale. Amongst others, he contributed to development of operational mixture approaches for various regulatory contexts, amongst which chemical safety assessment, life cycle impact assessment, food safety assessment, and environmental quality protection, assessment and management. He is member of the board of editors of Environmental Sciences Europe. His projects focus on the assessment of risks of human activities for the environment and human health, defining the problem, and on the evaluation of options to solve those problems in a sustainable way. Societal problems that are addressed range from local to global, and from chronic to acute. He contributes, amongst others, to the UNEP-SETAC/LCI initiative, to the UNEP/OCHA Joint Environment Unit tool for disaster assessment and management (FEAT, Flash Environmental Assessment Tool), and to solving complex environmental problems on water, soil and sediment pollution.