The ever-increasing release of harmful agents due to human activities has led in some areas of the world to heavy pollution. In order to protect human health and the environment, environmental standards that shall limit the release and the concentration of those toxic agents in the environment and hence the exposure to it have to be established. The related assessment and decision-making procedures have to be based on solid scientific data about the effects and mechanisms of these agents as well as on ethical, social and economic aspects. For risk evaluation, the knowledge of the dose response curve is an essential prerequisite. Dose responses without a threshold dose are most critical in this connection. Such dose responses are assumed for mutagenic and carcinogenic effects, which, therefore, dominate also the discussion in this book. In the environmentally important low dose range, risk estimation can only be achieved by extrapolation from higher doses with measurable effects. The extrapolation is accompanied with uncertainties which makes risk evaluation as well as risk communication frequently problematic. In order to ensure rational efficient and fair decisions beyond a sound scientific assessment the dialogue between disciplines, with the affected people and with the general public is necessary. In this book, the whole range of relevant and essential aspects of risk evaluation and standard setting is addressed. Starting with the ethical foundations, the sound analysis of recent scientific findings sets the frame for further reflections by theory of cognition, psychosocial sciences, and jurisprudence. The authors end up with concluding recommendations for coping with the recentproblems of standard setting in the field of environmentally relevant low doses. The book is designed to a readership of scientists, legislators, administrators, and the interested public.

The Europaische Akademie Bad Neuenahr-Ahrweiler GmbH is concerned with the scientific study ofthe consequences of scientific and technological advance for the individual, society and the natural environment and, therefore, not least with the study of consequences of recent developments in life-sciences and medical disci- plines. The Europaische Akademie intends to contribute to find a rational way for society to deal with the consequences of scientific progress. This aim is mainly realised by proposing recommendations for options of action with long-term social acceptance. The work of the Europaische Akademie mostly takes place in tempo- rary interdisciplinary project groups, whose members are recognised scientists from European universities and other independent institutes. In the light of recent discussions on the validity of scientific assumptions con- cerning the extrapolation ofharmful effects into the low-dose range the Europais- che Akademie set up a project on "Lew-Dose Exposures in the Environment their Risk Assessments and Regulatory Processes" in January 2001. Experts ofradiobi- ology, toxicology, medical epidemiology, modelling,jurisprudence, psychology and philosophy from different European countries wcre brought together to discuss cur- rent scientific developments in environmental standard setting and risk evaluation of substances and ionising radiation at very low doses in order to ensure rational, efficient, and fair decisions. I am glad that by means ofthis memorandum, that continues our work on envi- ronmental standards and after our recommendations with respect to the regulation ofcombined agents we can now focus on the effects and the regulation ofharmful agents in the very low-dose range.

Im Rahmen dieser Studie werden aus naturwissenschaftlich-medizinischer, soziologischer, oekonomischer, juristischer und philosophischer Perspektive Notwendigkeit, Realisierbarkeit und Konsequenzen von Umweltstandards fur kombinierte Expositionen untersucht. Auf Expositionen des Menschen - dabei besonders deren karzinogene sowie genotoxische Wirkungen - sowie Expositionen einer Auswahl von Pflanzen, anhand derer die pragmatisch dringlichsten Fragen beantwortet werden, ist das Hauptaugenmerk der Studie gerichtet. Auf der Grundlage einer auf Wirkungsmechanismen basierenden Kategorisierung kombinierter Expositionen werden Kriterien erarbeitet, die trotz der Komplexitat der einzelnen Wirkungszusammenhange eine Grenzwertsetzung zur Erhaltung bzw. Erreichung konkreter Umweltqualtitatsziele ermoeglicht.