1 Introduction.- 2 Ethical Aspects of Risk.- 3 Effects of Ionising Radiation in the Low-Dose Range - Radiobiological Basis.- 4 Toxicology of Chemical Carcinogens.- 5 Epidemiological Perspectives on Low-Dose Exposure to Human Carcinogens.- 6 Mathematical Models of Carcinogenesis.- 7 Comparing Summary of Action of Ionising Radiation and Chemicals in Carcinogenesis.- 8 Hypothesis Testing and the Choice of the Dose-Response Model.- 9 Risk Evaluation and Communication.- 10 Low Doses in Health-Related Environmental Law.- 11 Summary.- 12 Zusammenfassung.- 13 Recommendations for Environmental Risks to Human Health: Evaluation and Regulatory Processes.- 14 Glossary.- 15 Abbreviations.- 16 List of Authors.