GUEST EDITORIAL PART I: ICRP STATEMENT ON TISSUE REACTIONS PART II: EARLY AND LATE EFFECTS OF RADIATION IN NORMAL TISSUES AND ORGANS - THRESHOLD DOSES FOR TISSUE REACTIONS IN A RADIATION PROTECTION CONTEXT ABSTRACT PREFACE EXECUTIVE SUMMARY GLOSSARY 1. INTRODUCTION 1.1. Purpose of report 1.2. Definition and nature of tissue reactions to ionising radiation 1.3. General principles of radiation effects in cells and tissues 1.4. References 2. RESPONSE OF TISSUES AND ORGANS TO RADIATION 2.1. Haematopoietic and immune systems 2.2. Digestive system 2.3. Reproductive system 2.4. Skin 2.5. Cardiovascular and cerebrovascular systems 2.6. Eye 2.7. Respiratory system 2.8. Urinary tract 2.9. Musculoskeletal system 2.10. Endocrine system 2.11. Nervous system 2.12. References 3. MODIFIERS OF NORMAL TISSUE RESPONSE 3.1. Terminology 3.2. Mechanisms of action 3.3. Influence of modifiers on radiation response in tissue 3.4. References 4. THRESHOLD DOSES IN RELATION TO RADIOSENSITIVITY OF ORGANS AND TISSUES 4.1. Introduction 4.2. Haematopoietic and immune systems 4.3. Digestive system 4.4. Reproductive system 4.5. Skin 4.6. Cardiovascular and cerebrovascular systems 4.7. Eye 4.8. Respiratory system 4.9. Urinary tract 4.10. Musculoskeletal system 4.11. Endocrine system 4.12. Nervous system 4.13. Conclusions 4.14. References ANNEX A. SUMMARY OF STUDIES OF EXPOSURE AND OPACITIES OR CATARACTS