This report contains the collective views of an international group of experts and docs not necessarily represent the decisions or the stated policy of either the World Health Organization or the United Nations Environment Programme. Environmental Health Criteria 14 ULTRAVIOLET RADIATION Published under the joint sponsorship of the United Nations Environment Programme, the World Health Organization and the International Radiation Protection Association Is'' HI 21 World Health Organization -'- Geneva, 1979 /// I ISBN 92 4 154074 5 © World Health Organization 1979 Publications of the World Health Organization enjoy copyright protec- tion in accordance with the provisions of Protocol 2 of the Universal Copy- right Convention. For rights of reproduction or translation of WHO publi- cations, in part or in toto, application should be made to the Office of Publications, World Health Organization, Geneva, Switzerland. The World Health Organization welcomes such applications. The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or of certain manufacturers' products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not men- tioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters. PRINTED IN FINLAND 79/4447 - VAMMALAN KIRJAPAINO OY, VAMMALA - 6500 CONTENTS ENVIRONMENTAL HEALTH CRITERIA FOR ULTRAVIOLET RADIATION SUMMARY AND RECOMMENDATIONS FOR FURTHER STUDIES 10 1.1 Summary 10 1.2 Recommendations for further studies 12 1.2.1 Measurement of ultraviolet radiation from 12 natural and artificial sources 1.2.1.1 Measurement devices 12 1.2.1.2 Monitoring of natural sources 13 1.2.1.3 Monitoring of artificial sources 13 1.2.1.4 Development of personal monitoring devices 13 1.2.1.5 Improvement of high intensity sources 13 1.2.2 Effects of UV-B, ISV-A, and visible light on cells and their constituents 14 1.2.3 The relationship between ultraviolet radiation and skin cancer 14 1.2.4 Epidemiological studies of skin cancer and ultraviolet radiation deficiency in man 15 1.2.4.1 Non-melanoma skin cancer 15 1.2.4.2 Malignant melanoma 15 1.2.4.3 Identification of populations with an increased risk of skin cancer 15 1.2.4.4 UVR deficiency 15 1.2.5 Studies of the interaction of ultraviolet radiation and environmental chemicals 16 1.2.6 Studies of beneficial effects 16 1.2.7 Control measures and protection 16 1.2.7.1 Control measures 16 1.2.7.2 Sunscreen preparations 17 1.2.7.3 Behavioural modifications 17 2. PROPERTIES AND MEASUREMENT OF ULTRAVIOLET RADIATION 17 2.1 Sources 17 2.1.1 Solar radiation - the biologically active UVR spectrum 17 2.1.1.1 Influence of stratospheric constituents 18 2.1.1.2 Influence of clouds, haze, and smog 18 2.1.1.3 Amount of sea level solar ultraviolet radiation in the biologically active UVR spectrum 20 2.1.2 Artificial sources 21 2.1.2.1 Gas discharge arcs 21 2.1.2.2 Fluorescent lamps 22 2.1.2.3 Carbon arcs 22 2.1.2.4 Quartz halogen lamps 22 2.1.2.5 Oxyacetylene, oxyhydrogen, and plasma torches 23 2.2 Detection and measurement of ultraviolet radiation 23 2.2.1 Units and conversion factors 23 2.2.2 Chemical and biological detectors 24 2.2.2.1 Photographic plates 24 2.2.2.2 Chemical methods 25 2.2.2.3 Biological detectors 25 25 2.2.3 Physical detectors 2.2.3.1 Radiometric devices 25 2.2.3.2 Photoelectric devices 26 2.2.4 Measuring devices 26 BIOLOGICAL EFFECTS OF ULTRAVIOLET RADIATION ON UNICELLULAR ORGANISMS, MAMMALIAN CELLS AND TISSUE, AND INVERTEBRATES 26 3.1 Introduction 26 3.1.1 Absorption spectra 27 3.1.2 Evaluation of administered and absorbed doses 28 3.1.3 Action spectra 23 3.2 The molecular basis of the effects of ultraviolet radiation on living matter 29 3.2.1 Molecular lesions in DNA 29 3,2.2 Consequences of photolesions 30 3.2.3 Repair of TJVR-induced lesions 30 3.2.3.1 Prereplication repair 30 3.2.3.2 Repair during or after replication 31 3.2.3.3 SOS repair 31 3.3 Bacteria and yeasts 32 3.3.1 Effects on bacterial cell constituents and macromolecular synthesis 32 3.3.2 Sublethal effects 32 Effects of ultraviolet radiation of wavelengths 3.3.3 longer than 280 nm 32 3.3.4 Genetic factors in photosensitivity 33 3.3.5 Repair of photolesions in bacteria 33 3.3.6 Yeasts 33 34 3.4 Protozoa 3.5 Effects on mammalian cells in culture 34 3.5.1 Sublethal effects 34 3.5.2 Effects of UV-A 34 3.5.3 Lesions produced in DNA 35 3.5.3.1 Pyrimidine dimers 35 3.5.3.2 DNA-protein cross-links as 3.5.4 The consequences of photolesions in 35 mammalian cells 3.5.4.1 Inhibition of DNA synthesis 35 3.5.4.2 Chromosome aberrations and mutagenic effects 36 3.5.5 The repair of photolesions 36 3.5.5.1 Photoreactivation 36 3.5.5.2 Excision repair 36 355.3 Repair during or after replication 37 35.5.4 SOS repair 37 3.5.6 Effects on cell-virus relationships 37 3.5.6.1 Sensitivity to viral infection 37 3.5.6.2 Viral transformation 37 3.5.6.3 Activation of viruses 38 3.6 Effects on invertebrates 38 3.6.1 Effects on eggs and embryos of invertebrates 38 3.6.2 Effects on insects 39 3.7 Modification of the effects of ultraviolet radiation by chemical agents 39 3.7.1 Halogenated aoalogues 39 3.7.2 Caffeine 39 3,7.3 Furocoumarins 40 3.7.4 Other photoscositizing agents 40 3.7.5 Protection by carotene 41 3.8 Conclusions 41 THE BIOLOGICAL ACTION OF ULTRAVIOLET RADIATION ON VERTEBRATE ANIMALS 41 4.1 General aspects 41 4.2 Acute reactions in skin 42 4.2.1 Epidermal changes 42 4.2,2 Erythema and inflammation 43 4.2.3 Tanning 45 4.3 Acute changes in the eye 46 4.3.1 Photokeratitis and photoconjunctivitis 46 4.3.2 Cataracts 47 4.4 Effects of long-term exposure of skin to UVR 50 4.4.1 UVR-induced mutagenesis and earcinogcnesis 50 4.4.1.1 Mutagenesis 50 4.4.1.2 Mechanism of UVR carcinogencsis 51 4.4.1.3 Tumour types 51 4.4.2 Species-specificity 54 4.4.3 Ultraviolet radiation as an initiating agent 55 4.5 Interactions between ultraviolet radiation and chemicals 56 4.5.1 Chemically-enhanced photocarcinogenesis 56 4.5.2 Interaction between light and chemical carcinogens 56 4.5.3 UVR-induced carcinogen formation 57 4.8 Physical and quantitative aspects of ultraviolet irradiation in animal studies 57 4.6.1 Carcinogenic action spectrum 57 4.6.2 Dose-response relationships 58 4.6.3 Physical factors influencing UVR carcinogenesis 59 4.7 The immune response to tumour induction 60 EFFECTS OF ULTRAVIOLET RADIATION ON MAN 61 5.1 Beneficial effects 61 5.2 Induction of eryihema in human skin 63 5.2.1 Action spectra of human skin erythema 64 5.3 Natural protection against erythema-inducing ultraviolet radiation 64 5.3.1 Melanin (sec also section 4.2.3) 64 5.3.2 Thickening of the stratum corneum 66 5.4 Solar elastosis and other dermal effects of ultraviolet radiation (see also section 4.2) 66 5.5 Ultraviolet radiation and skin cancer in man (see also section 4.2) 67 5.5.1 Anatomical distributioa of skin cancer 68 5.5.2 Occupation and skin cancer 68 5.5.3 Genetics and skin cancer 68 5.5.4 Geographical distribution of non-melanoma skin cancer 69 5.5.5 Dose-response relationship for skin caacer (sec also section 4.5.2) 74 5.5.6 Mortality from skin cancer 74 5.5.7 Malignant melanoma 75 5.6 Phototoxic and photoallergic diseases 76 5.6.1 Phototoxicity 76 5.6.2 Photoallergy 78 5.7 Pterygium and cancer of the eye 79 EVALUATION OF HEALTH RISKS TO MAN 79 6.1 The significance and extent of different environmental sources of ultraviolet radiation and pathways of exposure 79 6.2 Types of biological effects and their significance for human health 80 6.3 The risk associated with combined exposure with other agents 81 6.4 The population at risk geographical distribution, genetic influences, and occupation 82 6.5 The reliability and range of known dose-effect and dose-response curves 83 6.5.1 Dose-effect curves for acute skin erythema 83 6.5.2 Averages and limits, minimal and slightly more than minimal erythema doses 85 6.5.3 The 'erythema range" effects 86 6.5.4 Dose-response curves for keratoconjunctivitis 86 6.5.5 Dose-response relationship for photocarcinogenesis 86 GUIDELINES FOR HEALTH PROTECTION 87 7.1 Range of exposure limits 88 7.1.1 Exposure to solar ultraviolet radiation 88 7.1.2 Occupational exposure to artificial ultraviolet radiation 88 7.1.3 Exposure of general population to artificial ultraviolet radiation 90 7.1.4 Measurement of natural and artificial ultraviolet radiation 90 7.2 Health effects of solar ultraviolet radiation in the general population 91 7.3 UVR deficiency and its prevention 91 7.3.1 Insolation and ISV irradiation of built-up areas 91 7.3.2 Sunbathing and air-bathing in the prevention of UVR deficiency 92 7.3.3 Artificial ultraviolet radiation in the prevention of UVR deficiency 92 7.4 Protection against ultraviolet radiation 92 7.4.1 Sunscreen preparations 93 7.4.2 clothing 93 7.4.3 Behavioural conformity with environment 93 7.4.4 Occupational protection 94 REFERENCES 95 NOTE TO READERS OF THE CRITERIA DOCUMENTS While every effort has been made to present information in the criteria documents as accurately as possible without unduly delaying their publication, mistakes might have occurred and are likely to occur in the future.