Radon and Public Health Report of the independent Advisory Group on Ionising Radiation RCE-11 Radon and Public Health Report of the independent Advisory Group on Ionising Radiation Documents of the Health Protection Agency Radiation, Chemical and Environmental Hazards June 2009 © Health Protection Agency 2009 Contents Foreword vii Membership of the Advisory Group on Ionising Radiation and the ix Subgroup on Radon Epidemiology Acknowledgements xiii Radon and Public Health 1 Executive Summary 3 1 Introduction 7 Key Points 7 1.1 Risks of radon exposure 8 1.2 Measures to limit human exposure to radon in UK homes 9 1.3 Policies on control of domestic exposures to radon in other countries 10 1.4 Remit of current report 10 2 Exposures to Radon in the UK 12 Key Points 12 2.1 Radon concentrations in homes 12 2.2 Distribution of residential exposures to radon in the UK 14 2.3 Maps of radon concentrations in UK homes 16 2.4 Occupational exposures to radon in the UK 18 2.5 Radon exposures in caves and abandoned mines 18 2.6 Radon concentrations in outside air 19 2.7 Radon in water 20 3 Risks of Lung Cancer from Radon 21 Key Points 21 3.1 European pooling study 23 3.2 North American pooling study 25 3.3 Chinese pooling study 26 3.4 Overall appraisal of risk of residential exposure to radon based on the three pooling studies 26 3.5 Summary of all evidence on risks of lung cancer 28 4 Number of Radon-induced Lung Cancers in the UK 31 Key Points 31 iii R ADON AND P UBLIC H EALTH 5 Effects of Radon Exposures Other than Lung Cancer 38 Key Points 38 5.1 Evidence from dose calculations 38 5.2 Evidence from epidemiology 40 5.3 Evidence from animal studies 42 5.4 Summary 42 6 Cost-effectiveness of Radon Preventive and Remedial Programmes in UK Homes 43 Key Points 43 6.1 Radon prevention in new homes 45 6.2 Radon remediation in existing homes 49 6.3 Discussion and conclusions 53 7 Conclusions 56 8 Recommendations 63 9 References 67 Appendices A Radiation Quantities and Units 71 A1 Quantities and units relating to radon exposure 72 A2 General dosimetric quantities 72 B Measurement of Radon Concentrations 75 B1 Rationale for measuring radon gas rather than decay products 75 B2 Time period of measurement 75 B3 Radon and radon decay product measurement methods 76 B4 Measurement of radon in water 78 B5 References 78 C Variability and Distribution of Residential Radon Concentrations 79 C1 Variability between measured radon concentrations in different homes in an area 79 C2 Year-to-year variability in measured residential radon concentrations 79 C3 Relationship between measured residential radon concentration and the long-term average for the UK 82 C4 Effect of year-to-year variability in measured residential radon concentrations in the European pooling study 84 C5 Distribution of residential radon concentrations in the UK 86 C6 References 89 D Radon Policy and Programmes in the UK 90 D1 References 93 iv C ONTENTS E Evidence from Radiobiology on the Induction of Lung Cancer by Radon 95 E1 Conclusions 97 E2 References 97 F Modelling Radon Doses to the Lung 99 F1 Estimation of absorbed dose to the lung from inhalation of radon 99 F2 Estimation of effective dose from inhaled radon decay products 105 F3 References 108 G Animal Evidence on Radon and Lung Cancer 111 G1 Conclusions 114 G2 References 114 H International Reviews of Radon Risks 116 H1 Lung cancer in radon-exposed miners 116 H2 BEIR VI Report 117 H3 IARC evaluation of radon risks 123 H4 EPA evaluation of radon risks 123 H5 References 124 I Epidemiology of Lung Cancer from Residential Exposure to Radon 126 I1 European pooling study 137 I2 North American pooling study 139 I3 Chinese pooling study 141 I4 Overall appraisal of risk of residential exposure to radon based on the three pooling studies 141 I5 Absolute risk of radon-induced lung cancer in the UK based on estimates of risk from the European pooling study 143 I6 Summary of all evidence on radon risks 143 I7 References 148 J Radon Doses to Organs Other than the Lung 152 J1 Doses to stomach 152 J2 Doses to skin 153 J3 Doses to haematopoietic tissue 155 J4 Comparison of doses to different organs 156 J5 Comparison of doses received from inhalation 158 J6 Comparison of doses received from ingestion 159 J7 Doses received by children 159 J8 References 160 K Cancers Other than Lung Cancer and Other Possible Health Effects 161 K1 All-cause mortality other than lung diseases 162 K2 Childhood cancer 163 K3 Adult haematological malignancies 168 v R ADON AND P UBLIC H EALTH K4 Gastric cancers 170 K5 Skin cancer 171 K6 Other cancers 172 K7 Other conditions 173 K8 Overall conclusions 174 K9 References 175 L Reducing Radon Concentrations 178 L1 Practical control of radon concentrations in new buildings 178 L2 Practical control of radon concentrations in existing buildings 179 L3 References 181 M Cost-effectiveness Analysis of Radon Preventive and Remedial Programmes in UK Homes 182 M1 Methods 183 M2 Data 187 M3 Results for new homes 190 M4 Results for existing homes 207 M5 Discussion and conclusions 223 M6 References 226 N Radon Testing as a Health Screening Programme 229 N1 Limitations of screening 229 N2 Criteria for adopting screening 230 Glossary 234 vi Foreword The Radiation Protection Division of the Health Protection Agency (HPA) undertakes research to advance knowledge about protection from the risks of ionising and non-ionising radiations. It provides laboratory and technical services, runs training courses, and provides expert information. It also has a statutory responsibility for advising UK government departments and those with regulatory responsibilities for ionising and non-ionising radiations in the fields of medical, public and occupational exposure. The HPA Radiation Protection Division was formed when the National Radiological Protection Board (NRPB) merged with the HPA on 1 April 2005. In 1995 the Director of the NRPB had set up the Advisory Group on Ionising Radiation (AGIR) that had as its terms of reference: ‘to review work on the biological and medical effects of ionising radiation relevant to human health in the occupational, public health, medical and environmental fields and advise on research priorities’ In addition, the AGIR was given the task of helping the NRPB, where appropriate, to deal with any urgent request for advice or work from the Department of Health or other government departments. The AGIR was reconstituted in 1999 as an independent body and reported directly to the Board of the NRPB; since April 2005 it reports to the HPA Board Subcommittee on Radiation, Chemical and Environmental Hazards. The remit of the AGIR is restricted to the provision of scientific judgements and does not include the development of specific recommendations relating to radiation protection policy. These are matters for the HPA and its Board. For details of the current work of the AGIR, see the website at www.hpa.org.uk. The AGIR has to date issued six reports that consider a heterogeneity in response to radiation, b guidance on promotion of further optimisation of medical exposures, c epidemiology of second cancers, d UK population risks for leukaemia, e review of risks from tritium, f high dose radiation effects and tissue injury. In 2000 the AGIR set up a Subgroup on Radon Epidemiology, with a remit to review the evidence of the effects of exposure to radon and its decay products on health, as relevant to the population of the UK. The present report prepared by the Subgroup also considers the available strategies for remediation of radon affected buildings and includes a health economics analysis of radon remediation. vii Radon and Public Health HAS BEEN PREPARED BY THE Subgroup on Radon Epidemiology of the Advisory Group on Ionising Radiation CHAIRMAN Professor J Little University of Aberdeen (until July 2004), University of Ottawa (from August 2004) MEMBERS Professor B A Bridges OBE University of Sussex Professor R A Cartwright Leeds University (retired) (from May 2004) Professor K K Cheng University of Birmingham (from October 2003 until May 2004) Dr C G Collier AEA Technology, Harwell Professor S C Darby University of Oxford Professor J S Fleming Southampton University Hospitals NHS Trust Dr D T Goodhead OBE Medical Research Council, Harwell (retired) Professor A Gray (from November 2001) University of Oxford Professor E Roman University of Leeds (from January 2002 until May 2003) Professor T Sorahan University of Birmingham (until September 2001) ix R ADON AND P UBLIC H EALTH ASSESSORS Dr R Hamlet Health Protection Agency, Chilton Dr G M Kendall University of Oxford (previously HPA) Dr A Macpherson Department for Environment, Food and Rural Affairs, London SECRETARIAT Dr J R Meara Health Protection Agency, Chilton Mr J C H Miles Health Protection Agency, Chilton Dr C R Muirhead Health Protection Agency, Chilton (Dr Kendall and Dr Hamlet also acted as Secretariat to the Subgroup) OBSERVERS Mr I Chell Department of Health, London Dr H Walker Department of Health, London x Advisory Group on Ionising Radiation CHAIRMAN Professor B A Bridges OBE University of Sussex MEMBERS Dr D T Goodhead OBE Medical Research Council, Harwell Professor P Hoskin University College London Hospitals Dr M P Little Imperial College Faculty of Medicine, London Professor T McMillan Lancaster University SECRETARIAT Dr S D Bouffler Health Protection Agency, Chilton HPA REPRESENTATIVE Dr J W Stather Health Protection Agency, Chilton OBSERVER Dr H Walker Department of Health, London xi Acknowledgements We would like to thank Mr C Scivyer (Building Research Establishment) and Mr R Shipman (Department for Communities and Local Government) for providing the information on the different methods of radon prevention and remediation and on their costs and effectiveness, and Dr P McGale and Dr S Read of the Clinical Trial Services Unit, University of Oxford, for assistance in preparing the report.