NRPB

Abstract

Lung cancer and radon in the home: first direct evidence of an effect in the UK population The National Radiological Protection Board (NRPB) has previously estimated that radioactive radon gas which emerges from the ground and accumulates within the home may account for roughly one in 20 cases of lung cancer in the UK. But this estimate, based on the experience of miners of uranium and other minerals, is indirect. Now, researchers at the Imperial Cancer Research Fund (ICRF) Cancer Epidemiology Unit at the University of Oxford have obtained the first direct evidence of the size of the risk in the UK Their findings agree with the NRPB's estimate. That very high concentrations of naturally occurring radon can cause cancer is well known. But estimates of the risk posed by radon at the lower concentrations found in the home have relied on data from miners whose occupational exposure to radon is relatively high. Staff working in the ICRF Cancer Epidemiology Unit, together with the NRPB, have supplemented these calculations with observations made in people's homes. `This study provides, for the first time, direct evidence on the risks associated with residential radon in the UK,' says Professor Sarah Darby, one of the investigators. `The results show that the risk is indeed about the size that had been suggested by the studies on miners.' The ICRF team carried out their research on people living in Southwest England, the region where indoor radon reaches its highest concentrations. The team contacted long term residents of the region who had been referred to the five hospitals in Devon and Cornwall where lung cancers are treated. To establish their exposure to radon, all patients were asked to list the addresses at which they had lived during the past 35 years. Two radon detectors were then installed in as many as possible of these homes, and left there for six months. Nine hundred and eighty-two lung cancer patients took part in the study, and the radon concentrations in their homes were compared with those of 3185 controls - either hospital patients not suffering from lung cancer, or representative members of the general population. The study results suggest that people who have lived for a long time in homes where the radon concentration is at the recommended UK Action Level (200 Bqm-3) have lung cancer rates about 20% higher than people whose homes have a concentration equal to the average for the whole country (20 Bqm-3). For those whose homes have a radon concentration of 400 Bqm-3 the estimated increase is around 40%. It is reckoned that in the UK around 50000 people are living in homes with radon concentrations at or above this level. Diagnostic Medical Exposures: Advice on Exposure to Ionising Radiation during Pregnancy A guidance booklet on the protection of the fetus during medical diagnostic procedures has been published jointly by the National Radiological Protection Board, The College of Radiographers and the Royal College of Radiologists. Certain modern diagnostic x-ray examinations can result in relatively high radiation doses to patients. For example, extensive computed tomography (CT) scans can give doses of several or even tens of milligrays (mGy) to patients, which are higher than the doses they would receive from standard diagnostic x-ray techniques. Given this, NRPB, CoR and RCR advise that such procedures should not be used on women patients who are definitely pregnant, or on women who could be pregnant, unless there are firm clinical reasons for the examination. This is to protect the embryo/fetus from exposure to relatively high radiation doses unless there is clear benefit to the mother. The booklet is aimed at radiographers, radiologists and those involved in nuclear medicine and provides practical guidance on how to minimise exposure of the embryo/fetus before pregnancy is known by the mother, and to reduce the risks of any exposures to acceptable levels. This pocket publication is based on the NRPB comprehensive advice first published in 1993. It is in a concise and user-friendly format for those working in hospital departments of radiology and nuclear medicine. As well as providing practical guidance on the implementation of NRPB advice in the everyday practice of radiology and nuclear medicine, it also provides the scientific background to the advice and the latest information on doses from diagnostic procedures in the UK. Single copies of the booklet can be obtained from the NRPB Information Office, Chilton, Didcot, Oxon OX11 0RQ (e-mail information@ nrpb.org.uk). For multiple copies, a charge of �1.00 per copy will be made (cheque with order, payable to NRPB).