G M Kendall

Doses to organs and tissues from radon and its decay products

This paper discusses the doses from radon and from its short-lived decay products to a number of organs and tissues and to the foetus. The aim is to put all these doses into context rather than concentrating only on the largest contributions. There is also a brief discussion of the evidence from epidemiology on the risks of exposure to radon and its decay products. As is well known, under normal circumstances the greatest hazard is to the respiratory tract from inhalation of radon decay products. Radon decay products may also give substantial doses to skin. Under some circumstances it seems likely that ingested radon could give significant doses to the stomach. Other risks appear to be smaller; the results given here allow them to be compared.

Further follow up of mortality and incidence of cancer in men from the United Kingdom who participated in the United Kingdom's atmospheric nuclear weapon tests and experimental programmes.

OBJECTIVES--To study the long term effects of participation in the United Kingdoms atmospheric nuclear weapon tests and experimental programmes and to test hypotheses generated by an earlier report, including the possibility that participation in tests caused small hazards of leukaemia and multiple myeloma. DESIGN--Follow up study of mortality and cancer incidence. SUBJECTS--21,358 servicemen and civilians from the United Kingdom who participated in the tests and a control group of 22,333 non-participants. MAIN OUTCOME MEASURES--Numbers of deaths; standardised mortality ratios; relative risks of mortality from all causes and 27 types of cancer. RESULTS--During seven further years of follow up the numbers of deaths observed in participants were fewer than expected from national rates for all causes, all neoplasms, leukaemia, and multiple myeloma (standardised mortality ratios 0.86, 0.85, 0.57, and 0.46); death rates were lower than in controls (relative risks 0.99, 0.96, 0.57, and 0.57; 90% confidence intervals all included 1.00). In the period more than 10 years after the initial participation in tests the relative risk of death in participants compared with controls was near unity for all causes (relative risk 0.99 (0.95 to 1.04) and all neoplasms (0.95 (0.87 to 1.04)); it was raised for bladder cancer (2.69 (1.42 to 5.20)) and reduced for cancers of the mouth, tongue, and pharynx (0.45 (0.22 to 0.93)) and for lung cancer (0.85 (0.73 to 0.99)). For leukaemia mortality was equal to that expected from national rates but greater than in controls for both the whole follow up period (1.75 (1.01 to 3.06)) and the period 2-25 years after the tests (3.38 (1.45 to 8.25)). CONCLUSION--Participation in nuclear weapon tests had no detectable effect on expectation of life or on subsequent risk of developing cancer or other fatal diseases. The excess of leukaemia in participants compared with controls seems to be principally due to a chance deficit in the controls, but the possibility that participation in the tests may have caused a small risk of leukaemia in the early years afterwards cannot be ruled out.

Follow up of mortality and incidence of cancer 1952–98 in men from the UK who participated in the UK's atmospheric nuclear weapon tests and experimental programmes

Aims: To extend and analyse follow up of mortality and cancer incidence among men who took part in the UKs atmospheric nuclear weapon tests and experimental programmes 40–50 years ago, with particular reference to multiple myeloma and leukaemia. Methods: A total of 21 357 servicemen and male civilians from the UK who participated in the tests and a control group of 22 333 male controls were followed over the period 1952–98. Analyses were conducted of mortality from various causes, and of mortality and incidence for 27 types of cancer. Results: Rates of mortality from all causes continued to be similar among test participants and controls with the longer follow up, with standardised mortality ratios (SMRs) of 89 and 88 respectively over the full follow up period. For all cancers, the corresponding SMRs were 93 for participants and 92 for controls. Mortality from multiple myeloma was consistent with national rates both for participants and controls, and the relative risk (RR) of myeloma incidence among participants relative to controls was 1.14 (90% CI 0.74 to 1.74) over the full follow up period and 0.79 (90% CI 0.45 to 1.38) during the extended period of follow up (1991–98). Over the full follow up period, leukaemia mortality among participants was consistent with national rates, while rates among controls were significantly lower, and there was a suggestion of a raised risk among test participants relative to controls (RR 1.45, 90% CI 0.96 to 2.17); the corresponding RR for leukaemia incidence was 1.33 (90% CI 0.97 to 1.84). After excluding chronic lymphatic leukaemia (CLL), which is not thought to be radiation inducible, the RR of leukaemia mortality increased to 1.83 (90% CI 1.15 to 2.93), while that for incidence was little changed. Analysis of subgroups of participants with greater potential for exposure provided little evidence of increased risks, although the numbers of men involved were smaller and the statistical power was therefore less. Among other types of cancer, only for liver cancer incidence was there evidence of differences in rates between participants and controls in both the earlier and in the additional period of follow up. Mortality rates among test participants from causes other than cancer were generally similar to those among the controls. Conclusions: Overall levels of mortality and cancer incidence in UK nuclear weapons test participants have continued to be similar to those in a matched control group, and overall mortality has remained lower than expected from national rates. There was no evidence of an increased raised risk of multiple myeloma among test participants in recent years, and the suggestion in the first analysis of this study of a raised myeloma risk is likely to have been a chance finding. There was some evidence of a raised risk of leukaemia other than CLL among test participants relative to controls, particularly in the early years after the tests, although a small risk may have persisted more recently. This could be a chance finding, in view of low rates among the controls and the generally small radiation doses recorded for test participants. However, the possibility that test participation caused a small absolute risk of leukaemia other than CLL cannot be ruled out.

Epidemiological studies of UK test veterans: II. Mortality and cancer incidence

An epidemiological study was set up in the 1980s of UK participants in the UK atmospheric nuclear weapons testing programme. A large cohort of test participants was established along with a closely matched comparison or control group. Three analyses of mortality and cancer incidence have been carried out. This review describes the development of the evidence on possible effects on test participants with especial emphasis on the most recent analysis. Other sources of evidence, particularly from studies of other groups of test participants, are also considered. It was concluded that overall levels of mortality and cancer incidence in UK nuclear weapons test participants were similar to those in a matched control group, and overall mortality was lower than expected from national rates. There was no evidence of an increased raised risk of multiple myeloma among test participants in recent years, and the suggestion in the first analysis of this cohort of a raised myeloma risk relative to controls is likely to have been a chance finding. There was some evidence of a raised risk of leukaemia other than chronic lymphatic leukaemia among test participants relative to controls, particularly in the early years after the tests. Whilst this could be a chance finding, the possibility that test participation caused a small absolute risk of leukaemia other than chronic lymphatic leukaemia cannot be ruled out.

Practical procedures for a radon etched track dosimetry service

Etched track detectors are widely used for the detection of radon and its decay products. They have many desirable attributes: they are small, cheap, simple, non-toxic and non-hazardous. Etched track detectors provide adequate accuracy for most radiological protection purposes provided stringent quality assurance is maintained. The UK validation scheme provides an important component of QA but continuous monitoring of conditions and results is also needed. If these conditions are observed, these detectors provide an entirely adequate tool for large-scale use in assessing levels of radon in houses. Accurate estimates of long-term average radon levels require a measurement over several months because of the short-term fluctuations in radon concentrations.

Controls on radioactivity in water supplies in England and Wales, with especial reference to radon

This note describes the legal and administrative controls on concentrations of radioactive materials, with especial reference to radon, in drinking water in England and Wales. These controls follow the EC Drinking Water Directive and Recommendations from the European Union. The Directive relates to radioactivity in drinking water generally, while the Recommendations are specific to radon. A distinction is made between private and public supplies, with more stringent controls on the latter. In general, problems in meeting the recommended levels are not expected in England and Wales.

Further analysis, incorporating assessment of the robustness of risks of cancer mortality in the National Registry for Radiation Workers

The mortality from leukaemia and other cancers in the National Registry for Radiation Workers is analysed to determine the subcategories of leukaemia in which the trend with dose is most marked. Differences between external (SMR) and internal analyses (of trends with external radiation dose) are assessed for the various leukaemia subtypes. The significance of the trend for leukaemia mortality observed in the previous analysis is largely accounted for by the group of chronic myeloid leukaemias. Sensitivity analyses are performed relating to various uncertain parameters to examine the robustness of the previously published findings. The magnitude (and significance) of the trend with dose for leukaemia is robust to a reasonable range of assumptions concerning the lag period; if a lag of 5 years is used the trend retains borderline levels of statistical significance (p=0.07); if lags of 0 or 2 years are employed rather more significant trends are apparent (p=0.03).

Epidemiological studies of UK test veterans: I. General description.

This review gives a general account of how and why epidemiological studies of UK participants in the nuclear weapons test programme were set up. There is a short description of the circumstances in which the tests were planned and executed and a discussion of the general considerations involved in designing studies to show whether the health of test participants suffered as a result of the tests. The companion review article summarises the results of the epidemiological studies.

Ionising radiation in infancy and adult cognitive function: Protocols for computed tomography must be optimised

Editor—Hall et al report adverse effects on adult cognitive function among male patients treated with radiation for skin haemangioma during infancy.1 The evidence for effects was strongest among those receiving the highest doses. It is unclear whether there was a dose threshold below which no effects occurred. This study of a sizeable cohort seems to be well conducted with minimal risk of bias. A group of patients with haemangioma was compared by brain dose rather than with an external group. Consequently confounding would seem plausible only if the severity of the clinical condition affected cognitive function and was correlated with brain dose. Other studies have shown adverse effects of radiation on intellectual development, although interpretation is complicated because some studies used higher doses from exposures in utero or may have been subject to confounding. Good radiation protection practice (reducing unnecessary exposures and minimising radiation doses) controls well established risks, largely of radiation induced cancers. Computed tomography entails higher doses than plain radiography. Computed tomography of the head is a first line examination only for children whose symptoms imply notable brain injury.2​2 Figure 1 Credit: PHILLIPPE PLAILLY/SPL Nevertheless, unless the protocol for computed tomography scanning is adjusted for infants, the brain dose (as opposed to the “effective dose,” which is integrated across the whole body) could exceed 100 mGy, within the upper range of doses in the study by Hall et al. This reinforces the need for optimising protocols for computed tomography, minimising the dose to the patient and restricting examinations to infants with clear clinical indications.