§ Mr. MaclennanTo ask the Secretary of State for Scotland when the report of the case study of leukaemia in the Dounreay area, recommended by the second report of the Committee on Medical Aspects of Radiation in the Environment will be published.
§ Mr. Michael ForsythThe report will be published tomorrow in theBritish Medical Journal and copies will be available in the House. The report, commissioned by the Scottish Office Home and Health Department, prepared by the information and statistics division of the Common Services Agency, concludes that the observed excess incidence of childhood leukaemia and non-Hodgkin's lymphoma—NHL—in the area within 25 km of Dounreay cannot be explained by paternal exposure to ionising radiation prior to conception. The authors point out that an apparent association between the use of beaches by the children in the vicinity of Dounreay and the incidence of childhood leukaemia and NHL should be treated with caution.
COMARE has stated in its advice that these results taken alone do not suggest paternal employment at Dounreay nuclear establishment as a factor in the causation of childhood leukaemia/NHL in the neighbourhood and indeed make it clear that such employment cannot be a full explanation of the excess incidence observed in the vicinity of Dounreay. However, the statistical power of the study is inevitably very low and the study cannot refute the suggestion from the study of Gardner et al. that fathers' recorded external radiation dose may be related to the incidence of leukaemia/NHL in their offspring.
The Dounreay study has been referred to the independent expert Committee on Medical Aspects of Radiation in the Environment (COMARE). The text of its advice, which the Government have accepted, is as follows:
COMARE Statement of Advice
Results of a case control study of leukaemia and non Hodgkins Lymphoma in children in Caithness near the Dounreay nuclear installation—Urquhart J. D., Black R. J., Muirhead M. J., Sharp L., Maxwell M., Eden O. B., Adams Jones D.
188WBackground
1. In 1988 COMARE published its second report "Investigation of the possible increased incidence of leukaemia in young people near the Dounreay Nuclear Establishment, Caithness, Scotland" (1). The report made eight recommendations to Government. The first of these concerned a case control study of young people registered as cases of leukaemia or lymphoma in the Dounreay area. The study was commissioned by the Scottish Home and Health Department in 1988 and was undertaken by the Information and Statistics Division of the Common Services Agency for the Scottish Health Service in conjunction with the Department of Paediatric Haematology, Royal Hospital for Sick Children Edinburgh. DN The findings have now been published in the British Medical Journal (2).
2. The authors' stated objective was "To examine whether the observed excess of childhood leukaemia and non-Hodgkin's lymphoma in the area around the Dounreay Nuclear Installation is associated with established risk factors or with factors related to the plant or with parental occupation in the nuclear industry".
3. The Minister of State at the Scottish Home and Health Department referred the results of the studies to COMARE for consideration and advice.
The Study
4. The authors ascertained 14 cases of leukaemia or non-Hodgkin's lymphoma (NHL) in under 15 year olds, resident in Caithness, registered between 1968 and 1986. Controls were matched for date of birth and mother's place of residence at child's birth (either within 25km of Dounreay or within the remainder of Caithness). Data from birth certificates and parental employment records from the nuclear industry were analysed for 13 cases and 47 controls. Questionnaire data were analysed for 11 cases and 36 controls.
5. In an attempt to explain the excess incidence of leukaemia and NHL in the Dounreay area, particularly between 1979 and 1986, the authors examined possible associations with a variety of factors relating to the child and/or the child's parents. These included parental occupation, age and social class, maternal birth place, family medical history, pregnancy history, possible exposure to non-ionising radiation and various aspects of lifestyle.
6. The study found that none of the cases of leukaemia or NHL had been exposed ante natally to diagnostic x-rays. In the analysis of parental occupation, children with leukaemia or NHL in either the immediate vicinity of Dounreay or in the rest of Caithness were found to be no more likely to have fathers who were, or had been employed in the nuclear industry, than were control children without malignant disease.
7. In the analysis of many other factors, the only associations to achieve statistical significance were the use of local beaches by case children in the years prior to diagnosis and the receipt of prescription medication by case mothers when pregnant. However, no two case mothers received the same medication.
COMA RE's advice to Government
8. COMARE has considered this study and our advice is set out below.
General Considerations
9. In our second report [1] we noted the considerable problems in interpretation of findings based on very small numbers of cases. As there were only 11 cases for the questionnaire based study, and 13 for the birth certificate/ employment record study any conclusion drawn from these results remains open to some uncertainty. It is not possible to assess whether interpretation of parts of the data may have been biased by the unavoidable exclusion of three cases from the questionnaire study or by the use of retrospective questionnaire data based on parental recall or by some of the difficulties in recruiting controls.
10. Nevertheless, the study was justified by the need to elucidate factors of possible relevance to the excess incidence of childhood leukaemia/NHL in the vicinity of the Dounreay Nuclear Establishment (DNE). In addition there is a need to accumulate information from areas around several nuclear sites as part of our overall strategy for evaluting possible causes of childhood malignancy in those areas.
189W11. Therefore, we have considered the results of this study in terms of whether it can provide a statistical explanation for the excess of childhood leukaemia in the Dounreay locality specifically, and in the wider context of other published studies. We have given particular consideration to how the results relate to those of the similar study undertaken by Gardner et al in West Cumbria [3].
Methodology
12. The Committee consider that the methods of investigation were appropriate to the aims of the study.
Results
13. The authors observe that for children resident within 25 km of Dounreay, only 2 of 8 cases (25 per cent.) of leukaemia/NHL had fathers employed at DNE at any time compared with 12 of 25 controls (48 per cent.). These results, taken alone, do not suggest paternal employment at DNE as a factor in the causation of childhood leukaemia/NHL in the neighbourhood and indeed make it clear that such employment cannot be a full explanation of the excess incidence observed in the vicinity of Dounreay. However, the statistical power of the study is inevitably very low and the study cannot refute the suggestion from the study of Gardner et al [3], that fathers' recorded external radiation dose may be related to the incidence of leukaemia/NHL in their offspring.
14. We note the finding of an apparent association between the use of the beaches in the proximity of Dounreay by children and the development of leukaemia/NHL. We advise that this finding should be interpreted with considerable caution since:
14.1 it relates to five cases only; 14.2 it is based on parental recall some years after the event which may be subject to human error; 14.3 the only comparable study [3] did not produce a similar result; 14.4 information, currently available, on the levels of radioactivity on the beaches, suggests that these are far too low to cause leukaemia on the basis of accepted models of leukaemogenesis. Nevertheless, we will incorporate a review of the Dounreay beach monitoring data into our future work programme.
15. Data on proximity of home address to the microwave communications installation outside Thurso were analysed for those 8 cases living within 25 km of Dounreay and 25 controls. We agree broadly with the authors' conclusion that the results of this analysis do not support the hypothesis that the microwave transmitter could be a source of risk. However, we will subject the matter to more detailed investigation with respect to the possible spread and power of the beam and its relation to places of residence of cases and controls.
General conclusions
16. We consider that this study does not identify an explanation for the excess of childhood leukaemia/NHL around Dounreay. The disparity beteween these findings and those of Gardner et al in Cumbria tends to weaken but does not exclude the suggestion that these two excesses have a similar causation. At the same time, the findings in this small study fail to support but do not negate the suggestion of an
190W
Table 4 Children in care at 31 March 1989 By accommodation Community Residential Responsible social work authority At home Relatives/ friends Foster parents Other1 Total Local authority home Voluntary home Residential school Special school Assessment centre Other2 Total Grand total Borders 60 12 23 14 109 8 0 1 3 0 0 12 121 Central 353 24 104 54 535 38 2 10 3 19 22 94 629 Dumfries/Galloway 70 7 86 9 172 32 7 0 0 5 5 49 221 Fife 105 27 75 19 226 4 1 3 9 11 21 49 275 Grampian 345 31 241 31 648 103 5 52 4 0 10 174 822 Highland 202 30 191 4 427 27 1 2 5 11 5 51 478 Lothian 687 14 346 48 1,095 102 17 63 20 22 23 247 1,342 Strathclyde 4,049 374 1,261 52 5,736 724 79 405 81 69 90 1,448 7,184 Tayside 349 69 211 26 655 80 58 23 9 20 26 216 871 Orkney 21 0 3 0 24 3 0 0 1 0 0 4 28 Shetland 5 3 11 0 19 4 0 0 1 0 0 5 24 Western Isles 16 3 8 0 27 14 0 0 0 1 0 15 42 association between paternal employment in the nuclear industry and leukaemia/NHL in children. We would reiterate the views expressed in the final conclusion of our 2nd report [1]. These were that the evidence of a raised incidence of leukaemia near Dounreay, taken in conjunction with that relating to the area round Sellafield is sufficient to warrant an intensified programme of investigation.
17. We undertake to update our advice on these issues as further relevant research data become available.
1. Committee on Medical Aspects of Radiation in the Environment (COMARE) second report London HMSO 1988 ISBN 0 11 32111422.
2. Urquhart J. D., Black R. J., et al. Results of a Case Control Study of Leukaemia and non-Hodgkins lymphoma in children in Caithness near the Dounreay nuclear installation, [BMJ 1991, 302, 687–692].
3. Gardner M. J., Snee M. P. et al. Results of Case Control Study of leukaemia and lumphoma among young people near Sellafield nuclear plant in West Cumbria BMJ 1990, 300, 423–429.