Radiation (Hansard, 2 April 1990)

§ Mr. Freeman

Yes. The Government are grateful to COMARE for its preliminary advice and accept all the committee's recommendations. We note that COMARE agrees with the study methodology, and with the broad thrust of the main conclusions.

The committee advises that there is evidence of a statistical association between the recorded external radiation dose of those employed at Sellafield and the incidence of childhood leukaemia in their offspring. However, we note that the committee is cautious in its interpretation of the results since the study conclusions are based on very small numbers and that further evidence from other studies currently under way is called for. In particular, we note COMARE's view that the case control study demonstrates a statistical association, but no causal relationship. The committee has stated in its advice that workers with relatively high external radiation exposures may also be subject to other factors. In the committee's view, these include possible internal radiation exposure, the possibility of contaminated materials being carried off the site, or other factors, including chemical exposure or contamination. The committee suggests that it is possible that one of these factors, or a combination, could be important.

In response to the Government's request for advice on possible risks to workers receiving relatively high radiation doses, we accept COMARE's view that it is unable to make specific recommendations on this until the results of other studies are known and there is further information on possible causal mechanisms. However, the committee strongly supports the actions that have been taken to continue to reduce occupational exposures.

In response to the committee's specific recommendations on studies of the offspring of radiation workers, and on the need for co-ordination of research effort, the 431W relevant Government Departments have set up arrangements to enable them to take this work forward as speedily as possible. COMARE will be kept informed at all stages and will be consulted as appropriate.

Following publication of the case control study, the Department and the Health and Safety Executive have received a number of related research proposals from various individuals and organisations. In addition to these expressions of interest, we will be advertising more widely to invite formal research proposals. Any such proposals will be subject to the usual independent review procedures, but will be considered as swiftly as possible.

Following is the full text of COMARE's preliminary advice:

"COMARE STATEMENT of ADVICE

Subject: The Case-control study of leukaemia and lymphoma among young people near the Sellafield nuclear plant in West Cumbria M. J. Gardner, M.P. Snee, A. J. Hall, C. A. Powell, S. Downes and J. D. Terrell.

BACKGROUND 1. In 1984, the Independent Advisory Group chaired by Sir Douglas Black, reported on the possible increased incidence of cancer in West Cumbria.¹ The group recommended that a case control study of leukaemia and lymphoma in young people resident in West Cumbria should be carried out. The study was commissioned by the Department of Health in 1984 and was undertaken by the Medical Research Council Environmental Epidemiology Unit at Southampton University. 2. The study was designed to examine whether the observed excess of childhood leukaemia and lymphoma near BNFL Sellafield was associated with established risk factors or with factors related to the plant. The results were published in the British Medical Journal dated 17th February 1990.² 3. The Parliamentary Under-Secretary of State for Health has referred the study to this Committee for urgent consideration and preliminary advice.³

Results of the case control study 4. The study documents an association between the excess of leukaemia and non-Hodgkin's lymphoma in children living in the vicinity of Sellafield, and employment of the fathers of the affected children at Sellafield over the period 1950 to 1985. The statistical association with employment at Sellafield generally and the risk of leukaemia in employee's offspring is raised, but is similar to that in the offspring of fathers employed in some other industries in West Cumbria namely the iron and steel, chemical and farming industries. 5. In particular, the study documents an association between the raised incidence of leukaemia and non-Hodgkin's lymphoma in young people and the recorded level of external radiation dose received by the father, while working at Sellafield, before conception of the affected child. 6. The authors comment that other factors, including ante-natal exposure to x-rays, maternal age, employment elsewhere, eating seafood and playing on the beach did not explain these relationships. The authors also conclude that these results can explain statistically the observed geographical excess of leukaemia and lymphoma in young people in Seascale.

Government's request to COMARE 7. The Government noted the results of the study with concern and, in view of its importance, the Parliamentary Under-Secretary for Health referred the study to COMARE for our urgent consideration and preliminary advice. We were asked to consider the study further in the longer term, in conjunction with the results of other studies, completed, underway or planned, recommended in the Black report¹, or in our own second and third reports⁴⁵.

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COMARE's preliminary advice to Government

METHODOLOGY 8. The Committee consider that the methods of investigation were appropriate to the aims of the study.

Conclusions 9. We agree with the broad thrust of the study's main conclusions which are outlined as follows. Although the number of cases is small, there is evidence of a statistical association between the recorded external radiation dose of those employed at Sellafield and the incidence of childhood leukaemia in their offspring during the study period. We note that the association between paternal occupational external radiation exposure and the incidence of leukaemia in their offspring could be sufficient to explain statistically the initial observation of an excess incidence of leukaemia in young people in Seascale. 10. We note that the risk of leukaemia in employees' offspring for some other industries in West Cumbria, namely iron and steel, chemicals and farming, is similar to that for employment at Sellafield generally. This study was not set up to investigate other industrial occupations in detail. The possible existence of health effects in offspring of workers in occupations other than those at Sellafield might be the subject of other investigations but they lie outside the scope of our own enquiries. Taken altogether, these results suggest to us that employment at Sellafield itself may not be such an important factor as certain specific occupations within Sellafield which are (in this study) characterised by a relatively high external radiation dose. 11. The important conclusions of this study are unavoidably based on very small numbers and as these are novel observations which have not been recorded previously, we are cautious in our interpretation. Further evidence from other studies currently underway and planned will enable us to make a firmer assessment of the implications of these results.

Possible causes 12. The case control study has demonstrated a statistical association between recorded external radiation dose and childhood leukaemia incidence but this type of study cannot provide evidence of causal relationship. Workers with relatively high recorded external exposures may also be subject to other factors. These include possible occupational internal radiation exposure (rather than external radiation exposure) which might involve radioactivity being concentrated in body fluids or tissues and might lead to a pre-conception or post-conception effect on their offspring; the possibility of contaminated materials being carried off the site leading to unexpected exposure of workers and their families, or other factors, including chemical exposure or contamination. The possibility that one of these factors or a combination of these factors could be important, needs to be investigated. In particular, the full occupational history of the group characterised by high recorded external exposure needs to be studied in detail. 13. The results from this study place greater emphasis on occupational rather than environmental factors. This is consistent with the view, as stated in our first report⁶, that "the increased doses [to the local population from the discharges from the Sellafield site] are still well below those that would readily explain the observed cases of leukaemia in Seascale using conventional risk estimates". However, we cannot exclude environmental radiation as a possible contributory factor because causal mechanisms have not yet been identified. 14. We have already postulated in our second and third reports that the excess of childhood leukaemia observed around the nuclear sites that we have investigated, could be partly related to parental occupation at those nuclear installations. We discussed possible mechanisms by which parental occupational exposure could be implicated. This study supports the case for further investigation of factors related to occupation.

Recommendations to Government 15. In our second and third reports, we have already recommended that case control studies around Dounreay and Aldermaston and Burghfield should be set up to investigate the importance of parental occupations and other relevant factors which might be associated with the increased incidence of childhood leukaemia [and other cancers] in those areas. 433W Recommendation 1. We now recommend that these case control studies, which are already underway, should be completed as soon as possible, subject to the maintenance of a high scientific standard. 16. In our second and third reports, we specifically recommended that epidemiological studies should be set up to consider any possible health effects in the offspring of parents occupationally exposed to radiation. The results of the current study strengthen the basis for those recommendations. Recommendation 2. We therefore recommend that these studies should be given high priority. A study involving direct approaches to workers to obtain information on their children's health and also a study linking records of all radiation workers to national records of childhood cancer and leukaemia would be complementary and we recommend that both should be undertaken. 17. We recognise that there are a number of areas of research where studies are necessary to confirm or refute these findings and further biological research is required to investigate possible causative mechanisms. However, we do not wish to see multiple independent studies which would cause undue inconvenience to the small numbers of individuals and families concerned. Recommendation 3. We, therefore, recommend that there needs to be some form of coordination of research, to ensure the best possible use of resources and to avoid unnecessary duplication of effort. This committee would wish to be consulted in any such research coordination. 18. In the longer term, as requested, we will reconsider the results from this study once the results of the various studies that we have recommended previously ⁴, ⁵ become available.

Interim action 19. At the request of Government, at the end of last year, we began a review of the situation around Sellafield.⁷ This includes both current epidemiological evidence and information on discharge and environmental data. We propose to investigate any unexpected potential routes of exposure to radiation including routes via workers. We understand that initiatives have been taken by both the Health and Safety Executive and BNFL in collaboration with the MRC Environmental Epidemiology Unit, to investigate the situation on the Sellafield site in more detail and, in addition, relevant experimental studies are being done by NRPB and others. We would wish to be kept informed about progress of these investigations as they relate to our own review. 20. We wish to reiterate that the result of the Cumbria case control study documents an association between occupational external radiation exposure of parents and the incidence of leukaemia in their offspring. However, these findings require confirmation from other studies currently in progress. Furthermore, the causal mechanisms which might lead to this observation are not known. Thus, we are unable, at present, to make specific recommendations to reduce possible risks. We strongly support the actions that have been undertaken to continue to reduce occupational exposures, particularly to those likely to have children, and to counsel workers on the possible risks.

1 "Investigation of the possible increased incidence of cancer in West Cumbria"—Report of the Independent Advisory Group, Chairman: Sir Douglas Black. HMSO 1984.

2 "Results of case-control study of leukaemia and lymphoma among young people near Sellafield nuclear plant in West Cumbria." M. J. Gardner, M.P. Snee, A. J. Hall, C. A. Powell, J. D. Terrell, British Medical Journal 300 (6722) 423-429.

³ Hansard Vol. 167 cols. 397-398.

⁴ "Investigation of the possible increased incidence of leukaemia in young people, near, the Dounreay Nuclear Establishment, Caithness, Scotland"—COMARE 2nd Report. HMSO 1988.

⁵ "Report on the incidence of childhood cancer in the West Berkshire and North Hampshire area, in which are situated the Atomic Weapons Research Establishment, Aldermaston, and the Royal Ordnance Factory, Burghfield"—COMARE 3rd Report. HMSO 1989.

⁶ "The Implications of the new data on the releases from Sellafield in the 1950s for the conclusions of the Report on the Investigation of the Possible Increased Incidence of Cancer in West Cumbria."—COMARE 1st Report. HMSO 1986.

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⁷Hansard Vol. 164 Cols. 662-663."