Childhood Cancer, Dounreay (Hansard, 19 July 1994)

§ Mr. Stewart

Details of this work, which was carried out on behalf of the Committee on the Medical Aspects of Radiation in the Environment, were published in theJournal of Epidemiology and Public Health on 16 June 1994. I will arrange for copies to be placed in the Library of the House.

The study found that in the period 1985–91, four cases of leukaemia and non-Hodgkin's lymphoma were observed in the one to 24 age group resident within 25 km of Dounreay, compared to 1.4 expected cases. The results have been examined by COMARE, which concluded that the results reinforced the previous findings that the raised incidence of childhood and young adult leukaemia in the area is a real phenomenon and is less likely to have arisen by chance. The committee concluded that further epidemiological research in the Dounreay area to try to determine causal mechanisms was not a practicable way forward at present. The Government accept this advice. Further studies are, however, under way on a national basis —one on the incidence of childhood cancer in the vicinity of all nuclear sites in Scotland, the other a case control study of childhood cancer in Scotland, linked with a parallel study in England and Wales.

The full test of the Committee's advice is as follows: Comare statement Incidence of Leukaemia and Non-Hodgkin's Lymphoma in Children and Young Adults Resident in the Dounreay Area of Caithness, Scotland, in 1968–1991. Black R. J., Sharp L, Harkness E. F., McKinney P. A. Background The second report of the Committee on Medical Aspects of Radiation in the Environment (COMARE), entitled 'Investigation of the possible increased incidence of leukaemia in young people near the Dounreay Nuclear Establishment, Caithness, Scotland', which was published in 1988, concluded that for the period 1968–1984: "There is evidence of a raised incidence of leukaemia in young people living in the vicinity of Dounreay.". Further case-control and cohort epidemiological investiga-tions were recommended and undertaken in subsequent years [Case-control study of leukaemia and non-Hodgkin's lymphoma in children in Caithness near Dounreay nuclear installation. Uruquhart et al, BMJ 1991; 302, 687–692. Incidence of leukaemia and other cancers in birth and school cohorts in the Dounreay area. Black et al, BMJ 1992; 304, 1401–1405]. In the 122W light of this work and other considerations, COMARE requested that the epidemiological data for childhood leukaemia and non-Hodgkin's lymphoma in the vicinity of Dounreay should be analysed to include the period 1984–1991. This work was undertaken by the Information and Statistics Division of the Scottish Office Home and Health Department and was published in the Journal of Epidemiology and Public Health on 16 June 1994. The Study The objective of this report was to review the geographical incidence of leukaemia and non-Hodgkin's lymphoma in children and young adults resident in the area less than 25km from the Dounreay nuclear installation, and in the reminder of the KW postcode area. The full-time period 1968–91 for which data are now available was studied to determine whether the excess incidence reported in the period up to 1984 has continued in subsequent years. In comparing observed and expected numbers of cases of leukaemia and non-Hodgkin's lymphoma, the expected numbers were based on Scottish national rates. The authors report that in 1968–91, 12 cases were observed compared with 5.2 expected in the zone within 25km of the Dounreay plant (p=0.007). In the latest period 1985–91, which was not included in the second COMARE report, 4 cases were observed compared with 1.4 expected (p=0.059). Comare's Advice to Government COMARE have considered this study and welcomed its publication. The Committee endorsed the methods used. Eight additional cases of childhood cancer are reported in this study for the period 1985–1991. Of these, 4 were within 25km of Dounreay and these cases give added weight to the previous findings that the raised incidence of childhood and young adult leukaemia and non-Hodgkin's lymphoma in this area is a real phenomenon. COMARE's second report concluded: Although chance cannot be entirely dismissed as an explanation of the raised incidence of childhood leukaemia in the vicinity of Dounreay, we consider that it is now less likely than when Sellafield was considered in isolation". The new findings reinforce that view. Regarding the causation of leukaemia and non-Hodgkin's lymphoma in the area, the Committee considered that this study neither adds nor removes support for the "population mixing" hypothesis suggested by Professor Kinlen. The Committee also noted that the data in the case-control study [Urquhart et all 1991], which examined parental exposure to radiation, showed that the "paternal preconception irradiation" hypothesis put forward by Professor Gardner could not account for the observed excess and that the new data did not change this position. The Committee concluded that further epidemiological research in the Dounreay area to try to determine causal mechanisms is not considered to be a practicable way forward at present, because of the small number of cases involved. However, the incidence of any new cases of childhood leukaemia which might arise should continue to be monitored at appropriate time periods. Rigorous analysis of pathological material from such individuals should continue to be strongly encouraged.