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CANCER AND LEUKAEMIA AND RADIOACTIVE POLLUTION FROM HM DOCKYARD, PLYMOUTH
RESULTS OF THE CANSAR QUESTIONNAIRE SURVEY 2003 IN THE WARDS OF KEYHAM AND TORPOINT
Chris Busby PhD Ian Avent (CANSAR) Occasional Paper 04/04 Aberystwyth: Green Audit March 2004
Summary
The recent authorisation to increase discharges of the radioactive isotope Tritium from the Devonport Royal Dockyard by 700% has caused concern among local groups. The question of the health effects of historic releases of radioactivity by the dockyard to the river Tamar is addressed by a study analysis of a cancer and leukaemia questionnaire carried out by CANSAR, a local organisation in the wards of Keyham near the dockyard and Torpoint opposite. The questionnaire was administered to a random number of houses in the two wards. There were 364 individuals listed in responses in Keyham and 415 in Torpoint, representing about 3% and 5% respectively of the 1991 census population of the wards. There were 39 cases of cancer in Keyham and 76 cases in Torpoint in the households who responded. Within these there were 7 cases of leukaemia in Keyham and 4 in Torpoint. In addition, there were 11 deaths from cancer in Keyham and 20 in Torpoint which were not included in the statistical results reported here. The dates of diagnosis for the individual cases were not available so the period over which the cases were diagnosed was assumed to be 10 years. On this basis, comparison with England and Wales National rates for cancer and leukaemia ( 1997) gave a Relative Risk of 18.4 for Leukaemia all ages in Keyham (E= 0.38; O = 7; p = 0.00000) and 4.7 in Torpoint (E = 0.84, O = 4; p = 0.0001). The excess was greatest in younger people. In the age group 0-54 Keyham had RR = 30.6 based on 3 reported and 0.098 expected. This age effect was not found in Torpoint for leukaemia. For all cancers, the risks were also elevated in both wards and greatest in younger people. For Keyham all ages, RR = 1.9; O = 39, E = 20; p = 0.0001 and Torpoint RR = 1.7; O = 76, E = 45.8; p = 0.0001. In the age group < 54, Keyham RR = 4.5; O = 18; E = 3.98; p = 0.00000 and Torpoint RR = 6.3; O = 10; E = 3.03; p = 0.0000. For the age group <44, Keyham RR = 7.46; O = 10; E = 1.34; p = 0.00000 and Torpoint RR = 9; O = 7; E = 0.78; p = 0.00000. In a proportional incidence study, the numbers of leukaemias reported were compared with the numbers of cancers reported. This method removes the need to know the period of time over which the cases were diagnosed. In Keyham the ratio of leukaemia to cancer was 19.8 times that expected (7/32) on the basis of national rates and in Torpoint the figure was 5.1 times roughly in good agreement with the Relative Risk calculation. In the discussion, these worrying and highly significant increases are suggested to be a manifestation of a sea-coast effect on cancer and leukaemia found by Green Audit researchers in small area cancer risk studies near the Irish Sea and near nuclear sites in Somerset and Essex. In the discussion, attention is drawn to data included in the submission to the consultation process by the local health authority which showed the existence of a 25-30% excess leukaemia risk in Plymouth between 1995-7. It is suggested that these data were indicative of the existence of a connection between historic discharges from the dockyard and local ill health. The health authority is criticized for not investigating further and for using poor scientific methods to marginalize this finding. Finally, the authors draw attention to recent evidence that the risk model of the International Commission on Radiological Protection used to underpin the Environment Agency's authorisation is unsafe when applied to exposure to internal man-made radioactivity of the kind released by the dockyard.
1. Introduction and background The decision to increase capacity for servicing Vanguard nuclear submarines at HM Dockyard Plymouth resulted in the requirement to increase discharges of radioactivity to the environment and accordingly in May 2000 Devonport Management Limited (DML) which operates the Devonport Royal Dockyard (DRD) applied to the Environment Agency (EA) to vary its authorisation to dispose of radioactive waste in the tidal river Tamar which borders the densely populated area of Plymouth. The new work would result in a substantial increase of the annual amount of Tritium to the Tamar river at Hamoaze from 120GBq to 800 GBq. There would also be an increase in atmospheric Tritium discharges from 1 to 5GBq/annum together with a new requirement for 45GBq of Carbon-14 and 15GBq of Argon-41. Local anti-nuclear groups and others were concerned at the possible health risks that such an authorisation would entail. Despite the assurances given by DML and other bodies that the exposures involved were very low compared with natural background, these arguments were seen by many to be based on the erroneous risk model of the International Commission on Radiological Protection (ICRP) which is presently under discussion by the new UK Department of Health Committee Examining Radiation Risk from Internal Emitters CERRIE. One question asked was whether historic releases from HM dockyard over the 20 years of its operation at the lower levels permitted by its previous licence had caused ill health. This question was apparently answered in a submission by the South West Devon Health Authority (SWDHA) to the public consultation. The SWDHA report concentrated on leukaemia in the Plymouth area, since it has been believed widely since the observation of correlation between exposure to ionising radiation and leukaemia (e.g. in the Hiroshima bomb survivors) that the disease is a flag for radiation exposure effects. Using figures from the South West Cancer Intelligence Unit, the SWDHA report showed that there was indeed a statistically significant 25- 30% excess of leukaemia incidence in men and women in all ages in Plymouth in 1995-7. However, the SWDHA report concluded that these increases were not related to the releases from the dockyard because (a) the crude death rates from leukaemia were not highest in the wards closest to the dockyard, Keyham and Torpoint and (b) radiation exposure from the releases was too small to cause any measurable increases in leukaemia. As we shall argue, (a) is a false analysis and (b) is an assumption based on the incorrect ICRP risk model. We have examined the levels of cancer and leukaemia in the two wards closest to the river and Dockyard, Keyham and Torpoint using a questionnaire study similar to the one recently undertaken in Burnham on Sea near the Hinkley Point nuclear complex in Somerset. Green Audit has made several studies of populations living near contaminated intertidal sediment e.g. in Wales, Ireland, Somerset and Essex and all have shown that there is an increased risk of both cancer and leukaemia in such populations [see attached references e.g. Busby 2000, Busby et al 2002, Busby et al, 2002A, Busby 2004].
2. The CANSAR survey This small random survey was based on the earlier Burnham on Sea survey carried out be Parents Concerned about Hinkley (PCAH) (Busby et al 2002). That study, was in turn based on the original prototype carried out in by STAD and Green Audit in Carlingford, Ireland in 1999 (Busby 2001). The Burnham on Sea study had intended to survey all the houses in Burnham North. In the event, due to lack of volunteers and other factors, only about a third of the households in the ward were visited. This however provided a random sample of about 1400 people who were shown to be a reasonable cross section by age of the 1991 census ward population. In the event, an oversight was made in transposing the Burnham questionnaire into a CANSAR questionnaire and the dates of diagnosis of the reported cancers and leukaemias were not asked for. The questionnaire was given by a volunteer from CANSAR to a small random selection of houses in the wards of Keyham (on the eastern side of the Tamar near the dockyard) and Torpoint (on the western side, opposite the dockyard) and the project was explained. It was filled in for each household surveyed by the head of or some responsible person in the household, with the assistance of an interviewer. The questionnaire asked for the sex and age of all persons living at the address. It then asked if any person at that address has been diagnosed with cancer, leukaemia or lymphoma in the previous ten years. Any deaths in the last ten years from cancer or leukaemia were also filled in separately. In the Burnham on sea questionnaire study, details of this person were then asked for, such as the type of cancer (site), their sex, the age at diagnosis and the year of diagnosis. This data enabled the direct calculation of relative risk in the sample population, relative to the national population. However, this question was omitted from the CANSAR survey by mistake. It was therefore necessary to analyse the results on the basis of limiting assumptions about the period over which the reported diagnoses spanned and also using the method of proportional incidence.
The population at risk The 1991 census population of Keyham is given in Table 1 together with the ages and sex of the people in the houses visited. Table 2 covers Torpoint. It is clear that unlike Burnham, where about 30% of the ward responded, in Keyham only about 3% of the census population of the ward are included in the survey and in Torpoint about 5%. The population of the two wards is more than six times greater than the population of Burnham on Sea. However, if these are random samples, the results should be representative for the wards.
The methods Two methods were used to evaluate the risk of leukaemia and cancer in the wards. First, using the previous method we have applied to such surveys, the population at risk was assumed to be those people living at the houses which returned fully completed questionnaires. The sex and age of these people are given in Table 1 and 2. We then calculated the expected number of (a) all leukaemias ICD9:204-208 and (b) all malignancies except non- melanoma skin cancer on the basis of the latest (1997) England and Wales national rates as published by the Office for National Statistics (ONS Cancer Statistics Registrations, Series MB1). Since we did not have the dates of diagnosis, the Relative Risk was then calculated by dividing the total number of leukaemias or cancers reported by the (a) ten year expectation. In previous surveys of this type, we have noted that the number of cancers or leukaemias reported for diagnosis in years more than ten years before the date of the survey represents less than 5% of the total, due to population leakage from the area. Thus the ten year period probably represents the best conservative estimate of risk, especially since the survey questionnaire asked for deaths within ten years of the survey.
Table 1 1991 census population of Keyham with details of the survey respondents.
Table 2 1991 census population of Torpoint with details of the survey respondents.
The second method we used does not depend on the year of diagnosis but is restricted to examining the rates of leukaemia. The method of proportional incidence compares the ratio of leukaemia to cancer in the survey respondents with that found in the England and Wales national figures. Any anomalous increase in leukaemia would then be flagged by a higher ratio of leukaemia to cancer than that expected.
Results Results are given in Tables 3, 4 and 5. They indicate significant and very substantial excess risk from leukaemia and to a lesser extent cancer in both wards. In addition, the ward of Keyham, close to the dockyard has much higher levels of leukaemia than Torpoint and the incidence is greatest in younger age groups. The proportional incidence method also supports the finding that there is an excess of leukaemia in both these populations, greatest in Keyham, and the relative risks calculated by this latter method are of a similar magnitude to those calculated directly.
Table 3 Relative Risk from All Leukaemia ( C91-C95) all ages in Keyham and Torpoint from CANSAR survey 2003 (based on England and Wales rates 1997)
Table 4 Relative Risk from All malignancy (except NMSC: C00-C97 x C44) all ages in Keyham and Torpoint from CANSAR survey 2003 (based on England and Wales rates 1997)
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