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18 March 2003

Cancer Mortality Around Bradwell Nuclear Power Station, Essex

There is no evidence of excess risk of cancer mortality in the vicinity of Bradwell power station in Essex. Analysis using the best available statistics has shown no significant excess in overall cancer mortality around Bradwell, and there is no significant excess of breast cancer mortality in women living near the Blackwater Estuary or in Maldon.

Using information from the Office for National Statistics (ONS), the environmental group Green Audit has claimed that there is increased mortality from cancer near Bradwell, in particular excesses of breast and prostate cancer mortality. A report to the North East Essex Health Authority by the Small Area Health Statistics Unit (SAHSU), also using mortality data from ONS, did not find any evidence of excess cancer mortality in the area. COMARE asked ONS to examine the large differences between the numbers of deaths in these two reports. To date, two further Green Audit reports and one further SAHSU report have now been produced concerning cancer mortality in the Bradwell area.

• COMARE concluded that all three reports from Green Audit contain errors that result in an over-estimation of cancer mortality risks. SAHSU's first report contained errors that led to an under-estimation of the risks. SAHSU's second report has corrected these errors. The second SAHSU report, as well as further analyses for COMARE (all of which use correct mortality figures and the most appropriate expected numbers of deaths) do not indicate any significant excess of cancer mortality around Bradwell. Furthermore, these analyses do not indicate any substantial or statistically significant risk of breast cancer mortality in groups of wards bordering the Blackwater estuary, or in Maldon compared with Burnham-on-Crouch as claimed by Green Audit.

• COMARE is concerned that independent reports, using mortality data obtained from ONS, could be produced with such noticeably different numbers of deaths. These differences have inevitably led to confusion and anxiety among some residents in the Bradwell area.

• COMARE has serious concerns about studies, such as those of Green Audit, that are published without formal peer review that would be carried out by a reputable scientific journal in the standard way. Such publications often raise public concern, which is subsequently difficult to allay if the results are unsubstantiated, as is the case here. The errors in the SAHSU Rapid Inquiry Facility (RIF) report came about as the result of the termination of post-codes in the area. Given that RIF reports are very likely to become public, COMARE recommends that systems are put in place to ensure that changes in post-coding in a particular area are incorporated into the SAHSU database prior to the production of a RIF report for that area. Public health officials at the North Essex Health Authority had access to the ONS mortality data and could have checked the figures in the first Green Audit report. Had they done so, the errors in Green Audit's numbers of deaths should have been readily apparent.

COMARE wishes to emphasise that any organisation or individual dealing with epidemiological data has a responsibility to ensure that the data are correct before publication.

Press Enquiries to Professor Bryn Bridges (Telephone No. 01235-832447)

Notes to Editors

COMARE is an independent expert committee with members chosen for their medical and scientific expertise. The Secretariat is provided by the National Radiological Protection Board (NRPB). The committee's terms of reference are "to assess and advise Government and the Devolved Authorities on the health effects of natural and man-made radiation in the environment and to assess the adequacy of the available data and the need for further research". The committee was set up in 1985 and is chaired by Professor Bryn Bridges OBE.

The Small Area Health Statistics Unit (SAHSU) is an independent research group based at Imperial College, London and is funded by 7 Government Departments or Agencies, including DH and DEFRA. The Rapid Inquiry Facility (RIF) reports produced by SAHSU offer an initial rapid assessment of the available health statistics to help Directors of Public Health decide if further action is required.

SAHSU has accepted COMARE's recommendations and has put in place a system to check that post-coded data is updated before any new RIF reports are produced. This will ensure that there can be no repeat of the errors included in the first SAHSU Bradwell report.

Committee on Medical Aspects of Radiation in the Environment
c/o National Radiological Protection Board, Chilton, Didcot, Oxon OX11 0RQ
Tel: 01235-832447 (Scientific)
Tel: 01235-822629 (Administration)
Fax: 01235-832447/822630
Chairman: Professor Bryn Bridges OBE

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