When is a cluster not a cluster?

Answer? When you might be able to find an explanation

Editorial of Radioactive Times Vol. 2 No. 4 June 1998


Once upon a time the death of just one canary would trigger the evacuation of an entire coal mine. These days, we suspect, it would take a whole cageful, and even then some epidemiologists would cry "No problem, business as usual!"

We wonder how long it will be before the citizens' epidemiology group in Newbury is persuaded that research into the excess of leukaemia in the south of the town is pointless, on the grounds that the cluster is simply part of the natural distribution of random events. Lay investigators face accusations of being "Texas Sharpshooters" - of drawing tight boundaries around clusters of cases in order to heighten their apparent significance. But the opposite logic - "boundary loosening" - which the epidemiological establishment insists on is equally suspect. The official view is that clusters must be analysed in the context of their post code district or their electoral ward. In the case of Newbury the obviously linear leukaemia cluster happens to be bisected by a ward boundary which makes it into two clusters. The establishment can conveniently conclude that no action is needed, for both fall below the limit of statistical significance. Of what possible significance is the ward boundary unless the polling station is a point source of some toxin? What does the post code have to do with it unless the postman is a Typhoid Mary?

As Radioactive Times has reported in recent issues, there is a concerted campaign to write off all clustering of disease as insignificant. Street of Doom - BBC tv's documentary on a leukaemia cluster in Northampton screened last June - must be seen as part of this effort, and the Broadcasting Standards Commission must be condemned for falling into its intellectual trap. In rejecting a complaint (report on this site) BSC has accepted nonsenses which undermine the whole purpose of epidemiology; for example

"... the process of examining cases post hoc and trying to correlate them with environmental features has no scientific validity."
They have accepted the BBC's bizarre claim that when they showed randomly generated dots on computer screens frequently falling into clusters they did not intend to suggest to viewers that the Northampton cluster was a random event. They have accepted the BBC's excuse for failing to show the map of the Northampton cluster which reveals that all the childhood leukaemia cases occur in one street alongside the railway; the BBC claimed that "... the map would reveal nothing unless allowance was made for population density". In fact, since they were dealing with an urban area, population density could be taken as uniform. Unaccountably, the BSC also accepted that "... to assert that the location map ... revealed a non-random pattern assumed that random cases could not cluster, which was wrong". No-one is claiming that random cases cannot cluster, but the BBC is claiming that all clusters are part of the random distribution and that there is no explanation to be found.

There used to be railway sidings next to Pembroke Road, where nuclear waste trains would be stored over the weekends. Over the years a number of such sidings (including Pembroke Road) have been decontaminated because radioactive debris has been found to have dripped from the flasks. In May 1998 the French authorities stopped all nuclear trains because leakage has contaminated 25% of flasks and 35% of wagons arriving at la Hague. The next month British MPs were calling for nuclear trains to be banned because they leak 60 times international safety limits. When the Pembroke Road sidings were lifted some years ago the authorities dug out and removed the ballast and the underlying soil to the depth of a metre. But Street of Doom stated tersely that stories of a nuclear leak had been discounted, and asked viewers to believe that the deaths of children in nearby homes were not worth examining for any environmental factors. To support their case they called on a team of epidemiologists led by Dr Ray Cartwright, a member of the Organising Committee of the British Nuclear Energy Society. Dr Cartwright supervises a 6 million nation-wide study of childhood leukaemia which he designed and which explicitly excludes any possibility of finding that man-made ionising radiation causes the disease. Were Dr Cartwright and his Leukaemia Research Fund colleagues really the only reputable epidemiologists the BBC could find?

Street of Doom's producer told the Commission that there were "no answers in this cluster or in any cluster", and that the programme "unpicked that, scientifically". We must ask why a programme with such an agenda was so lacking in scientific rigour and balance. Who stands to gain?

No public funds are dedicated to research on the health effects of ingesting and inhaling low levels of contamination.
Some cancer registries are going to extraordinary lengths to resist releasing data on cancer incidence, especially in areas like Oxfordshire, where radiation is a major embarrassment.
Clusters like Seascale, Northampton, and Newbury have been discovered not by health authorities or the government, but by the efforts of the victims, their families, and journalists.
But when they are discovered officialdom bends its own efforts towards persuading itself and the public that there is no point on looking for causes.

There is much at stake; the world- wide distribution of radioactivity means that localities near nuclear sites are only a little more contaminated that the rest of us. It follows that local clusters may be the indicators of a far larger problem - the inexorable increases in cancer, leukaemia and many other genetically determined disorders. Perhaps we should not be too surprised to see public money being diverted into propaganda broadcasts.


Report of BSC hearing

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