NucNet News No. 245
Industry Welcomes Results of New 'Cancer Cluster' Study
British Nuclear Fuels (BNFL) has welcomed the results of a further study into
the possible causes of previously-identified 'cancer clusters' in the area
surrounding its Sellafield nuclear fuel reprocessing plant.
A BNFL spokesman said the results of the latest study - Leukaemia and
non-Hodgkins lymphoma in children of male Sellafield radiation workers - were
"overwhelmingly reassuring", and further reinforced the growing scientific
consensus that such clusters were largely due to the effects of 'population mixing'.
Nuclear industry opponents say the latest study appears to provide fresh
statistical evidence to support the now largely-discarded 1990 'Gardner
hypothesis' of a direct link between increased cancer risk and higher levels of
parental pre-conception irradiation (PPI).
The study, which was first published earlier this year in the International
Journal of Cancer, confirmed previous findings of excess rates of leukaemia and
non-Hodgkins lymphoma (LNHL) among the children of radiation workers born in
Seascale, and said there was a statistical association between the level of PPI
and the risk of children contracting one of the two.
However, it stressed that the estimated excess risk was "substantially lower"
than that identified by the 1990 study, and concluded that a "substantial
proportion" of cases were clearly due to population mixing - where previously
isolated communities are exposed to infections from large influxes of new
populations.
The authors say the study represented "the largest and most comprehensive
investigation of the risk of LNHL in children of the workforce with the highest
occupational exposure to ionising radiation in Western Europe and North America".
It was based on a database comprising registration details of all 274 170 live
births to mothers in Cumbria between 1st January 1950 and 31st December 1991, and
included 1737 subjects where the PPI level was at least 100 millisieverts (mSv).
Presenting the results of the study to workforce representatives at Sellafield,
one of the authors, Louise Parker, said: "There is no evidence at all that
radiation workers employed today and working under current radiological
protection guidelines are putting their children at any increased risk." She
added that the study had "no relevance at all" for any current worker planning to
start a family.
Paul Thomas, BNFL's director of health, environment, safety and quality, said:
"This study is very reassuring for our workforce and confirms that the excess
risk of LNHL particularly in Seascale can be largely attributed to population
mixing. The statistical association between PPI and LNHL is weak and of
borderline statistical significance.
"International studies using various different sets of data have failed to find
any support for Gardner's idea that PPI increased the risk of childhood leukaemia
and could therefore be responsible for the excess in Seascale. Taking all these
studies together, the weight of scientific evidence points away from PPI as a
cause of childhood leukaemia."
Source: BNFL / International Journal of Cancer
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