The "Second Event" theory:
A misapprehension originating from NRPB

from NRPB's Radiological Protection Bulletin No. 208, December 1998
EDITORS - In Bulletin No.201 Dr Jack Valentin, commenting on Dr Chris Busby's `Second Event' Theory, wrote: ... the epidemiological observation originally prompting the invention of this theory seems to have been an artefact of erroneous cancer registry data ...`. This is not true.
Formulation of the Second Event Theory began in the 1980s with the idea that sequential emitters when immobilised in body tissue represent a unique hazard compared with random hits from natural background radiation (NBR).
In 1993, the Wales Cancer Registry announced a validation exercise of bone cancer registrations, following publicity about an excess incidence of that disease in Wales. The revised figures showed a smaller excess which correlated with strontium-90 fallout from weapons testing 20 years earlier. In a subsequent revision the excess entirely vanished. We do not doubt the sincerity of Dr Valentin, nor that of some NRPB staff whom we have heard voicing the same criticism, but the facts are that the Second Event Theory preceded the hone cancer observation by some years and that Dr Busby always said that bone cancer a rare disease - was not crucial to his case. Nevertheless, if the theory is valid one would expect to find epidemiological evidence of it. The second revision of the bone cancer data has been criticised by Dr Peter Meyer (Radioactive Times, volume 2, number 1). In October 1997 the new Welsh Cancer Intelligence and Surveillance Unit undertook to answer Meyer's criticisms; its response is still awaited,
Dr Busby has recently reworded [NRPB misprint for "reworked"] the maths of the Second Event Theory showing that at the 0.1 mGy dose level the probability of a second hit to any one cell during the cell repair cycle is 200 times greater from incorporated strontium 90 than from random external radiation (NBR). At the 0.01 mGy level the relative hazard is 1900 times greater. It is to be hoped that the peer-reviewed literature will soon publish this paper.
Richard Bramhall, Low Level Radiation Campaign

Author's Reply
EDITORS - I am grateful to Richard Bramhall for explaining that the Second Event Theory preceded the disputed Welsh bone cancer findings, which thus did not "originally prompt" the theory.
However, as he says, if the theory is correct, then epidemiological observations should support it. The Welsh bone cancer data are disputed; I am not familiar with the details of the leukaemia data he refers to, [Dr V. means childhood leukaemia in Wales - NRPB had cut this from Bramhall's letter] but to the best of my knowledge there is certainly no such evidence in the Nordic countries which are well known for their very reliable cancer registries and which had their share of fallout from weapons testing as well as from the Chernobyl accident. Furthermore, the statistical uncertainties about the theory remain, in particular until it has been published in the peer reviewed literature.
Therefore, while I regret my misunderstanding of the origin of the Second Event Theory, I stand by my conclusion that the theory is as yet in dispute on both epidemiological and theoretical grounds.
Jack Valentin Scientific Secretary. ICRP

Bramhall observes: "Presumably Dr Valentin is referring to the infamous 1993 Nordic leukaemia study of Darby, Doll and others."

Busby replies to Dr V.
Sir, Replying to my colleague Richard Bramhall, Dr. Jack Valentin says (RPB No. 208) that statistical uncertainties about my Second Event theory remain until it has been published in the peer-reviewed press.
Following the rejection of the original paper I published it (together with the reviewers' opinions and their elementary errors) in Wings of Death in 1995. Subsequently, notwithstanding the lack of peer review, NRPB's Dr Roger Cox and Dr Ken Chadwick of the European Commission vigorously attacked the mathematics, but they failed to find anything I had not already accounted for. They now decline to address it at all.
I myself have recently corrected a flaw in the original paper which nobody else has drawn attention to, presumably because they didn't find it.
The purpose of peer-review is to filter, and this theory has been adequately filtered, I think. It well known now. It is more accessible through the internet (at http://www.llrc.org/secevnew.htm ) than it would be if it were published in some obscure journal, and many people have said that it is worthy of and capable of being empirically tested.
No-body claims that peer-review is a perfect system. One of its principal failings is that paradigm challenging work, however robust, can be blocked by those who adhere to more established views. The fate of my theory is an example; the establishment's reluctance to pick up the gauntlet seems to have more to do with cultural shiboleths than with scientific truth-seeking.
Chris Busby



NRPB's Radiation Protection Bulletin failed to publish Busby's letter in issue #209 (Jan.- Feb. 1999).
However, Dr Roger Cox head of NRPB Bio-Medical Effects, speaking at a meeting between NRPB, LLRC and Environment Minister Michael Meacher on 8th February '99, said that he was aware of the latest version of the Second Event theory "from a website on the internet". He undertook to discuss it with colleagues at NRPB and to see if he could assist with getting it published in the peer reviewed literature.
RPB #210 (March 1999) published Busby's letter in full.
Alongside it was this reply from Dr Cox:

EDITORS
I wish to respond to the comment from Dr Chris Busby which implies that criticism of his Second Event Theory has been withdrawn. This is not so. His original formulation of the theory was judged by Professor Dudley Goodhead of the UK Medical Research Council to exaggerate the claimed risk from 90Sr by around 10 000 fold. At the same meeting I pointed out, making comparison with natural background gamma dose rate, that the so-called critical double hits from 90Sr decay and its decay product 90Y were in no way unique (see The Health Effects of Low Level Radiation Green Audit (Wales) Aberystwyth 1997, ISBN: 1-897761-14-7).
More recently Dr Busby seems to have accepted the original geometrical errors in his theory which now appears in a modified form on the web site he cites in his letter. Risk enhancement as a consequence of double hits is substantially reduced but, in my view, problems remain with the physical parameter values used. Very recently (8 February 1999) I informed Dr Busby that I would provide him with what I believe to be the correct form of the calculation, made on the basis of the rather unusual biological parameters that he sets. This calculation provides no evidence of the 90Sr risk enhancement he proposes in order to lend biological plausibility to his epidemiological claims of substantial low dose cancer risk from weapons fallout and other sources.
It is my intention to seek peer-reviewed publication of these calculations together with a commentary on which Dr Busby may choose to respond.
Roger Cox
NRPB

LLRC observed [in 1999] that
    Dr Cox's "intention to seek peer-reviewed publication" is not quite the same offer he made in the meeting with Mr Meacher, but it should suffice to give the Theory a much deserved airing.
    Busby was not, as far as we can see, suggesting that Dr Cox's criticisms had been withdrawn. Busby wrote that Dr Cox and Dr Chadwick were "declining to address it". We have letters from them which can be interpreted in no other way.

    As far as Busby having "accepted .. errors" and "Risk enhancement ... substantially reduced" are concerned, Dr Cox seems to have read Busby's
revised paper rather selectively (see the relevant table for the full picture). No matter - all this will come out in the wash, if the peer review idea actually comes to fruition. It finally has! [in January 2000] See this link.


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