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It is disturbing that the Interphone study group first publishes
several papers purportedly finding negative results but only now
publishes a validation study showing that the methods used to measure
exposure are so deeply flawed that it was unlikely the previously
published studies would detect an increase in risk of brain tumour in
mobile phone users(1).
In the validation study of 672 vo...
In the validation study of 672 volunteers recall of phone use over a
3-8 months period about six months later, was compared with objective data
from phone bills and use of special soft-ware modified phones. The study
found large random errors in recall which can be expected to have a “large
impact” and bias risk estimates toward a null effect. There was also a
wide variation between countries which further emphasises the randomness
of recall (and the difficulty in conducting a meta-analysis of results
from participating countries). Moreover the validation study design
minimises the errors of recall for several reasons. It largely used
"colleagues and acquaintances of the investigators". These volunteers
would have been well informed of the intent of the study and the
importance of accurately recalling mobile phone usage, and are therefore
different from the naïve subject in the actual studies whose recall would
be even more random. Also the validation study only sought recall of
mobile phone use for 3-8 months about six months later, whereas in the
actual studies recall for up to 10 years was sought which is likely to
lead to even more randomness in recall. The validation study did not
address the problem of impaired recall in the cases with brain tumours who
are likely to have their memory affected from their tumour and subsequent
surgery, radiotherapy, chemotherapy and psychological distress, let alone
the accuracy of surrogates (spouses) used in some studies.
The validation study reveals at a minimum the flawed methodology
being used in the Interphone studies which would lead to Type2 (false
negative) errors thus lessening the ability to except with confidence the
published negative papers regarding the health effects of mobile
phones(2). The late publication of a key methods paper after publication
of many results papers raises concerns about the processes within the
Interphone study group.
Dr Bruce Hocking.
1. Vrijheid M, Cardis E, Armstrong BK, Auvinen A, Berg G, Blaasaas
KG, Brown J, Carroll M, Chetrit A, Christensen HC, Deltour I, Feychting M,
Giles GG, Hepworth SJ, Hours M, Iavarone I, Johansen C, Klaeboe L, Kurttio
P, Lagorio S, Lonn S, McKinney PA, Montestrucq L, Parslow RC, Richardson
L, Sadetzki S, Salminen T, Schuz J, Tynes T, Woodward A; Interphone Study
Group. Validation of short term recall of mobile phone use for the
Interphone study. Occup Environ Med. 2006 Apr;63(4):237-43.
2. Hocking B. Mobile phone use and risk of acoustic neuroma.
Br J Cancer. 2006 May 8;94(9):1350; author reply 1352-3.