Helsinki/Finland, January 11, 2012-Epidemiological studies are given the most weight in evaluation of human health effects. Therefore, when researchers started their effort to find out whether cell phone radiation causes brain cancer, epidemiology was given the most of attention - and the most funding.
However, and please let me play “devils advocate”, is the epidemiology overrated?
Will epidemiology ever give us reliable answers concerning cell phone radiation and brain cancer?
In 2010 and in 2011, two of the largest epidemiological studies on brain cancer were published. It appears that the time and money were used generously, but the studies failed to provide reliable answers concerning cell phones radiation and brain cancer. Flaws in the design of both studies prevented delivering conclusive answers.
It was 1999 when the largest case-control epidemiological study, INTERPHONE, was planned. At that time, optimists hoped that by the end of this project in 2004 we would know whether cell phone radiation causes brain cancer.
After several delays, INTERPHONE published the results of the glioma brain cancer study in 2010.
The results were confusing, to say the least. Use of the cell phone for less than 10 years seemed to have a “protective” effect, whereas the use of the cell phone for more than 10 years showed a small increase in glioma occurrence.
Several problems with the design of INTERPHONE were debated. By design, the INTERPHONE study was unable to detect brain cancer induced by cell phone radiation because of its long (over 10 years) latency period.
At the time of execution of INTERPHONE (2000-2004), cell phones were in common use for only a few years. There would be not enough time for the development and diagnosis of brain cancer if it was caused by cell phone radiation.
However, there was an even more important design flaw. The information about the extent of exposures to cell phone radiation was based on individual recollection of the subjects in the study. The study subjects were asked about their history of using cell phone, including how long and how many phone calls they made in the past.
It is a very unreliable method. Who of us remembers how many and how long calls made a few days ago? The study subjects were asked to recall cell phone use up to ten years before the study.
Therefore, by design, INTERPHONE compared reliable information concerning diagnosed cancers with entirely unreliable information about exposures. Such kind of comparison can not produce reliable result, as was seen in the confusing results of the study published by INTERPHONE in 2010.
In 2011, the Danish Cohort published another largest study, evaluated in this column in December 2011.
Similarly to INTERPHONE, the Danish Cohort compared reliable information on diagnosed brain cancers with the absolutely unreliable information about exposures based not on the use of cell phone but on the length of subscription with the network operator. The study also contaminated the control group with the cell phone users.
Again, as with the INTERPHONE, the Danish Cohort made comparison of reliable data on cancer with the unreliable information about exposures cannot produce reliable final result.
Brain cancer is a rare disease, somewhat in the range of around 10 cases per 100,000 people. It means that in order to reliably detect the change, which seems to be less than 50% according to flawed INTERPHONE, tens of thousands of the study subjects should be analyzed. This is very expensive but not necessarily productive.
As shown by the experiences with INTERPHONE and Danish Cohort, large amounts of money (tens of millions of Euros) and ample amounts of time (over 10 years) were used and no reliable answers received.
In the current situation, with the above presented experience, should the epidemiology be the first kind of studies to use our scarce research resources? Epidemiology is very expensive and takes a very long time to get results. Any flaw in the study design sets us back by ten or more years.
Would we be we better off using the available funding for the human studies examining acute effects of cell phone radiation on physiology? This would, of course, include studies of the known molecular events leading to initiation and development of cancer. We still do not know if cell phone radiation triggers any such events in living humans.
Performing physiological studies on volunteer will provide information whether any known carcinogenic events are triggered by cell phone radiation. Depending on the result, we could act immediately by imposing preventive measures based on scientific evidence.
To provide such information, epidemiology will still need tens of years before it is able to perform effective studies, assuming that studies will be designed without any major flaws. Volunteer studies examining physiology and pro-carcinogenetic events would provide information much faster.
In this time of scarce resources, we need to make choices how to obtain, most reliably and expeditiously, information about the possible effect of cell phone radiation on brain cancer.
Based on the experience of the last 10-15 years, epidemiology does not seem to be the method of choice.
Read more from Dariusz Leszczynski in his science blog “BRHP - Between a Rock and a Hard Place” at http://betweenrockandhardplace.wordpress.com Dariusz is a Research Professor at the Radiation and Nuclear Safety Authority in Finland.
Follow Dariusz on twitter: @blogBRHP
Disclaimer: the opinions presented in this column are author’s own and should NOT be considered as the official opinions of the STUK - Radiation and Nuclear Safety Authority in Finland.
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