The Interphone Study Shows We Still Need to be Careful with Cell Phones

May 11th, 2010 - by: David Servan-Schreiber, M.D., Ph.D.

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The researchers of the Interphone study finally published their conclusions in the International Journal of Epidemiology on May 17. This was long overdue. The publication of their results was originally scheduled for mid 2005, but lengthy delays after the end of the study were followed by extensive negotiations to hammer out an agreement that satisfied all the signatories. The dispute between the Interphone researchers dated from the first, preliminary analysis of their results. Some had concluded that there was no risk associated with cell-phone use; other scientists felt that the study demonstrated a "possible" risk. To my mind, detailed analyses of the results - which were not all presented in the formal article that was published May 17 -- suggests that the "worried" group of researchers is also the more rational. Let's get back to the facts.

The results of the Interphone study, which were published on May 17 2010 in the International Journal of Epidemiology, conclude that there is insufficient proof of a causal link between frequent use of cell phones and malignant brain tumors. At the same time, the authors suggest that there is a higher risk of glioma (brain cancer) in the study group characterized by the greatest cell-phone use (≥1640 hours over 10 years, in other words 30 minutes per day over 10 years). This risk is higher on the side of the brain where users say they habitually hold the phone.

Furthermore, in an "Appendix 2" that was published on the website of the International Journal -- but not in the print version of the article proper -- some of the researchers note that when the comparison of study groups was effected according to a different method -- designed to reduce the effects of bias arising from the study's selection of subjects -- the results were totally different. Those who used a cell-phone for longer than ten years were twice as likely to develop a malignant brain tumor ('glioma'). This increase in risk is statistically significant -- in other words, it is considered scientifically reliable. And the result holds irrespective of the method used to quantify the duration of exposure to the phone -- whether it be number of years of use, total duration of conversations, or total number of calls. Furthermore, there was even a sketchy "dose-response relationship," in that the longer the duration of exposure, the higher the risk. (See below the table published in Appendix 2 of the Interphone study).

Interviewed on the website Microwave News, Elisabeth Cardis, who led the study, said these results were "important and very suggestive". Nonetheless, in order to achieve a consensus among all the authors, they were published separately, in an appendix. They were not addressed in the summary of the study that was made widely available to the media.

I am further worried by a number of other, disconcerting limits to the Interphone study -- particularly considering the massive use of cell-phones, now adopted by almost 5 billion people whose age has become steadily younger.

Firstly, the study only analyzes a maximum of ten years of use, and focuses only on adults. As the editors of the International Journal of Epidemiology emphasized, ”None of the today’s established carcinogens, including tobacco, could have been firmly identified as increasing risk in the first 10 years or so since first exposure.”

Secondly, this data is old. The researchers began gathering data in 2000, and the 21,770 persons they queried were asked to measure their average use over the preceding decade -- a period in which the use of cell-phones was far less widespread than it is today. "Major users" were thus defined as people who used their phones for thirty minutes per day. But as many of you know -- particularly if you use a cell-phone for work -- if you combine calls received and calls made, you're very often way over this level. In some countries there are almost no land-lines any more: practically all phone conversations take place on cell-phones.

The published results of the study also neglect to discuss acoustic neurinomas and tumors of the parotid gland, even though the study itself did receive data about these pathologies. It's my strong opinion that all the study's data should be given to the public -- even if they’re inconclusive -- to avoid any suspicion that something is being concealed.

Cell phones are a wonderful tool, and in emergencies they often save people's lives. I use mine every day, but I take some basic precautions. The results of the Interphone study certainly don't sweep away our doubts about their use, particularly concerning the increased risk of brain cancer. So I recommend that we should all continue to be vigilant, and apply the simple advice featured in the June 2008 appeal that was made by 20 scientists and cancer-specialists (including myself).

I'll remind you again of the main points:

1. Don’t allow children under 12 to use a cell-phone except in emergencies. Organs that are still developing are more sensitive to the possible influence of exposure to electromagnetic fields. A child's skull is thinner than an adult's, and every millimeter between the handset that's emitting electromagnetic waves and the child's brain cells can make an enormous difference.

2. During calls, do your best to keep your cell-phone well away from your body. (When the handset is held four inches away, the amplitude of the electromagnetic field drops to one-quarter of its full value, and it is 50 times smaller when the phone is a yard away). Use the "loudspeaker" mode whenever possible, and a hands-free mode or Bluetooth earpiece (which on average gives less than one hundredth of the phone's normal electromagnetic emissions).

3. Keep your cell-phone conversations short. The biological effects are directly linked to duration of exposure. Text as much as possible.

4. Avoid using cell-phones when moving rapidly, for example when in a car or train. (There's an automatic increase in power to maximum when the phone is trying to pick up a new -- or increasingly distant -- relay antenna).

5. Choose the phone with the lowest possible Specific Absorption Rate (SAR) for your needs. (The SAR measures the quantity of radio frequency energy absorbed by your body). Classifications of the SAR values of phones from various manufacturers are available on a number of websites.

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These recommendations are easy to put into practice, and they're particularly crucial regarding children. As Martha Linet, chief of the Radiation Epidemiology Branch of the National Cancer Institute put it in a report that was recently delivered to President Obama, "The most urgent issue that we need to address … is whether children or adolescents using cell phones are at increased risk ". This is a question that the Interphone study completely ignores, and it absolutely must be addressed in upcoming studies such as the COSMOS study and Mobi-kids.


Note (1) My thanks to Louis Slesin, director of the website and newsletter www.microwavenews.com, for his rigorous and detailed analyses of the scientific literature on the biological effects of cell-phones, and his commentaries on the Interphone study over the past five years. It was a report on his website that drew my attention to the Appendix 2 of the Interphone study, whose table I've reproduced here, with his highlighting.


Sources :
The INTERPHONE Study Group, “Brain tumour risk in relation to mobile telephone use: results of the INTERPHONE international case-control study,” Int. J. Epidemiol. (Mai 17, 2010): dyq079.

Rodolfo Saracci et Jonathan Samet, “Commentary: Call me on my mobile phone...or better not?--a look at the INTERPHONE study results,” International Journal of Epidemiology (Mai 17, 2010): dyq082.

Seung-Kwon Myung et al., “Mobile Phone Use and Risk of Tumors: A Meta-Analysis,” Journal of Clinical Oncology 27, no. 33 (Novembre 20, 2009): 5565-5572.

Interphone study finds hints of brain cancer risk in heavy cell-phone users, Science News

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