On May 17, 2010 the Interphone International Study Group, consisting of 21 scientists in 13 countries, published the results of a decade-long study conducted to determine the relationship between mobile phone use and brain cancer risk. Initiated in 2000 by the International Agency for Research on Cancer (IARC), Interphone was the largest case-controlled study of its kind ever conducted.
Medical, environmental and mobile phone industry experts and concerned lay people alike have anxiously awaited the results of this study to end debates as to whether cell phones cause cancer and industry standards should be revised. Finally published, the Interphone results leave us back where we started, though: with the need for more research to determine relative risk of brain cancer associated with cell phone use, especially in persons under 21 years old.
Taking precautionary measures can’t hurt us when it comes to cell phone use! Do we and our loved ones really want to risk becoming the statistical proof of the link between cell phone use and cancer in future studies?
Remember, folks, prevention is always easier than cure…
During a May 17th press conference,1 IARC representatives stated that,until we know more about how cell phone use will affect health, we should limit our exposure to cell phone RF (radio frequency) by:
• Sending text messages in lieu of talking on the phone,
• If talking, keep conversation time to a minimum, and;
• Using the speakerphone function (the further a cell phone from the head, the less the exposure); or
• Using a wired head set (HMDI recommends one with an air tube).
HMDI also recommends:
• Limiting RF exposure / cell phone use by children and adolescents
• Turning the phone off when not using it to speak, text, or check messages (this may mean relying on a wristwatch again to keep time).
• That you do not keep the phone on or near your body when it’s turned on, but several feet away, at least.
Interphone Study Basics:
Who Participated?
The Interphone study involved analyzing data collected from 10, 751 people through in-person, computer assisted interviews conducted by trained interviewers. The majority of study participants were confirmed to have either glioma (2708 cases) or meningioma (2409 cases) brain tumors, or they were cancer-free and comprised the 5634 controls.
Basis of Cancer Risk Assessment
Through the interviews, the Interphone scientists collected detailed information about past cell phone use, as well as occupational exposure to ionizing radiation (which causes “thermal” effects like mutations and cancer), medical history of the self and family, exposure via medical tests to ionizing and non-ionizing radiation (which may cause “non-thermal” or biological effects that disrupt cell physiology), socio-demographic factors, and possible smoking habits. For those with cancer, the type and anatomical location of the tumors were noted. Scientists validated the questionnaire interviews by comparing them with mobile phone records and other phone information.
Inconclusive Results Point to Study Biases and Limitations
Unable to reach a consensus for several years about the study results, the Interphone scientists eventually agreed upon inconclusion: that study biases and limitations precluded the finding of any risk or lack of risk of brain cancer associated with cell phone use.2 The unbelievable results showed an overall reduced risk of brain cancer for cell phone users, but a significantly increased risk at the highest exposure levels.
During the May 17th press conference, Professor Elizabeth Cardis, Principal Investigator of the Interphone study, stated that this finding of a protective effect is “not very biologically plausible and probably reflects participation bias or other limitation in the study.” Since the finding of a protective effect in the study was found unreliable due to biases or other limitations, the finding of a causal relationship between brain cancer risk and significant cell phone use in the 10% of study participants with the highest exposure was also prevented.
While this is probably the only study demonstrating that cell phones may actually protect against cancer, it’s certainly not the only one to yield results showing a link between cell phone use and cancer risk.3 Although the majority of studies indicate a need for more research on the subject, the baby, indeed, got thrown out with the bath water in the Interphone study.
Industry Response
Michael Milligan, Secretary General of the Mobile Manufacturers Forum (MMF), stated in a press release:
“The INTERPHONE project… provides significant further reassurance about the safety of mobile phones… reporting no increased health risk from using mobile phones…Mobile phone users can take comfort in the fact that there is already a substantial body of scientific evidence on the long-term use of mobile phones through whole-of-life animal studies, which have found no link between long-term exposure to radiofrequency and health impacts.”
Milligan’s absolute position with regard to cell phone safety makes clear that consumer safety is not the industry’s main priority.
Limitations: Sign of the Times
When the Interphone study was conducted, cell phone usage was not nearly as prevalent as it is now. In comparison with today’s usage patterns, the patterns of use among study participants were much lighter. In fact, median mobile phone use was 100 hours during an Interphone participant’s lifetime. This amounts to 2 to 2.5 hours of use per month. Even the heaviest users in the study who spent 1,000+ hours of their lifetime on a cell phone averaged 30 minutes per day. Not a far cry from the amount of time people now spend talking on cell phones each day…
Since the study participants with the highest exposure in the study did develop cancer, is it safe to say that 30 minutes per day on a cell phone significantly increases one’s risk of brain cancer?
Maybe…but why wait to find out until it’s proven in a study without biases and limitations? Acting preventatively is our best defense.
The Interphone design was also limited by the long latency period of brain cancer. Glioma, in particular, can take several decades to develop and most of the study participants had not been using cell phones for more than a decade at the time the study was conducted.
An additional study limitation was the exclusion of child and adolescent participants; omission of such a significant group of cell phone users necessarily underestimates the overall risk of brain cancer associated with cell phone use. Independent studies have shown that children and adolescents may be at much greater risk of developing brain cancer because their rapid development, thinner skulls and likelihood of longer-term use; the younger the child, the greater his or her risk.4
During the May 17th press conference, Professor Cardis did communicate that the exclusion of children and adolescents in the study, coupled with concerns about the dramatic increase of cell phone use among this population segment, has fueled a new project called MobiKids, which will focus on the risk of brain tumors in young people who use cell phones.
Again, though… why wait until studies prove such risk before taking precautionary measures?
Unfortunately, the list of study limitations and biases goes on and on.Changes in cell phone technology, selection bias, recall bias, lack of examination of biological effects other than cancer that may be related to cell phone use, the use of questionnaires (as opposed to experimentally-based studies), possible industry influence, etc. have been raised as problems preventing accurate assessment of brain cancer risk through this study.
Future Projects in the Making
In addition to the MobiKids project, IARC also plans to further evaluate carcinogenic risk associated with cell phone use through a comprehensive review of all published epidemiological and experimental evidence, as well as new data from Interphone in May 2011.
Hopefully Interphone was the learning curve for future studies about the relationship between cell phone use and developmental health conditions like cancer. What we have learned is that we cannot be overly safe when it comes to cell phone use. Limiting our exposure through precautionary measures is the key to protecting ourselves from becoming cancer statistics. We need to spread the word until the science catches up: Prevention is easier than cure.
1. The World Health Organization (WHO) Press Conference about the Interphone Study 5/17/2010; Available at http://www.iarc.fr/
2.See the WHO International Agency for Research on Cancer Press Release: “Interphone study reports on mobile phone use and brain cancer risk.” May 17, 2010.
3. The following are some examples studies finding a link between cancer and cell phone use:
- Carpenter DO. Electromagnetic fields and cancer: the cost of doing nothing. Rev Environ Health. 2010 Jan-Mar;25(1):75-80. [Abstract]
- Hardell L, Carlberg M, et al. Meta-analysis of long-term mobile phone use and the association with brain tumours. Int J Oncol. 2008 May;32(5):1097-103. [Abstract]
- Hardell L, Carlberg M, et al. Long-term use of cellular phones and brain tumours: increased risk associated with use for > or =10 years. Occup Environ Med. 2007 Sep;64(9):626-32. Epub 2007 Apr 4. [Abstract]
- Khurana VG, Teo C, Kundi M, Hardell L, Carlberg M. Cell phones and brain tumors: a review including the long-term epidemiologic data. Surg Neurol. 2009 Sep;72(3):205-14; discussion 214-5. Epub 2009 Mar 27. [Abstract]
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