Arguments
In May 2011, a Working Group of 31 scientists from 14 countries met at the IARC in Lyon to assess the potential carcinogenic hazards from exposure to radiofrequency electromagnetic fields. The Working Group did not quantitate the risk of cellphone use; however, according to Science Daily one study examined by them showed a 40% increased risk for gliomas in the highest category of heavy users (reported average: 30 minutes per day over a 10year period). [source]
This special report by KTVU News in 2009 was a fore-warning of cellphones as a potential health risk.
"Mobile Phones Don't Cause Cancer, Major Study Reveals"
These were headlines that appeared following the publication of the Danish Study in October 2011 and is a repeat of similar headlines which appeared in 2006 when the original Danish Cohort study was published.
But in May 2011, the IARC panel of 30 scientists who judged RF exposure as a Class 2B possible human carcinogen commented on the 2006 Danish study, as published in the Lancet journal:
"In this study, reliance on subscription to a mobile phone provider, as a surrogate for mobile phone use, could have resulted in considerable misclassification in exposure assessment." [Lancet, 22 June 2011]
The more recent Danish study has the same limitations. Briefly, these are a few of the concerns:
a. Biased sample set
According to the researchers, "A limitation of the study is potential misclassification of exposure. Subscription holders who are not using their phone will erroneously be classified as exposed and people without a subscription but still using a mobile phone will erroneously be classified as unexposed. Because we excluded corporate subscriptions, mobile phone users who do not have a subscription in their own name will have been misclassified as unexposed."
Corporate subscribers (who were excluded) tend to be the heaviest users.
b. Risk remains for heavy users
The researchers also added: “A small to moderate increase in risk for sub-groups of heavy users or after even longer induction periods than 10-15 years cannot be ruled out.
Earlier this year, the World Health Organisation warned that mobile phones could possibly cause cancer and the heaviest category of cellphone user was classified by WHO as 30 mins/day for 10 years. These days people are on the phone far more than a decade ago.
c. The conclusion didn't take into account the increased power of cellphone technology today
Another limitation of the study according to the researchers is that “as data on mobile phone subscriptions were available only until 1995, individuals with a subscription in 1996 or later were classified as non-users."
Pre-1995 almost all these subscribers used analogue mobile phones which operate quite differently to more recent handsets. Analogue mobile phones were slightly higher powered but did not pulse in the way 3G phones do.
Consequently, the Apple iPhone 4 safety manual says "When using iPhone near your body for voice calls or for wireless data transmission over a cellular network, keep iPhone at least 15 millimeters (5/8 inch) away from the body."
And BlackBerry Bold advises users to "keep the BlackBerry device at least 0.98 inch (25 millimeters) from your body when the BlackBerry device is transmitting."
4. Control group also exposed
Another concern is the choice of individuals in the control group. The Danish researchers compared the rates of brain tumors that occurred from 1990 to 2007 in those who began using cell phones after 1987 with the rates in those who were nonsubscribers when the study started.
"This understates risk, because most of those who began as 'nonsubscribers' to cell phone service (i.e., the 'controls' at the time the cohort was collected) became cell phone users later on, and accumulated almost as many years (on average per person) as the 'exposed' subscribers. Hence, the comparison to the population not contained in the subscriber sample is a comparison between 2 exposed groups.
When Michael Kundi and colleagues from the Medical University of Vienna mathematically corrected for this concern in an earlier report from this Danish study, they found a significantly increased risk for brain tumors," the group writes. [4]