Few public health issues have been as controversial as the question of whether or not cellphones cause cancer. One thing we do know is that each time a cellphone is pressed to the ear, electromagnetic energy pulses through the skull bone at 186,000 miles per second. The exact nature of how this may affect living tissue remains a matter of contention.
Throughout the last decade, there appeared to be a growing consensus that cellphones do not cause brain cancers as originally alleged in the failed 1992 lawsuit that made the issue an international concern. Some of the most meaningful research during these years was conducted in association with the Danish Cancer Society and made possible by the Scandinavian countries' unique national health care databases. Led by Christoffer Johansen, MD, PhD, the largest population-wide study originally published in 2001 and updated in 2006
was internationally hailed in the press as the "definitive" finding that cellphones do not increase brain-cancer risk.
In June, when the World Health Organization's International Agency for Research on Cancer (IARC) announced it was adding cellphone radiation to the "Category 2B" list of agents that were "possibly carcinogenic," it appeared to contradict the widely respected findings of Johansen and his team.
Johansen heads the Department of Psychosocial Research at the Danish Cancer Society's Institute of Cancer Epidemiology; his country was part of the world's earliest nationwide cellphone network established in the 1980s and, hence, its population has some of the longest exposure to mobile phone radiation. Denmark also maintains population-wide cancer registries that date to 1942, and centralized files of the health records of every Danish citizen since 1968.
420,000 mobile phone users Crossing that anonymized medical data with access to phone company records of every Danish citizen who has subscribed to mobile phone service since 1982, Johnansen's team studied more than 420,000 mobile phone users' medical conditions over periods as long as 20 years.
Their report concluded that mobile phone use had no impact on the level of cancer risk throughout that broad study population.
The LDI Health Economist asked Dr. Johansen to comment on the IARC's latest announcement as it related to his own studies and the public confusion about the issue. The recent floods in Copenhagen that damaged the Danish Cancer Society's facilities delayed his reply. This is what he had to say:
Christoffer Johansen: The World Health Organization's International Agency for Research in Cancer (IARC) meets a couple times each year to assign groups of experts the task of writing monographs on various potentially carcinogenic agents. These papers are widely viewed as the most authoritative documents in the cancer research field.
In June, 2011, an IARC paper concluded that the EMF (electromagnetic fields) emitted by mobile telephones was possibly carcinogenic, a Level 2B classification.
This classification focused solely on glioma, a certain type of brain tumor. In addition, 2B includes a benign brain tumor named acousticus neuroma (AN).
The IARC mentions no risk associated with use of mobile phones and for meningioma, the other major form of brain tumor. Likewise nothing is mentioned about other cancers, so the focus is clearly and exclusively on glioma and AN tumors. This is an important point.
Glioma not increased The large studies I've been involved in have shown that the incidence of glioma is not increased by use of mobile phones in the Scandinavian countries. This is based on a population of close to 22 million people with complete population registration and complete follow-up.
We're talking about the world's oldest population-based, nationwide cancer registries that cover the period from 1998 to 2003, the time when possible associations between mobile phone use and cancer risk would be informative about an induction period of 5-10 years.
Likewise we have carried out a large prospective cohort study including more than 420,000 cellular telephone subscribers, in which we found no evidence of an association between tumor risk and phone use among either short-term or long-term users.
Narrow confidence intervals Moreover, the narrow confidence intervals in the study report provide evidence that any large association of risk of cancer and cellular telephone use can be excluded.
In a study focused on the location of gliomas in relation to the preferred side of head favored by the phone user, results did not suggest that gliomas in mobile phone users are preferentially located in the parts of the brain regularly exposed to the highest levels of EMF.
Overall, high quality data -- which can almost exclude recall bias or selection bias -- do not point to an increased risk of glioma associated with the use of cellular telephones.
However, a number of case-control studies, which -- more or less -- suffer from these methodological limitations point to an increased risk and therefore the IARC had to classify the "agent" -- or phone device -- as 2B.
The IARC's advice to the public is to use hands-free sets and reduce the amount of voice communications or use text messages as an alternative.
My advice, on the other hand, is this: do not fear your cellular telephones.
