Cell Phones and Brain Tumors: Is There a Connection?

There has long been a question about whether use of handheld cellular phones increases the risk of brain tumors. Are children and adolescents at higher risk because of their developing brain and smaller head size?

A quick search of my university’s reference database produced close to 100 separate titles on this subject since 2000.

Concern about the health risk of radiowaves and electronic radiation was heightened in May, 2011 when the World Health Organization’s International Agency for Research on Cancer published its findings that cell phones were possibly carcinogenic to humans.¹ More precisely, the working group led by Jonathan Samet, MD, classified cell phones as a risk category 2B. 

To quote directly:

“This category is used for agents for which there is limited evidence of carcinogenicity in humans and less than sufficient evidence of carcinogenicity in experimental animals. It may also be used when there is inadequate evidence of carcinogenicity in humans but there is sufficient evidence of carcinogenicity in experimental animals. In some instances, an agent for which there is inadequate evidence of carcinogenicity in humans and less than sufficient evidence of carcinogenicity in experimental animals together with supporting evidence from mechanistic and other relevant data may be placed in this group. An agent may be classified in this category solely on the basis of strong evidence from mechanistic and other relevant data.” (The italics are theirs.)

This does not read as hard evidence of a relationship. In fact, a review of available evidence does not support a significant increase in risk for the average user.  

The Evidence Against Increased Risk
There are a number of studies in animal models and in humans-both adult and children-that argue against a relationship between cell phone use and brain tumors. A 2001 animal model study showed that there was no “statistically significant evidence” that radiofrequency fields caused brain tumors.² 
In a human adult study in Denmark, using the national data base, comparing all citizens with mobile phone contracts to all those without contracts, there was no increased risk of brain tumors in the cell phone group.³ The CEFALO study of children and adolescents in Denmark, Sweden, Norway, and Switzerland, also found no relationship.⁴

Some studies do suggest a relationship and some suggest a potential increased risk only for the long-term or high-use cell phone subgroup.^5,6 Even this association has been questioned, however.⁷
There is no evidence that radiation from a handheld cell phone causes any DNA changes. Therefore, the biologic basis of any increased risk must be related to local heat production.⁸ If this is the case, should we be studying the increased risk of brain tumors associated with childhood fevers?

Most significantly, despite an exponential increase in the use of handheld mobile phones in the past 10 years in both the United States and Great Britain, there has been no corresponding increase in brain tumors.^9,10 One would assume that if there was such an association, that there would have been some corresponding increase in incidence of these malignancies.

All this information can make one comfortable that the likelihood of there being a relationship between cell phone use and brain cancer is quite small, and -if one exists- then it does so only for very heavy users.

Would it be prudent for heavy users to use a hands-free device? All one can say is, it certainly couldn’t hurt.

However, if we put all of this into perspective, we are left with 2 important questions:

1. Is this a moot issue? Are teenagers and young adults, in fact, even holding cell phones to their ears any more? An ever increasing proportion of communication is done by texting, and more and more of the remaining voice communication is done using a hands-free device, so the phone is nowhere near the head.

2. Are brain tumors the real risk? Even if the risk of brain cancer was shown to be increased with cellular phone use, the numbers would be small and would pale in comparison to the risk of injury and death caused by inattention while texting and voice cell phone use during driving.

References:
1. World Health Organization. International Agency on Research for Cancer classifies radiofrequency electromagnetic fields as possibly carcinogenic to humans. Press release 208. May 31, 2011. http://www.iarc.fr/en/media-centre/pr/2011/pdfs/pr208_E.pdf
2. Zook BC, Simmens SJ. The effects of 860 MHz radiofrequency radiation on the induction or promotion of brain tumors and other neoplasms in rats. Radiat Res. 2001;155:572-583.
3.  Frei P, Poulsen AH, Johansen C, et al. Use of mobile phones and risk of brain tumours: update of Danish cohort study. BMJ. 2001;343:d6387. http://www.bmj.com/content/343/bmj.d6387
4. Aydin D, Feychting M, Schuz J, et al. Mobile phone use and brain tumors in children and adolescents: a multicenter case-controlled study. J Nat Cancer Inst. 2011;103:1-13.
5.  Cardis E, Armstrong K, Bowman JD, et al. Risk of brain tumours in relation to the estimated RF dose from mobile phones: results from five Interphone countries. Occup Environ Med. 2011;68:631-640.
6. Khurana V, Teo C, Kundi M, et al. Cell phones and brain tumors: a review including the long-term epidemiologic data. Surgical Neurol. 2009;72:205-215.
7. Swerdlow A, Feychting M, Green A, et al.  Mobile phones, brain tumors, and the interphone study: where are we now? Environ Health Perspect. 2011;119:1534-1538.
8. Ahlbom A, Green A, Kheifets L, et al. Epidemiology of health effects of radiofrequency exposure. Environ Health Perspect. 2004;112:1741-1754.
9. Inskip PD, Hoover RN, Devesa SS. Brain cancer incidence trends in relation to cellular telephone use in the United States. Neuro Oncol. 2010;12:1147-1151.
10. de Vocht F, Burstyn I, Cherrie JW. Time trends (1998-2007) in brain cancer incidence rates in relation to mobile phone use in England. Bioelectromagnetics. 2011;32:334-339.