The hard cell
Alarmist reports that seek to persuade us that mobile phones are dangerous take a selective approach to the evidence.
In the past two years, a number of reports have appeared from activist groups in the US alerting us to the possible dire effects of cellphones on human health.
First was the ‘Bioinitiative Report’ issued in 2007, which declared that ‘existing public safety limits’ on the radiation from phones and other wireless technologies are ‘inadequate’ (1). Then, last summer the University of Pittsburgh Cancer Institute issued an alert to its faculty and staff citing new, but unpublished, evidence that cellphone use causes brain cancer (2). The latest report, ‘Cellphones and Brain Tumors – 15 Reasons for Concern: Science, Spin and the Truth Behind Interphone’ (3) appeared just last month, featuring endorsements from some impressive-sounding individuals including academics and politicians.
These authoritative-appearing documents have rosters of PhDs and MDs and display vivid radiological images of the brain, adding to their scientific cachet. One note of caution would be to ask what those PhDs were awarded for. For example, one endorser of the most recent report, British Green Euro MP Caroline Lucas, was awarded her PhD in English and Women’s Studies. What expertise this provides for assessing the effect of radiation on brain cells is not clear.
The basic thrust of these reports is to argue that there is credible evidence that mobile phone use is associated with increased risk of brain cancer and non-malignant tumours of the brain, then invoke the ‘precautionary principle’ and counsel ‘prudent avoidance’ to reduce one’s risk and, particularly, that of children.
To the lay reader these reports are likely to appear to be serious and impartial assessments coming from independent-minded scientists concerned about the public’s welfare. Their authors, we are given to believe, are speaking out in order to expose the flaws of industry-funded research and inadequate government regulation. And, as one might expect, these alarming reports have received widespread coverage in the media.
What the reports have in common, and what is most striking to someone who is moderately conversant with the scientific evidence concerning the health effects of cell phone use, is the astoundingly selective and slanted presentation they give of the relevant evidence. In reading them one feels oneself in the world of Dr Jekyll and Mr Hyde.
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Here are some of the relevant considerations which these reports studiously avoid acknowledging.
At the outset, one should be clear about the physical properties of the agent one is discussing. The radiofrequency energy (RF) used in cellphone technology is many, many orders of magnitude lower in energy than ionizing radiation, the kind that can damage DNA and thereby initiate cancer. According to the Institute of Electrical and Electronic Engineers, which sets standards for RF exposure in the United States, ‘there is no evidence, from laboratory or epidemiology studies, that exposure to RF energy at levels below recommended limits has any health significance for humans’.
We need to keep in mind that little is known about the causes of brain cancer. The only established environmental risk factor is, in fact, ionizing radiation, which accounts for only a small proportion of brain cancers.
It is relevant to consider brain cancer incidence rates over recent decades. Incidence rates for brain cancer in some industrialised countries have shown a small increase over the past few decades. However, these increases appear to be limited to the older age groups. Furthermore, it is generally agreed that at least part of the increase is due to improved diagnostic methods. In other developed countries, incidence rates for brain cancer have been flat over decades.
Given the huge growth of cellphone use in the past 15 years, the fact that there is no evidence of an increase in brain cancer incidence in younger age groups is at least reassuring and worthy of mention, even if sufficient time has not yet elapsed for the full effects of cellphone use (if any) to make themselves felt.
Even if there were some statistical link between phone use and cancer, that would be insufficient if there was no plausible way in which we could see how the phones might actually cause cancer. It is also worth noting here that experimental studies have failed to demonstrate any reproducible effects of RF energy below the level where heating occurs. In addition, there is no known mechanism whereby this type of energy can induce or promote the development of cancer. On theoretical grounds, it has been pointed out that the energy absorbed from cellphones is orders of magnitude lower than the normal excitation of the molecules in our bodies, making it hard to see how cellphone use could have any effect whatsoever.
What about the results of epidemiologic studies in humans that we hear so much about and that the latest report focuses on? All informed discussions of the epidemiologic studies acknowledge the considerable problems of these studies and the biases they suffer from. For example, brain cancer is rare so small numbers of cases can make a big difference in any particular study. There can be selection bias due to failure to contact cases before they are too ill to participate.
There is also the problem of obtaining accurate information on exposure of individuals: how on earth do you figure out how much someone has used a phone, or been exposed to radiation from phones, over a period of decades? Self-reporting is notoriously inaccurate, not just for phone use but for all sorts of other areas of study. It is also likely that those with a terrifying illness like cancer will answer questions about their use of cellphones differently from the healthy individuals they are being compared with.
What this means is that one has to be very cautious in interpreting individual results from individual studies. One should expect to see ‘blips’ simply due to chance and due to the biases referred to above. What is important is the overall pattern of results from the totality of studies. There are many critical reviews of the epidemiologic evidence, and most have concluded that the results of these studies do not provide evidence of an association of cellphone use with brain cancer risk. There is a tendency, however, for some researchers and activists to seize on a few results that appear to indicate a risk.
In contrast to the far-fetched notion that cellphones are capable of causing brain cancer, there is indisputable evidence of a very real risk of death and serious injury from collisions caused by drivers distracted by the use of cellphones and other wireless devices while at the wheel.
These alarmist reports by activist groups represent a parallel narrative to the much less satisfying narrative of scientific inquiry. Activist ‘science’ focuses on results that appear to fit with one’s thesis and ignores information and comprehensive assessments of the evidence which do not. The authors can count on the appearances – references to the scientific literature, higher degrees and affiliations of the authors and ‘endorsers’, and conclusions that sound reasonable – to arouse concern in the public and to galvanize politicians eager to respond to the latest threat to the public’s health.
Geoffrey Kabat is a cancer epidemiologist at the Albert Einstein College of Medicine in New York and the author of Hyping Health Risks: Environmental Exposures in Daily Life and the Science of Epidemiology (Columbia University Press, 2008). (Buy this book from Amazon(UK).)
(1) BioInitiative Report: A Rationale for a Biologically-based Public Exposure Standard for Electromagnetic Fields (ELF and RF)
(2) For example, see The Case for Precaution in the Use of Cell Phones: Advice from University of Pittsburgh Cancer Institute Based on Advice from an International Expert Panel, Cell-Phone-Dangers, 23 July 2008
(3) Cell Phones and Brain Tumors - 15 Reasons for Concern: Science, Spin and the Truth Behind Interphone