New Article on Science Based Medicine
A lot has happened in the past year since IARC issued its report in which it classified cell phones as possibly carcinogenic. We have written a comprehensive update on this report entitled: Are Cell Phones a Possible Carcinogen? An Update on the IARC Report, which is posted on the web site Science Based Medicine. In short the article explains how the evidence on which IARC based its assessment was weak to begin with. It also includes the results of new papers published over the past year that substantially undermine this already weak evidence.
The text of our original article from a year ago is retained below to provide some context. For the new article follow this link.
The International Agency for Research on Cancer (IARC) which is a part of the World Health Organization (WHO), has issued a press release which states that radiofrequency electromagnetic fields are possibly carcinogenic to humans. Expert groups of most of the world's major public health organizations have concluded that there is no credible evidence that cell phones cause cancer. The WHO has issued a new fact sheet on the health effects of cell phones. This fact sheet states: "A large number of studies have been performed over the last two decades to assess whether mobile phones pose a potential health risk. To date, no adverse health effects have been established as being caused by mobile phone use". The IARC classified cell phones in Category 2B, which is "possibly carcinogenic to humans". The IARC maintains a list of substances in this category. A total of 266 substances are listed, most of which are chemical compounds. The following familiar items are also included in this list: coffee, coconut oil, pickled vegetables, carbon black (carbon paper), gasoline exhaust, talcum powder, and nickel (coins). The IARC provides the following definition of the 2B category (P 23): "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".
The evidence that the IARC cites to support their conclusion that cell phones are possibly carcinogenic is far from convincing. In a brief commentary the National Cancer Institute noted that the IARC press release singled out one particular finding from the Interphone study that showed that "for a small proportion of study participants who reported spending the most total time on cell phone calls, there was some increased risk of glioma, but the researchers considered this finding inconclusive". Furthermore the NCI noted that the Interphone study had concluded that "overall, cell phone users have no increased risk of the most common forms of brain tumors -- glioma and meningioma. In addition, the study revealed no evidence of increasing risk with progressively increasing number of calls, longer call time, or years since beginning cell phone use". See our own extensive analysis of the Interphone study.
The IARC press release also included a reference to a study which attempted to correlate the physical location of gliomas (a type of brain cancer) in the brain with the area of maximum radiation from the cell phone. However this study failed to find any strong correlation. The abstract included the following conclusion: "These results do not suggest that gliomas in mobile phone users are preferentially located in the parts of the brain with the highest radio-frequency fields from mobile phones". It is a mystery as to why the IARC would reference a study that seems to contradict their precautionary 2B categorization of cell phone EMF.
The IARC press release also mentioned two new papers that will soon be published that are based on further analysis of data from the Interphone study (these are references 4b & 4c in the press release). It will be interesting to review these studies once they are published. However, as has been noted in our own analysis of Interphone, the quality of this study is entirely dependent on the memory of brain cancer patients. Patients who have been diagnosed with brain cancer are asked to recall - purely from memory - how much they used their cell phones over their lifetimes. Their responses are compared with controls who do not have brain cancer. Such studies may suffer from what is known as "recall bias". The authors of Interphone acknowledged this potential source of error, and found actual evidence of false recall. The conclusion of Interphone was: "Overall, no increase in risk of glioma or meningioma was observed with use of mobile phones. There were suggestions of an increased risk of glioma at the highest exposure levels, but biases and error prevent a causal interpretation. The possible effects of long-term heavy use of mobile phones require further investigation."
A Danish retrospective cohort study was much more reliable than the Interphone study because it was based on actual cell phone records, not memory of past cell phone use. This study was cited in the NCI commentary: "Furthermore, a large population-based cohort study in Denmark has found no evidence of increased risk of brain tumors." The NCI also noted: "It is noteworthy that brain cancer incidence and mortality rates in the population have changed little in the past decade" (see graphs on our cell phone page and the following article from CNN/Fortune as well as the following humorous take on the brain cancer incidence data.
Examples of Epidemiological Studies with Incorrect Results
The controversy over whether cell phones cause cancer is similar to problems with case control epidemiological studies in other areas. For example, based on studies such as "Fruit, vegetables, and cancer prevention: a review of the epidemiological evidence" published in 1992, many scientists believed that eating certain fresh fruits and vegetables had a protective effect against cancer. A recent article in the NY Times reported that this finding was finally overturned by a definitive study in Europe. The NY Times article said: "A major study tracking the eating habits of 478,000 Europeans suggests that consuming lots of fruits and vegetables has little if any effect on preventing cancer." This new study was the culmination of a series of multiple studies most of which were negative. In an editorial accompanying the new article overturning the "anti-cancer" effects, Dr. Walter Willett stated "However, the evidence for a large preventive effect of fruits and vegetables came primarily from case-control studies, which can be readily biased by differences in recall of past diet by patients with cancer and healthy control subjects". This is precisely the main problem with cell phone studies such as Interphone.
Another class of epidemiological studies with incorrect results were in the area of sperm counts. A recent NY Times article highlighted the concerns raised by these flawed studies: "It is one of the most fraught topics in environmental health. Are men becoming less fertile, with declining sperm counts and diminishing sperm quality?" "The idea that sperm counts were plummeting began with an alarming paper published in 1992 by a group of Danish researchers. Sperm counts, they reported, declined by 50 percent worldwide from 1938 to 1991, and the trend would continue, they said." "The study, said Dolores Lamb, a fertility expert at Baylor College of Medicine and president-elect of the American Society of Reproductive Medicine, "was problematic and raised alarms in society without critical thinking about the caveats and weaknesses inherent in the data and its analysis". A number of poorly done studies have also been done on sperm quality in connection with the use of cell phones. These poorly done studies have also been rejected by mainstream scientists.
As the authors of the latest sperm count study note: "Almost 20 years ago, a longstanding debate over possible declines in sperm counts was reignited by a paper in BMJ, claiming that sperm counts had declined worldwide by 50%. Despite its rather weak documentation, this paper by Carlsen et al had a strong impact in the public media, and has been cited in more than 1000 scientific papers - in part because the authors were bold enough to include a linear regression line pointing forward toward continuing declines and a doomed society. Since the publication of that paper, numerous studies have reported secular trends and geographical shifts in sperm counts, with conflicting findings and no emerging consensus. However, recent developments may be changing this picture"...."Although we cannot change the data quality of the past, we can improve studies prospectively. Toward this end, a Danish research project was started in 1996 with support from Danish government agencies to prospectively monitor semen quality of young Danish military draftees...These data provide no indication that semen quality has changed during the past 15 years".
The examples cited above illustrate how certain epidemiological studies, sometimes of questionable quality, have triggered major multi year controversies. In these cases a series of false positive studies have been contradicted by better quality negative studies. The examples are close parallels to the controversy over cell phones and brain cancer. In addition to the persuasive evidence against cell phones and cancer provided by objective data such as brain cancer incidence rates; there are also the laws of physics. It is universally accepted that cell phone radiation is non-ionizing and cannot break DNA bonds. However, in addition, physicists have analyzed every other conceivable interaction between cell phone radiation and biological processes. For instance the physical deformations of proteins and protein interactions such as activation of signaling pathways and docking with receptors on cell membranes have all been studied. In every case, the calculated strength of cell phone EMF has been negligible relative to the other forces at work at the molecular level. In every case, the normal thermal agitation of proteins has been a far greater force. Physicists say with a high degree of confidence that there is no known mechanism that cell phone EMF can have a significant effect on biological activity.
Links to Articles on the WHO/IARC Press Release
The following are links related to the recent IARC Press Release on cell phones as a possible carcinogen.
* This is a link to the original IARC Press Release.
* This is a link to the new WHO fact sheet on cell phones and health.
* This is a link to a statement by the US National Cancer Institute (NCI) concerning the WHO/IARC press release
* Cancer Research UK commentary on WHO/IARC press release.
IEEE: What the WHO cancer statement really means
* Fortune Commentary: Cell phone use way up, so why did brain cancer rates fall?
* Report in LA Times: If cell phones cause cancer, how do they do it?
* Report in USA Today on the WHO/IARC press release.
* NY Times report on WHO/IARC press release.
* Globe & Mail: The sun is a cancer risk, not the cellphone
* The Detroit News: Cell phone risk: call it slim
* Report in Wall Street Journal: The Cellphone Panic
* CNN Opinion Bernard Leikind: No cell phones don't cause cancer
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