Geoffrey Kabat, a cancer epidemiologist at the Albert Einstein College of Medicine, lays out how WHO’s cancer conclusions don’t square with actual science.
We rely on health and regulatory agencies to provide impartial assessments of potential health risks. Unfortunately, these agencies can be subject to the same political and professional pressures at work in society generally.
An example of this is the recent, widely-publicized pronouncement by the International Agency for Research on Cancer (which is part of the World Health Organization) to the effect that radiofrequency radiation (or RF) from cell phones was “possibly carcinogenic.” Coming only a year after publication of the results of a large multi-country study, which showed no convincing evidence of a hazard, IARC’s announcement left the public as well as many scientists nonplussed.
IARC is a prestigious agency that since the early 1970s has been producing respected monographs evaluating the evidence for a wide range of chemical, physical, and hormonal agents in the carcinogenic process. The cell phone report was the result of an intensive, week-long review by a committee of experts.
In spite of the consternation caused by the report in professional circles, there has been little insight into how the IARC could evaluate all of the relevant scientific evidence and come up with an impossibly vague conclusion. Like many of my colleagues, I was dismayed by the IARC announcement, which did not square with my reading of the scientific evidence.
Hints that not everything was harmonious in the IARC process seeped out but have not been pursued. These include the dismissal from the committee of one of the foremost experts on non-ionizing radiation, a Swedish epidemiologist, due to a “conflict of interest” and the resignation from the committee of an epidemiologist specializing in brain tumors at the National Cancer Institute.
In June I contacted both of these colleagues asking if they would agree to answer questions about the committee’s deliberations, but in both cases they politely declined. One colleague, who is knowledgeable about both IARC and the National Cancer Institute group, offered that scientists involved in this contentious issue have a strong incentive to keep a low profile.
Determined to speak to someone who had participated in the committee, I contacted a molecular toxicologist, Dr. Vijayalaxmi, at the University of Texas, who was only too happy to discuss the committee’s proceedings and to answer my questions.
The IARC cell phone “working group” was composed of approximately thirty members. At the start of the week-long meeting in Lyon, France, where IARC is located, committee members were divided into four separate groups that reviewed the evidence in different areas: epidemiology, dosimetry, animal studies, and “other relevant evidence.” Members of each subgroup were kept informed on a daily basis about the deliberations of the other subgroups.
According to Dr. Vijayalaxmi, in all of the evidence reviewed there was one animal study that showed “weak evidence” of carcinogenicity and one study in the “other evidence” category providing what was also judged to be “weak evidence.” The vast majority of the experimental evidence showed nothing. Beyond that, there were the human (epidemiology) studies. These have been reviewed critically by the International Commission on Non-Ionizing Radiation Protection, which found no convincing evidence of a link between cell phone use and the occurrence of brain tumors.
At the end of the week-long meeting everyone voted, but, interestingly, the vote was only on the epidemiology. In other words, all the other evidence from experimental studies was left out of the final decision on how to classify RF. The choices in the IARC classification scheme are: “sufficient evidence of carcinogenicity”; “probable carcinogen”; “possible carcinogen”; or “insufficient evidence.” A majority of committee members voted to classify RF as “possible carcinogen,” while a small minority voted for “insufficient evidence.”
Since the agency’s classification hinged on the epidemiology alone, it is highly significant that one of the committee members was Dr. Lennart Hardell, another Swedish researcher who has carried out epidemiologic studies of mobile phone use and brain tumors. Hardell has been a vocal promoter of his results as indicating that long-term cell phone use appears to be associated with increased risk of glioma, the most fatal type of brain tumor.
However, Hardell’s work is viewed as seriously flawed by some of the most respected academic epidemiologists working in this area. It appears that he was included as a member of the working group in response to pressure from activists and the media. One well-informed scientist told me that she thought the committee member who resigned did so in disgust at the weight given to the Hardell studies.
According to Dr. Vijayalaxmi, in issuing its report IARC wanted to send a message that we still have limited information about the possible effects of prolonged and heavy use of cell phones, especially among users who start as children and adolescents. She is comfortable with the classification and thinks that it will be an “eye-opener for people who abuse the technology, which is meant for benefit, not for overuse and abuse.”
But if this were the goal, there was no need to carry out another exhaustive evaluation of the evidence. And once having carried out such a review, by any set of criteria for evaluating evidence, the conclusion should have been that – although we have not monitored the effects of cell phone use for long enough – the substantial evidence currently available provides no suggestion that cell phone use contributes to the risk of brain tumors. The ambiguous label “possible carcinogen” is unfortunate because it means one thing to scientists working for IARC and something quite different to the general public when trumpeted in the headlines.
In classifying RF as a “possible carcinogen,” IARC has aligned itself with the “precautionary principle,” which sounds perfectly reasonable, except that it is often used to conjure up the existence of a possible hazard in the face of extensive and solid evidence suggesting the non-existence of a hazard. Of course, we need to spell out the limits of current knowledge, but we also need to rely on scientists and health agencies to use logic, analytic rigor, and clear language to assess what things are worth worrying about.
Geoffrey Kabat, Ph.D., is a cancer epidemiologist at the Albert Einstein College of Medicine and the author of “Hyping Health Risks: Environmental Hazards in Daily Life and the Science of Epidemiology.”
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