|Gliobastoma (astrocytoma) WHO grade IV - MRI coronal|
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Why there can be no increase in all brain cancers tied with cell phone useby Devra Davis, Anthony B. Miller, and
L. Lloyd Morgan, blog.oup.com,
16 May 2016
Several widely circulated opinion pieces assert that because there is no detectable increase in all types of brain cancers in Australia in the past three decades, cell phones do not have any impact on the disease. There are three basic reasons why this conclusion is wrong.
First of all, the type of brain cancer increased by cell phones is glioblastomas. Glioblastomas are in fact increasing, as exemplified in those age 35-39 in the United States, in precisely those parts of the brain that absorb most of the microwave radiation emitted or received by phones. But this increased trend in glioblastomas of the frontal and temporal lobes and cerebellum is not evident when all brain cancers are considered.
Secondly, proportionally few Australians or others were heavy cell phone users 30 years ago. In 1990, just one out of every hundred Australians owned a cell phone and calls were short and relatively costly. The first Motorola brick phone weighed close to two pounds, stood about a foot tall, lasted about half an hour of talk time, and cost almost $4000 – about $9600 in 2016. Only in the last few years have cell phones become ubiquitous with the heaviest use occurring in relatively young users.
Finally, the lag between when an exposure takes place and evidence of a disease occurs depends on two factors: how many people were in fact exposed and how extensive their exposure has been. While cell phones have been around since the 1990s, they have only lately become an affordable major component of modern life.
Consider what we know happened with tobacco smoking, according to the US Centers for Disease Control. The rate of smoking reached close to 70% in US males in the late 1950s, while the rate of lung cancer did not peak until the late-1990s. Thus, a lag of nearly four decades took place between an exposure that was shared by most of the population and a major increase in a related disease, as documented by the American Cancer Society, using data from the CDC and US Department of Agriculture.
The link between the carcinogenic effects of tobacco and cancer did not come about from studying population trends, but by special study of high-risk groups using case-control designs of selected cases and comparing their histories with those of persons who were otherwise similar but did not smoke, and cohort studies of groups with identified smoking histories followed for up to 40 years, as in the American Cancer Society and British Doctors studies. The fact that population-based trends in Australia do not yet show an increase in brain cancer does not mean it will not be detectable in the future—perhaps soon.
In point of fact, several studies from Australia and the United States do find increased rates of gliomas in those who have been the heaviest users of cell phones for a decade or longer. A paper from noted neurosurgeons Vini Khurana and colleagues examined reports from centers in New South Wales (NSW) and the Australian Capital Territory (ACT), with a combined population of over seven million and reported that from 2000-2008, there was an annual increase in gliomas of 2.5% each year, with an even greater increase occurring in the last three years of the study.
Another study by Zada and collegues in the US found significant increases in gliomas in those regions of the brain that are known to absorb the most microwave radiation—the cerebellum and the frontal and temporal lobes. Paralleling this result, the California Cancer Registry, which covers 36 million people, also reported significantly increased risks of gliomas in those same regions. Recent studies from China as well as those from the US Director of the National Institute of Drug Abuse, Nora Volkow, reporting in the Journal of the American Medical Associationhave noted significantly increased metabolic activity in these same components of the brain after 50 minutes of exposure to cell phone radiation.
Only a generation ago, the hazards of ionising radiation were unrecognized. It was common to find X-ray machines freely available in shoe stores so that you could see how new shoes fit relative to the skeletal bones of your feet. Teens were treated for the disease of acne with radiation to their faces, and those treated with X-rays for ringworm, later incurred increased thyroid and other cancers. Pelvic X-rays of pregnant mothers were routine until the 1970s when leukemia risks were established in children who had been exposed prenatally decades earlier. Today, those who worked as radiographers and radiologists years ago have increased rates of a number of types of cancer. In every one of the preceding instances, the hazards were not recognized by population-based data, but by special studies that compared detailed information on exposures that took place in those with diseases in contrast to those without them.
Thus the lack of an increase in all brain cancers in the general population of Australia or any other modern country is to be expected in light of what is known about this complex of more than 100 different diseases. These unexplained increases in glioma remain gravely worrisome as this is the tumor type that we expect to see grow if indeed cell phones and wireless radiation are playing an important role.
As public health experts who have documented the dangers of smoking, both active and passive, and tracked the growing experimental and epidemiological literature on the dangers of cell phone radiation to reproductive and brain health, we appreciate that the need for precaution must be exercised judiciously. There is no question that the digital world has transformed commerce, the nature of scientific discourse and research, our response to emergencies, and all forms of communication. The epidemic of lung cancer tied with smoking four decades prior provides sobering lessons about why we should invest in reducing exposures to wireless radiation. Like diagnostic radiation equipment today, wireless radiation transmitting devices can be designed to be as low as reasonably achievable (ALARA). In our considered judgment, based on more than one hundred years of professional experience in this field, it is of critical public health importance that every effort be made now to reduce and control exposures to these wireless transmitting devices, especially to infants, toddlers, and young children.
Featured image credit: Cell phone by Matthew Kane. CC0 Public Domain via Unsplash.
Devra Davis, PhD, MPH is an award-winning writer and President of Environmental Health Trust. She is a Visiting Professor of Medicine at the Hadassah Medical Center and Ondokuz Mayis University Medical Center. She is also a member of the Founding Editorial Board of Oxford Bibliographies in Environmental Science.
Anthony B. Miller, MD, is Professor Emeritus of the Epidemiology Division, Office of Global Public Health Education & Training at the University of Toronto Dalla Lana School of Public Health.
L. Lloyd Morgan, BSEE, is a Senior Research Fellow at the Environmental Health Trust.