In 2004, a rash of early scientific reports suggested that cell phones, which produce radio frequency energy, might cause a fatal form of brain cancer called ‘glioma,’ reminisces Siddhartha Mukherjee in The Emperor of all Maladies: A biography of cancer ( >www.harpercollins.co.in ). “Gliomas appeared on the same side of the brain that the phone was predominantly held, further tightening the link. An avalanche of panic ensued in the media…”
Recall bias
The Pulitzer-winning book goes on to inform that an enormous British study was launched in 2004 to confirm these ominous early reports; and ‘cases’ (patients with gliomas) were compared to ‘controls’ (men and women with no gliomas), in terms of cell phone usage.
The study, reported in 2006, appeared initially to confirm an increased risk of right-sided brain cancers in men and women who held their phones on their right ear, the author notes. He adds, however, that when researchers evaluated the data meticulously, a puzzling pattern emerged – that right-sided cell phone use reduced the risk of left-sided brain cancer.
The simplest logical explanation for this phenomenon, as Mukherjee mentions, was ‘recall bias,’ that is, patients diagnosed with tumours unconsciously exaggerated the use of cell phones on the same side of their head, and selectively forgot the use on the other side.
When the researchers corrected for this bias, there was no detectable association between gliomas and cell phone use overall, reads an apparently reassuring message in the book. “Prevention experts, and phone-addicted teenagers, may have rejoiced – but only briefly. By the time the study was completed, new phones had entered the market and swapped out old phones – making even the negative results questionable.”
New carcinogens
In the author’s view, the cell phone case is a sobering reminder of the methodological rigour needed to evaluate new carcinogens. While it is easy to fan anxiety about cancer, he reminds that identifying a true preventable carcinogen, estimating the magnitude of risk at reasonable doses and at reasonable exposures, and reducing exposure through scientific and legislative intervention is far more complex.
The landscape of carcinogens is not static, instructs Mukherjee. “We are chemical apes: having discovered the capacity to extract, purify, and react molecules to produce new and wondrous molecules, we have begun to spin a new chemical universe around ourselves.” As a result, he observes that our bodies, our cells, our genes are being immersed and reimmersed in a changing flux of molecules, in the form of pesticides, pharmaceutical drugs, plastics, cosmetics, estrogens, food products, hormones, and even radiation and magnetism.
“Some of these, inevitably, will be carcinogenic. We cannot wish this world away; our task, then, is to sift through it vigilantly to discriminate bona fide carcinogens from innocent and useful bystanders,” advises Mukherjee, therefore.
A book that you may find yourself grabbing like a crab.
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