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Siddhartha Mukherjee deftly tells you everything you need to know about the current state of knowledge of the risks to human health from use of cellular phones. Mukherjee, a doctor and professor of medicine at Columbia, does so in a few thousand words in the New York Times without dismissing concerns, and while explaining why this issue is so fraught with interpretation bias and confusion.
Mukherjee's key points are well understood in epidemiological circles, and typically misstated in the mainstream press. They are:
• Rates of cancer types expected to be associated with long-term mobile phone use have declined in America during the rise of cell calling.
• The low incidence of such expected cancers in the general population makes it nearly impossible to conduct prospective longitudinal studies: find a large cohort of people with no disease and follow them for 5, 10, or 20 years to see in which groups normal and abnormal rates occur.
• Retrospective studies that ask people to remember past usage of cell phones are deeply flawed due to recall bias.
• Cellular tests examining DNA after exposure to phone emissions were found in a meta-review of papers and research to have no provable link.
(Mukherjee also explains that the recently reported "cell phones make your brain light up" study showed unexplained brain activity when a silent cell phone was active in areas adjacent to the phone, which was near one or the other of a subject's ears. However, the brain activity wasn't harmful–it was similar to activity from other routine activities–just inexplicable. And the study only involved under 50 people.)
I've been reading cell-phone and RF exposure studies for a decade, starting at a point where I was convinced that the industry must have known of a link and was trying to hide it. Who trusts multi-billion-dollar corporations with everything to lose, where executives might even be sent to prison as a result? Of course, they might hide evidence or fund fake studies.
Over time, though, as I learned more of the science and read increasingly well-designed and comprehensive surveys, I found the evidence compelling. No credible research backs up an increased risk of cancer or other health risks. (If you write about this subject, and I imagine we'll see it in the comments, you'll be told that all the mainstream research except the few outlier studies is bogus and corrupted by the cellular industry, and that numerous other studies outside the scientific establishment prove a link.)
Retrospective studies are the worst culprits here, because if you ask someone with cancer how often (and even on what side of the head) they used their cell phone during the last X years, you not surprisingly get a biased response. It is not their fault. They are looking for an explanation for their condition. I had a brush with cancer in the late 1990s. I'd like to believe it was because of exposure to some particular substance, but cancer that requires treatment (as opposed to the cancerous precursors that constantly grow in our bodies and are dispatched by our defenses) is proving to be a complex outcome of genetics, environmental causes, and random mischance.
Mukherjee doesn't mention a related issue, which is that dozens of studies that have attempted to find an association between so-called electrosensitivity–an adverse reaction to the presence of normal levels of urban electromagnetic radiation–have found no correlation in self-identified sufferers, nor in control groups. You can read a meta-review of 46 studies involving 1175 sufferers from 2009 that concludes: "Despite the conviction of IEI-EMF sufferers that their symptoms are triggered by exposure to electromagnetic fields, repeated experiments have been unable to replicate this phenomenon under controlled conditions." (Some studies have found that such sufferers do have measurable symptoms and distress which they may experience in the lab, but that this happens whether or not EMF signals are in use.)
Mukherjee explains one aspect of the problem with retrospective studies in regards to the international Interphone study of thousands of users across several countries. As a whole, no correlation between cell usage and brain tumors were found, but certain subsets of data analyzed separately produced contradictory results: regular phone users had decreased incidence and heavy phone users had increased risks.
…some men and women with brain cancer recalled a disproportionately high use of cellphones, while others recalled disproportionately low exposure. Indeed, 10 men and women with brain tumors (but none of the "controls") recalled 12 hours or more of use every day–a number that stretches credibility. In a substudy of Interphone, researchers embedded phones with special software to track phone usage. When this log was compared with the "recalled" usage, there were wide and random variations: some users underreported, while others overreported use.
Mukherjee's article is intended to make a larger point: that there is a reasonable desire to want to find a true cause for an inexplicable illness or impairment, whether it's autism in your child or cancer in your partner's brain. We reach out for what we think are causative effects, whether or not the research ultimately backs this up.
The Internet needs a kind of medal to hand out to writers who can summarize vast arrays of information into accurate, sensible, and fair articles that don't trivialize multiple facets of a complex issue into "on the one hand, on the other hand" presentations. Mukherjee would get my vote for the 2011 award even this early in the season.