After a short hiatus, we are pleased to resume publication of "N9GL's RF Safety Column." Author Greg Lapin, N9GL, is chairman of the ARRL RF Safety Committee. -- Ed.

In recent months, I have been made aware of two such instances of this scientific rumor mill. In May of this year, I received an e-mail from someone describing himself as a "cancer researcher" who wanted to know why I was ignoring the proven danger of cell phones: "My colleagues in Sweden and Japan tell me that exposure to microwave radiation from cell phones are potentially dangerous -- and that this should be acknowledged by the phone companies (which they don't bother acknowledging)." He went on to describe his colleagues' experiments with mice in RF fields that had increased incidence of brain tumors. I found the description of this research to be surprising, since no such research has appeared recently in the scientific literature.

In July of this year, a more extreme example of the same type of underground science hit the news. Dr Ronald B. Herberman, director of the University of Pittsburgh Cancer Institute, circulated a memo to 3000 faculty and staff members at his Institute, warning them that children should use cell phones only for emergencies because their brains are still developing. He also said that everyone should keep the phone away from their heads and use the speakerphone or a wireless headset. He even warned against using cell phones in public places because it exposes others.

On what does Dr. Herberman base this warning? "Early unpublished data." He says it takes too long to get answers from science. "Really, at the heart of my concern is that we shouldn't wait for a definitive study to come out, but err on the side of being safe, rather than sorry later," he stated.

The Scientific Process

The gentleman who sent me the alarming e-mail and Dr Herberman both consider themselves to be scientists. The basis of science is the investigative process. It is a set of experimental and analysis procedures that have been developed over the history of science to address the potential for avoiding the common errors that are prevalent when people, especially those with inherent biases, perform research. People are fallible, and the breadth of science is so deep that it is virtually impossible to control every variable when studying the effect of one thing. As a result, science requires that a study be designed with a "null hypothesis" that the scientist then must disprove to illustrate an effect.

For instance, to study if people are harmed by RF energy, the scientist must first assume that people are not affected by RF energy and then study what happens when they are exposed. Generally, in any type of study, some individuals -- whether people or lab animals -- are affected and some are not. To demonstrate that the effect is real, the scientist must show that there is less than a 5 percent probability that the null hypothesis is true.

It is proper scientific technique to write all of the details of a study in a paper that is then reviewed by a number of unrelated experts in the same field who critique the work and, if they determine that there were no procedural errors in the design and implementation of the study, they recommend it for publication. The body of scientific research is based on such peer-reviewed publications. Even after all of the careful review of a study, the many uncontrollable factors that could affect the results leave open the possibility for error. Generally, the results of such a study must be replicated at least once -- preferably by an unrelated scientific laboratory -- to show that the results are real.

The null hypothesis also presents somewhat of a dilemma to scientists: Since it cannot be disproven absolutely, science can only conclude that there is a probability that it is not true. The public does not want to hear that. They want an absolute assurance that something is safe. Of course, no such thing exists. Every time you get in your car there is a probability that you won't live through the ride. In fact, that probability is far higher than the probability that you will contract a disease from your cell phone. Yet, most people don't think twice about jumping in the car to go someplace. Dr Herberman, as a scientist, should know that the "definitive study" he is waiting for will never materialize. At best, the succession of studies will only serve to further decrease the probability that the null hypothesis is true.

A Heavily Studied Field of Science

Biological effects of electromagnetic energy are among the most heavily studied topics in science. The studies began in earnest in the 1960s and have continued to the present day. In nearly 50 years, there have been more than 2500 peer-reviewed publications in the field. Of course, there are peer reviews and there are peer reviews. Some of those studies were better performed than others.

To make sense of this large body of research, the Institute of Electrical and Electronic Engineers (IEEE) commissioned a review. From 2002 to 2004, each paper was re-read by at least three expert reviewers and critiqued for its applicability to the field of knowledge based on what we consider to be a good study with today's understanding of EM exposures. The results of this literature study netted 1411 publications that were considered to be the best work in the field; these were used to develop the latest edition of the IEEE safety standard: C95.1 -2005: IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz. Human exposure from cell phones and Amateur Radios alike is limited by FCC regulation to be lower than what the safety standard calls Maximum Permissible Exposure (MPE).

After 50 years and 1411 good scientific studies, what additional research could my correspondent and Dr Herberman know about that is vastly different? Certainly it was not research that was peer-reviewed, much less independently replicated. As scientists, they should know better than to base their scientific beliefs on such weak evidence. Granted, they are not experts in the field of electromagnetic bio-effects and are probably not aware of the wealth of knowledge that has been developed on this topic. But that's all the more reason that they should not overreact to anecdotal information that has not been subjected to scientific confirmation. Unfortunately, when the director of a large cancer institute makes such a proclamation, it is widely believed by people who know even less about the science than he does.

Dr Herberman never said not to use cell phones. Instead he advised caution. How can anyone argue with the admonition to be cautious? From a public policy standpoint, I can't disagree with that attitude. I'm a cautious driver and I look both ways when I cross the street. Both of these activities are far more likely to cause me harm than using a cell phone. If you read the news in the week following Dr Herberman's memo, you saw considerable concern from parents who decided to take cell phones away from their children. The unscientific pronouncement only served to increase anxiety in scores of people who use cell phones. Anxiety has been shown to cause more harm than cell phone use. From a scientific standpoint, there is no more basis for being cautious with cell phone use than there is for any other every day activity.

Greg Lapin, N9GL, started working in the RF safety world after spending many years first studying cardiac function imaging and then brain tumor kinetics. He serves as chairman of the ARRL RF Safety Committee and as a member of the FCC Technological Advisory Council. A former professor of Biomedical Engineering and Neurology at Northwestern University, Lapin now works as a consulting professional engineer in the electronics industry. He was first licensed while a teenager in 1969 and continues to be fascinated by virtually all aspects of Amateur Radio. One of his many interests is electronic design, and he is the author of Chapter 8, "Analog Signal Theory and Components" in The ARRL Handbook for Radio Amateurs. His non-ham interests include making things grow in his garden and serving as commissioner of the local children's softball league. At other times -- when he is not working or helping his kids with their homework -- you might find him with the local emergency services agency, climbing his tower, building a new QRP rig, playing with his APRS setup, responding to QSL cards, going off on a DXpedition or trying to get that "new one." You can reach him via e-mail at g.lapin@ieee.org. The ARRL RF Safety Committee page contains a link to archives of previously posted editions of N9GL's RF Safety Column.

Gregory Lapin, PhD, PE, N9GL
Chairman, ARRL RF Safety Committee