Last month's topic was epidemiology, the science of statistical analysis of populations. In my continuing discussion of scientific investigation and its effects on RF safety, I had reached epidemiology. At the same time, the RF Safety Committee began collaboration with an investigator from the National Cancer Institute on an epidemiological study of radio amateurs (see "Researcher Undertaking Epidemiological Study of Radio Amateurs," or The ARRL Letter Vol 19, No 20, May 19, 2000).

Over the past few weeks, I have received correspondence from several hams with questions and concerns about epidemiology as it applies to RF Safety and Amateur Radio. Before moving on to the topic of laboratory studies of RF effects, I'll use this month's article to answer the questions, and hopefully clear up some of the lingering confusion, about epidemiology.

"Why bother doing an epidemiological study?"

After I had described some of the weaknesses of epidemiology, some people were convinced that there is no value in performing epidemiological studies. I'm sorry if I gave that impression.

Epidemiological studies are very valuable, as long as they are interpreted properly. They look at data that cannot be studied any other way, particularly life-long exposures. Compared with laboratory studies, epidemiological studies are far less costly and can often be performed more quickly.

As I had stated earlier, the results of an epidemiological study provide clues to things that should be looked at in more detail. Again, I must emphasize that these clues, though valuable as scientific evidence, should not be mistaken for proof of a cause-and-effect relationship.

"Why Hams?"

Some people felt that hams were being picked on because we are an easy target. I don't agree.

If long-term exposure to RF energy has any deleterious effects, the population of hams would be the first in which they would appear. I have always found it suspicious that people could accuse cellular telephones of causing their various maladies since that particular technology has not been available for very long. Most diseases, such as cancer, require very long exposures before the disease is evident. Known carcinogens--such as cigarette smoke, PCBs, and ultraviolet sunlight--rarely result in disease until decades of exposure have occurred. Thus, hams are the most logical people to look at to see if RF causes any diseases.

As in many other areas of technology, and as it was meant to by its charter, the Amateur Radio Service is providing the service of technological innovation by being part of this epidemiological study.

"Why is the ARRL sticking its neck out?"

The NCI study was already in progress when the FCC suggested that the ARRL be contacted to help. If we had declined, the study would have continued anyway, and would be less likely to be as accurate. We already have had a misleading epidemiological study of hams (15 years ago by Samuel Milham) that left many people with the unsubstantiated impression that ham radio causes leukemia. By helping to make sure that the NCI study is accurate, we are helping to counteract those impressions.

"Other industries have been badly hurt by EPA surveys."

Some people fear that taking too close a look at the diseases that hams get will harm ham radio. I have seen two types of industries that have been harmed this way: The industries in which there were actual risks (such as those that used PCBs) and those in which there was an unfounded perceived risk (such as silicon breast implants). In the former, if those industries could not adapt to safer materials and practices, it was not unreasonable that they went out of business. In the latter, lack of good science led to the demise of the companies.

If exposure to RF is life-threatening, I think that we would all like to know. If any dangers exist and we learn exactly what they are, we should be clever enough to adapt the hobby to remove those dangers. If exposure to RF is not life threatening, but smooth talking lawyers and bad science convince juries that it is, we could see the demise of ham radio more rapidly than if it actually was dangerous.

By helping NCI do better science, we will have more ammunition to fight the bad science.

"What is new about this NCI study that hasn't been studied before?"

This is only the second time that an epidemiological study of hams is being attempted. Like the prior Milham study, the current NCI study is preliminary. The NCI study is working with a far larger group of subjects than the Milham study, and with the help of ARRL, inaccuracies should be minimized.

A preliminary study is fast and costs relatively little to perform. The down side is that the results are less meaningful. If a preliminary study shows no increased association between particular diseases and the study group (in this case, hams) there is no more to do, with little wasted effort or expense. If, however, significant associations do result from the preliminary study, there is good reason to follow it up with a more detailed epidemiological study. The Milham study did not follow up with additional detail, and for maximum effectiveness the same subjects used in the preliminary study should be used in the follow-up.

The detailed follow-up study can use interviews with family and friends, and even written records such as log books, to attempt to clarify some of the unknowns that can affect the results of an RF exposure study: What did the ham do for a living? How often did the licensed ham operate? What modes, frequencies, and power levels were used? What types of antennas were used? Was the ham regularly exposed to potentially dangerous chemicals? Did the ham have a history of disease in his lineage? As these kinds of details are added, the epidemiological results become more meaningful.

To clarify the concerns that were raised by the Milham study, a larger study, with greater accuracy, and the potential for follow-up is necessary.

Epidemiology and Ham Radio

The ham radio community is fortunate to have been given the opportunity to take part in a well-designed epidemiological study. The question of how RF affects the public health is much talked about--and very confused of late. There are so many poor and misinterpreted studies mixed in with the good ones, that the picture is cloudy, at best. Any chance to clarify the situation should be grasped with both hands.

Editor's note: 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 is currently chairman of the ARRL RF Safety Committee and a member of the IEEE Committee on Man and Radiation. A former professor of Biomedical Engineering and Neurology at Northwestern University, he now works as a consulting professional engineer in the electronics industry. He was first licensed as a ham when he was a teenager in 1969 and continues to be fascinated by 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 doing his kids' 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 Greg Lapin, N9GL, via email at g.lapin@ieee.org