(FORTUNE Magazine) – THE BOTTOM LINE of all the hullabaloo over whether cellular phones cause brain cancer: Nobody knows. Why not? Because -- as with electromagnetic radiation from other sources like video display terminals (VDTs) and power lines -- industry and the U.S. government haven't done enough research. Despite a correlation between proximity to power lines and some forms of cancer, and worrisome experimental results involving cellular phones and VDTs, follow-up remains minimal -- largely for lack of money. In 1971 an advisory council of radiation experts originally appointed under President Johnson warned of ''a distressing lack of data on the possible . . . subtle, long-term, and cumulative effects'' of low-level electromagnetic radiation, the type that's produced by cellular phones, power lines, hair dryers, baby monitors, pencil sharpeners, electric shavers, some desk lamps, and dozens of other devices people use every day. After more than 20 years of desultory funding and piecemeal research, the council's scary conclusion remains all too accurate. The world is at the brink of what many giddily call ''the wireless revolution.'' Computers and telephones are shedding their tethering wires and roaming freely with their ever more mobile owners. Companies are peddling wireless cash registers, highway toll collectors, vehicle guidance systems -- even wireless mice for use with PCs. All these require transmitters that send out electromagnetic radiation. ''We are bathing ourselves in this stuff,'' says Paul Saffo, a researcher at the Institute for the Future in Menlo Park, California, and a leading U.S. expert on information technology. So the need to identify and evaluate potential risks -- or else dismiss them conclusively -- grows increasingly urgent. Ten million Americans already use cellular phones, and their number is rising fast. Says Louis Slesin, publisher of Microwave News, an activist who cautions regularly against this sort of risk: ''If we're going to have 50 million Americans holding these devices to their heads, don't you think we ought to find out if they're safe?'' What scant evidence of possible hazards there is applies mostly to the extremely low frequency, or ELF, electromagnetic fields created by transmitting electricity. (Cellular phones transmit higher-frequency radio waves, not electricity, and radiate a completely different field.) The ELF research is more and more worrisome. Most disturbing so far: two long-term epidemiological studies in Sweden that showed clear associations between exposure to ELF fields and various forms of cancer. The results were announced last September. One study found increased brain cancer and leukemia in men exposed to ELF fields in a variety of work situations. The other found three times the normal rate of leukemia in children who live near high-tension lines. These were among the largest and most careful studies of possible hazards from ELF fields ever conducted. Both suggested that a danger to health appears at very low exposure levels -- only a couple of times greater than what hundreds of millions of people experience every day from appliances and wiring in their homes and offices. Says Granger Morgan, who heads the engineering and public policy department at Carnegie Mellon University: ''The likelihood that there is a problem has moved up closer to even odds now. There's clearly cause for concern.'' In Sweden, those two studies moved the government to action. The day the results were announced, the National Board for Industrial and Technical Development, a regulatory body, declared that it will proceed ''on the assumption that there is a connection between exposure to lower frequency magnetic fields and cancer, in particular childhood cancer.'' As a result, in January Sweden's Radiation Protection Institute recommended taking steps to reduce the fields ''where such countermeasures can be made at reasonable cost.'' A homely example: moving a bed away from the corner of the room where electrical lines enter a house. Sweden stands alone in taking the issue so seriously, but its actions are slowly gaining attention elsewhere. (For more on the Swedish response, see box, page 89.) Scientists are by no means unanimous. The most outspoken skeptic is certainly Robert Adair, a professor of physics at Yale, who asserts flatly: ''Worries about cellular phone and power line frequencies range from inane nonsense to foolish inane nonsense. Nothing happens, and there are no experiments that show that anything has happened.'' Policymakers in the Reagan and Bush Administrations tended to downplay the issue, and so far the U.S. government has only yawned at the Swedish data. But the American public seems increasingly fearful. Last year USA Weekend magazine, distributed to 33.5 million Sunday newspaper buyers nationwide, asked its readers to name the health issues they worried about most. Topping the list: electromagnetic fields. In January, when CNN's Larry King Live publicized a single lawsuit in which a Florida man alleged that a cellular phone caused his wife's fatal brain cancer, the reaction was explosive. Some cellular industry stocks dropped 20%. (They later rebounded.) How do power lines relate to cellular phones? Both emit low-level electromagnetic radiation, but at very different frequencies (see spectrum diagram). ELF fields from power lines are a byproduct of the flow of electricity through the wires. Similar fields are also produced by such devices as appliance motors or the transformers in VDT or TV picture tubes. Cellular phones, on the other hand, use transmitters to send much higher radio frequency (RF) signals to nearby relay stations. The latest cordless telephones use frequencies near those of cellular phones. Both ELF and RF fields carry very little energy. That's why scientists find it so hard to imagine how either type could affect living cells. The RF emitted by cellular phones can cause heating in tissue at higher power levels than the phones are allowed to produce. After all, microwave ovens operate not awfully far in the spectrum from cellular phones, and they do a fine job of warming things up. The much less energetic ELF fields from power lines cannot by themselves induce any heating. Even now there are no widely accepted theories about how exposure to a so-called nonthermal electromagnetic field -- one that can't heat anything -- could affect living cells, much less threaten health. DESPITE THE LACK of a scientific explanation, several developments raise the possibility that nonthermal fields do affect people. The first is the growing body of epidemiology suggesting a connection between exposure to power-line ELF and various cancers, mostly leukemia and brain tumors. The Swedish studies are the most notable, though several U.S. researchers have also shown similar correlations, especially in children. Louis Slesin of Microwave News calls the Swedish results a ''smoking gun.'' He adds, ''A few years ago it was considered impossible for either ELF or RF to have health effects. But if you show that one may be risky, you've got to open the book on the other. It's just common sense.'' One provocative fact: The incidence of diseases that epidemiologists suggest may be related to electromagnetic fields has increased significantly over the past 20 years. For example, among children under 15 in the U.S., brain and nervous system cancer rose 28.6% from 1973 to 1989, and one of the most common forms of leukemia increased 23.7%. In addition to the epidemiology associating electromagnetic fields with cancer, an important study in Finland completed last year found a correlation between ELF and miscarriages in women who use VDTs at work. The study was the first anywhere to compare actual magnetic field measurements with the health of VDT users. Magnetic field intensity is measured in gauss. The background level in a typical house or office is about 1 milligauss (mG). The Finnish researchers found that women exposed to over 3 mG from a VDT had more than three times as many miscarriages as those exposed to less than 1 mG. Many VDTs emit 3 mG or more, though shielded models are now widely available. Epidemiology alone proves nothing about what causes a disease. All it does is demonstrate a statistical correlation. It's possible, for example, that children living near power lines are more exposed than others to carcinogenic defoliants sprayed beneath the wires to retard plant growth. Indeed, many who are convinced that electromagnetic fields contribute to cancer believe that the fields act more to promote the disease once it has struck than to cause it in the first place. As epidemiologists have been mustering their evidence, biophysicists conducting experiments on living cells in test tubes and petri dishes, and in a few cases on animals, claim to have identified a variety of biological effects from exposure to nonthermal levels of both ELF and RF fields. Their work is critical. Finding a biological effect in a cell is by no means the same thing as demonstrating an effect on human health, but it does increase the likelihood that the epidemiology is correctly connecting electromagnetic fields with cancer. The data are sketchiest for RF fields, the kind associated with cellular phones. Though many investigations have failed to identify any adverse effects, several recent efforts cry out for further exploration. Two studies published in 1990 by Stephen Cleary, a biophysicist at the Medical College of Virginia, showed that both normal human blood cells and one type of cancer cell grew abnormally after two-hour exposures to either the frequency at which microwave ovens operate or a lower frequency emitted by industrial equipment that uses high-intensity RF to fuse plastics. (In that case he was exploring possible dangers to the operators.) Cleary, who testified before a House subcommittee in February, says he would not use a cellular phone until the uncertainties are resolved. IN THE much lower ELF range, at least 11 studies have found effects of nonthermal fields on immune-system cells exposed to frequencies little higher than those of power transmission fields. While none involved intensities anywhere near as low as those the Swedish studies associated with cancer, they nonetheless buttress the notion that something does go on. Several have shown that ELF exposure modifies the concentrations of calcium inside a cell. That may be significant, since calcium levels are closely related to many fundamental cell functions, including the ability to divide and make proteins. Critic Adair of Yale says that until demonstrable effects of radiation are readily and independently replicated, nothing meaningful has been shown. But others counter, for example, that one paper published in December verified earlier results showing effects on cellular calcium from rock-bottom ELF fields. Many scientists accept Adair's criticism that they need to reproduce more results, though they say the reason they haven't is largely lack of funds. And there are still no studies that show anything happening to cells or tissue at the exact intensity and frequency of cellular phones. A key observer disagrees, perhaps surprisingly, with Adair's blanket dismissal of the results: Stanley Sussman, who manages electromagnetic field research at the Electric Power Research Institute in Palo Alto, California, which is funded by the electric utility industry. Says Sussman: ''Knowing some of the researchers involved and their labs and the way they do experiments, I think it's likely that some of them are showing true results.'' One reason it's so hard to know what to make of all the lab research is the sheer dumbfounding complexity of factors that can come into play. Among the variables: wavelength, intensity, duration of exposure, time of day, interaction with the earth's magnetic field (which some experiments show could alter the impact of radiating fields), and other fields that might be affecting an experiment, such as those emanating from lighting or power supplies in the laboratory. Many experiments haven't been repeated partly because it's so difficult to precisely duplicate this long list of experimental parameters. Dr. Ross Adey, a neurologist at the Veterans Administration Medical Center in Loma Linda, California, and perhaps the most eminent U.S. researcher in this area, believes scientists may eventually discover that what most affects human health is the aggregate effect of exposure to many different frequencies. He points out that when you switch on an electric motor, the initial surge of power creates a range of harmonic frequencies much higher than the basic household current frequency. Says Adey: ''I wouldn't focus on cellular phones when other things we have around our heads, like electric hair dryers and shavers, may be much more biologically active.'' Adey is conducting research under contract for Motorola, the No. 1 cellular phone maker. The company has cited his work as evidence that the phones are safe, but Adey doesn't put it so simply. He says he would still use one -- but for no more than 30 minutes a day. He also worries about the next generation of phones, which will employ digital compression to allow more phones to operate on the same channel. Instead of emitting a continuous signal, each phone will spritz out RF in quick pulses, perhaps as brief as one-fiftieth of a second. ''That opens up a Pandora's box of knowns and unknowns,'' says Adey. ''One thing we do know is that when a continuous radio signal is interrupted at that kind of low frequency rate, it interacts with tissue more powerfully than does an uninterrupted signal. I can't say if we should be worried, but I certainly think we should look into it.'' THE CELLULAR PHONE industry has yet to address public fears convincingly. In a January statement, Thomas Wheeler, president of the Cellular Telecommunications Industry Association, insisted cheerily, ''I'm comfortable using my portable phone, and I'm comfortable telling others to continue using their portable phones.'' But he conceded the need for more reassurance and announced that the industry would spend over $1 million on research -- but only ''to revalidate the findings of the existing studies, which have found that the radio waves from cellular phones are safe.'' That won't do. Says Samuel Koslov, a physicist at Johns Hopkins and, along with Adey, a member of that presidential panel back in 1971: ''It's something of a national scandal that government and industry are so unwilling to fund research to get an adequate understanding of what's going on.'' No studies of | the health of cellular phone users exist. Slesin of Microwave News rejects statements by the industry association and Motorola that 10,000 studies prove cellular phones safe. Says he: ''Almost none of the studies address cancer or any other long-term effects. Are you telling me that an industry that's invested $10 billion in capital projects can't afford it?'' At the Electric Power Research Institute, spending on electromagnetic field health studies this year will total about $15 million, more than double what it was two years ago. Granger Morgan of Carnegie Mellon terms the dearth of ELF research dollars ''a disgrace.'' He adds, ''We've done enough research to suggest there may be a problem, but not enough to resolve it. If we don't crank up and get some answers we're going to have a long, expensive period of chaos.'' He thinks total federal support for ELF research, now about $7 million a year, ought to top $20 million. While the measurable danger from electromagnetic radiation so far seems much less than the risk you run if you don't fasten your seat belt, the public won't be reassured by anything less than thorough, conclusive studies.

CHART: NOT AVAILABLE CREDIT: NO CREDIT CAPTION: A SPECTRUM PRIMER The electromagnetic spectrum ranges through many types of energy, which travels in waves. Near the bottom end, below left, fall the extremely low frequency (ELF) emissions of power lines, at 60 hertz (Hz, or cycles per second). Their wavelength is about 2,000 miles -- one-quarter the diameter of the earth. ELF fields are generated as a byproduct of the movement of alternating electrical current, and vary in intensity with the amount of power flowing. Cellular phones use transmitters to send signals to nearby relay stations. They emit radio frequency (RF) fields at about 850 megahertz (MHz), or 850 million cycles per second. The wavelength is about the distance between the fingers on your outstretched arms. The higher the wave frequency, the greater the energy. X-rays, far up the frequency scale, are so energetic they can ionize atoms, knock electrons out of orbit -- and cause cancer. But both ELF and RF are non-ionizing and carry very little energy. If they do affect human cells, the mechanism has yet to be found.