ONE OF THE IRONIES of scientific advances is that for every problem the wizards in white solve for us they seem to turn up another, even more pressing, along the way. Take, for instance, the team the National Research Council in Ottawa put to work on the problem of birds that flock around airports and immolate themselves in jet engines, occasionally taking the engine and the airplane with them.
The researchers appear to have solved that one; to get rid of the birds, they say, bombard them with radar. A burst of “slightly thermal” radar — in the intensity range of about 40 milliwatts per square centimeter — will cause a bird in a cage to keel over, with one wing paralyzed, within four seconds. An airplane fitted with suitable radar could sweep a safety corridor for about a mile ahead of itself; the beam would cause any bird to tumble out of harm’s way before the plane passed, with no permanent damage to bird or plane. The technique has been tried in the lab and seems to work; it will be given a field try at Ottawa Airport this spring.
So far, so good. But why does the radar have this effect? It was in pursuit of this question that the scientists were driven up against what Dr. J. A.
Tanner, chief of the NRC research team, calls “some rather disquieting implications.”
The radar beam is described as “slightly thermal.” It interacts with the nervous system, and induces an electric current in the tissue which produces a disorientation of some kind in the animal. A human in the radar path would experience a heat sensation. Something, not yet clearly understood, happens when an intense radar beam falls on living tissue. Any living tissue. Insects confined under the beam were knocked out and eventually killed. Short bursts of radar during the insects’ reproductive cycle produced what Dr. Tanner called “some quite monstrous things — offspring with very little relationship to the adult.”
This is not radioactivity, atom bombs or gamma rays, but radar; and radar, after all, is merely a form of electromagnetic radiation, like a microwave signal or a TV transmission. We are bathed every day by an everincreasing range of electromagnetic signals of varying frequency and intensity. What do they do to us?
“Nobody knows,” said Dr. Tanner. “We only know that the assumptions we used to make about the perfect safety of such phenomena have been called into question.”
In 1959, the U.S. set an arbitrary safety standard for exposure to electromagnetic radiation at 10 milliwatts per square centimeter over any period of time, and that is far higher than anything we are likely to encounter in the ordinary course of living. Recently, however, the Russians set their own standard, at exactly 1/1000th of the U.S. level, or .01 mW per square centimeter for continuous exposure. According to the Russians, .1 mW is safe for an hour, and 1 mW for 20 minutes. On this scale, ordinary radar is safe enough (you need not fear for your progeny when you are zapped by a police speed trap; you are getting less than 1/100th of the Russian standard), and there’s nothing to fear from the beam from a microwave tower. But a man working under a TV transmitter, for instance, could be receiving from 1 to 2 mW and might have cause for concern.
In light of the Russian figures, the Americans have begun a re-examination of their standards, but not enough work has been done yet to permit any conclusions. Just the same, says Dr. Tanner, the time has come to consider the implications of the everpresent, ever-growing band of signals which are part of today’s communications explosion. “We’re communicating all right,” Dr. Tanner says, “but what are we doing to animal life, to human life, in the meantime?”
He does not suggest that we start turning off our TV sets or radar transmitters; he does suggest though, that we take a new look at the danger we may be letting ourselves in for some day.
“I wouldn’t want people to get into a panic over this,” he said, “but we ourselves are very alarmed.”
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