|Back To Previous Page|
|Print This Page|
Regulators in Europe are taking a harder look at mobile phone safety. Although claims that fields from power lines could cause cancer have been authoritatively refuted by the U.S. National Research Council (NRC), that body acknowledged that sufficiently strong electrical and magnetic fields can have behavioral effects on animals. Now experiments on mice conducted at the National Radiological Protection Board in the U.K. have confirmed an apparent effect of magnetic fields on learning in animals that was first identified by a U.S. researcher.
In 1994 Henry Lai of the University of Washington showed that microwave radiation seems to slow down learning in rats. He placed rats in a maze that had 12 arms leading from it, each baited at its far end with a morsel of food. After a few days of daily training sessions, rats learned to visit each arm once only.
Lai and his colleagues observed that exposing rats to 45 minutes of pulsed microwave radiation each day before putting them in the apparatus slowed down their mastering of the task. The effect occurred when the amount of microwave energy absorbed in the experimental animals each minute was close to levels that might be absorbed by the brain of a cellular phone user. The effect of the fields could be eliminated by pretreating the rats with drugs affecting two neurochemical systems in the brain: the endogenous opioid system and the cholinergic system. Lai thus proposed that fields can affect those brain systems.
Lai, who last year demonstrated a similar behavioral effect from exposure to 60-hertz power-line-frequency fields, also has indications that microwave-frequency fields can cause DNA breaks. Moreover, he has some evidence that such effects may be cumulative. Lai speculates that if cellular phones caused forgetfulness, they might cause accidents, for example, among drivers. But he emphasizes that the microwaves in his experiments were of a higher frequency than those used by cellular phones.
An industry-funded body known as the Wireless Technology Research Group (WTRG) is now planning its own experiments. The WTRG's chairman, George L. Carlo, says he is "quite impressed" by Lai's theoretical framework. He maintains, though, that animals exposed to peak microwave levels in Lai's microwave experiments might have heard a distracting noise from the equipment that could have influenced their subsequent learning. The organization, which Carlo says is scientifically independent, is already attempting to reproduce Lai's finding of DNA damage.
H. Keith Florig of Carnegie Mellon University, an engineer and expert on the effects of electromagnetic fields on cells, declares Lai "is a reputable scientist" who has won grants from the National Institutes of Health. Another expert, Frank Barnes of the University of Colorado, concurs. "There is a lot of evidence going around that shows something is going on" that could allow low-intensity microwaves to affect the brain, Barnes observes. But he notes that nobody has demonstrated any harmful effects and that the science is complex.
Intrigued by Lai's behavioral results, Zenon J. Sienkiewicz of Britain's National Radiological Protection Board--which is a major player in a European Commission study on the safety of microwaves--decided to check whether he, too, could detect an effect of fields on learning. To start with, Sienkiewicz exposed mice to power-line-frequency magnetic fields of 50 hertz. In a paper submitted to Bioelectromagnetics, Sienkiewicz reports that in four separate experiments using a multiarm maze, "exposure significantly reduced the rate of acquisition of the task," although the exposed mice did catch up eventually. The fields he studied were stronger than those found in homes. But inspired by the results with Lai's test, Sienkiewicz is now planning experiments with microwave-frequency fields.
In the U.S. the NRC reported earlier this year that there is "convincing evidence" that animals can respond behaviorally to electromagnetic fields, albeit ones stronger than those found domestically. Federal agencies are waiting for the results of the WTRG studies before deciding whether regulation is warranted. Carlo predicts the results will start to be published early next year. But at least one company is not waiting for answers. Hagenuk in Kiel, Germany, started advertising "low-radiation" cellular phones in Europe this past summer.