In 2010, Hanyia Naqvi was working on a Yale School of Medicine project to study the effects of cell phone radiation on brain growth. The researchers taped old flip phones to the sides of cages with pregnant mice inside. The phones fascinated the mice, remembered Naqvi, a master’s degree candidate at Southern Connecticut State University. “Some mice would just come and sit there,” she said.
Two years later, the data from the study, finally published, reveals that pregnant women should be wary of spending any unnecessary time with their phones. Hugh Taylor ’83, one of the authors of the study, said his team exposed the unborn mice to radiation from phone signals constantly until their birth, a total of about 19 days. The pups later showed subtle but consistent differences in behavior, and samples of their brain tissue responded differently in electrical experiments.
Taylor and the other authors stressed that their findings, published online in Scientific Reports on March 15, may not apply to humans. But as a simple precaution, Taylor suggested that pregnant women keep their phones away from their bodies as much as possible. This study adds to concern among scientists about a number of suspected health consequences of cell phone radiation, but is the first experimental confirmation of an effect on brain development in utero that lasts into adulthood.
“This is really just the beginning of a wider investigation,” Taylor said.
The researchers conducted a number of behavioral tests on the mice, including one for memory in which they gave the mice toys such as rubber duckies and ping pong balls. The following day, the researchers returned the same toys to the mouse’s cage, but on the third day, they gave the mice only one of the toys along with something new. The goal was to see if the mice were more interested in the new object, or if they seemed to remember the old toy at all.
Taylor described the mice in the experimental group as “hyperactive” and “happy-go-lucky.” They had weaker memories, were more active, and less anxious than their counterparts who had not been exposed to cell phone radiation. He said the differences were slight and would not have been apparent without the tests.
He and his co-authors noted that according to recent research, children today are more likely to develop hyperactivity disorders, and the group speculated that pregnant women’s use of cell phones might be a partial explanation.
John Walls, a vice president of the Washington, D.C., lobbying group CTIA-The Wireless Association, emphasized the differences between mice and humans in response to the concerns raised by the study.
“This new animal study presents results that, as the study authors themselves recognize, require other analysis and validation before any scientific conclusions may be reached of any relevance to human health,” he said in an email.
Bryan Luikart, a professor at Dartmouth Medical School, said he would not recommend that people use their cell phones differently based on the results of the Yale study. The scale of the changes found in mouse behavior is relatively small, even though the mice’s mothers had been exposed to radiation from the phones constantly during pregnancy, he said. He added that he would like to see the experiment duplicated by another group.
“There are a lot of differences between mice and humans, so I don’t want to be alarmist,” Taylor said. Still, he added: “What’s wrong with precaution?”
The researchers also took tissue samples from the prefrontal cortexes of mice in the experiment. As in humans, the prefrontal cortex is the part of the brain controls a mouse’s attention. Slight differences in how these tissues conducted electrical signals suggested that the radiation from the phones had somehow altered the structure of the mice’s brain cells.
That the effect of the radiation lasted well after the mice had been separated from the phones was “a significant finding,” said John Wargo FES ’81 GRD ’84, a professor at the Yale School of Forestry & Environmental Studies.
Wargo was not involved in the research for this study, but he and Taylor worked together on a review of dozens of studies on cell phones and health. The report, released in February, was published by Environmental and Human Health, an advocacy group in North Haven.
Some of the studies they reviewed had alarming results, such as suggesting that people who begin using cell phones as adolescents are much more likely to develop some brain cancers, and linking cell phone radiation to reduced male fertility.
But other studies were inconclusive. It is hard to say anything confidently about the health risks of cell phones, Wargo said, because wireless technology changes so quickly that controlled, long-term studies are difficult. At the end of the report, however, he and his co-authors, including Taylor, recommended that the federal government set manufacturing standards for the amount of radiation emmitted by cell phones.
Wargo explained that caution is necessary not because he is certain that cell phones are dangerous, but because there is growing evidence of “biological responses” to normal levels of cell phone exposure.
Taylor is the director of the reproductive endocrinology and fertility division at the School of Medicine. He advises his patients: “If you’re in your car, put the phone on the seat next to you instead of in your pocket. If you’re in your home or office, put the phone on a table or a desk. A small difference in distance makes quite a difference in radiation exposure.”
Cell phones emit radiation which is less intense than microwaves but more intense than radio waves.