The FCC provides information about the specific absorption rate (SAR) of cell phones produced and marketed within the last 1 to 2 years. The SAR corresponds with the relative amount of radiofrequency radiation absorbed by the head of a cell phone user (47). Consumers can access this information using the phone’s FCC ID number, which is usually located on the case of the phone, and the FCC’s ID search form.
In addition to the increased brain cancer risk, in male rats there was also “clear evidence” of a link between the radiation and malignant heart tumors and “some evidence” of a link to adrenal-gland tumors, according to the release. In mice and in female rats, however, the link between radiation and tumors was “equivocal,” or uncertain. The hierarchy, from most to least certain, of characterizations used by the NTP is: “clear evidence”; “some evidence”; “equivocal evidence”; and “no evidence.”Today’s cellphones use higher-frequency radiation that is less able to penetrate animal tissues than the radiation used in the study, the Times reports. Further, since cellphones became popular, epidemiologists have not observed an overall increase in the frequency of brain cancers known as gliomas in humans. 
That brings us back to the main question here: Do cellphones cause tumors? We chose to focus this story on cancer risk, since it seems like the most common health concern people have about cellphones. But before we get to the answers, we need to take another (brief) detour to explain how this science has been done with human subjects. To do that, we need to zoom in on a nerdy subject: research methods.
Unfortunately, however, we’ll probably never have an RCT on cellphones and cancer in humans. It’d be too difficult and too expensive to randomly assign particular levels of cellphone use to thousands of people and have them stick with those plans for enough time (we’re talking at least five years) to figure out whether certain types of phones or phone use patterns cause cancer to develop. That’s not to mention the fact it’d be nearly impossible to find a group of people willing to not use cellphones and then make sure they actually stick to their promise.

The guidelines, issued last week, note that “some laboratory experiments and human health studies have suggested the possibility that long-term, high use of cell phones may be linked to certain types of cancer and other health effects.” These include brain cancer, tumors of the acoustic nerve and salivary glands, lower sperm count, headaches and effects on learning, memory, hearing, behavior and sleep.
Several studies that will provide more information are under way. Researchers from the Centre for Research in Environmental Epidemiology in Spain are conducting another international case–control study—Mobi-Kids—that will include 2000 young people (aged 10–24 years) with newly diagnosed brain tumors and 4000 healthy young people. The goal of the study is to learn more about risk factors for childhood brain tumors.
Launched at the U.S. Food and Drug Administration’s request 10 years ago, the NTP study dosed rats and mice of both sexes with RF radiation at either 1.5, 3 or 6 watts of radiation per kilogram of body weight, or W/kg. The lowest dose is about the same as the Federal Communications Commission’s limit for public exposure from cell phones, which is 1.6 watts W/kg. The animals were exposed nine hours a day for two years (about the average life span for a rat), and the exposures were cranked up steadily as the animals grew, so the absorbed doses per unit body weight remained constant over time.
Some studies have found a possible link. For example, several studies published by the same research group in Sweden have reported an increased risk of tumors on the side of the head where the cell phone was held, particularly with 10 or more years of use. It is hard to know what to make of these findings because most studies by other researchers have not had the same results, and there is no overall increase in brain tumors in Sweden during the years that correspond to these reports.
Leibovich was very careful to point out in our interview that Cellsafe is not claiming that the radiation absorbed by the body during phone use leads to health issues like brain tumours, male infertility or damage to unborn babies. But the Cellsafe website strongly suggests these links. Its homepage (image below) leads with the phrase "You should be concerned!" in an eye-catching red, and there is as much screen real estate on the site dedicated to information about the dangers of radiation, as there is for descriptions of the Cellsafe products. This information refers to "high levels of RF radiation" in several places, but it doesn't say whether this describes radiation from phone use.
Over time, the number of cell phone calls per day, the length of each call, and the amount of time people use cell phones have increased. Because of changes in cell phone technology and increases in the number of base stations for transmitting wireless signals, the exposure from cell phone use—power output—has changed, mostly lowered, in many regions of the United States (1).
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