It seems like for decades now that health experts have continuously struggled to determine whether or not mobile phones really can cause cancer in an individual after extensive use. Recently, a federal agency released the final results of what experts call the world’s largest and most costly experiment to look into that very question. But did the study get to the bottom of the long thought-provoking question?
The study itself originated in the Clinton administration, cost $30 million and involved approximately 3,000 rodents. During its process, the experiment, by the National Toxicology Program, found positive but relatively modest evidence that radio waves from some types of mobile phones could in fact raise the risk that male rats in particular could develop brain cancer.
The exposures used in the studies cannot be compared directly to the exposure that humans experience when using a cell phone,” John Bucher, a senior scientist at the NTP, a government program within the department of Health and Human Services, says in a press release. “In our studies, rats and mice received radio frequency radiation across their whole bodies. By contrast, people are mostly exposed in specific local tissues close to where they hold the phone. In addition, the exposure levels and durations in our studies were greater than what people experience.”
During the study, the participating rats were exposed to a level of radiation with a frequency of 900 megahertz, which is equally as typical of the mobile phones in use when the study was conceived earlier in the 90s, for approximately nine hours per day for a total of two years. The lowest levels of radiation used in the study were equivalent to the maximum exposure a phone can cause and still receive federal regulatory approval; the highest levels to which the animals were exposed were four times that. Two to three percent of irradiated male rats developed malignant gliomas, compared with none of the rats in the unexposed control group, as reported by the New York Times.
Kevin McConway, from Open University, says the research actually tells us nothing about the risk of phone use in humans, and even the evidence that RFR causes tumours in rats is “pretty weak.”
“Well, it establishes that, under certain conditions radiation of the same kind as produced by some mobile phones, but generally much stronger and much longer lasting, can lead to an increase in a certain type of tumour in certain rats,” says McConway. “That’s worth knowing, but it’s a bit like a hypothetical experiment where rats are run over by heavy boulders. That would doubtless establish that heavy boulders have the potential to harm rats, but it doesn’t tell us anything at all about the risk to humans arising from the existence of heavy boulders in the world. To investigate that risk requires a completely different type of research.”
In addition to his statement, researchers have stated that the increased brain cancer risk, in male rats specifically was also “clear evidence” of a link between the radiation and malignant heart tumours and “some evidence” of a link to adrenal-gland tumours, according to the release. In mice and in female rats, however, the link between radiation and tumours was deemed to be “equivocal,” or uncertain.
However, the hierarchy, from most to least certain, of characterisations used by the NTP is: “clear evidence”; “some evidence”; “equivocal evidence”; and “no evidence.” Today’s mobile phones tend to use higher-frequency radiation that is less able to penetrate animal tissues than the radiation used in the study, the Times reports. Further, since mobile phones have became popular, epidemiologists have not observed an overall increase in the frequency of brain cancers known as gliomas in humans.