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Evidence grows for safety of mobile phones

BMJ 2001; 322 doi: https://doi.org/10.1136/bmj.322.7279.129/a (Published 20 January 2001) Cite this as: BMJ 2001;322:129
  1. Scott Gottlieb
  1. New York

    Regular use of mobile telephones does not seem to cause an increased incidence of brain tumours, but further studies are needed to account for longer induction periods, especially for slow growing tumours, according to the results of two new studies.

    The studies, which together involved more than 1250 patients with brain tumours and an equal number of healthy individuals, found no increased risk of cancers among those who used the devices more frequently. The results are not likely to put the issue of potential harm completely to rest, but they join a growing body of evidence suggesting that the only important risk associated with the handheld devices is a higher likelihood of traffic accidents.

    “In all of the available scientific literature, there is nothing that indicates any adverse health effects from using cell phones,” said Russell Owen, chief of the Food and Drug Administration's radiation biology branch. The two studies leave open the question of whether longer use of the devices could pose a problem. That issue is being addressed in a still larger European trial now under way, but results are not expected until 2003 at the earliest.

    In the first study, a team headed by epidemiologist Joshua Muscat of the American Health Foundation in Valhalla, New York, and Dr Mark Malkin of Memorial Sloan-Kettering Cancer Center, New York city, looked at 469 men and women aged 18 to 80 in whom brain cancer was diagnosed between 1994 and 1998. They were compared with 422 people who were closely matched for age, sex, race, years of education, and occupation but who did not have brain cancer. The mean duration of use was 2.8 years for cases and 2.7 years for controls (JAMA 2000;284:3001-7).

    On average, both groups used mobile phones about three hours or less each month and had used them for an average of slightly less than three years. Researchers found no increased risk of brain tumours among those individuals who used mobile phones for longer durations and no link between which hand routinely held the phone and the side of the head on which a cancer occurred.

    In the second study, another group of researchers, led by Dr Peter Inskip of the National Cancer Institute, Bethesda, Maryland, compared 782 patients in whom brain cancer was diagnosed between 1994 and 1998 with 799 people who were admitted to the same hospitals for conditions other than cancer. The investigators found no evidence that the risks of brain cancer were higher among people who used mobile phones for 60 or more minutes a day or regularly for five or more years. They also found that tumours did not occur disproportionately on the side of head on which the telephone was typically used (New England Journal of Medicine 2001:344;79-86).

    Mobile phones emit low levels of radiation that some animal research suggests may be powerful enough to damage DNA. But other evidence suggests the radiation that may be absorbed from mobile phones is not powerful enough to inflict genetic damage on brain cells. In addition, researchers said that if radiation from mobile phones triggered tumours, they would expect to find them in brain areas near the ear on the side that the phone was typically held. In both studies there was no such pattern.

    Despite these reassuring results, however, many people still believe that a link may remain between mobile phones and brain cancer. Last year Swedish researchers linked use of mobile phones to an increased risk of brain cancer among more than 600 subjects. Around the same time, the US Food and Drug Administration announced that it would oversee industry funded research into the possible link over the next few years.