Study suggests risk not increased with short-term cell phone use
CHICAGO -- The use of handheld cellular telephones does not appear to be associated with the risk of brain cancer, but further studies are needed to account for longer induction periods, especially for slow-growing tumors, according to an article in the December 20 issue of The Journal of the American Medical Association (JAMA).
Joshua E. Muscat, M.P.H., of the American Health Foundation, Valhalla, N.Y., and colleagues conducted a case-control study from 1994 to 1998 to test the hypothesis that using handheld cellular telephones is related to the risk of primary brain cancer. A total of 469 men and women aged 18 to 80 with primary brain cancer and 422 matched controls without brain cancer took part in the study. Patients were interviewed at Memorial Sloan-Kettering Cancer Center, New York University Medical Center, and Columbia Presbyterian Hospital in New York; Rhode Island Hospital in Providence, R.I.; and Massachusetts General Hospital in Boston.
According to background information cited in the study, there were more than 86 million cellular phone users by the end of 1999. The use of cellular telephones is one of several suspected risk factors for brain cancer, although the causes of this disease remain poorly understood. The health effects due to using cellular telephones are currently being studied in a number of populations. In preliminary reports of a case-control study conducted in Sweden, the risk of brain cancer was unrelated to using a handheld cellular telephone.
Cellular telephones include handheld or mobile telephones, car telephones, and portable or bag telephones that operate on radiofrequency (RF) signals in the 800- to 900-MHz range. Concerns have been raised about possible adverse health effects due to exposure to these signals. In particular, the concern that the use of handheld cellular telephones causes brain cancer is based on the close proximity of the antenna, which is incorporated into the telephone receiver, to the head of the user.
The authors used a structured questionnaire to interview patients. The patients were asked if they had ever used a handheld cellular telephone on a regular basis. “Regular” was defined as having had a subscription to cellular telephone service. Information was obtained on the number of years of use, minutes/hours used per month, year of first use, manufacturer, and reported average monthly bill. Information on which hand was used to hold the cellular telephone was collected from 700 (78.6 percent) of the 891 patients.
“The use of handheld cellular telephones was unrelated to the risk of brain cancer in the current study,” the authors write.
“The median monthly hours of use were 2.5 for cases and 2.2 for controls,” they report. “Compared with patients who never used handheld cellular telephones, the multivariate odds ratio (OR) associated with regular past or current use was 0.85. The OR for infrequent users (less than 0.72 hours per month) was 1.0 and for frequent users (more than 10.1 hours per month) was 0.7.”
“The mean duration of use was 2.8 years for cases and 2.7 years for controls; no association with brain cancer was observed according to duration of use,” they continue.
The study found that among brain cancer cases, cerebral tumors occurred more frequently on the same side of the head where cellular telephones had been used (26 vs. 15 cases). But in cases of temporal lobe cancer, a greater proportion of tumors occurred in the opposite side of the head (9 vs. 5 cases).
The authors report the odds ratio was less than 1.0 (i.e., no increase in risk) for all histologic categories of brain cancer except for an uncommon type of brain cancer called neuroepitheliomatous.
“The current study shows no effect with short-term exposure to cellular telephones that operate on (primarily) analog signals,” the authors conclude. “Further studies are needed to account for longer induction periods, especially for slow-growing tumors. The RF fields emitted from digital cellular telephones might have different effects on biological tissue than analog telephones, and studies are under way in several European countries that use primarily digital telecommunication networks.” (JAMA. 2000; 284:3001-3007)
Editor’s Note: This work was supported by a contract from Wireless Technology Research LLC and by grants from the Public Health Service.
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