Danish study finds no link between cell phoneuse and cancer

Abstract

No relationship between cellular telephone use and theincidence of cancer was found in a study of all Danish users of cellphones. The study, which covered more than 400000 Danish users of cell phonesfrom 1982 through 1995, compares the numbers of cancers observed in thegroup with the expected numbers of cancers calculated for cancerincidence rates in the entire Danish population. No excesses of brain or nervoussystem cancers, of cancer of the salivary gland, of leukaemia, or ofcancer generally, were observed in cell phone users. Theseresults, the first nationwide cancer incidence study of cell phoneusers, were published recently by Christoffer Johansen andcolleagues from the Danish Cancer Society, and colleagues from theInternational Epidemiology Institute, Rockville, MD, in volume 93,issue 3 (203-7) of the Journal of the National Cancer Institute. Danish users of cellular telephones were identified from the records ofthe two companies that provide such services, and resulted in a finalstudy population of 420095 individuals. Cancer among these individualswas determined by linkage to the Danish Cancer Registry using thepersonal identification number assigned to all Danish citizens at birth.The numbers of cancers in the study population were remarkably close tothose expected from the incidence rates in the general population. Riskfor the cancers of interest (brain/nervous system, salivary gland andleukaemia) did not vary with duration of cell phone use, time since firstsubscription, age at first subscription, or whether the phone was analogueor digital. There was also no association found between cell phone useand brain tumours near the ear, where cell phones are typically held. Cellular telephones transmit and receive radiofrequency (RF) signals inthe microwave region of the electromagnetic spectrum. A typical cellphone operates at a power output of 0.25 W, which is associated with amaximum rise in brain temperature of only 0.1 °C. Thus, the authorsnote that any biological effects from cell phone use would not be thermal innature. Also, because RF radiation does not possess enough energy toremove electrons from atoms or molecules, it is impossible forionisation to occur. Despite these facts, there is public concern andsome limited laboratory evidence in rats of a potential link betweencell phone use and cancer. However, the authors conclude that this firstnationwide cancer incidence study evaluating cell phone use does notsupport the hypothesis of an association between cell phone use andcancer. In an editorial, Robert Park, of the American Physical Societyand the University of Maryland, says that cell phones are dangerous - whenused by people while driving. However, the large number of peopleinvolved and the rock-solid database of the Danish study make itdifficult to take issue with the conclusion that cell phones do notcause cancer. Despite the evidence, Park notes, there will be people whoargue that the issue has not been settled. Dr Park concludes that,because in science few things ever are settled completely, thescientific community has a responsibility to put all the evidence intoperspective for the public.