by Harry Rudin
The results of two studies --- actually collections of studies --- have been published just recently. These are the Europe-wide Interphone study and the Swiss National Research Program NRP 57, Entitled “Non-Ionizing Radiation – Health and Environment”. In few words, neither has identified measurable health dangers arising from cell-phone use --- but both recommend further study and caution.
Swiss NRP 57 Study
The Swiss National Science Foundation financed eleven research projects in four categories: dosimetry and exposure assessment, laboratory studies and epidemiology, cell biology, and risk perception. The projects were carried out over a three-year period.
In the first category, a study was made to discover the major source of non-ionizing radiation. There are many wireless devices that radiate but, based on an extensive set of week-long measurements made in the city of Basel, the major source of radiation remains the cell phone. How much radiation depends on the transmission system used (UMTS radiates less than the older GSM) and using a headset reduces the exposure by a factor of ten. A surprising and upsetting result of the study is that the modern induction stove causes very strong electromagnetic fields and could well be a substantial danger for pregnant women and their unborn children. This is particularly true for professional cooks.
In the second category, it was clearly shown that the pulse-modulated radio-frequency fields emitted by cell phones do affect the human brain. First, these induce short-term effects observable in the brain’s electro-encephalogram. Some effects continued after the exposed person went to sleep but these effects did not have a sleep-disturbing result. Changes in the cerebral blood circulation and heart rate were also observed but these were small and no negative effect on a person’s well being was observed.
In the cell-biology category, DNA fragmentation in mammalian cells was shown. The frequency of the radiation was not cell-phone frequencies but normal household 50 Hz. The observed effect on cellular processes was very weak and presumably of no medical consequence.
As to results of the risk-perception study, the Swiss public accepts wide-spread cell-phone use but at the same time is somewhat apprehensive of the radiation coming from base stations. Some 5 % believe that they are hypersensitive to electromagnetic fields and suffer health problems as a result.
While the NRP 57 studies found no direct evidence for health problems caused by cell-phone radiation, the recommendation is that research be continued, particularly as cell-phone usage increases and technology changes so rapidly. The first link below is a summary of the findings.
The Interphone study is the largest study yet of potential cell-phone dangers, having been carried out in thirteen European countries and having identified some 6500 cancer patients. The patients were selected on the basis of four different kinds of brain tumors. The cell-phone use of these 6500 patients was compared with the cell-phone use of a similar number of healthy individuals. Many individual (country-based) studies had been published earlier but only recently have the results of all the studies been pooled together in the hopes of providing greater statistical certainty.
The results are confusing, a likely result of imprecision inherent in the interviews used to estimate cell-phone usage. Cancer patients were identified and interviewed to learn of their cell-phone use. For comparison, non-patients from a similar environment were identified and also questioned about cell-phone usage. The study was based on 30 to 60 year olds.
If one casually looks at the results one could conclude that for very high usage, the chance of a brain glioma (one of the four tumor types investigated) resulting from cell-phone radiation is significant. Casually looking at other usage categories, one could conclude that for some types of tumors, moderate cell-phone use has a protective effect! This is hard to explain on a medical basis. These observations and the results of a calculation of the statistical confidence interval (which show relatively little confidence in the results) weaken the study’s conclusions. Quoting from the report referenced below: ”The possible effects of long-term, heavy use of mobile phones require further investigation.”
Probably the difficulties are a result of the interviews: How accurate are a person’s recollection of the intensity of his or her cell-phone use two, five, or even ten years in the past? And, what biases are introduced when a person has learned that he or she actually has a tumor?
If there is a weak conclusion, it is that prolonged high usage may cause a brain glioma. The glioma develops on the side of the head where the cell phone is held. High usage is defined as a total accumulation of more than 1640 hours of cell-phone use.
Again, quoting from the conclusion of the study, “… biases and errors limit the strength of the conclusions we can draw from these analyses and prevent a causal interpretation” (quoted from the third link below). Clearly there is a need for further study as usage --- particularly among young people --- is growing and there is a fear that adolescents may be more sensitive. These worries may be balanced by newer technologies with reduced radiation.
The second link below is a very readable summary of the results of the Interphone study --- but in German. The third link was written in English by the study’s coordinator and gives details of the study.
What has been learned? Non-ionizing radiation from cell phones does have an effect on our bodily processes; whether this has an effect on our health remains unclear. There is a weak indication that heavy cell-phone use may cause a brain glioma but this is by no means certain. Until further results become available, we might take advantage of having learned that the use of a headset reduces radiation delivered to the head by a factor of ten.
Non-Ionizing Radiation – Health and Environment; Synthesis report (in English)
G. Duerrenberger’s analysis of the Interphone study (in German)
“Brain tumor risk in relation to mobile telephone use: results of the INTERPHONE international case–control study” (in English)
Swiss Editor for ERCIM News