Subject: Dr. Kjell Hansson Mild, Study on mobile phones..... (fwd) Date: Mon, 18 May 1998 093713 -0500 (CDT) From: "Roy L. Beavers" <rbeavers@llion.org> To: emfguru@hotmail.com -------------------------------------------------- Hi everybody: When I received the following via e-mail, it was slightly garbled. So I have done some "cleaning up" in what I forward below..... I believe that in doing so, I did not do any injustice to the accuracy of the info in Dr. Mild's work. You will be receiving more on this study and this subject.... Note: NMT phones are the earlier "analogue" phones, and GSM phones are the more recent "pulse-signal" phones.... Cheerio..... Roy Beavers (EMFguru) rbeavers@llion.org..............http://www.feb.se/EMF-L/EMF-L.html ................................It is better to light a single candle ... than to curse the darkness............................................... mobile phone users and symptoms A Swedish-Norwegian epidemiologial study Kjell Hansson Mild1, Gunnhild Oftedal2, Monica Sandstrіm1, Jonna Wilщn1, Tore Tynes3, Bjarte Haugsdal3, Egil Hauger4 1. National Institute for Working Life, Umeх, Sweden, 2. SINTEF Unimed, Trondheim, Norway*, 3. Norwegian Radiation Protection Authority, Oslo, Norway 4. Telenor Research and Development, Kjeller, Norway *Current address: Norwegian University of Science and Technology Dept of Physics, Trondheim, Norway ****Summary During 1995 many people reported symptoms experienced while using the mobile phone. Among the symptoms were headaches, feeling of discomfort, warmth behind/around the ear and on the ear, and difficulties to concentrate. The number of complaints from users of mobile phones was larger for GSM users, i.e. with pulse modulated fields. In the scientific literature there is a tendency for lower thresholds for biological effects from exposure to modulated fields. Our main hypothesis was thus that GSM users experience more symptoms than do NMT users. Across sectional epidemiological investigation was initiated including 6379 GSM-users and 5613 NMT-users in Sweden, and 2500 from each category in Norway. The persons were randomly selected from subscription registers where a company was the subscriber, but an individual was assigned to the phone. Questionnaires were used to register exposure factors, symptoms (both in general and symptoms related to the use of the mobile phone), and possible confounding factors such as gender, age, VDT-work and psychosocial factors for which the calculated odds ratios were adjusted. The estimated adjusted response rates were 64% for Norway and 76% for Sweden. The response rates were almost equal for the GSM-subscribers and NMT-subscribers. For none of the symptoms were the prevalence statistically significant higher for GSM-users than for NMT-users. Our hypothesis was therefore falsified. However, we observed a statistically significant lower risk for warmth sensation on and behind or around ear for GSM-users compared with NMT-users. The same trend was seen in the Swedish data for headache. Factors distinguishing the two systems (electromagnetic emission, temperature of the phones, and various ergonomic factors) are candidates to explain these results as well as the side finding: A statistically significant association between calling time/number of calls per day and the prevalence of warmth on ear, warmth behind or around ear, headache and fatigue. Further studies are required to verify or falsify our findings and to explore the role of the various physical factors. SINTEF Arbetslivsinstitutet Norway Sweden ****Background During 1995 many people with complaints of symptoms experienced while using the mobile phone (MP), contacted manufacturers, net operators and researchers working with electromagnetic fields. The symptoms reported were for example headaches, feeling of discomfort, warmth behind/around and on the ear, and difficulties to concentrate. Present knowledge of health effects from low level microwave radiation is limited. Symptoms have previously been described in connection with exposure to low level radio frequency fields or microwaves, but no studies linking the effect to the exposure has been published. It was thought of interest to start an epidemiological study to find out more about the prevalence of the symptoms and if there was any connection to the use of MPs and if so to a particular transmitter system, i.e NMT or GSM. In the scientific literature of biological effects of weak microwaves there is a tendency for lower thresholds for reported biological effects from exposure to modulated fields. The number of complaints from users of MPs was larger for GSM users, i.e. with pulse modulated fields. Our main hypothesis was thus that GSM users experience more symptoms than do NMT users. Thus, two groups of users of the different systems were identified, NMT900 and GSM. ****Materials and methods The study population was people with a mobile phone where a company was the subscriber, but an individual was assigned to the phone. In both countries we used the register of the net operators supporting services for both NMT and GSM. The final mailing lists consisted of 6379 GSM and 5613 NMT users in Sweden, and in Norway the corresponding figures were 2500 for each category. ****Questionnaire To be able to include the best description of symptoms we randomly selected 10 persons of those calling and asked them to participate in a medical interview. These interviews were done in spring 1996. Based on these interviews and knowledge from the literature of low level RF effects and our own experience from earlier questionnaire studies of similar phenomenas among video display terminal (VDT) users we formulated questions about symptoms. Questions about exposure factors included requests about transmitter system, makes and model, calling time and number of calls per day. Possible confounding factors registered were gender, age, occupation, geographical location, psychosocial factors, and VDT-work. The questionnaire was divided into two parts; the first to be filled in by all participants, the second was to be used by those who experienced symptoms and complaints connected to the use of a MP or an ordinary phone. In addition we wanted information about how swift symptoms developed, how long they lasted, and conditions under which the symptoms typically occurred etc. In this report mainly the results from the first part of the questionnaire filled in by all participants will be reported. Each questionnaire was type-set for optical reading and markings were read by computer. Handwritten information and comments filled in by the participants were manually typed. To estimate the psychosocial work load an index was created. It was based on the four commonly used questions, and obtained by summing the score of each of them. Many people in our study had more than one MP. Most commonly occurring is a combination of one NMT900 and one GSM phone. For each person we added the calling time for all MPs and the number of calls for all MPs respectively. Odds ratios (OR) were used as a measure of the different risk factors and the outcome variables. The OR is an estimation of the relative risk of having a symptom. A result was considered to be statistically significant when the result was within the 95% confidence interval. ****Results The adjusted response rate to the questionnaire was 64% for Norway and 76% for Sweden. The response rates were almost equal for the GSM and NMT-subscribers. The responders also evaluated their state of health. The relative number of responders that indicated that their state of health was good was higher among the Norwegian responders (83%) than among the Swedish responders (71%). There were only small differences in the state of health between GSM-users and NMT-users. An individual was defined to have a symptom if he/she had marked that the symptom occurred at least once a week. The results suggest that both individual factors as well as all work related factors might influence the prevalence of some symptoms. For instance factors such as age, gender, psychosocial work load, occupation, and amount of VDT-work are important for the prevalence of most of the symptoms. Also the exposure factors calling time and number of calls per day are of importance for the prevalence of symptoms. In the analysis of the effect of transmitter system and other exposure factors we therefore have adjusted for these variables. In general there is a higher prevalence of symptoms among the Norwegian responders as compared to the Swedish responders. Fatigue seems to be a more dominating symptom in Sweden while feeling of warmth on/behind ear is more dominating in Norway. Three percent in Norway and 5% in Sweden respectively reported other symptoms and here eye, ear and neck problems were dominating. In Sweden, also facial skin complaints was rather common. We analyzed whether persons that reported sensation of warmth on the ear and behind the ear experienced other symptoms more often than did persons without the warmth sensation experience. The risk for having a vegetative symptom was about two 2 to 4 times higher among those who had reported sensation of warmth on or behind the ear compared with those who did not report any of these symptoms. One exception was the facial skin symptom tingling/tightness for which this relative risk was about 5 to 8. Persons reporting one of the two warmth sensation symptoms had 10 to 20 times higher risk of having the other warmth sensation symptom and the sensation of burning skin. ****Symptoms versus exposure factors Our main hypothesis was that the users of GSM MPs experienced more symptoms than did NMT users. For most symptoms there were no statistically significant differences between the prevalence of symptoms with regard to the different transmitter systems. Our hypothesis is therefore falsified. However, both in Norway and in Sweden the study indicated a statistically significant lower risk for warmth sensation on and behind ear for GSM-users compared to NMT-users. The same trend was also seen in the Swedish data for headache. See table 1. The effect of transmitter system and number of calls or calling time per day was analyzed by using the category with the lowest number of calls/the shortest calling time irrespectively of transmitter system as the reference category. Increased risk was observed for most symptoms for groups with longer calling times and higher number of calls per day. The effect was particularly pronounced for the warmth sensation variables. Among the vegetative symptoms the most pronounced effects were seen for headache and fatigue, see further table 2. Symptoms experienced in connection with mobile telephone calls In Sweden 13% and in Norway 30% of the responders had experienced at least one symptom in connection with MP calls. In addition to asking for symptoms experienced in connection with MP use, we asked whether symptoms occurred or were aggravated in connection with the use of ordinary phone and VDT. More persons attributed their symptoms to MP use than to the use of ordinary phone. According to paired sign tests the differences were statistically significant (p < 0.001) for all symptoms. ****Discussion The hypothesis originally posted, that GSM users had a higher prevalence of symptoms than did NMT users, was falsified by the study. Actually, for some symptoms the result came out opposite to the hypothesis, i.e. GSM users experienced less problems than the NMT users for the phenomena of warmth sensations on the ear and behind/around the ear. We also, as a side finding, observed pronounced positive trends both with respect to Calling time and Number of calls per day for the warmth variables and for some of the vegetative symptoms. Several factors, emission as well as design, and other factors related to the use of mobile phone might have been responsible for the differences seen between the NMT-users and the GSM-users and for the increasing prevalence of symptoms with increasing Calling time/Number of calls. The role of the different factors such as radio frequency radiation, heated phones as well as the possible influence of methodological defectiveness and problems are open for discussion. The radio frequency output power is lower for the GSM phones than for the NMT900 phones, and the temperature increase of NMT phones due to the heating from the current drawn from the battery is usually more pronounced than of GSM phones. In addition to factors related to electromagnetic fields, factors such as audio quality, size and shape also differ between GSM and NMT phones. In the analog system (NMT phones), the speech may be partly masked by noise, and this is most prominent when the connection with the base station is poor. On the other hand, the audio quality of the digital system might be reduced by interruptions of silent periods. When the connection with the base station is too poor, it closes completely. All these audio disturbances may cause stress and might thereby indirectly be a source of vegetative symptoms such as headache and fatigue. Factors that may be important for the observed difference between GSM-users and NMT900-users also are actual candidates for explaining the increase in prevalence for warmth sensation and several of the listed vegetative symptoms with increasing Calling time and Number of calls. We found about the same tendencies for GSM-users as for NMT-users. Because the output power as well as the phone heat are lower from GSM phones than from NMT phones, for GSM-users the influence of factors such as modulation and low frequency magnetic fields can not be excluded. Among the various potential methodological reasons for the observed results, bias might to a certain extent be responsible for the correlation between symptom occurrence and Number of calls/Calling time. Furthermore there might be confounding factors that have not been identified and taken into account. We observe that the effect of Number of calls and Calling time is more marked for warmth sensation than for the various vegetative symptoms, furthermore, there is a good correlation between the occurrence of warmth sensation and each of the symptom s headache and fatigue, suggesting that these symptoms may be related to the sensation of warmth. ****Conclusions The hypothesis originally posted, that GSM users had a higher prevalence of symptoms than had NMT users, was falsified by the study. Actually, GSM users reported warmth sensation on the ear and behind or around the ear less frequently than did NMT-users. Based on these results we can not deduce the role of radio frequency emission, temperature of the phones and other physical differences between GSM phones and NMT phones. Demonstrable statistical associations between both Calling time and Number of calls per day and the occurrence of warmth sensation as well as headache and fatigue were found both among NMT users and GSM users in both countries. Whether this association also demonstrates a causal relation between MP use and the genesis of the different symptoms can not be determined. The finding, however, gives rise to the hypothesis that the Calling time and Number of calls are associated with the sensation of warmth and some vegetative symptoms. Further studies are required to test this hypothesis and to explore the role of various physical factors in genesis of the observed symptoms. Table 1. Adjusted OR and in brackets 95% confidence interval for different symptoms with respect to transmitter system. Reference category is NMT900. [guru's note: The following tables are hard to read in this version. Alisdair Philips has organized the following data into a much easier to read format, which will be forwarded separately in the next message.....] SymptomsOR (95% C.I.)NorwaySwedenFatigue1.07 (0.83-1.37)0.85 (0.70-1.03)Headache0.94 (0.71-1.24)0.78 (0.63-0.97)Warmth behind ear0.71 (0.56-0.91)0.74 (0.55-0.99)Warmth on ear0.71 (0.56-0.90)0.56 (0.43-0.73)Burning skin0.83 (0.60-1.15)0.99 (0.72-1.36) Table 2. Adjusted ORs and in brackets 95% confidence intervals for calling time. Reference category is calling time less than 2 min/day. A:Norway, B: Sweden . A: Norway OR (95% C.I.)NMTGSM Symptoms2-15 min/d15-60 min/d> 60 min/d2-15 min/d15-60 min/d> 60 min/dFatigue1.14 (0.64-2.02)1.59 (0.89-2.81)2.47 (1.16-5.24)1.10 (0.63-1.92)1.55 (0.88-2.74)4.14 (1.86-9.22)Headache1.81 (0.82-3.98)3.31 (1.53-7.18)6.36 (2.57-15.8)1.94 (0.90-4.20)2.69 (1.24-5.88)6.31 (2.35-17.0)Warmth behind ear2.42 (1.20-4.89)4.29 (2.13-8.62)18.1 (7.83-41.8)1.68 (0.83-3.40)2.93 (1.45-5.92)16.0 (6.34-40.4)Warmth on ear2.65 (1.35-5.18)5.30 (2.72-10.3)12.4 (5.52-27.8)1.65 (0.84-3.24)3.94 (2.02-7.71)8.37 (3.41-20.6)Burning skin1.44 (0.53-3.94)4.29 (1.65-11.1)11.8 (4.14-33.6)1.56 (0.59-4.13)3.48 (1.33-9.07)8.42 (2.70-26.2)In bold p<0.05 B: Sweden OR (95% C.I.)NMTGSM Symptoms2-15 min/d15-60 min/d> 60 min/d2-15 min/d15-60 min/d> 60 min/dFatigue1.33 (0.94-1.89)2.26 (1.54-3.32)2.32 (1.06-5.07)1.25 (0.89-1.75)1.80 (1.25-2.59)1.40 (0.65-3.00)Headache1.81 (1.22-2.69)3.24 (2.12-4.95)3.40 (1.43-8.12)1.49 (1.02-2.19)2.50 (1.66-3.75)2.83 (1.37-5.85)Warmth behind ear4.28 (1.90-9.64)10.7 (4.74-24.1)30.3 (11.2-81.8)2.63 (1.16-5.98)9.00 (4.05-20.0)21.9 (8.46-56.7)Warmth on ear6.18 (2.92-13.1)15.3 (7.19-32.5)47.8 (18.9-121)2.73 (1.26-5.91)10.2 (4.81-21.5)22.4 (9.10-55.0)Burning skin1.05 (0.61-1.81)2.12 (1.20-3.74)4.17 (1.59-11.0)1.06 (0.64-1.77)2.34 (1.40-3.92)2.77 (1.13-6.75)In bold p<0.05 PAGE 1 5 ї c U] A ѓнунѓунунѓш Ua b c ё № < Ж и ИG ? ? ;§N RV hь№є ? 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