Ray McKenzie

How well do adolescents recall use of mobile telephones? Results of a validation study

BackgroundIn the last decade mobile telephone use has become more widespread among children. Concerns expressed about possible health risks have led to epidemiological studies investigating adverse health outcomes associated with mobile telephone use. Most epidemiological studies have relied on self reported questionnaire responses to determine individual exposure. We sought to validate the accuracy of self reported adolescent mobile telephone use.MethodsParticipants were recruited from year 7 secondary school students in Melbourne, Australia. Adolescent recall of mobile telephone use was assessed using a self administered questionnaire which asked about number and average duration of calls per week. Validation of self reports was undertaken using Software Modified Phones (SMPs) which logged exposure details such as number and duration of calls.ResultsA total of 59 adolescents participated (39% boys, 61% girls). Overall a modest but significant rank correlation was found between self and validated number of voice calls (ρ = 0.3, P = 0.04) with a sensitivity of 57% and specificity of 66%. Agreement between SMP measured and self reported duration of calls was poorer (ρ = 0.1, P = 0.37). Participants whose parents belonged to the 4th socioeconomic stratum recalled mobile phone use better than others (ρ = 0.6, P = 0.01).ConclusionAdolescent recall of mobile telephone use was only modestly accurate. Caution is warranted in interpreting results of epidemiological studies investigating health effects of mobile phone use in this age group.

Comparison of measuring instruments for radiofrequency radiation from mobile telephones in epidemiological studies: implications for exposure assessment.

The debate on mobile telephone safety continues. Most epidemiological studies investigating health effects of radiofrequency (RF) radiation emitted by mobile phone handsets have been criticised for poor exposure assessment. Most of these studies relied on the historical reconstruction of participants’ phone use by questionnaires. Such exposure assessment methods are prone to recall bias resulting in misclassification that may lead to conflicting conclusions. Although there have been some studies using software-modified phones (SMP) for exposure assessment in the literature, until now there is no published work on the use of hardware modified phones (HMPs) or RF dosimeters for studies of mobile phones and health outcomes. We reviewed existing literature on mobile phone epidemiology with particular attention to exposure assessment methods used. Owing to the inherent limitations of these assessment methods, we suggest that the use of HMPs may show promise for more accurate exposure assessment of RF radiation from mobile phones.

Comparison of the Effects of Continuous and Pulsed Mobile Phone Like RF Exposure on the Human EEG

It is not clear yet whether Global System for Mobiles (GSM) mobile phone radiation has the ability to interfere with normal resting brain function. There have been reports that GSM exposure increases alpha band power, and does so only when the signal is modulated at low frequencies (Huber, R., Treyer, V., Borbely, A. A., Schuderer, J., Gottselig, J. M., Landolt, H.P., Werth, E., Berthold,T., Kuster, N., Buck, A and Achermann, P. Electromagnetic fields, such as those from mobile phones, alter regional cerebral blood flow and sleep and waking EEG. J Sleep Res 11, 289-295, 2002.) However, as that research employed exposure distributions that are not typical of normal GSM handset usage (deep brain areas were overexposed), it remains to be determined whether a similar result patterning would arise from a more representative exposure. In this fully counterbalanced cross-over design, we recruited 12 participants and tried to replicate the modulation linked post exposure alpha band power increase described above, but with an exposure source (dipole antenna) more closely resembling that of a real GSM handset. Exposures lasted for 15 minutes. No changes to alpha power were found for either modulated or unmodulated radiofrequency fields, and thus we failed to replicate the above results. Possible reasons for this failure to replicate are discussed, with the main reason argued to be the lower and more representative exposure distribution employed in the present study. In addition we investigated the possible GSM exposure related effects on the non-linear features of the resting electroencephalogram using the Approximate Entropy (ApEn) method of analysis. Again, no effect was demonstrated for either modulated or unmodulated radiofrequency exposures.

Mobile Phones and Brain Tumours: A Review of Epidemiological Research

There has been a great deal of public concern regarding the possibility that the use of mobile phone-related technologies might result in adverse health effects. Corresponding to this, there has been substantial epidemiological research designed to determine whether the use of mobile phones (MP) has any effect on health, and in particular whether it increases the risk of developing head and neck tumours. Such literature is particularly heterogeneous, which makes it difficult to pool in a meta-analysis. This paper thus reviews the epidemiological literature pertaining to the use of mobile phones and mobile phone-related technologies, and head and neck tumours, in an attempt to consolidate the various reports. Although there have been individual reports of associations between MP-use and tumours, this research is not consistent and on balance does not provide evidence of an association. There are reports of small associations between MP-use ipsilateral to the tumour for greater than 10 years, for both acoustic neuroma and glioma, but the present paper argues that these are especially prone to confounding by recall bias. The reported associations are in need of replication with methods designed to minimise such bias before they can be treated as more than suggestive.

Predictors of mobile telephone use and exposure analysis in Australian adolescents

Aim:  Australian adolescents are increasingly using mobile telephones (MP) while the debate on MP safety persists. This group is not generally engaged in full‐time employment, suggesting that their MP use is not work related. We investigated possible predictors of MP use in young people.

Potential GPRS 900/180-MHz and WCDMA 1900-MHz Interference to Medical Devices

This study compared the potential for interference to medical devices from radio frequency (RF) fields radiated by GSM 900/1800-MHz, general packet radio service (GPRS) 900/1800-MHz, and wideband code division multiple access (WCDMA) 1900-MHz handsets. The study used a balanced half-wave dipole antenna, which was energized with a signal at the standard power level for each technology, and then brought towards the medical device while noting the distance at which interference became apparent. Additional testing was performed with signals that comply with the requirements of the international immunity standard to RF fields, IEC 61000-4-3. The testing provides a sense of the overall interference impact that GPRS and WCDMA (frequency division duplex) may have, relative to current mobile technologies, and to the internationally recognized standard for radiated RF immunity. Ten medical devices were tested: two pulse oximeters, a blood pressure monitor, a patient monitor, a humidifier, three models of cardiac defibrillator, and two models of infusion pump. Our conclusion from this and a related study on consumer devices is that WCDMA handsets are unlikely to be a significant interference threat to medical electronics at typical separation distances.

A new method to determine laterality of mobile telephone use in adolescents

Objectives As more children use mobile (cellular) telephones, public anxiety grows about the possible adverse health effects of radiofrequency (RF) exposure upon developing nervous systems. Most epidemiological studies investigating the health effects of mobile telephones have relied on self-reports from questionnaires. While there are some validation studies investigating the accuracy of self-reported mobile phone use in adults and adolescents, self-reported laterality of use has not been validated at any age. Although this study mainly sought to validate the accuracy of self-reported laterality of mobile telephone use in adolescents, investigation also covered number and duration of calls. Methods We monitored 455 calls in 30 students, mean age (SD) 14 (0.4) years. For 1 week, participants used hardware modified phones (HMPs) which logged dosimetric parameters such as laterality (side of head), date, number and duration of calls. These ‘gold standard’ measurements were compared with questionnaire self-reported laterality and estimated typical weekly phone use. Results Agreement between HMPs and self-reported laterality was modest (κ=0.3, 95% CI 0.0 to 0.6). Concordance between HMP measured and self-reported number of calls was fair (intraclass correlation coefficient (ICC)=0.38, 95% CI 0.07 to 0.69), but poor for duration (ICC=0.01, 95% CI 0.00 to 0.37) with wide limits of agreement for both. Conclusions These results suggest that adolescent self-reported laterality was of limited validity. Adolescent self-reported phone use by number and duration of calls was generally inaccurate but comparable to recent adult studies. Epidemiological studies of mobile phone use based on self-reported information may underestimate true associations with health effects.

Use of hardware modified phones for exposure assessment in health studies in Australia: verification of compliance with standards

Most epidemiological studies investigating health effects of mobile telephone use have been criticised for poor quality of exposure assessment. Most used questionnaires which have limited precision to assess exposure. Clearly more relevant and direct methods of exposure assessment are needed. We describe the calibration of hardware modified phones (HMPs) for exposure assessment and dosimetry and verified their compliance with Australian and international standards. Specific energy absorption rate (SAR) values at various tilts and rotations and their combinations were obtained for the HMPs using a ‘DASY3’ SAR measuring system. Calibration involved placing HMPs on human head phantoms and taking measurements at 900 and 1800 MHz bands on right and left sides of the phantom. At 900MHz the maximum SAR obtained with HMPs at the touch position was 0.9W/kg and 0.4W/kg at 30 degrees tilt but at 1800MHz, SAR at the touch and 30 degrees tilts were 1.1W/kg and 1.3W/kg respectively. Whilst tilt and rotation each had an effect on SAR at constant frequency, no interaction was observed with rotation and frequency, however one was observed between tilt and frequency. At 1800 MHz mean SAR at 30 degrees tilt was 0.22W/kg higher (95% CI 0.15, 0.30) than at 0 degrees, whereas at 900 MHz mean SAR at 30 degrees tilt was 0.60W/kg lower (95% CI 0.52, 0.67) than at 0 degrees. Our results indicated that tilts influence SAR more than rotations. SAR values obtained at both 900/1800 MHz for the HMPs were well below ICNIRP limits for the general public. The phones were compliant with both international and Australian standards.

Evaluation of hematopoietic system effects after in vitro radiofrequency radiation exposure in rats

Purpose: This study was designed to investigate the effect of a 900-MHz continuous-wave (CW) radiofrequency radiation (RFR) exposure on the hematopoietic system in the rat. Materials and methods: Rat long bones (femur and tibia) were divided into two groups: Sham-exposed and radiofrequency (RF)-exposed. The mean Specific energy Absorption Rate (SAR) at 900-MHz averaged over the bone marrow (calculated by the finite-difference-time-domain ( fdtD) method) was 2 W/kg at 16.7 W root mean square (rms) forward power into a Transverse Electromagnetic (TEM) cell. The bones, placed in a Petri dish containing media, were kept in the TEM cell for 30 min duration of sham or RF exposure. After exposure, the bone marrow cells were extracted and the following end points were tested: (a) Proliferation rate of whole bone marrow cells, (b) maturation rate of erythrocytes, (c) proliferation rate of lymphocytes, and (d) DNA damage (strand breaks/alkali labile sites) of lymphocytes. Results: Our data did not indicate any significant change in the proliferation rate of bone marrow cells and lymphocytes, erythrocyte maturation rate and DNA damage of lymphocytes. Conclusion: Our findings revealed no effect on the hematopoietic system in rats for 900 MHz CW RF exposure at the 2 W/kg localised SAR limit value recommended by the International Commission for Non-Ionising Radiation Protection (ICNIRP) for public exposures.

Walkie Talkies Cause More Electromagnetic Interference to Medical Equipment Than Mobile Phones

It is generally realised that mobile phones can interfere with medical electrical equipment and many hospitals have policies which aim to minimise the risk to their patients from this cause. Walkie talkies are also used in hospitals, but very little information is available concerning their ability to interfere with hospital equipment. Two walkie talkies and three mobile phones have been used to study and compare interference in 29 items of patient-connected equipment in a large hospital. Test results show that with some equipment there will be signal distortion and/or false alarms, and a Power off/on Reset may be necessary. In rare cases, when equipment is subjected to extreme signal strengths, it is possible to observe equipment failure requiring the replacement of failed components. For these tests the walkie talkies were set at 4W of output power and they caused significantly more interference than the mobile phones. The observed effects have been classified according to the maximum distance at which they were observed and according to the criticality of the possible outcome for the patient. It is concluded that, except for emergency services, the use of walkie talkies should be restricted in hospital buildings.