Validation of short term recall of mobile phone use for the Interphone study

Aim

To validate short term recall of mobile phone use within Interphone, an international collaborative case control study of tumours of the brain, acoustic nerve, and salivary glands related to mobile telephone use.

Methods

Mobile phone use of 672 volunteers in 11 countries was recorded by operators or through the use of software modified phones, and compared to use recalled six months later using the Interphone study questionnaire. Agreement between recalled and actual phone use was analysed using both categorical and continuous measures of number and duration of phone calls.

Results

Correlations between recalled and actual phone use were moderate to high (ranging from 0.5 to 0.8 across countries) and of the same order for number and duration of calls. The kappa statistic demonstrated fair to moderate agreement for both number and duration of calls (weighted kappa ranging from 0.20 to 0.60 across countries). On average, subjects underestimated the number of calls per month (geometric mean ratio of recalled to actual = 0.92, 95% CI 0.85 to 0.99), whereas duration of calls was overestimated (geometric mean ratio = 1.42, 95% CI 1.29 to 1.56). The ratio of recalled to actual use increased with level of use, showing underestimation in light users and overestimation in heavy users. There was substantial heterogeneity in this ratio between countries. Inter‐individual variation was also large, and increased with level of use.

Conclusions

Volunteer subjects recalled their recent phone use with moderate systematic error and substantial random error. This large random error can be expected to reduce the power of the Interphone study to detect an increase in risk of brain, acoustic nerve, and parotid gland tumours with increasing mobile phone use, if one exists.     

Validation of self-reported cellular phone use

BACKGROUND: In recent years, concern has been raised over possible adverse health effects of cellular telephone use. In epidemiological studies of cancer risk associated with the use of cellular telephones, the validity of self-reported cellular phone use has been problematic. Up to now there is very little information published on this subject. METHODS: We conducted a study to validate the questionnaire used in an ongoing international case-control study on cellular phone use, the "Interphone study". Self-reported cellular phone use from 68 of 104 participants who took part in our study was compared with information derived from the network providers over a period of 3 months (taken as the gold standard). RESULTS: Using Spearman's rank correlation, the correlation between self-reported phone use and information from the network providers for cellular phone use in terms of the number of calls per day was good (r=0.62, 95% CI: 0.45-0.75), while that of the average duration of each call was rather moderate (r=0.34, 95% CI: 0.11-0.54). Similar results were found when Kappa coefficients were estimated. A value of r=0.56 (Spearman's correlation, CI: 0.38-0.70) was found for cumulative cellular phone use. CONCLUSION: Our study suggests that cellular phone use is easier to recall in terms of number of calls made than in terms of cumulative phone use and should thus be used as the basis for the dose-response analysis.     

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.     

Cellular phones: are they detrimental?

The issue of possible health effects of cellular phones is very much alive in the public's mind where the rapid increase in the number of the users of cell phones in the last decade has increased the exposure of people to the electromagnetic fields (EMFs). Health consequences of long term use of mobile phones are not known in detail but available data indicates the development of non specific annoying symptoms on acute exposure to mobile phone radiations. In an attempt to determine the prevalence of such cell phones associated health manifestations and the factors affecting their occurrence, a cross sectional study was conducted in five randomly selected faculties of Alexandria University. Where, 300 individuals including teaching staff, students and literate employee were equally allocated and randomly selected among the five faculties. Data about mobile phone's users and their medical history, their pattern of mobile usage and the possible deleterious health manifestations associated with cellular phone use was collected. The results revealed 68% prevalence of mobile phone usage, nearly three quarters of them (72.5%) were complainers of the health manifestations. They suffered from headache (43%), earache (38.3%), sense of fatigue (31.6%), sleep disturbance (29.5%), concentration difficulty (28.5%) and face burning sensation (19.2%). Both univariate and multivariate analysis were consistent in their findings. Symptomatic users were found to have significantly higher frequency of calls/day, longer call duration and longer total duration of mobile phone usage/day than non symptomatic users. For headache both call duration and frequency of calls/day were the significant predicting factors for its occurrence (chi2 = 18.208, p = 0.0001). For earache, in addition to call duration, the longer period of owning the mobile phone were significant predictors (chi2 = 16.996, p = 0.0002). Sense of fatigue was significantly affected by both call duration and age of the user (chi2 = 24.214, p = 0.0000), while burning sensation was only affected by frequency of calls/day (chi2 = 5.360, p = 0.020). According to the 95% confidence interval of frequency and duration of calls, the study recommended not to increase the call duration more than four minutes and limit their frequency to less than seven calls/day with total duration of exposure less than 22 min./day.     

An international prospective cohort study of mobile phone users and health (COSMOS): Factors affecting validity of self-reported mobile phone use

This study investigates validity of self-reported mobile phone use in a subset of 75 993 adults from the COSMOS cohort study. Agreement between self-reported and operator-derived mobile call frequency and duration for a 3-month period was assessed using Cohen’s weighted Kappa (κ). Sensitivity and specificity of both self-reported high (≥10 calls/day or ≥4 h/week) and low (≤6 calls/week or <30 min/week) mobile phone use were calculated, as compared to operator data. For users of one mobile phone, agreement was fair for call frequency (κ = 0.35, 95% CI: 0.35, 0.36) and moderate for call duration (κ = 0.50, 95% CI: 0.49, 0.50). Self-reported low call frequency and duration demonstrated high sensitivity (87% and 76% respectively), but for high call frequency and duration sensitivity was lower (38% and 56% respectively), reflecting a tendency for greater underestimation than overestimation. Validity of self-reported mobile phone use was lower in women, younger age groups and those reporting symptoms during/shortly after using a mobile phone. This study highlights the ongoing value of using self-report data to measure mobile phone use. Furthermore, compared to continuous scale estimates used by previous studies, categorical response options used in COSMOS appear to improve validity considerably, most likely by preventing unrealistically high estimates from being reported.     

Mobile phone use and the risk of acoustic neuroma

BACKGROUND: Radiofrequency exposure from mobile phones is concentrated to the tissue closest to the handset, which includes the auditory nerve. If this type of exposure increases tumor risk, acoustic neuroma would be a potential concern. METHODS: In this population-based case-control study we identified all cases age 20 to 69 years diagnosed with acoustic neuroma during 1999 to 2002 in certain parts of Sweden. Controls were randomly selected from the study base, stratified on age, sex, and residential area. Detailed information about mobile phone use and other environmental exposures was collected from 148 (93%) cases and 604 (72%) controls. RESULTS: The overall odds ratio for acoustic neuroma associated with regular mobile phone use was 1.0 (95% confidence interval = 0.6-1.5). Ten years after the start of mobile phone use the estimates relative risk increased to 1.9 (0.9-4.1); when restricting to tumors on the same side of the head as the phone was normally used, the relative risk was 3.9 (1.6-9.5). CONCLUSIONS: Our findings do not indicate an increased risk of acoustic neuroma related to short-term mobile phone use after a short latency period. However, our data suggest an increased risk of acoustic neuroma associated with mobile phone use of at least 10 years' duration.     

The INTERPHONE study: design, epidemiological methods, and description of the study population

The very rapid worldwide increase in mobile phone use in the last decade has generated considerable interest in the possible health effects of exposure to radio frequency (RF) fields. A multinational case–control study, INTERPHONE, was set-up to investigate whether mobile phone use increases the risk of cancer and, more specifically, whether the RF fields emitted by mobile phones are carcinogenic. The study focused on tumours arising in the tissues most exposed to RF fields from mobile phones: glioma, meningioma, acoustic neurinoma and parotid gland tumours. In addition to a detailed history of mobile phone use, information was collected on a number of known and potential risk factors for these tumours. The study was conducted in 13 countries. Australia, Canada, Denmark, Finland, France, Germany, Israel, Italy, Japan, New Zealand, Norway, Sweden, and the UK using a common core protocol. This paper describes the study design and methods and the main characteristics of the study population. INTERPHONE is the largest case–control study to date investigating risks related to mobile phone use and to other potential risk factors for the tumours of interest and includes 2,765 glioma, 2,425 meningioma, 1,121 acoustic neurinoma, 109 malignant parotid gland tumour cases and 7,658 controls. Particular attention was paid to estimating the amount and direction of potential recall and participation biases and their impact on the study results. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Baruch Modan is deceased.     

Estimating transmitted power density from mobile phone: an epidemiological pilot study with a software modified phone

The aims of this study were to evaluate the weekly and annual cumulative radiofrequency-electromagnetic field (RF-EMF) exposure attributed to mobile phone (MP) use, and assess whether a novel app (Quanta Monitor?) could be employed in a small human sample to characterise the RF-EMF exposures associated with the use of MPs. Ten participants provided their two months’ daily objective data on their MP exposures (i.e. transmitted and received power densities) attributed to different modes of MP usage such as cellular calls, cellular data and Wi-Fi. The results demonstrated that total transmitted power density (cellular phone calls, data and Wi-Fi surfing) could be many orders of magnitude higher than that from the total received power density. Of the total transmitted power density, cellular data use contributed the largest portion. Our study showed that Quanta Monitor? could be employed in prospective assessment of exposures to MPs in epidemiological studies.     

Mobile phones in the hospital: improved mobile communication and mitigation of EMI concerns can lead to an overall benefit to healthcare

There is a growing trend in hospitals throughout the world to incorporate mobile phones and other wireless technology to offer more efficient, cost effective, and higher quality healthcare. Misunderstanding of mobile phone systems, electromagnetic interference with medical devices, and available management solutions, however, has led to a wide range of inconsistent hospital policies. Recent reviews and commentaries on the subject have provided inconsistent and in some cases factually incorrect information that confuses the issue. At one extreme, unmanaged use of mobile phones in areas where life-critical medical devices are in operation can result in atypical situations that may place patients at risk. At the other extreme, overly-restrictive policies based upon speculation may deny benefits by acting as an obstacle to technology. Overly-restrictive policies may also not address growing and legitimate communication needs of patients and visitors in times of crisis. While it may not be feasible for hospitals to manage every mobile phone handset that is randomly brought into their facility without certain limits on use in areas where life-critical devices are commonly in operation, restrictions are not usually necessary throughout the entire facility. Restrictive policies are also better facilitated when easily accessible areas are designated where mobile phone use is encouraged. Controlled mobile phone systems for use by doctors and staff for hospital-specific communication, by contrast, can operate compatibly throughout the entire hospital facility with appropriate system design and management, even in sensitive areas, and such systems have already been deployed in a number of hospitals throughout the U.S.     

Mobile phone consultation for community health care in rural north India

We conducted a study to ascertain the acceptability and feasibility of consultation by mobile phone in a rural area of northern India. The mobile phone number of a community physician was advertised to the general public and people were invited to telephone at any time for a medical consultation. Details of the calls received were recorded. During a seven-month study, 660 calls were received. The mean call duration was 2.7 min. Eighty percent of calls were made by men. Forty-eight percent of calls were made during office hours. A total of 417 (63%) calls were for seeking advice, 146 (22%) were for outpatient follow-up, 23 (4%) were for seeking appointments and the remaining 74 (11%) for other reasons. The most common problems were skin, respiratory, mental health and sexual problems. Of the 387 callers who were interviewed at follow-up, 302 (78%) stated that they had followed the advice provided. Of these, 91% found the advice very helpful in managing their health problems. About 96% of users wished to continue to use the service in future. The majority of calls made were of a primary care nature which could easily be dealt with by phone. The concept of using mobile phones for medical consultation seemed to be acceptable to people in rural Haryana.     

某市市级医院医务人员手机带菌状况与影响因素研究

目的为了解某市市级医院医务人员手机使用及其表面带菌状况,探讨手机使用行为和带菌状况的影响因素。方法2016年4—6月对某市24所市级医院中111名医务人员进行问卷调查、现场观察及手机表面采样。结果共发放并回收有效问卷111份,回收率及有效率均为100.00%。调查对象平均年龄为(32.00±9.03)岁,以女性和护士为主。调查对象中95.50%使用触屏手机,24.32%的医务人员诊疗时有使用手机的现象,65.77%的医务人员每天手机使用时间2 h,93.69%对手机进行过清洁消毒。98.20%医务人员认为手机表面存在病原微生物。共采集111份手机表面样本,合格率80.18%,污染率95.50%,平均菌落数为2.90 CFU/cm~2,最大细菌含量为111.60 CFU/cm~2。44份手机样本表面共检出18种55株致病菌或条件致病菌。年龄、性别、职业是手机使用行为和对手机认知态度的影响因素。性别、职业、手机使用持续时间的手机表面合格率分别比较,差异均有统计学意义(均P0.05);年龄、性别、职业、手机使用持续时间、是否使用手机壳/套的手机表面细菌染菌量分别比较,差异均具有统计学意义(均P0.05)。结论手机表面存在的潜在致病菌可能会通过医务人员诊疗过程中使用手机的行为引发医院感染。     

初中生对出行时使用手机与出行安全的认知

了解初中生对在道路上使用手机与出行安全关系的态度及其相关影响因素,为预防初中生交通伤害提供参考.方法 采用分层整群抽样的方法,于2016年12月选取上海市某区某街道3所中学六~九年级1 793名学生作为研究对象进行问卷调查,问卷内容包括人口学基本信息和对在道路上使用手机的危险程度判断.结果 认为“驾驶机动车时使用手机发微信”“驾驶电动车/助动车时使用手机”危险性高的比例分别为83.8%和85.3%,而认为“骑自行车时使用手机或戴耳机听音乐”“驾驶机动车时使用手机打电话”和“步行时使用手机”危险性高的比例分别仅为62.3%,61.8%和61.7%.针对部分在路上使用手机的危险程度判断上,女生、独生子女分别优于男生、非独生子女,差异均有统计学意义(P值均<0.05).结论 初中生对在道路上使用手机的危险性整体认知水平尚需提升,应重点加强对男生及非独生子女的交通安全认知干预,建议通过社区交通安全氛围构建提升初中生的认知水平.     

Mobile satellite systems

Satellite communication is a technique which has been used in telemedicine, often for educational purposes. Almost all of the work has concerned the use of fixed satellite terminals. Mobile satellite services (MSS) provide two-way voice and data communication from hand-held terminals, where the final link to the subscriber is by satellite. A number of new MSS systems are expected to become operational by 2001, providing either regional or global coverage. The most well developed proposals are Globalstar, ICO, Iridium and Odyssey. All the proposed systems use non-geostationary satellites. The MSS systems will allow international travellers to make and receive calls using a unique telephone number for their handset anywhere in the world where the service has been authorized by the local regulatory authorities. Data and fax services will also be available. By 2002 the proposed MSS systems might serve a million subscribers in Western Europe, although this is less than 1% of the expected number of mobile phone users. To recoup the development costs, the price of MSS airtime is expected to be high compared with existing mobile phones.     

Electromagnetic interference from GSM and TETRA phones with life-support medical devices

Disturbances in hospital devices caused by cellular telephone signals were investigated. The interference sources were GSM900, GSM1800, and TETRA380 phones. The number of medical appliances tested was 23. Most measurements were taken in a semi-anechoic laboratory. To simulate the worst situation, the phones were adjusted to emit at their maximum power levels. No interference was observed if the distance from GSM1800 phone was over 5 cm. Corresponding safety distance for GSM900 phone was 70 cm, and for TETRA phones over 3 m. Hence, the use of GSM1800 type mobile phones can be considered safe, whereas GSM 900 and TETRA phones may cause considerable interference in hospital devices, which can result in life-endangering situations.     

SMS versus telephone interviews for epidemiological data collection: feasibility study estimating influenza vaccination coverage in the Swedish population

This study compared the use of Short Message Service (SMS) on mobile phones and the use of telephone interviews in collecting self-reported data about influenza vaccination. Through random selection from the Swedish population registry, 2,400 individuals were assigned to be contacted through SMS (SMS-group), and 2,150 were assigned to undergo personal telephone interviews (TI-group). Both groups were asked three questions about influenza and influenza vaccination. Mobile phone numbers were found for 1,055 persons in the SMS-group of whom 154 (6% of the original sample; 15% of all who had a listed mobile phone number) responded. Landline or mobile phone numbers were found for 1,636 persons in the TI-group and 1,009 (47% of the original TI sample; 62% of those where a telephone number was found) responded. The vaccination data collected via SMS was not statistically significantly different from data collected through telephone interviews, and adjustment for different background factors did not change this. Compared to the original sample, there was an under representation of elderly and less educated individuals among the participants in the SMS-group, and under representation of less educated in the TI-group. Though the participation rate was low, SMS is a feasible method for collection of information on vaccination status data among the Swedish population compared to telephone interviews.     

胶质瘤发病风险与手机使用的系统评价

目的评价胶质瘤与手机使用危险性的联系。方法计算机检索MEDLINE、Web of Science、EMBASE、EBSCO、Cochrane Library、ScienceDirect数据库;收集胶质瘤与手机使用相关的病例对照研究文献,检索时间2000-2011年,采用RevMan5.1进行Meta分析。结果 8篇病例对照研究文献纳入,规律使用手机未见有胶质瘤危险性增高;而长期使用手机10年以上者与胶质瘤发生存在联系,OR=1.24(95%CI=1.10~1.40),长期同侧使用手机发生胶质瘤危险性增加58%,OR=1.58(95%CI=1.30~1.94)。结论规律使用手机并不增高胶质瘤的发生风险,长期频繁使用手机可能增加胶质瘤发生的风险,但分析中的偏倚与混杂因子可能影响因果关系的解释。     

Recall bias in the assessment of exposure to mobile phones

Most studies of mobile phone use are case-control studies that rely on participants' reports of past phone use for their exposure assessment. Differential errors in recalled phone use are a major concern in such studies. INTERPHONE, a multinational case-control study of brain tumour risk and mobile phone use, included validation studies to quantify such errors and evaluate the potential for recall bias. Mobile phone records of 212 cases and 296 controls were collected from network operators in three INTERPHONE countries over an average of 2 years, and compared with mobile phone use reported at interview. The ratio of reported to recorded phone use was analysed as measure of agreement. Mean ratios were virtually the same for cases and controls: both underestimated number of calls by a factor of 0.81 and overestimated call duration by a factor of 1.4. For cases, but not controls, ratios increased with increasing time before the interview; however, these trends were based on few subjects with long-term data. Ratios increased by level of use. Random recall errors were large. In conclusion, there was little evidence for differential recall errors overall or in recent time periods. However, apparent overestimation by cases in more distant time periods could cause positive bias in estimates of disease risk associated with mobile phone use.     

Long-term mobile phone use and brain tumor risk

Handheld mobile phones were introduced in Sweden during the late 1980s. The purpose of this population-based, case-control study was to test the hypothesis that long-term mobile phone use increases the risk of brain tumors. The authors identified all cases aged 20-69 years who were diagnosed with glioma or meningioma during 2000-2002 in certain parts of Sweden. Randomly selected controls were stratified on age, gender, and residential area. Detailed information about mobile phone use was collected from 371 (74%) glioma and 273 (85%) meningioma cases and 674 (71%) controls. For regular mobile phone use, the odds ratio was 0.8 (95% confidence interval: 0.6, 1.0) for glioma and 0.7 (95% confidence interval: 0.5, 0.9) for meningioma. Similar results were found for more than 10 years' duration of mobile phone use. No risk increase was found for ipsilateral phone use for tumors located in the temporal and parietal lobes. Furthermore, the odds ratio did not increase, regardless of tumor histology, type of phone, and amount of use. This study includes a large number of long-term mobile phone users, and the authors conclude that the data do not support the hypothesis that mobile phone use is related to an increased risk of glioma or meningioma.     

Communicating textual health information to the mobile phones of visually-impaired users

We investigated how short messages communicating health information would best be distributed to people with vision difficulties using mobile phones. Twelve visually-impaired persons who were unable to read short message service (SMS) messages directly compared three methods of presenting text messages as speech: (1) ordinary SMS messages were sent to the users and converted into speech by the mobile phone; (2) multimedia messages were sent to the users with prerecorded speech-synthesized information; and (3) mobile phone calls were placed to the users and prerecorded speech-synthesized messages were streamed to them. The latter two approaches used server-generated sound files. Over a three-month trial period, we sent a total of 88 SMS messages to the subjects, 111 multimedia messaging service (MMS) messages and 104 telephone calls. All of the SMS messages, 88% of the MMS messages and 69% of the telephone calls were received. In subsequent interviews, we asked the users which presentation method they preferred. SMS scored significantly better than both MMS (P = 0.033) and telephones (P = 0.006). All three methods had serious drawbacks. However, the study suggests that it might be possible to develop suitable technology for communicating with people with vision difficulties by mobile phone.