Browsing by Author "Deltour, Isabelle"
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- ItemAnalysis of three-dimensional SAR distributions emitted by mobile phones in an epidemiological perspective.(2011-11-01) Deltour, Isabelle; Wiart, Joe; Taki, Masao; Wake, Kanako; Varsier, Nadège; Mann, Simon; Schüz, Joachim; Cardis, ElisabethThe three dimensional distribution of the specific absorption rate of energy SAR in phantom models was analysed to detect clusters of mobile phones producing similar spatial deposition of energy in the head The clusters characteristics were described from the phones external features frequency band and communication protocol Compliance measurements with phones in cheek and tilt positions and on the left and right side of a physical phantom were used Phones used the Personal Digital Cellular PDC Code division multiple access One CdmaOne Global System for Mobile Communications GSM and Nordic Mobile Telephony NMT communication systems in the 800 900 1500 and 1800 MHz bands Each phone s measurements were summarised by the half ellipsoid in which the SAR values were above half the maximum value Cluster analysis used the Partitioning Around Medoids algorithm The dissimilarity measure was based on the overlap of the ellipsoids and the Manhattan distance was used for robustness analysis Within the 800 MHz frequency band and in part within the 900 MHz and the 1800 MHz frequency bands weak clustering was obtained for the handset shape bar phone flip with top and flip with central antennas but only in specific positions tilt or cheek On measurements of 120 phones the three dimensional distribution of SAR in phantom models did not appear to be related to particular external phone characteristics or measurement characteristics which could be used for refining the assessment of exposure to radiofrequency energy within the brain in epidemiological studies such as the Interphone
- ItemThe effects of recall errors and of selection bias in epidemiologic studies of mobile phone use and cancer risk.(2006-07-17) Vrijheid, Martine; Deltour, Isabelle; Krewski, Daniel; Sanchez, Marie; Cardis, ElisabethThis paper examines the effects of systematic and random errors in recall and of selection bias in case control studies of mobile phone use and cancer These sensitivity analyses are based on Monte Carlo computer simulations and were carried out within the INTERPHONE Study an international collaborative case control study in 13 countries Recall error scenarios simulated plausible values of random and systematic non differential and differential recall errors in amount of mobile phone use reported by study subjects Plausible values for the recall error were obtained from validation studies Selection bias scenarios assumed varying selection probabilities for cases and controls mobile phone users and non users Where possible these selection probabilities were based on existing information from non respondents in INTERPHONE Simulations used exposure distributions based on existing INTERPHONE data and assumed varying levels of the true risk of brain cancer related to mobile phone use Results suggest that random recall errors of plausible levels can lead to a large underestimation in the risk of brain cancer associated with mobile phone use Random errors were found to have larger impact than plausible systematic errors Differential errors in recall had very little additional impact in the presence of large random errors Selection bias resulting from underselection of unexposed controls led to J shaped exposure response patterns with risk apparently decreasing at low to moderate exposure levels The present results in conjunction with those of the validation studies conducted within the INTERPHONE study will play an important role in the interpretation of existing and future case control studies of mobile phone use and cancer risk including the INTERPHONE study
- ItemEstimating associations of mobile phone use and brain tumours taking into account laterality: a comparison and theoretical evaluation of applied methods.(2012-11-23) Frederiksen, Kirsten; Deltour, Isabelle; Schüz, JoachimEstimating exposure outcome associations using laterality information on exposure and on outcome is an issue when estimating associations of mobile phone use and brain tumour risk The exposure is localized therefore a potential risk is expected to exist primarily on the side of the head where the phone is usually held ipsilateral exposure and to a lesser extent at the opposite side of the head contralateral exposure Several measures of the associations with ipsilateral and contralateral exposure dealing with different sampling designs have been presented in the literature This paper presents a general framework for the analysis of such studies using a likelihood based approach in a competing risks model setting The approach clarifies the implicit assumptions required for the validity of the presented estimators particularly that in some approaches the risk with contralateral exposure is assumed to be zero The performance of the estimators is illustrated in a simulation study showing for instance that while in some scenarios there is a loss of statistical power others in case of a positive ipsilateral exposure outcome association would result in a negatively biased estimate of the contralateral exposure parameter irrespective of any additional recall bias In conclusion our theoretical evaluations and results from the simulation study emphasize the importance of setting up a formal model which furthermore allows for estimation in more complicated and perhaps more realistic exposure settings such as taking into account exposure to both sides of the head
- ItemThe estimation of 3D SAR distributions in the human head from mobile phone compliance testing data for epidemiological studies.(2009-09-23) Wake, Kanako; Varsier, Nadège; Watanabe, Soichi; Taki, Masao; Wiart, Joe; Mann, Simon; Deltour, Isabelle; Cardis, ElisabethA worldwide epidemiological study called INTERPHONE has been conducted to estimate the hypothetical relationship between brain tumors and mobile phone use In this study we proposed a method to estimate 3D distribution of the specific absorption rate SAR in the human head due to mobile phone use to provide the exposure gradient for epidemiological studies 3D SAR distributions due to exposure to an electromagnetic field from mobile phones are estimated from mobile phone compliance testing data for actual devices The data for compliance testing are measured only on the surface in the region near the device and in a small 3D region around the maximum on the surface in a homogeneous phantom with a specific shape The method includes an interpolation extrapolation and a head shape conversion With the interpolation extrapolation SAR distributions in the whole head are estimated from the limited measured data 3D SAR distributions in the numerical head models where the tumor location is identified in the epidemiological studies are obtained from measured SAR data with the head shape conversion by projection Validation of the proposed method was performed experimentally and numerically It was confirmed that the proposed method provided good estimation of 3D SAR distribution in the head especially in the brain which is the tissue of major interest in epidemiological studies We conclude that it is possible to estimate 3D SAR distributions in a realistic head model from the data obtained by compliance testing measurements to provide a measure for the exposure gradient in specific locations of the brain for the purpose of exposure assessment in epidemiological studies The proposed method has been used in several studies in the INTERPHONE
- ItemThe INTERPHONE study: design, epidemiological methods, and description of the study population.(2007-09-12) Cardis, Elisabeth; Richardson, Lesley; Deltour, Isabelle; Armstrong, Bruce; Feychting, Maria; Johansen, Christoffer; Kilkenny, Monique; McKinney, Patricia; Modan, Baruch; Sadetzki, Siegal; Schüz, Joachim; Swerdlow, Anthony; Vrijheid, Martine; Auvinen, Anssi; Berg, Gabriele; Blettner, Maria; Bowman, Joseph; Brown, Julianne; Chetrit, Angela; Christensen, Helle Collatz; Cook, Angus; Hepworth, Sarah; Giles, Graham; Hours, Martine; Iavarone, Ivano; Jarus-Hakak, Avital; Klaeboe, Lars; Krewski, Daniel; Lagorio, Susanna; Lönn, Stefan; Mann, Simon; McBride, Mary; Muir, Kenneth; Nadon, Louise; Parent, Marie-Elise; Pearce, Neil; Salminen, Tiina; Schoemaker, Minouk; Schlehofer, Brigitte; Siemiatycki, Jack; Taki, Masao; Takebayashi, Toru; Tynes, Tore; van Tongeren, Martie; Vecchia, Paolo; Wiart, Joe; Woodward, Alistair; Yamaguchi, NaohitoThe 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
- ItemMobile phone use and incidence of glioma in the Nordic countries 1979-2008: consistency check.(2012-02-09) Deltour, Isabelle; Auvinen, Anssi; Feychting, Maria; Johansen, Christoffer; Klaeboe, Lars; Sankila, Risto; Schüz, JoachimSome case control studies have reported increased risks of glioma associated with mobile phone use If true this would ultimately affect the time trends for incidence rates IRs Correspondingly lack of change in IRs would exclude certain magnitudes of risk We investigated glioma IR trends in the Nordic countries and compared the observed with expected incidence rates under various risk scenarios
- ItemQuantifying the impact of selection bias caused by nonparticipation in a case-control study of mobile phone use.(2008-12-09) Vrijheid, Martine; Richardson, Lesley; Armstrong, Bruce K; Auvinen, Anssi; Berg, Gabriele; Carroll, Matthew; Chetrit, Angela; Deltour, Isabelle; Feychting, Maria; Giles, Graham G; Hours, Martine; Iavarone, Ivano; Lagorio, Susanna; Lönn, Stefan; McBride, Mary; Parent, Marie-Elise; Sadetzki, Siegal; Salminen, Tina; Sanchez, Marie; Schlehofer, Birgitte; Schüz, Joachim; Siemiatycki, Jack; Tynes, Tore; Woodward, Alistair; Yamaguchi, Naohito; Cardis, ElisabethTo quantitatively assess the impact of selection bias caused by nonparticipation in a multinational case control study of mobile phone use and brain tumor
- ItemRecall bias in the assessment of exposure to mobile phones.(2009-04-20) Vrijheid, Martine; Armstrong, Bruce K; Bédard, Daniel; Brown, Julianne; Deltour, Isabelle; Iavarone, Ivano; Krewski, Daniel; Lagorio, Susanna; Moore, Stephen; Richardson, Lesley; Giles, Graham G; McBride, Mary; Parent, Marie-Elise; Siemiatycki, Jack; Cardis, ElisabethMost 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
- ItemTime trends in brain tumor incidence rates in Denmark, Finland, Norway, and Sweden, 1974-2003.(2009-12-16) Deltour, Isabelle; Johansen, Christoffer; Auvinen, Anssi; Feychting, Maria; Klaeboe, Lars; Schüz, JoachimIn Denmark Finland Norway and Sweden the use of mobile phones increased sharply in the mid 1990s thus time trends in brain tumor incidence after 1998 may provide information about possible tumor risks associated with mobile phone use We investigated time trends in the incidence of glioma and meningioma in Denmark Finland Norway and Sweden from 1974 to 2003 using data from national cancer registries We used joinpoint regression models to analyze the annual incidence rates of glioma and meningioma During this period 59 984 men and women aged 20 79 years were diagnosed with brain tumors in a population of 16 million adults All statistical tests were two sided From 1974 to 2003 the incidence rate of glioma increased by 0 5 per year 95 confidence interval CI 0 2 to 0 8 among men and by 0 2 per year 95 CI 0 1 to 0 5 among women and that of meningioma increased by 0 8 per year 95 CI 0 4 to 1 3 among men and after the early 1990s by 3 8 per year 95 CI 3 2 to 4 4 among women No change in incidence trends were observed from 1998 to 2003 the time when possible associations between mobile phone use and cancer risk would be informative about an induction period of 5 10 years