Mobile phone exposures in children Joachim Schüz Institute of Medical Biostatistics, Epidemiology and Informatics () University of Mainz, Germany
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... the widespread use of mobile phones by children for non-essential calls should be discouraged.... justification of the precautionary approach: - the developing nervous system (more vulnerable?) - the greater energy absorption in the head (higher exposure per call?) - a longer lifetime exposure (higher cumulative exposure?)
Three Questions Is there support for the assumption that today s children will have a higher cumulative exposure to radiowaves from mobile phones than today s adults when they are at their age? What are current patterns of use in children and are there typical characteristics of kids using mobile phones regularly? What types of exposure are related to mobile telecommunications that are relevant for children?
Higher cumulative exposure? 70 60 % of regular users 50 40 30 20 10 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 year of first use [Christensen et al., 2004] male female Proportion of regular MP users over time among middle-aged persons
Higher cumulative exposure? 250 200 150 decrease of 58% 100 50 0 95 96 97 98 99 00 01 02 03 frequent user rare user Costs associated with the use of a mobile phone over the years (Germany, Year 2000 = 100) [Federal Office of Statistics]
Higher cumulative exposure? 180000 Number of public phones in Germany (1990 to 2003) 150000 120000 90000 60000 30000 0 90 91 92 93 94 95 96 97 98 99 00 01 02 03
Higher cumulative exposure? % of regular users 90 80 70 60 50 40 30 20 10 0 20-29 30-39 40-49 50-59 60-69 age male female [Christensen et al., 2004] Proportion of regular MP users by age group
Higher cumulative exposure? 140 120 100 Number of calls per month 80 60 40 20 0 12 10 8 20-29 6 30-39 40-49 50-59 60-69 Minutes of MP use per day 7 4 6 5 4 2 0 20-29 30-39 40-49 50-59 60-69 Duration per call (in minutes) 3 2 1 0 20-29 30-39 40-49 50-59 60-69
Summary Today s children will have a higher cumulative exposure because: - they have a longer lifetime period of exposure - they use mobile phones more often, because - the use of mobile phones gets cheaper and cheaper - mobile phones become more and more devices of everyday s life - children are very familiar with the technology - mobile phones are particularly attractive for children; even if they don t use it for making calls, mobile phones offer a variety of other features
Current patterns? Typical characteristics? US Canada Australia Ireland Spain France Japan* Germany UK Finland Sweden 40 52 65 67 72 81 86 87 90 90 91 0 20 40 60 80 100 % of MP owners among 15-19 years old [Mobile Youth 2002 except * (survey)]
Current patterns? Typical characteristics? MP use and ownership by age, Italy, 2002:
Current patterns? Typical characteristics? Australian Kids Consumer Insights, 2/2003: Kids aged 6-9 Kids aged 10-13 Sometimes use a friend's mobile phone 6% 22% Sometimes use their parent's mobile phone 93% 59% Own their own mobile phone 5% 36% Mobile phone ownership, all ages Africa, 5/2004: 2.8% fixed-line customers compared to 6% mobile phone customers annual increase of 65% over the last 5 years China, 7/2002: 15% mobile phone customers, corresponds to 180 million people
Current patterns? Typical characteristics? Studybase Period: November 2002 February 2003 Location: Mainz, Germany (city with about 200 000 inhabitants) Population: All children in their fourth elementary school year (typically aged 9-10 years) in Mainz and near surroundings. Participation: 1933 children from 34 primary schools (participation rate of 87.8%; 110 children did not attend school at the day of the interview, 158 children from 3 schools that refused participation). Interview: standardized questionnaire with 14 easy-phrased questions, read out loud in class by a trained interviewer, teacher questionnaire [Böhler, Schüz, in review]
Current patterns? Typical characteristics? Percent of cellular telephone owners per school (%) 60 55 50 45 40 35 30 25 20 15 10 5 0 overall: 34.7% school-location Surroundings Suburbs City Proportion of MP owners by school
Current patterns? Typical characteristics? 41,9% 6,2% 6,4% Mobile phone use for making calls 45,6% daily several times a week rarely never 3,7% 6,2% 25,8% Mobile phone use for sending text messages 64,2% daily several times a week rarely never
Current patterns? Typical characteristics? MP ownership MP regular use Increasing age Being an only child - Watching TV (>3 hrs/day) Computer games (>3 hrs/day) Membership sport club Picked up from school by car - Going to bed late Foreign children in class (>14) - Socially disadvantaged in class (>14) no impact: gender, attention of the class, private/state-run school, location
Summary The prevalence of mobile phone ownership and use is already very high among teens and increasing among younger children There is variation across countries but a general trend of increasing mobile phone penetration Due to the costs associated with the purchase and the use of a mobile phone, the finding of a high prevalence among children from socially disadvantaged families is rather surprising
Types of exposure? I Radiowaves from mobile phones Proportion of calls totally at highest power level: 31.1% Highest variation with: -network -phone model [Berg et al., in press; Interphone Germany]
Types of exposure? II ELF-EMF from mobile phones [Data provided by Dr J Bowman, U.S. National Institute for Occupational Safety and Health (NIOSH); measurements supported by Interphone and NIOSH.] Magnetic Field Profile with Distance from Phone Nokia Mobile Phone ELF Magnitude vs. Power Level Nokia Software Modified Phone 1.4 Magnetic field magnitude (µt) 60.0 900 MHz 1800 MHz 50.0 40.0 2.0 1.5 1.0 0.5 Static magnetic field ELF magnetic field ELF magnetic field magnitude (µt) 1.2 1.0 0.8 0.6 0.4 0.2 900 MHz 1800 MHz 0.0 0 2 4 6 8 10 12 0.0 max mid min Distance from phone top (cm) Power
Types of exposure? II ELF-EMF from mobile phones source of ELF-MF: during the pulsed transmissions from digital phones, a lot of current is drawn from the battery dominant frequency in GSM phones: 217 Hz, the pulse rate. variable field pattern around phones from different makes; analog phones without pulses have much lower ELF emissions than digital phones magnitude of ELF-MF own measurements: 0.2 0.8 µt due to the pulsed signal, magnetic fields from GSM phones have a time derivative db/dt about 100 times greater than the derivative of powerfrequency MF with the same magnitude; since db/dt determines the electric fields induced in the brain, these emissions should be studied further.
Types of exposure? III Environmental exposures to radiowaves 100 Power density, mw m -2 10 1 0.1 0.01 0.001 Outdoor Indoor 0.0001 0 50 100 150 200 250 [provided by Dr S Mann, NRPB] Distance from antennas, m Mobile phone base stations
Types of exposure? III Radiowaves from environmental sources ecological study in the vicinity of Vatican Radio station sample measurements revealed E-fields of 2-20 V/m in a distance of 1-4 km increased childhood leukemia incidence within 4 km of the transmitters, but based on only 4 cases three further ecological studies on this subject with equivocal results [Michelozzi, Am J Epidemiol, 2002]
Types of exposure? III Radiowaves from environmental sources [Source: BAKOM]
Summary Mobile phones operate at maximum power in a relevant fraction of all calls Mobile phones can produce ELF-magnetic fields up to some µt Compared to emissions from mobile phones, exposures from other sources of radiowaves are very low; however, for young children, who use mobile phones rather sparsely, continuos exposures from sources like TV and radio transmitters may be relevant
The End there is already a substantial proportion of children who use mobile phones regularly; among teens, the number of non-users is steadily decreasing towards a very minor fraction exposure assessment in epidemiological studies is easier than for adults, due to fewer competing exposure sources and less mobility, leading to less exposure misclassification for analyses today s children will have a much higher cumulative exposure than today s adults when they are at their age mobile phones are dominant sources of radiowave exposures and relevant sources of ELF-EMF