Thomas S, Heinrich S, von Kries R, Radon K. Exposure to radio-frequency electromagnetic fields and behavioural problems in Bavarian children and adolescents. Eur J Epidemiol. Dec 4, 2009 Ahead of print.
Children and adolescents may be particularly susceptible to the adverse health effects of radiofrequency (RF) fields from mobile phones because of their developing nervous system and the potential for higher cumulative RF exposure during their lifetimes. A few studies have investigated the association between perceived health and mobile phone use among children and adolescents and have found that self-reported use of mobile phones was associated with poor perceived health. In the one study that examined the relationship between self-reported pre-natal and postnatal exposure to RF fields and behavioural problems in children, a significant association was found.
The aim of this study was to investigate the effects of exposure to RF fields assessed using personal dosimetry on mental health behaviour in Bavarian (Southern Germany) children and adolescents.
Between 2006 and 2008, children (ages 8-12) and adolescents (ages 13-17) were randomly recruited from registration offices of 4 Bavarian cities. All invited participants filled in a short questionnaire, regardless of their eventual participation in the study. Participants then completed a more detailed questionnaire that included items on well-being, socio-demographic characteristics, and potential sources of exposure to RF fields. Mental health was assessed by 25 questions that related to emotional symptoms, conduct problems, hyperactivity/inattention, and peer relationship problems. Parents of children also completed the same questionnaire as the child. After the interview, a personal dosimeter was worn by the child/adolescent for 24 hours.
Overall, 6,386 children and adolescents were invited, of which 5,870 were eligible and 4,452 (76%) answered the short questionnaire. In total, 1,498 children and 1,524 adolescents participated in the interview and exposure measurement (52% of eligible). Half of the children and 92% of adolescents owned a mobile phone; 96% and 77% did not use their phone daily, respectively for children and adolescents. Exposure to RF assessed using personal dosimetry ranged from a mean of below the limit of detection to a mean of 0.92% of the ICNIRP reference level per second during waking hours. Measurements made at night were discarded. Abnormal overall behaviour was slightly more common among children (7%) than adolescents (5%). The prevalence of emotional problems was higher in adolescents (6%) than in children (3%). The overall agreement in the assessment of behaviour problems between children and their parents ranged from 75% to 90%. Adolescents with the highest RF exposure more frequently reported overall behavioural problems. A significant association between exposure and conduct problems was seen for both children and adolescents, however no association with emotional problems, hyperactivity, or peer relationship was seen.
Interpretation and Limitations
The prevalence of behavioural problems seen in this study is in accordance with another German study, but not with 2 Norwegian studies that used the same questionnaire. Similarly, the exposure levels seen in this study are in accordance with other studies. The major limitations of this study are its reliance on self-reported behavioural problems, the possibility that behavioural problems cause increased mobile phone use, and the lack of information on maternal exposures known to increase the risk of behavioural problems. In addition, the participants tended to be more concerned about health effects of RF exposure than were non-participants, which may be a sign of selection bias.
This study found an association between RF exposure and behavioural problems in children and adolescents. However, since potential biases cannot be excluded, these results should be confirmed in other studies.