Temporal and spatial variability of personal exposure to radio frequency electromagnetic fields in children in Europe

摘要

Background: Mobile communication technologies represent the main source of exposure to radio frequency electromagnetic fields (RF-EMF) in the general population and little is known about this exposure in children. There is concern that children today are exposed to more RF-EMF than ever before and that this accumulated exposure over a lifetime could lead to adverse health outcomes which have not yet been evaluated. Therefore studies characterizing RF-EMF exposure in children have been identified as high priority by the World Health Organization. This study aims to describe personal RF-EMF exposure levels in European children over a 72 hour period. Methods: In Denmark, the Netherlands, Slovenia, Switzerland, and five regions of Spain, 559 children and adolescents (ages 8-18 years) were recruited for personal RF-EMF measurements. Measurements were collected for 529 children over a 72-hour period between 2014 and 2016. Measurements of RF-EMF in the 87.5 MHz-6 GHz range were collected using personal portable exposure meters which measured 16 different frequency bands, with a measurement interval of four seconds. Questionnaires were collected regarding presence of child in different microenvironments (home, school, transport, outdoors) as well as use of RF-EMF sources and location of the exposimeter. Measurements were categorized in six general frequency bands according to source: total (all frequency bands), DECT (cordless phones), broadcast transmitters (TV and FM), uplink (mobile phones), downlink (mobile phone base stations), and WiFi. Measurements in these general frequency bands were categorized by low (50~th percentile), medium (50~th-90~th per-centile) and high (90~th percentile) to assess differences between countries, age groups, and habits of mobile phone use. Calculations were performed in power flux density unit (μW/m2). For 28 children in the Sabadell region of Spain, measurements were repeated one year later to test repeatability of measurements through Spearman rank correlations. Results: In general, downlink was the largest contributor to total levels of RF-EMF (median 27.20 μW/m~2) followed by broadcast transmitters (median 9.89μW/m~2 ). Exposure from uplink accounted for a median of 4.71 μW/m~2 . WiFi and DECT contributed very little to exposure levels. Measurements were generally highest while children were traveling and much lower at home or in school. Mean duration of measurements was 62 hours. Urbanicity of home, parents' highest level of education, and number of people living in home were all associated (p < 0.05) with measurements in the 90th percentile. One year later, repeatability was low for almost all general frequency bands (Spearman's rho = 0.40 for total measurements). However, measurements of downlink exposures were more consistent (Spearman's rho= 0.70). Conclusion: This study assesses RF-EMF exposure in a large number of children from different age groups (8-18y) in five European countries. RF-EMF measurements were generally highest while children were traveling, coming mainly from mobile phone base stations.. While higher personal exposure levels were associated with several demographic factors, levels were not consistent one year later in a small sample. It would be informative to test repeatability in a larger sample.