Two strategies to analyze the data were applied: a time-to-event analysis and an incidence density cohort analysis. For the time-to-event analysis, we included children who were under age 16 years and living in Switzerland on the date of the 2000 census. Time at risk started on the date of the census and lasted until the date of diagnosis, death, emigration, the child's 16th birthday, or December 31, 2008, whichever occurred first. For the incidence density cohort analysis, no linkage between SCCR and Swiss National Cohort data was necessary. We included in this cohort all SCCR-registered patients diagnosed between January 1985 and December 2008 and residing in Switzerland at the time of diagnosis.
calculation: RF-EMF levels from the transmitters were modeled for an area with a radius of 10 km around each transmitter for the years 1990 and 2000 as well as for short- and medium-wave transmitters within a radius of 20 km for the years 1993 and 1997; exposure was assessed for each study participant at the place of residence
Reference group 1
exposure to radio-frequency electromagnetic fields from broadcast transmitters: < 0.05 V/m
exposure to radio-frequency electromagnetic fields from broadcast transmitters: 0.05 - 0.2 V/m
exposure to radio-frequency electromagnetic fields from broadcast transmitters: > 0.2 V/m