Epidemiological study (observational study)

Exposure to Radio-Frequency Electromagnetic Fields From Broadcast Transmitters and Risk of Childhood Cancer: A Census-based Cohort Study epidem.

By: Hauri DD, Spycher B, Huss A, Zimmermann F, Grotzer M, Von der Weid N, Spoerri A, Kuehni CE, Röösli M

Published in: Am J Epidemiol 2014; 179 (7): 843-851

Aim of study (acc. to author)

A cohort study was conducted in Switzerland to investigate the association between exposure to radiofrequency electromagnetic fields from broadcast transmitters and childhood cancer, particularly leukemia and tumors of the central nervous system.

Further details

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.

Endpoint/type of risk estimation

Type of risk estimation:

incidence

(hazard ratio, incidence rate ratio)

Exposure

- 500 kHz–862 MHz
- UHF fields
- Radio/TV transmitter
- TV broadcast (VHF/UHF)
- FM broadcast (UKW)
- AM radio transmitters
- DAB
- DVB-T
- residential

Assessment

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

Exposure groups

Group	Description
Reference group 1	exposure to radio-frequency electromagnetic fields from broadcast transmitters: < 0.05 V/m
Group 2	exposure to radio-frequency electromagnetic fields from broadcast transmitters: 0.05 - 0.2 V/m
Group 3	exposure to radio-frequency electromagnetic fields from broadcast transmitters: > 0.2 V/m

Population

Group:
- children
Age: 0–15 years
Observation period: 1985 - 2008
Study location: Switzerland
Data source: Swiss Childhood Cancer Registry, Swiss National Cohort

Study size

Type	Value
Total	1,332,944
Eligible	1,287,354

Other:

7,627,646 person-years

Statistical analysis method:

Cox proportional regressions analysis
Poisson regression model

(adjustment:

age
sex
benzene, natural background ionizing gamma radiation, distance to nearest power line, degree of urbanization

)

Results (acc. to author)

Eleven percent of all children were exposed to a predicted radio-frequency electromagnetic fields between 0.05 V/m and 0.2 V/m, and 4% were exposed above 0.2 V/m. From the whole study sample, 51% lived within the modeled area.
Based on 997 cancer cases, adjusted hazard ratios in the time-to-event analysis for the highest exposure category (>0.2 V/m) as compared with the reference category (<0.05 V/m) were 1.03 (CI 0.74-1.43) for all cancer types, 0.55 (CI 0.26-1.19) for childhood leukemia, and 1.68 (CI 0.98-2.91) for childhood central nervous system tumors. Results of the incidence density analysis, based on 4,246 cancer cases, were similar for all types of cancer and leukemia but did not indicate a central nervous system tumor risk (incidence rate ratio 1.03, CI 0.73-1.46).
The authors concluded that the results of this study did not suggest an association between predicted exposure to radio-frequency electromagnetic fields from broadcasting and the risk of childhood leukemia. Results for central nervous system tumors were less consistent, but the most comprehensive analysis did not suggest an association.

Study funded by

Federal Office of Public Health (FOPH; Bundesamt für Gesundheit), Switzerland
Federal Office of the Environment (FOEN; Bundesamt für Umwelt), Switzerland
Swiss Cancer League, Switzerland
Swiss National Science Foundation (SNF)

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