Study type: Epidemiological study (observational study)

Residential exposure to extremely low-frequency magnetic fields and risk of childhood leukaemia, CNS tumour and lymphoma in Denmark epidem.

Published in: Br J Cancer 2015; 113 (9): 1370-1374

Aim of study (acc. to author)

This study is an update of the case-control study by Olsen et al (1993) on the association between residential exposure to extremely low-frequency magnetic fields and the risk of childhood leukemia, CNS tumor and malignant lymphoma in Denmark. The previous study covered the time period 1968-1986, the present study additionally included the period 1987-2003.

Further details

Analyses were conducted separately for each cancer type and for all three cancers combined. Relative risks were estimated for the period 1968-1986, 1987-2003 and for the total period 1968-2003.

Endpoint/type of risk estimation

Type of risk estimation: (relative risk (RR))



Exposure groups

Group Description
Reference group 1 magnetic flux density:< 0.1 µT
Group 2 magnetic flux density: 0.1 - 0.39 µT
Group 3 magnetic flux density: ≥ 0.4 µT


Case group

Control group

Study size

Cases Controls
Eligible 3,277 9,129
Statistical analysis method:

Results (acc. to author)

Considering the total period 1968-2003, only 11 cases were exposed to 0.4 µT or more at home (group 3).
For the recent period 1987-2003, the relative risk was 0.88 (CI 0.32-2.42) combined for the three tumor types leukemia, CNS tumor and malignant lymphoma for children exposed to magnetic flux densities ≥ 0.4 µT compared with the reference group (< 0.1 µT), while for the total period (1968-2003) the relative risk was 1.63 (CI 0.77-3.46).
The authors conclude that the previous finding of a five- to six-fold higher risk for leukemia, CNS tumor and malignant lymphoma could not be confirmed when including data from the more recent time period. For the total time period, the results for childhood leukemia were in line with large pooled analyses showing relative risks between 1.5 and 2.

Study funded by

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