Study type: Epidemiological study (observational study)

Risk of cancer in Finnish children living close to power lines epidem.

Published in: BMJ 1993; 307 (6909): 895-899

Aim of study (acc. to author)

The risk of cancer in children exposed to magnetic fields of power transmission lines was investigated in a nationwide cohort study in Finland.

Further details

Buildings located within 500 m of power lines were identified to calculate the magnetic fields of the central points based on load flows. Children were classified as exposed if they lived in buildings with magnetic fields ≥ 0.2 µT or if the cumulative exposure was ≥ 0.4 µT years.

Endpoint/type of risk estimation

Type of risk estimation: (standardized incidence rate (SIR))



Exposure groups

Group Description
Reference group 1 magnetic field: 0.01 - 0.19 µT
Group 2 magnetic field: ≥ 0.2 µT
Reference group 3 cumulative exposure: 0.01 - 0.39 µT years
Group 4 cumulative exposure: ≥ 0.4 µT years


Study size

Type Value
Total 134,800

978100 person years; 140 cases of childhood cancer

Results (acc. to author)

Only 7300 children (5.4 %) had been exposed to magnetic fields of power lines of 0.2 µT and more. 12 900 children (9.6 %) had a cumulative exposure of more than 0.4 µT years.
No significant increased risk for leukemia, lymphoma, or cancers overall was observed among children at any exposure level. The significantly increased risk for central nervous tumors (based on 5 cases) was found in boys, which is likey to be a chance finding. The results suggested that magnetic fields of power lines do not form a major public health risk regarding childhood cancer.

Study funded by

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