Study type: Epidemiological study (observational study)

Residential and occupational exposure to 50-Hz magnetic fields and brain tumours in Norway: a population-based study. epidem.

Published in: Int J Cancer 2005; 115 (1): 137-141

Aim of study (acc. to author)

A population-based case-control study was conducted in Norway to investigate whether residential and occupational exposure to 50-Hz magnetic fields increased the risk for brain tumour.

Further details

The study population included all adults in Norway living in a corridor around a high-voltage power line (33 to 420 kV, 40 to 300 m). Residential exposure was calculated as time-weighted average of the magnetic fields generated by power lines. Occupational exposure was assessed as follows: the jobs were classified in categories of hours per week in a magnetic field above background level (0.1 µT), the categories were cumulated and multiplied by number of years working in the job.

Endpoint/type of risk estimation

Type of risk estimation: (odds ratio (OR))

Exposure

Assessment

Exposure groups

Group Description
Reference group 1 not exposed
Group 2 residential magnetic fields: < 0.05 µT
Group 3 residential magnetic fields: 0.05 - 0.19 µT
Group 4 residential magnetic fields: ≥ 0.20 µT
Group 5 occupational magnetic fields: < 18 (occupational exposure category - years)
Group 6 occupational magnetic fields: 18 - 30 (occupational exposure category - years)
Group 7 occupational magnetic fields: ≥ 31 (occupational exposure category - years)

Population

Case group

Control group

Study size

Cases Controls
Eligible 454 908
Statistical analysis method: (adjustment: )

Conclusion (acc. to author)

90 % of the cases and 92 % of the controls had a residential exposure to magnetic fields of less than 0.05 µT( background level).
A statistically non-significant, moderately elevated risk for residential exposure to magnetic fields and brain tumors was observed. However, no clear exposure-response pattern was found. Occupational exposure to magnetic fields showed an inversed association to the risk of brain tumor.

Study funded by

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