Study type: Epidemiological study (observational study)

Maternal occupational exposure to extremely low frequency magnetic fields and the risk of brain cancer in the offspring epidem.

Published in: Cancer Causes Control 2009; 20 (6): 945-955

Aim of study (acc. to author)

The association of the maternal occupational exposure to extremly low frequency magnetic fields immediately before and during pregnancy and childhood brain tumor was investigated in a pooled analysis of two case-control studies in Canada.

Further details

Exposure was assessed by a job exposure matrix and an estimation of the individual exposure based on job title and duration of exposure.

Endpoint/type of risk estimation

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



Exposure groups

Group Description
Group 1 electrical workers
Group 2 sewing machine operators
Group 3 office machine operators
Group 4 food and beverage preparers
Group 5 broadcasting and entertainment industries
Group 6 cumulative exposure in the 2-year period before pregnancy: ≥ 214.8 µT-days
Group 7 average exposure in the 2-year period before pregnancy: ≥ 0.30 µT
Group 8 peak exposure in the 2-year period before pregnancy: ≥ 0.4 µT
Group 9 cumulative exposure during pregnancy: ≥ 73.6 µT-days
Group 10 average exposure during pregnancy: ≥ 0.28 µT
Group 11 peak exposure during pregnancy: ≥ 0.4 µT


Case group

Control group

Study size

Cases Controls
Participants 760 548

239 cases of astroglial tumor, 145 cases of primitive neuroectodermal tumor, and 81 cases of other gliomas

Statistical analysis method: (adjustment: )

Results (acc. to author)

An elevated risk for all types of brain tumor was observed among children of mothers who were employed as sewing machine operators. An increased risk was found for astroglial tumors using the average exposure ≥ 0.30 µT before conception. During the pregnancy period, a significantly increased risk was observed for astroglial tumors and for all childhood brain tumors with the average magnetic field exposure of ≥ 0.26 µT.
The authors concluded that the results were suggestive of a possible association between maternal occupational exposure to extremely low frequency magnetic fields and certain brain tumors in their offspring.

Study funded by

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