Study type: Epidemiological study (observational study)

Los Angeles study of residential magnetic fields and childhood brain tumors. epidem.

Published in: Am J Epidemiol 1996; 143 (2): 105-119

Aim of study (acc. to author)

A retrospective case-control study was conducted in the USA to investigate the association between the exposure to residential magnetic fields and childhood brain tumors.

Further details

Magnetic field exposure was assessed by 24-hour measurements, spot measurements, wire code classification and questions about the use of domestic electric appliances.

Endpoint/type of risk estimation

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

Exposure

Assessment

Exposure groups

Group Description
Group 1 24-h measurement in child's room: > 0.2 µT
Group 2 24-h measurement in child's room: > 0.25 µT
Group 3 24-h measurement in child's room: > 0.3 µT
Group 4 24-h measurement in other room: > 0.2 µT
Group 5 24-h measurement in other room: > 0.25 µT
Group 6 24-h measurement in other room: > 0.3 µT
Group 7 spot measurement at front door: > 0.2 µT
Group 8 spot measurement at front door: > 0.25 µT
Group 9 spot measurement at front door: > 0.3 µT
Group 10 exterior static magnetic fields: 0.332-0.477 µT
Group 11 exterior static magnetic fields: 0.478-0.489 µT
Group 12 exterior static magnetic fields: 0.490-0.503 µT
Group 13 exterior static magnetic fields: 0.504-0.637 µT
Group 14 interior static magnetic fields: 0.303-0.468 µT
Group 15 interior static magnetic fields: 0.469-0.480 µT
Group 16 interior static magnetic fields: 0.481-0.497 µT
Group 17 interior static magnetic fields: 0.498-0.589 µT
Group 18 wire code: underground
Group 19 wire code: very low current and ordinary low configuration (VLCC + OLCC)
Group 20 wire code: ordinary high current configuration (OHCC)
Group 21 wire code: very high current configuration (VHCC)
Group 22 use during pregnancy: electric blanket
Group 23 use during pregnancy: electric water bed
Group 24 use during pregnancy: electric clock
Group 25 use during pregnancy: electric heat radiant
Group 26 use during pregnancy: microwave
Group 27 use during pregnancy: ham radio
Group 28 use by child: electric blanket
Group 29 use by child: electric water bed
Group 30 use by child: electric clock
Group 31 use by child: electric heat radiant
Group 32 use by child: microwave
Group 33 use by child: ham radio
Group 34 use by child: hair dryer
Group 35 use by child: curling iron
Group 36 use by child: black/white television
Group 37 use by child: baby monitor

Population

Case group

Control group

Study size

Cases Controls
Eligible 437 433
Contacted 352 405
Participants 298 298
Statistical analysis method:

Conclusion (acc. to author)

Overall, the results did not show an increase in risk of developing a childhood brain tumor with increasing exposure to magnetic fields, as assessed by 24-hour measurements, spot measurements, or wire code classification. However, when analyses were restricted to very high magnetic field exposure inside the home (> 0.3 µT), the results were consistent with the hypothesis of elevated risk, although the numbers of subjects living in homes with very high interior fields was to small to show an effect clearly.
The authors conclude that in Los Angeles County, where magnetic fields in homes are relatively low compared with other geographic areas, overhead power lines appear unrelated to the risk of childhood brain tumor.

Limitations (acc. to author)

The proportion of homes with magnetic fields of more than 0.3 µT was too low to detect a moderate effect of the magnitude reported in other studies.

Study funded by

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