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Epidemiological Study (case-control study)

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

By: Preston-Martin S, Navidi W, Thomas D, Lee PJ, Bowman J, Pogoda J
Published in: Am J Epidemiol 1996; 143 (2): 105 - 119 ( open external web page full article, open external web page PubMed Entry , open external web page Journal web site )

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Aim of study (according 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.
Background/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.

Comment on Aim of Study (up to 2000 characters):

Endpoint/type of risk estimation

Estimate of incidence by odds ratio (OR)

Comment on Endpoints (up to 2000 characters):

Exposure

groups of exposure:

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 

Comment on exposure (up to 2000 characters):

Population

Further parameters acquired by interview (ionizing radiation, predisposing genetic syndromes, occupational history, history of residences)

Study size i cases  controls 
number eligible 437433
number contacted 352405
number participating 298298

Comment on population (up to 2000 characters):

Statistical analysis using unconditional logistic regression

Results/conclusion (according 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 (according 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.

Comment on outcome (up to 2000 characters):

(Study character: epidemiological study, case-control study)

General comment on article (up to 2000 characters):

Study funded by

  • California Department of Health Services, USA
  • California Public Health Foundation, USA
  • National Institutes of Health (NIH), Maryland, USA

Published comments on this article:Related articles i
Glossary: 50/60 Hz, AC, benign, biological, brain, brain tumor, case-control study, childhood, CNS tumor, cranial, cranial nerves, electric, epidemiological, exposure, genetic, histologically, hypothesis, incidence, ionizing radiation, magnetic fields, malignant, matching, meninges, OR, overhead power lines, predisposing, primary tumor, questionnaire, retrospective, risk, static magnetic field, statistical, subjects, unconditional logistic regression, wire code

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