Ahlbom et al. pooled analysis of magnetic fields and childhood leukaemia (2000)
A pooled analysis of nine studies that produced the 0.3–0.4 µT figure still cited in every ELF policy discussion, reporting roughly twice the relative risk above that level.
Last verified 12 August 2026.
- Authors
- Ahlbom A, Day N, Feychting M, et al.
- Year
- 2000
- Design
- systematic review
- Exposure studied
- Residential 50/60 Hz magnetic field, time-weighted average
- Place in the evidence base
- high
- Primary document
- https://pubmed.ncbi.nlm.nih.gov/10970686/
Finding
No excess risk below 0.4 µT; a relative risk of about 2.0 for exposures at or above 0.4 µT, consistent across the pooled datasets.
What it cannot establish
Very few children were in the highest exposure category, so the estimate is statistically fragile. Possible selection bias in participation, and no mechanistic explanation. Pooling reduces random error but not shared systematic error.
Related records
- IARC classification of ELF magnetic fields as Group 2B (2002)
IARC classified extremely low frequency magnetic fields as possibly carcinogenic to humans (Group 2B) on the basis of consistent epidemiological associations with childhood leukaemia above roughly 0.3–0.4 µT.
Research record
- WHO/IARC ELF magnetic field association threshold (0.3–0.4 µT)
The average daily exposure level above which pooled epidemiological studies report an association with childhood leukaemia, and the basis for the IARC Group 2B classification of ELF magnetic fields.
Exposure limits
Sources
- ahlbom-2000 A pooled analysis of magnetic fields and childhood leukaemia — British Journal of Cancer, 2000. peer-reviewed, link checked 2026-08-12.
- who-elf Electromagnetic fields and public health: exposure to extremely low frequency fields — World Health Organization, 2007. government, link checked 2026-08-12.
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