IARC classification of ELF magnetic fields as Group 2B (2002)

Finding

Group 2B, driven by pooled analyses showing roughly a doubling of childhood leukaemia risk at time-weighted average exposures above 0.3–0.4 µT (3–4 mG), a level reached in only a small percentage of homes.

What it cannot establish

No established biophysical mechanism at these field strengths, and selection bias and confounding cannot be excluded in the underlying studies. Animal and in-vitro evidence was considered inadequate. The association has not been shown to be causal.

Related records

• 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

• High-voltage transmission line

  Fields directly beneath a loaded transmission line reach tens of milligauss and fall off roughly with distance for a balanced three-phase circuit, reaching background at 30–60 m for typical loadings.

  Sources & emitters

Sources

1. iarc-monograph-80 IARC Monographs Volume 80: Non-Ionizing Radiation, Part 1: Static and Extremely Low-Frequency Electric and Magnetic Fields — International Agency for Research on Cancer, 2002. peer-reviewed, link checked 2026-08-12.
2. who-elf Electromagnetic fields and public health: exposure to extremely low frequency fields — World Health Organization, 2007. government, link checked 2026-08-12.
3. ahlbom-2000 A pooled analysis of magnetic fields and childhood leukaemia — British Journal of Cancer, 2000. peer-reviewed, link checked 2026-08-12.