For short-term exposure to ELF magnetic fields, the WHO noted that “there are established biological effects from acute exposure at high levels (well above 100 µT) that are explained by recognized biophysical mechanisms. External ELF magnetic fields induce electric fields and currents in the body which, at very high field strengths, cause nerve and muscle stimulation and changes in nerve cell excitability in the central nervous system.” The limits from ICNIRP guidelines serve to prevent such effects from short-term exposure.
NEA also noted that, in 2002, the International Agency for Research on Cancer (IARC) published a monograph classifying ELF magnetic field as possibly carcinogenic to humans (Group 2B Carcinogen). The classification was based on pooled analyses of epidemiological studies demonstrating consistent patterns of a two-fold increase in childhood leukaemia associated with average exposure to residential power-frequency magnetic field above 0.3 to 0.4 µT.
However, the ICNIRP stated that “a causal relationship between magnetic fields and childhood leukaemia has not been established nor have any other long term effects been established”.
WHO's Recommendations
In 2007, WHO published the Environmental Health Criteria 238 on extremely low frequency fields. The publication highlighted that there is epidemiological evidence suggesting an association between chronic exposure at above 0.3 – 0.4 µT and an increased risk of childhood leukaemia; however evidence for a causal relationship is limited. Hence, the WHO has provided a list of recommendations which include:
- Provided that the health, social and economic benefits of electric power are not compromised, implementing very low-cost precautionary procedures to reduce exposure is reasonable and warranted.
- Policy-makers, community planners and manufacturers should implement very low-cost measures when constructing new facilities and designing new equipment including appliances.
The ELF levels near electrical substations and switchrooms in Singapore are low and well within ICNIRP guidelines. Nonetheless, in line with WHO’s recommendation,
NEA encourages developers to explore the implementation of cost effective measures as a precaution to further lower exposure to ELF radiation when building new facilities or modifying existing facilities.
Idiopathic Environmental Intolerance
Some individuals may have experienced symptoms which they suspect are due to exposure to EMF (including ELF radiation).
The WHO has stated the following:
- Electromagnetic hypersensitivity is characterised by a variety of non-specific symptoms, which afflicted individuals attribute to exposure to EMF
- A more general term for sensitivity to environmental factors is Idiopathic# Environmental Intolerance (IEI)
- There is no scientific basis to link IEI symptoms to EMF exposure
The Academy of Medicine Singapore has issued a statement on IEI. Details of the statement can be found
here.
#Note: Idiopathic means relating to an unknown cause
Reference:
1The World Health Organisation. Environmental Health Criteria 238 Extremely low frequency fields https://www.who.int/peh-emf/publications/Complet_DEC_2007.pdf
2The World Health Organisation. Exposure to extremely low frequency fields https://www.who.int/teams/environment-climate-change-and-health/radiation-and-health/non-ionizing/elff
3The International Agency for Research on Cancer. Non-Ionizing Radiation, Part 1: Static and Extremely Low-frequency (ELF) Electric and Magnetic Fields https://publications.iarc.fr/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Non-ionizing-Radiation-Part-1-Static-And-Extremely-Low-frequency-ELF-Electric-And-Magnetic-Fields-2002
4The International Commission on Non-Ionizing Radiation Protection. Fact sheet on the guidelines for limiting exposure to time-varying electric and magnetic fields (1 Hz to 100 kHz) https://www.icnirp.org/cms/upload/publications/ICNIRPFactSheetLF.pdf