When talking about health risks in connection with magnetic fields, a distinction is made between possible long-term effects (eg cancer) of relatively weak fields and known acute effects. The latter may be the effects on the central nervous system caused by fields much stronger than the ones we normally find around electricity supply installations and household appliances.
The Danish precautionary approach
Denmark does not operate with exposure limits for possible long-term effects of magnetic fields. Instead we have adopted a precautionary approach to be observed when constructing new power lines near residential housing and vice versa. The precautionary approach was originally defined by the Danish health authorities in 1993.The authorities adhere to the internationally acknowledged exposure limits for acute effects of strong magnetic fields. In 2007, the authorities assessed that there was no reason to modify the precautionary approach.
The World Health Organization (WHO) does not find that there is a scientific background for defining exposure limits, but in 2007 WHO recommended adopting a precautionary approach.
Exposure limits for strong fields
The International Commission on Non-Ionizing Radiation Protection (ICNIRP) (1998) and the EU have both chosen to recommend exposure limits for the known acute effects of very large magnetic fields but not due to any long-term effects.
In 2004, the EU chose to adopt the ICNIRP recommendation as the basis for an EU directive on the exposure of workers to electromagnetic fields. The exposure limit for magnetic fields is 500 µT (microtesla) and 10 kV/m for electric fields. The EU member states were originally to have implemented the directive in their respective legislations in 2008 at the latest, but the EU will probably postpone this until 2012. The Danish Working Environment Authority uses the exposure limits recommended by the ICNIRP.
The individual EU member states will decide for themselves whether they want to use the exposure limits defined in the Council's recommendation from 1999 on public exposure. These are the same as those recommended by the ICNIRP, ie 100 µT and 5 kV/m.