WHO recommendations on precaution

The following is the section on "Protective Measures" from Chapter One, "Summary and recommendations for further work", from WHO Environmental Health Criteria Monograph No 238 published in 2007. 

WHO also produced a  Factsheet No 322 based on this Monograph, which makes similar recommendations but shorter and in slightly different words.

Finally, we include some information on the WHO "Precautionary Framework", which was developed during the 2000s but never issued.

Monograph 238

1.1.12 Protective measures

It is essential that exposure limits be implemented in order to protect against the established adverse effects of exposure to ELF electric and magnetic fields. These exposure limits should be based on a thorough examination of all the relevant scientific evidence.

Only the acute effects have been established and there are two international exposure limit guidelines (ICNIRP, 1998a; IEEE, 2002) designed to protect against these effects.

As well as these established acute effects, there are uncertainties about the existence of chronic effects, because of the limited evidence for a link between exposure to ELF magnetic fields and childhood leukaemia. Therefore the use of precautionary approaches is warranted. However, it is not recommended that the limit values in exposure guidelines be reduced to some arbitrary level in the name of precaution. Such practice undermines the scientific foundation on which the limits are based and is likely to be an expensive and not necessarily effective way of providing protection.

Implementing other suitable precautionary procedures to reduce exposure is reasonable and warranted. However, electric power brings obvious health, social and economic benefits, and precautionary approaches should not compromise these benefits. Furthermore, given both the weakness of the evidence for a link between exposure to ELF magnetic fields and childhood leukaemia, and the limited impact on public health if there is a link, the benefits of exposure reduction on health are unclear. Thus the costs of precautionary measures should be very low. The costs of implementing exposure reductions will vary from one country to another, making it very difficult to provide a general recommendation for balancing the costs against the potential risk from ELF fields.

In view of the above, the following recommendations are given.

  • Policy-makers should establish guidelines for ELF field exposure for both the general public and workers. The best source of guidance for both exposure levels and the principles of scientific review are the international guidelines.
  • Policy-makers should establish an ELF EMF protection programme that includes measurements of fields from all sources to ensure that the exposure limits are not exceeded either for the general public or workers.
  • 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.
  • Changes to engineering practice to reduce ELF exposure from equipment or devices should be considered, provided that they yield other additional benefits, such as greater safety, or little or no cost.
  • When changes to existing ELF sources are contemplated, ELF field reduction should be considered alongside safety, reliability and economic aspects.
  • Local authorities should enforce wiring regulations to reduce unintentional ground currents when building new or rewiring existing facilities, while maintaining safety. Proactive measures to identify violations or existing problems in wiring would be expensive and unlikely to be justified.
  • National authorities should implement an effective and open communication strategy to enable informed decision-making by all stakeholders; this should include information on how individuals can reduce their own exposure.
  • Local authorities should improve planning of ELF EMF-emitting facilities, including better consultation between industry, local government, and citizens when siting major ELF EMF-emitting sources.
  • Government and industry should promote research programmes to reduce the uncertainty of the scientific evidence on the health effects of ELF field exposure.

Factsheet 322

WHO's guidance

For high-level short-term exposures to EMF, adverse health effects have been scientifically established (ICNIRP, 2003). International exposure guidelines designed to protect workers and the public from these effects should be adopted by policy makers. EMF protection programs should include exposure measurements from sources where exposures might be expected to exceed limit values.

Regarding long-term effects, given the weakness of the evidence for a link between exposure to ELF magnetic fields and childhood leukaemia, the benefits of exposure reduction on health are unclear. In view of this situation, the following recommendations are given:

  • Government and industry should monitor science and promote research programmes to further reduce the uncertainty of the scientific evidence on the health effects of ELF field exposure. Through the ELF risk assessment process, gaps in knowledge have been identified and these form the basis of a new research agenda.
  • Member States are encouraged to establish effective and open communication programmes with all stakeholders to enable informed decision-making. These may include improving coordination and consultation among industry, local government, and citizens in the planning process for ELF EMF-emitting facilities.
  • When constructing new facilities and designing new equipment, including appliances, low-cost ways of reducing exposures may be explored. Appropriate exposure reduction measures will vary from one country to another. However, policies based on the adoption of arbitrary low exposure limits are not warranted.

The WHO Precautionary Framework (for historical interest)

In the 2000s, WHO was developing a Precautionary Framework for EMFs.  It went through several drafts and never finalised or officially adopted. This page therefore describes what was then “work in progress” and should not be seen as a statement of official WHO policy. The documents above have replaced the Framework as the place where WHO's thinking on precaution is expressed.

In October 2004 The World Health Organization (WHO) released an updated draft of its “Framework to Develop Precautionary Measures in Areas of Scientific Uncertainty.” The new draft was substantially rewritten and expanded from the first draft issued in June of the previous year. In particular, newly added Appendices B and C applied the framework to ELF EMF and RF EMF as case studies.

The Framework

According to the draft document, the framework is intended to

“guide WHO Member States in the development of their public health policies and application of precautionary measures in the face of scientific uncertainty.”

These measures are aimed at optimising the overall benefit for society. The framework is not a mechanical formula, the WHO says, but a process for clarifying and analysing key issues. Its basic premise is that

“precaution should be viewed as an overarching philosophy for risk management which is to be applied to all aspects of managing an actual or potential health risk.”

The WHO expands the scope of factors to be considered in risk assessment and management from solely scientific information to social, political, and public health points of view as well. These factors may include vulnerable populations, heightened concern for the foetus and the child, inequities in the distribution of risk, the total number of individuals exposed, and potential effects on the quality of life.

The risk evaluation entails the traditional principles of science-based risk assessment, e.g. weight of evidence, scientific uncertainties, and underlying assumptions. In addition, however, the WHO’s precautionary approach operates from a broader knowledge base. It attempts to clarify what is not known, as well as what is uncertain.

WHO encourages the consideration of a broad range of options, not restricted to specified statutory exposure limits. These are assessed with either a cost-benefit or cost-effectiveness analysis. The depth of the analysis will depend on the certainty and size of the risk, and the WHO recommends that even very low-cost options be given a rudimentary analysis. The options selected should provide the best outcome for society and should be based upon balancing health protection and cost. The process for making the selection must be transparent to all stakeholders.



This seven-page appendix applies the precautionary framework to exposure to ELF fields from the generation, transmission, and use of electricity. It states that the IARC classification of magnetic fields as “possibly carcinogenic” means that

“Under the WHO Precautionary Framework, [childhood leukaemia] warrants a thorough consideration of precautionary measures including detailed cost-benefit or cost-effectiveness analyses”

WHO examines and assesses the full range of options. With respect to exposure limits, the report states:

“WHO believes exposure limits should be based on effects conventionally regarded as established and are not an appropriate mechanism for implementing precautionary approaches. Therefore WHO does not recommend including exposure limits based on the childhood leukaemia data as an option.”

Based on the facts that childhood leukaemia is a relatively rare disease and only a small fraction of the population is exposed at levels associated with a significantly increased risk, WHO states that

“in view of these factors, and even after fully allowing for the legitimate desire by society to err on the safe side, it seems likely that only very low-cost measures will be justified.”

The report then lists examples of these low-cost measures. Its full conclusions on the possible options are:

  • exposure limits set at 0.4 µT or similar levels seem unlikely to be justifiable. WHO considers that exposure limits for EMF should continue to be based on science conventionally regarded as “established”
  • any measures involving changes to engineering practice seem unlikely to be justifiable, unless they bring other benefits as well, such as greater safety, or unless local circumstances mean they of particularly low cost.
  • it seems unlikely that a precautionary approach to EMF alone could justify a change to distribution grounding practices, but EMF should be considered alongside safety, reliability and economics when changes are contemplated
  • appliance manufacturers should investigate whether magnetic fields could be reduced at low cost, and whether offering consumer choice of low-field appliances could be an advantageous marketing strategy
  • enforcing existing wiring codes so as to reduce unintentional ground currents must be sensible, but high costs in proactively seeking out and identifying existing errors are unlikely to be justifiable
  • the costs of changes to planning regimes for high-voltage power lines are dependent on national circumstances, and no generalisation is possible. However, procedures may be adopted which require efficient reduction of exposure for each new project
  • continued and enhanced research programmes are desirable to remove uncertainty in the future
  • communication to the public allowing informed decision making seems eminently sensible and justifiable