2007 WHO Research Agenda for Extremely Low Frequency Fields
Introduction
In 1997, the WHO International EMF Project developed a Research Agenda in order tofacilitate and coordinate research worldwide on the possible adverse health effects ofelectromagnetic fields (EMF). In subsequent years, this agenda has undergone periodic
review and refinement.
In October 2005, WHO carried out a health risk assessment of extremely low frequency (ELF)
electromagnetic fields up to 100 kHz, which is published as a WHO Environmental HealthCriteria monograph1. Gaps in knowledge about possible health effects of ELF field exposure
are identified in this monograph, and form the basis for research recommendations given inthis Research Agenda.
Following a standard health risk assessment process, it was concluded that there were no
substantive health issues related to ELF electric fields at levels generally encountered bymembers of the public. Thus this Research Agenda addresses further research concerning thepossible acute and long term effects of exposure to ELF magnetic fields.
In general, acute effects are known to result from exposure to ELF magnetic field which
induces electric fields and currents in the body. These can, at high experimentally induced
field strengths (well above 100 µT), cause nerve and muscle stimulation and changes in nerve
cell excitability in the central nervous system. Various research recommendations are madewhich address uncertainty in the threshold levels of these acute effects. With regard to longterm effects, epidemiological studies have presented data indicating an association between
ELF exposure above approximately 0.3-0.4 µT and an increased risk of childhood leukaemia.
Despite several decades of work, however, compelling evidence from experimental studies tosupport a causal relationship is lacking. In addition, there is no widely accepted mechanism
by which ELF fields at normal environmental and occupational exposure levels might affectthe incidence of cancer or any other disease in the human population. Therefore, there is aneed to support the epidemiological evidence by establishing an in vitro cell response or
animal model response to ELF fields that is widely transferable between laboratories, if
indeed such responses occur.
Most studies carried out have concerned the possible effects of exposure to power frequency
fields. Further research on intermediate frequencies, usually taken as frequencies between 300
Hz and 100 kHz, is required given the present lack of data in this area. For these frequencies
very little of the required knowledge base for a health risk assessment has been gathered andmost existing studies have contributed inconsistent results, which need to be further
substantiated. General requirements for constituting a sufficient intermediate frequencies
1

World Health Organization (2007). Extremely Low Frequency Fields. Environmental Health Criteria
238. Geneva, World Health Organization (see: www.who.int/emf).

1database for health risk assessment include exposure assessment, epidemiological and humanlaboratory studies, and animal and cellular (in vitro) studies.
Researchers are encouraged to use the present Research Agenda as a guide to studies thathave high value for future health risk assessments. To maximize the effectiveness of large
research programs, government and industry funding agencies are encouraged to address the
WHO Research Agenda in a coordinated fashion. Such coordination will minimize
unnecessary duplication of effort and will ensure the timeliest completion of the studies
identified as being of high priority for health risk assessment.
This Research Agenda is ordered in successive sections according to the weight each research
activity carries in human health risk assessment: epidemiology, laboratory studies in humans,
animals, cellular systems, and mechanisms. It should be recognized that, while
epidemiological and human laboratory studies directly address endpoints related to humanhealth, cellular and animal studies are of value in assessing causality and biologicalplausibility.
Research topics relating to social sciences are included in this Research Agenda because of
the need to better understand the perception of risk from the general public and to better
communicate with the public on issues relating to ELF field exposure and health.
Each research activity is given a priority as follows:-High priority research needs: Studies to fill important gaps in knowledge that areneeded to significantly reduce the uncertainty in the current scientific information
relevant to health risk assessment.

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Other research needs: Studies to better assist the understanding of the impacts of ELF
field exposure on health and that would contribute useful information to health risk
assessment.

Epidemiology
Epidemiological studies are of primary importance in health risk assessment. When planningepidemiological studies, investigators should consider international coordination andcollaboration to maximize statistical power to estimate small risks and to evaluate the role of
exposure patterns in different countries. Studies should focus not only on cancer but also on
non-cancer endpoints (e.g. chronic diseases such as neurodegenerative diseases, sleep
disturbances). Particular attention should be paid to the use of adequate estimates of exposure
from all relevant sources.
High priority research needs:• Pooled analyses of existing childhood brain tumour studies
Rationale: Brain cancer studies have shown inconsistent results. This was also the case forchildhood leukaemia studies and here, pooled analyses have been very informative.
Therefore a pooled analysis of childhood brain cancer studies is recommended. Suchpooled analysis can inexpensively provide greater and improved insight into existing data,
including the possibility of a selection bias, and, if studies are sufficiently homogeneous,provide the best estimate of risk.
• Update of existing pooled analyses of childhood leukaemia with new information
Rationale: Since the pooled analyses have been performed, several new epidemiologicalstudies have been published. The pooled analyses should be updated with the results fromthese recent studies.
• Further study of the risk of amyotrophic lateral sclerosis in ‘electric’ occupations

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Rationale: Several studies have observed an increased risk of amyotrophic lateral sclerosisin ‘electric occupations’. It is considered important to investigate this association further inorder to find whether ELF magnetic fields are involved in the causation of this rareneurodegenerative disease. This research requires studies in which sufficient information iscollected on ELF magnetic field exposure, electric shock exposure as well as exposure toother potential confounders.

Other research needs:• Update of existing pooled and meta-analyses of adult leukaemia and brain tumour
studies and cohorts of occupationally exposed individuals
Rationale: For adult leukaemia and brain cancer, it is recommended that existing large
cohorts of occupationally exposed individuals be updated. Occupational studies and pooled
and meta-analyses for leukemia and brain cancer have been inconsistent and inconclusive.
However, new data have subsequently been published and should be used to update theseanalyses.
• Further study of the possible link between miscarriage and ELF magnetic field
exposure
Rationale: There is some evidence that the risk of miscarriage may be affected by ELF
magnetic fields exposure. Taking into account the potentially high public health impact ofsuch an association, further epidemiological research into this hypothesis is recommended.
• Further study of the risk of Alzheimer’s disease in relation to ELF magnetic field
exposure
Rationale: For Alzheimer’s disease, it remains a question whether ELF magnetic fields
constitute a risk factor. The data currently available are not sufficient and this association
should be further investigated. Of particular importance is the use of morbidity rather thanmortality data.
Human volunteer studies
Human laboratory studies allow ELF field effects to be studied on humans with control ofexperimental parameters, but are confined to investigations of acute, transient effects. For allvolunteer studies, it is mandatory that research on human subjects is conducted in full accord
with ethical principles, including the provisions of the Helsinki Declaration2.
High priority research needs:
None.
Other research needs:• Cognitive, sleep and EEG studies in volunteers, including children and occupationally
exposed subjects, using a wide range of ELF frequencies at high field strengths
Rationale: Studies of adult volunteers and animals suggest that acute cognitive effects may
occur with short-term exposures to intense fields. The characterization of such effects isvery important for the development of exposure guidance, but there is a lack of specific data
concerning field-dependent effects, particularly in children. It is recommended that
2World Medical Association (2004). Declaration of Helsinki: Ethical Principles for Medical Research
Involving Human Subjects. (http://www.wma.net/e/ethicsunit/helsinki.htm, accessed 12-2-2007).

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laboratory-based studies of cognition and changes in electroencephalograms (EEG) in
people exposed to ELF magnetic fields be performed, including children and occupationally
exposed adults.

Animal studies
Animal studies are used when it is unethical or impractical to perform studies on humans andhave the advantage that experimental conditions can be rigorously controlled, even forchronic exposures.

High priority research needs:• Development of transgenic mouse models of childhood leukaemia for use in EMF
studies
Rationale: Resolving the conflict between epidemiological results and experimental andmechanistic results for childhood leukaemia is the highest priority. It is recommended thatepidemiologists and experimental scientists collaborate on this. To this end, thedevelopment of transgenic mouse models for childhood leukaemia should be undertaken inorder to provide appropriate experimental animal models relevant to the epidemiological
data showing an association of EMF exposure with childhood leukaemia.
• Evaluation of co-carcinogenic effects of ELF fields
Rationale: For animal studies the weight of evidence is that there are no significant
carcinogenic effects of ELF magnetic fields alone. Therefore high priority should be given
to studies in which ELF fields are rigorously evaluated as a co-carcinogen.

Other research needs:• Studies of pre- and post-natal EMF exposure up to 100 kHz on subsequent cognitive
function in animals
Rationale: Behavioural studies with immature animals provide a useful indicator of
possible cognitive effects in children. Possible effects of pre- and post-natal exposure on thedevelopment of the nervous system and cognitive function should be studied. These studies
could be usefully supplemented by investigations on the effects of exposure to ELF
magnetic fields and induced electric fields on nerve cell growth using brain slices orcultured neurons.
• Further investigation of opioid and cholinergic responses in animals
Rationale: There is a need to further investigate potential health consequences suggested bya considerable body of experimental data showing opioid and cholinergic responses inanimals. Studies examining the modulation of opioid and cholinergic responses in animals
should be extended and the exposure parameters and the mechanistic biological basis forthese behavioural responses should be defined.
• Studies of ELF magnetic field exposure on immune and haemopoietic systems
development in juvenile animals
Rationale: While changes observed in immune and haematological parameters observed in
adults exposed to ELF showed inconsistency, there are essentially no research data
available for children. Therefore, the recommendation is to conduct studies on the effects of
ELF magnetic exposure on the development of the immune and haemopoietic systems injuvenile animals.

4Cellular studies
Studies in tissues, living cells and cell-free systems play a supporting role in health risk
assessments and are usually used to investigate mechanisms of interaction with EMFs.
However, they are not generally taken alone as evidence of effects in vivo (in animals or
people).
High priority research needs:• Evaluation of co-carcinogenic effects using in vitro studies
Rationale: The weight of evidence supports the view that there are no significant
carcinogenic effects of ELF magnetic fields alone. Therefore high priority should be given
to studies in which ELF fields are rigorously evaluated as a co-carcinogen.
Other research needs:• Replication of in vitro genotoxic studies
Rationale: With regard to other in vitro studies, experiments reporting the genotoxic effects
of intermittent ELF magnetic field exposure should be replicated.
Biophysical mechanisms
If ELF electric or magnetic fields, at very low levels, can adversely affect health, then abiophysical interaction must occur through some mechanism whereby biological changes thatare detrimental to health are produced in an exposed person. The experimental evidence
concerning particular biological effects would be strengthened by the identification ofplausible interaction mechanisms that can lead to such effects.
There are three main areas where there are obvious limits to current understanding of
mechanisms: signal-to-noise ratios in multi-cell systems such as neuronal networks, magnetic
particles in the body and the radical pair mechanism.
High priority research needs:• Determination of threshold responses to ELF-induced internal electric fields on multicell systems, such as neural networks, using theoretical and in vitro approaches
Rationale: The extent to which multi-cell mechanisms operate in the body, especially in thebrain, to improve signal-to-noise ratios should be further investigated in order to develop atheoretical framework for quantifying this or for determining any limits on it. In addition,
further investigation of the threshold and frequency response of the neuronal networks in
the hippocampus and other parts of the brain should be examined using in vitro approaches.
Other research needs:• Further study of radical pair mechanisms in immune cells that generate reactive
oxygen species as part of their phenotypic function
Rationale: The radical pair mechanism is one of the more plausible low-level interaction
mechanisms, but it is yet to be shown that it is able to mediate significant effects in cell
metabolism. It is particularly important to understand the lower limit of exposure at which
it acts, so as to judge whether this could or could not be a relevant mechanism for
carcinogenesis. It is recommended that cells of the immune system that generate reactive
oxygen species as part of their immune response be used as cellular models for5

investigating the potential of the radical pair mechanism, given recent studies in which
reactive oxygen species were increased in immune cells exposed to ELF.
• Further theoretical and experimental study of the possible role of magnetite in ELF
magnetic field sensitivity
Rationale: Although the presence of magnetic particles (magnetite crystals) in the humanbrain does not, on present evidence, appear to confer sensitivity to environmental ELF
magnetic fields, further theoretical and experimental approaches should explore whether
such sensitivity could exist under certain conditions. Moreover, any modification that thepresence of magnetite might have on the radical pair mechanism discussed above should be
pursued.
Dosimetry
Expert dosimetric support for experimental studies of all types is critical to their proper design
and interpretation. Computational dosimetry provides the link between an external magnetic
field and the internal electric fields and induced currents in living tissues within the field.
Such theoretical techniques allow the fields to be characterized in specific tissues and organs.
High priority research needs:
None.
Other research needs:• Further computational dosimetry relating external electric and magnetic fields tointernal electric fields, particularly concerning exposure to combined electric andmagnetic fields in different orientations
Rationale: In the past, most laboratory research was based on induced electric currents inthe body as a basic metric and thus dosimetry was focused on this quantity. Only recently
work started to explore the relationship between external exposure and induced electricfields. For a better understanding of biological effects and for the development of exposure
guidelines, more data on internal electric fields for different exposure conditions are needed.
Computation should be made of internal electric fields due to the combined influence of
external electric and magnetic fields in different configurations: vectorial addition of out-ofphase and spatially varying contributions of electric and magnetic fields is necessary toassess basic restriction compliance issues.
• Calculation of induced electric fields and currents in pregnant women and in the
foetusRationale: Very little computation has been carried out on advanced models of the pregnant
human and the foetus with appropriate anatomical modelling. It is important to assess
possible enhanced induction of electric fields during foetal life in relation to the childhood
leukaemia issue. Both maternal occupational and residential exposures are relevant here.
• Further refinement of microdosimetric models taking into account cellulararchitecture of neural networks and other complex suborgan systems
Rationale: There is a need to further refine microdosimetric models to take into account thecellular architecture of neural networks and other complex sub-organ systems identified as
being sensitive to induced electric field effects compared to other tissues. This modellingneeds to take into account influences in cell membrane electrical potentials and on therelease of neurotransmitters.

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Sources, Measurements and Exposures
The identification of sources of ELF electric and magnetic fields, the measurement of fields
they emit and the exposure of members of the public and workers to such fields is a primarystep in the assessment of the possible health consequences of such exposure.
High priority research needs:• Identification of gaps in knowledge about occupational ELF exposure, such as in MRI
Rationale: It is suspected that in some cases of occupational exposure the present ELF
guideline limits are exceeded. More information is needed on exposures (including nonpower frequencies) related to work on, for example, live-line maintenance, work within ornear the bore of MRI magnets (and hence to gradient switching ELF fields) and work ontransportation systems.
Other research needs:• Further characterization of homes with high ELF magnetic field exposure in different
countries
Rationale: Further characterization of homes with high ELF exposure in different countries
to identify relative contributions of internal and external sources, the influence of
wiring/grounding practices and other characteristics of the home could give insights into
identifying a relevant exposure metric for epidemiological assessment. An importantcomponent of this is a better understanding of foetal and childhood exposure to EMFs,
especially from residential exposure to under-floor electrical heating and from transformers
in apartment buildings.
• Assessment of the ability of residential wiring outside the USA to induce contact
currents in children
Rationale: Exposure to contact current has been proposed as a possible explanation for the
association of magnetic fields with childhood leukaemia. Research is needed in countries
other than the USA to assess the capability of residential electrical grounding and plumbing
practices to give rise to contact currents in the home. Such studies would have priority incountries with positive associations between ELF magnetic field exposure and childhood
leukaemia.
Social Issues
The benefits of the use of electric power, and the possible costs to society of any adverse
effects on health that might result from exposure to the electromagnetic fields that electricalequipment generates, are important socio-economic issues. In addition, the development ofadequate health protection policies for communities and the communication of appropriate
information concerning risk also form an important part of the way in which developing
technologies are integrated into society.
High priority research needs:
None.
Other research needs:7• Further research on risk perception and communication focused on ELF magnetic
fieldsRationale: Psychological and sociological factors influencing risk perception in general
have been widely investigated. However, limited research has been carried out to analyse
the relative importance of these factors in the case of ELF magnetic fields, or to identify
other factors that are specific to the risk perception of these fields. Recent studies havesuggested that precautionary measures, conveying implicit risk messages, can modify risk
perception by either increasing or reducing concerns. Deeper investigations in this area are
therefore warranted.
• Development of cost-benefit/effectiveness analysis for mitigation of ELF magnetic
fieldsRationale: The use of cost-benefit and cost-effectiveness analysis for evaluating whether apolicy option is beneficial to society has been researched in many areas of public policy.
The development of a framework that will identify which parameters are necessary in orderto perform this analysis for ELF magnetic fields is needed. Due to uncertainties in theevaluation, quantifiable and unquantifiable parameters will need to be incorporated.
• Research on the development and implementation of health protection policies inareas of scientific uncertainty
Rationale: When there are uncertainties about the potential health risk an agent imposes onsociety, precautionary measures may be warranted in order to ensure appropriate protectionof the public and workers. Only limited research has been performed on this issue for ELF
magnetic fields, and therefore more research would be useful to policy makers.

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