On the 9th and 10th of June 2004, the WHO conducted an international workshop in Istanbul on potential adverse health effects on children through exposure to low frequency and radio frequency electromagnetic fields (EMF). Scientists specialised in different disciplines developed recommendations on future approaches to research in this field. The recommendations are published as "New Children's EMF Research Agenda" (www.who.int/peh-emf/research/children/en). The integral points are summarised as follows.

Introduction

Generally WHO research studies give human beings the highest weight. However, it has also been determined that results of epidemiological studies can be influenced by bias e.g. a selection of subjects or disturbance variables and therefore causal connections are difficult to establish. Laboratory studies with volunteers can provide valuable insight into acute effects but are subject to strong ethical restrictions. This is particularly relevant in studies on children. Experimental studies on animals provide qualitative information regarding potential health effects, but the question whether the results may be transferred to human beings must even be taken into account in well-established animal models. Studies carried out at cellular level are mainly used to investigate possible mechanisms of interaction or molecular target structures. They, however, do not bear evidence as to whether the effects observed in cell cultures will also occur in living organisms or are relevant to health. Dosimetry, in turn, provides necessary data on actual exposure. Each type of study has to play a role in determining the scientific plausibility of any potential health risk.

Research recommendations on static magnetic fields

Static magnetic fields were not specifically addressed at the Workshop. It was nevertheless recommended, to carry out laboratory studies to examine the influence of intense static magnetic fields on developing organisms. Background to the recommendation is e.g. is the use of increasingly intense magnetic fields in medical diagnostics (magnetic flux density above 1 Tesla) and the need to improve data in this area.

Research recommendations on extremely low frequency fields

A. High Priority

Pooled results analysis of several epidemiological studies has proved very informative when examining whether low frequency magnetic fields increase the risk of developing childhood leukaemia. It is therefore recommended to use pooled analysis for existing studies on other childhood cancers as well. Innovative approaches are needed for future epidemiological studies (e.g., a cohort study), which help to minimise selection bias, as opposed to case-control studies. If a highly exposed or especially susceptible population can be identified, than studies of these subgroups are also recommended.

Laboratory-based studies on subjects are suited to examine the endpoints cognition (perception, thinking, recognition, memory) and changes in electroencephalograms (EEGs) in children during which strict adherence to ethical obligations are assured.

Further experimental studies using appropriate animal models are recommended. Up to now, an animal model for the most common form of childhood leukaemia, childhood B-cell acute lymphoblastic leukaemia, has not been available. However, a potentially suitable animal model has recently been developed by a French research group, but has so far not been published in scientific journals. Further experimental studies on animals are recommended to investigate possible effects of prenatal exposure and the combined effects of low frequency electromagnetic fields and known carcinogens.

On the cellular level, studies are recommended to investigate the potential effect of low frequency electromagnetic fields on the development of e.g. cell differentiation, during haemopoiesis in bone marrow and on nerve cell growth.

Dosimetry modelling of the interaction between low frequency electro magnetic fields and juvenile limbs should be undertaken. For this purpose, age-dependent parameters such as surface resistance, bone calcification and a higher percentage of active bone marrow in children as compared to adults have to be taken into account.

B. Medium Priority

Methodically improved epidemiological studies are encouraged with medium priority to research potential connections between maximum exposure as compared to low frequency fields and the risk of miscarriages, as previously undertaken studies to this endpoint show methodological weaknesses.

A further recommendation concerns animal studies on the potential developmental effects on immune function, on the induction of minor skeletal variations and on the development of cognitive function. Effects of prolonged, intermittent exposure from the early postnatal period should be taken into consideration. On the cellular level it is recommended to research into the effect of EMF exposure on the protectiveness of melatonin against oxidative damage e.g. in hematopoietic tissue.

C. Low Priority

Further studies for possible carcinogenic mechanisms of low frequency fields, both alone and in combination with known carcinogens, have low priority. Also of low priority is the assessment of exposure through 217-Hz nonsinusoidal magnetic fields from mobile phones (dosimetry section).

Research recommendations on radio frequency fields

A. High Priority

As the use of mobile phones amongst children has increased, one of the main focus points of the study research has to be on the assessment whether children are more vulnerable to radio frequency (RF) radiation than adults.

In the epidemiology section, a prospective cohort study of children mobile phone users and all health outcomes other than brain cancer but including cognitive effects and effects on sleep quality is recommended.

Brain cancers are too rare in children and so this is not likely to be a feasible end-point for a cohort study. For this research question, case control studies are preferable.

It is further recommended to carry out a case control study nested in a cohort study on base stations and TV and radio towers (end point childhood cancer diseases). A prerequisite for such studies, however, would be improved exposure assessment as compared to older studies.

A laboratory-based study with subjects to investigate the end points cognition, EEG, and sleep in children is recommended as a part of a larger prospective cohort study.

In experimental studies on animals potential effects of prolonged exposure of developing organisms, especially the central nervous system (CNS) are given special emphasis. Duration of exposure should include the development in the womb and early postnatal development phases. Potential research endpoints are behaviour, morphology (e.g., synapse formation between nerve cells), changes on a molecular level and the development and maturation of the blood-brain barrier.

On the cellular level it is recommended to carry out research into the possible effects on cell differentiation, e.g., during haemopoiesis in bone marrow, and on nerve cell growth.

In the area of dosimetry, the main focus is on the assessment of exposure of children, e.g. through mobile communication technology. Research is needed to document in greater detail the complex and changing patterns of phone use (SMS, telephone calls, games etc.), which influence exposure. The development of improved dosimetric models for absorption distribution in children and foetuses, hereby taking into consideration thermoregulation processes in children, is deemed necessary.

B. Medium Priority

Studies with medium priorities evaluate animal experiments concerning the effects of radio frequency fields on the development of the immune system or on autoimmune reactions in the brain, as well as cell culture experiments on possible mechanisms of action of radio frequency fields.

Implementation of the WHO recommendations

Many countries , including Germany, e.g. as part of the German Mobile Telecommunication Research Programme (DMF) are carrying out studies which implement the WHO recommendations.

An important example is an epidemiological study investigating the hypothesis of an increased risk of childhood leukaemia in the vicinity of intense TV and radio towers. The final report of the pilot study can be accessed at: www.emf-forschungsprogramm.de/.../epi_015_Pilot.pdf . Start of the main phase of the study: March 2006.

At this point a reference to an epidemiological study carried out as part of the British MTHR programme ("Mobile Telecommunications and Health Research Programme") seems useful. The study examines possible cancer risks in early childhood (main focus on leukaemia and non-Hodgkin lymphoma) in the proximity of mobile phone base stations and should be concluded in July 2006. (Please see: www.mthr.org.uk/.../elliot2.htm).

A further population-related, cross-sectional study carried out within the framework of the DMF, intends to examine potential connections between acute subjective disposition and the perceived and individually measured exposure to mobile communication fields in children and young adults. For this purpose, newly developed personal dosimeters are used, which can be handled by children.

Many of the current animal research studies carried out within the framework of the DMF, meet the recommendations required by the WHO on long-term exposure on the developing organism. One long-term study should be pointed out, in which laboratory rodents are exposed to radio frequency fields over three generations, therefore also during prenatal development phases. The study focuses mainly on the assessment of potential learning and memory deficits, and, in addition, examines potential effects on the blood-brain-barrier as well as stress and immune responses.

A further study incorporating several generations of laboratory rodents, examines if long-term exposure to radio frequency fields according to UMTS standards concerns the endpoints reproduction capability and development.

One in vitro (cell culture) project looks at the potential effects of GSM mobile radiation on specific functions of cells in the immune system, such as phagocytosis activity or the production of reactive oxygen compounds.

Initially, a feasibility study was carried out to look at the question of age-dependent effects of high-frequency electromagnetic fields, with the aim of a comprehensive analysis and evaluation of currently available data on age-dependent biophysical and biological factors. The objective of the study is to clarify whether the hypothesis that children and young adults are more vulnerable to high-frequency electromagnetic fields can be substantiated with available scientific information. If applicable, relevant target structures should be proposed as basis for a further main study. The feasibility study has been concluded in the meantime, the final report can be accessed at: www.emf-forschungsprogramm.de/.../bio_055_AbschB.pdf. Based on the research results of the feasibility study, the DMF is conducting a main research study, which examines the issue of extent and dispersion of radio frequency radiation absorption and temperature changes in a child’s head using modelling of a child's head as well as of the radiation source which is as realistic as possible. Hereby the age-dependent variability of physiological, biophysical and anatomic parameters must be taken into consideration as far as possible. The resolution of the anatomic model has to be adequate to be able to include target structures such as the pineal organ, hippocampus, hypothalamus and cranial bones with bone marrow.

More information about content and progress of the numerous projects of the German Mobile Telecommunication Research Programme (DMF) can be found on this website under the heading Research Projects. Further information to low frequency and radio frequency electromagnetic fields can be found on the websites of the Federal Office for Radiation Protectionwww.bfs.de/elektro.