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|Switzerland||Created: 8 Jun 2009|
Children's EMF Research Agenda: Radio Frequency Fields: 1: Epidemiological studies
There is little relevant epidemiology at present that examines health effects in children; the following recommendations address general health effects, including cancers in children who use mobile phones or live near base stations or radio or TV towers.
* Prospective cohort study of children mobile phone users and all health outcomes other than brain cancer (see below) but including more general health outcomes such as cognitive effects and effects on sleep quality. High Priority
Rationale: Since many children are heavy mobile phone users and will continue to be in the future, they represent a unique population. The type of mobile use among children (e.g. text messaging), their potential biologic vulnerability and longer lifetime exposure make such a study desirable. Cognitive effects and other general health outcomes have been anecdotally reported in mobile phone users. They can be assessed in a prospective cohort study of children. A separate study of children was found necessary, as it is not possible to just extend the age range of a cohort study of adults because the outcomes have to be assessed by different methods in children and adults, and children’s exposure probably differs from that of adults’ (more use of pay-as-you-go SIM-cards, more frequent change of phones and operator).
* Case-control study of children mobile phone users and brain cancer. High Priority
Rationale: Brain cancer is an important end-point to study given the location of the antenna for the phone, but it is rare in children and so this is not likely to be a feasible end-point for a cohort study.
* Nested case control studies of childhood cancer with improved exposure assessment for (1) base stations and (2) TV and radio towers. High Priority
Rationale: There is at present a lack of information concerning health effects associated with living in close proximity to base stations or TV or radio towers. One particular difficulty is exposure assessment. Further investigation into improved measures is a critical step in better capturing exposure from these sources and in determining the feasibility of epidemiological studies of children living in the vicinity of these sources.
2. Volunteer studies
The following recommendations address effects seen in laboratory-based studies using adult volunteers.
* A laboratory-based assessment of effects of RF exposure on cognition, EEGs, and sleep in children is recommended as a part of a larger prospective cohort study (see the Epidemiology section). If ethical approval can be obtained, acute effects on cognition and EEGs should also be investigated in children exposed to RF fields in the laboratory. High Priority
Rationale: Cognitive effects are a priority research area in RF studies. However there is a paucity of data concerning RF effects on children (Goldstein et al, 2003; AGNIR, 2003; WHO RF Research Agenda).
3. Animal studies
A large U.S. National Toxicology Program (NTP) rodent (both rats and mice) study is likely to be funded in the near future. The study will examine the toxicity and carcinogenicity of RF radiation characteristic of mobile phones; animals will be exposed in utero and postnatally. A full histopathology will be carried out, along with assays of endocrine levels, estrus cycling and sperm levels, urinary metabolite patterns (as indicators of physiological perturbation), haematology and genotoxicity (i.e., micronucleus frequency, DNA-strand breaks, etc.). There will be a particular focus on changes in blood-brain-barrier permeability and any concomitant neuropathology. [Tissue may be made available to other research groups; contact Ron Melnick, email: email@example.com]
The recommendations given below focus on the developing central nervous system, haemopoietic (bone marrow) tissue and immune system. Experimental protocols should include prenatal and/or early postnatal exposure to EMFs.
* Studies investigating the effects of prolonged exposure of immature animals to RF fields on the development and maturation of the CNS, using behavioural, morphological (e.g., synapse formation) and molecular (e.g., using gene microarrays) endpoints. High Priority
Rationale: Possible RF effects on children were specifically raised by the UK’s Independent Expert Group on Mobile Telephones (IEGMP, 2000); the CNS was considered potentially one of the most susceptible of the various organs and tissues that continue to develop during childhood.
* Effects of prenatal exposure to RF fields on the development and maturation of the blood-brain barrier. [Note that funded work is likely to begin on this topic in the near future; see above.] High Priority
Rationale: Possible effects on the adult blood-brain barrier and the potential for resulting neuropathology have long been a controversial issue in RF research (e.g., IEGMP, 2000; WHO RF Research Agenda). These studies should be extended to cover pre- and postnatal development of the blood-brain barrier. (In humans, this development is complete at approximately 6 months [Rodier, 2004].)
* Studies investigating the effects of prolonged exposure of immature animals to RF fields on the development of the immune system, including microglia cells (resident macrophages) and induction of autoimmunity in the brain. Medium Priority
Rationale: The immune system also develops during early childhood and is a critical tissue with regard to possible effects of RF exposure. Studies performed in the former USSR showed induction of autoimmunity after exposure to RF fields (Vinogradov, 1993).
4. In vitro studies
Studies of possible RF effects on carcinogenic processes, particularly effects on differentiation pathways and haemopoietic tissue, continue to be of interest. In addition, effects on nerve cell growth and synaptogenesis are considered worthy of further research. The possibility that biological tissue can somehow demodulate modulated RF signals to produce biologically significant ELF electric fields and currents has long been a controversial area. Research into this area, based on a recently proposed, very sensitive method of detection, is being funded in the UK (Challis, in press). If real, this effect could have important implications for both childhood and adult exposure. Other mechanistic studies were also recommended.
* Studies of RF effects on cell differentiation, e.g., during haemopoiesis in bone marrow, and on nerve cell growth using brain slices/cultured neurons. High Priority
Rationale: Cancer cells are generally locked into a rapidly dividing and relatively undifferentiated state, and the possibility that haemopoietic and/or neuronal tissue shows a growth response to EMF exposure was considered to be an important area for further investigation.
* Continued studies of possible mechanisms of RF interaction. Medium Priority
Rationale: Research hypotheses based on plausible interaction mechanisms are a key part of the design and execution of animal and epidemiological studies carried out in order to evaluate possible risks to health. There are two hypotheses that are worthy of further investigation (Challis, this issue): (1.) Whether the mechanism leading to an increase in free-radical concentrations that has been demonstrated at frequencies below 80 MHz might also apply at higher frequencies. 2. Whether the above-average temperature rises that might be expected to occur in electrically conducting regions within thermally insulated parts of the body, such as the cochlea and vestibular apparatus, are large enough to cause concern.
5. Dosimetry and exposure assessment
A key issue in this area has been the development of a personal dosimeter in order to greatly improve exposure assessment (for example, around base stations) for epidemiological studies (Wiart, in press). Recommendations were made for improved childhood exposure assessment and dosimetric and thermal modelling.
* Research is needed to document rapidly changing patterns of phone use (SMS, email, classical phone communication, etc.) and exposure of different parts of the body for children and foetuses. High Priority
Rationale: This research would be required to complement epidemiological studies. Exposure surveys (in contrast to simple source evaluations) to assess children’s exposure are lacking, but urgently needed. Service providers are important sources of information regarding exposure and should be encouraged to participate in exposure surveys and epidemiological studies.
* Dosimetric models of RF energy deposition in children and foetuses, combined with appropriate models of human (childhood) thermoregulatory responses, should be developed. High Priority
Rationale: These dosimetric and thermoregulatory models are required in order to predict potential hazards associated with specific RF exposure conditions (Goldstein et al., 2003; WHO RF Research Agenda). Dosimetric calculations and realistic modelling of exposure to the foetus under various exposure scenarios (e.g., with and without a hands-free device) are needed.
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|Source: WHO, 2009|
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