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Summary In recent years there has been a rapid increase in the use of wireless communications devices, and a great deal of research has been carried out to investigate possible biological or human health effects resulting from the use of these devices. In a more focused initiative, the U.S. Food and Drug Administration (FDA) of the Department of Health and Human Services asked the National Academies to organize a workshop of national and inter national experts to identify research needs and gaps in knowledge of bio- logical effects and adverse health outcomes of exposure to radiofrequency (RF) energy from wireless communications devices (for full statement of task see Appendix A). To accomplish this task, the National Academies appointed a seven member committee to plan the workshop (Appendix B). Following the workshop, the committee was asked to issue a report based on the presentations and discussions at the workshop that identifies, in the committeeâs judgment, research needs and current gaps in knowledge. The committeeâs task did not include the evaluation of health effects or the generation of recommendations relating to how identified research needs should be met. The requested workshop was held on August 7-9, 2007 (Appendix C). It was organized into five sessions to identify research needs and gaps in the following areas: ⢠dosimetry and exposure, ⢠epidemiology, â Committee on Identification of Research Needs Relating to Potential Biological or Adverse Health Effects of Wireless Communications Devices.
IDENTIFICATION OF RESEARCH NEEDS ⢠human laboratory studies, ⢠mechanisms, and ⢠animal and cell biology. A sixth session, which was held on the morning of the third day of the workshop, introduced overarching issues and solicited research needs and gaps from workshop speakers and other interested parties. The organizing committee invited experts from 9 countries (Appen- dix D) to speak on research needs and gaps relating to potential biologi- cal or adverse health effects of wireless communications devices. Written contributions relating to research needs and gaps were also solicited for consideration prior to and at the workshop (individuals who submitted written contributions are listed in Appendix E). The report contains the committeeâs evaluation of the workshop pre- sentation and discussion sessions followed by the committeeâs identification of research needs and gaps. RESEARCH NEEDS AND GAPS For the purposes of this report, the committee defines âresearch needsâ as research that will increase our understanding of the potential adverse effects of RF energy on humans. âResearch gapsâ are defined as areas of research where the committee judges that scientific data that have potential value are presently lacking, but that �������������������������������������� closing of these gaps is ongoing, and results should be awaited before judgments are made on further research needs, or the gaps are������������������������������������������������������ ����������������������������������������������������� not judged by the committee to be of as high a prior- ity at this time. To the extent possible, near-, mid-, and long-term research opportuni- ties have been characterized as follows: the committee judged that âresearch needsâ are near-term research opportunities. âResearch gapsâ that are cur- rently being filled may result in mid-term research opportunities, depending on the outcome of the current research. âResearch gapsâ defined as being of lower priority with respect to ��������������������������������������������� ������������������������������������������������������������� directly addressing health concerns���������� ��������� comprise possible long-term research opportunities. Abbreviated versions of committee judgments on research needs and gaps are organized below in the Summary in order of the five sessions that comprised the first two days of the workshop. The reader is referred to the text of the report for details on research needs and gaps.
SUMMARY Dosimetry and Exposure Research Needs 1. There is a need to characterize exposure of juveniles, children, pregnant women, and fetuses, both for personal wireless devices (e.g., cell phones, wireless personal computers [PCs]) and for RF fields from base station antennas including gradients and variability of exposures, the enviÂronment in which devices are used, and exposures from other sources, multilateral exposures, and multiple frequencies. 2. Wireless networks are being built very rapidly, and many more base station antennas are being installed. A crucial research need is to character- ize radiated electromagnetic fields for typical multiple-element base station antennas and for the highest radiated power conditions with measurements conducted during peak hours of the day at locations close to the antennas as well as at ground level. 3. The use of evolving types of antennas for hand-held cell phones and text messaging devices need to be characterized for the Specific Absorp- tion Rates (SARs) that they deliver to different parts of the body so that this data is available for use in future epidemiologic studies. 4. RF exposure of the operational personnel close to multi-element newer base station antennas is unknown and could be high. These expo- sures need to be characterized. Also needed are dosimetric absorbed power calculations using realistic anatomic models for both men and women of different heights. Research Gaps Research Ongoing 1. Although several dosimetric models are currently available for children and individuals of reduced stature, a research gap remains in the further development of models of several heights for men, women, and chil- dren of various ages for use in the characterization of SAR distributions for exposures characteristic of cell phones, wireless PCs, and base stations. Judged to Be of Lower Priority 2. Presently, there is negligible or relatively little knowledge of local SAR concentration (and likely heating) in close proximity to metallic adorn- ments and implanted medical devices for the human body. 3. There is a need for improved exposure systems for human labo- ratory studies including reliable and accurate exposure assessment for designs of next generation exposure systems for human laboratory studies. Furthermore, location-dependent field strength needs to be accounted for
IDENTIFICATION OF RESEARCH NEEDS in the characterization of exposures. A very important consideration is the validation of results by several independent investigators so that reliable and accurate exposure assessments are available for both comparisons between systems and between laboratories. 4. There is a need for an updated survey in a properly selected sample of the U.S. population to characterize and document rapidly changing expo- sures to electromagnetic field strengths that would improve our knowledge of the exposure levels for the population at large, taking into account the large number of new cell phones and base stations, radio and TV stations, and a wide array of other communications devices, including a survey of measured personal exposure with information on location and activity at the time of measurement including the difference between indoor and out- door environments. EPIDEMIOLOGY The committee identified significant research needs for a number of epidemiologic studies, particularly of children. Adults Research Needs 1. Prospective Cohort Studies. A prospective cohort study will allow for the evaluation of diverse outcomes, but a very large sample size and extended follow-up is required for rare outcomes or those that occur only with very long latencies. 2. Occupational Cohorts with Medium to High Exposure. None of the occupational studies to date have been based on an adequate exposure assessment. Much work is needed to identify occupations with potentially high RF exposures and to characterize them. Research Gaps Judged to Be of Lower Priority 1. Nested case-control studies of rare diseases. 2. Observational studies on subjective outcomes.
SUMMARY Children Research Needs 1. Prospective Cohort Studies of Pregnancy and Childhood. Children are potentially exposed from conception through maternal wireless device use and then postnatally when they themselves become users of mobile phones. 2. Case-control Study of Children Mobile Phone Users and Brain Cancer. Owing to widespread use of mobile phones among children and adolescents and the possibility of relatively high exposures to the brain, investigation of the potential effects of RF fields in the development of childhood brain tumors is warranted. Research Gaps Research Ongoing 1. Case-control studies of childhood cancer with improved exposure assessment taking into account all major fixed point sources of RF exposure (base stations, AM, FM, TV antennas, and other sources). HUMAN LABORATORY STUDIES Research Needs There are some significant research needs for human laboratory studies. Due to the paucity of data from identically replicated experiments, 1. There is a need for experiments focusing on possible adverse RF effects identified by changes in electroencephalogram activity as well as a need to include an increased number of subjects. Research Gaps Research Ongoing 1. Little or no information is available on possible neurophysiological effects developing during long-term exposure to RF fields. 2. Risks of exposure to RF fields in elderly volunteers are not well explored. 3. There is a continuing need for experiments focusing on possible ad- verse RF effects identified by changes in cognitive performance functions.
IDENTIFICATION OF RESEARCH NEEDS Judged to Be of Lower Priority 4. There is a need to conduct human volunteer studies to investigate potential ����������������������������������������������������������������� health implications arising from interaction of cell phones with �������������������������������� hearing aids and cochlear implants. Mechanisms Research Needs 1. The effect of RF electromagnetic fields on neural networks is a topic needing further investigation. There are indications that neural net- works are a sensitive biological target. 2. Evaluation of doses occurring on the microscopic level is a topic needing further investigation. Research Gaps Research Ongoing 1. Mechanisms that can be modeled theoretically with the use of software-based nonlinear cell models that describe field-induced molecular changes.�������������������������������������������������������������������� It is currently unclear if a nonlinear biological mechanism exists that could lead to demodulation effects. There is some research with respect to this question underway. Judged to Be of Lower Priority 2. It is unclear whether low-level RF exposure can trigger effects through stimulation of cellular thermo-receptors. 3. Knowledge is lacking concerning the effects of electromagnetic fields on ion and molecular transport through the cell membrane. In Vivo and In Vitro Studies in Experimental Model Systems Research Needs 1. Additional experimental research focused on the identification of potential biophysical and biochemical/molecular mechanisms of RF action is considered to be of the highest priority.
SUMMARY Research Gaps Research Ongoing 1. Following completion of several large ongoing studies, a âweight- of-the-evidenceâ analysis can be conducted to synthesize and evaluate the entire data set. At that time, rational, informed decisions can be made concerning the value of conducting additional oncogenicity studies in standard-bred laboratory animals. 2. The use of genetically engineered animals may increase the sensi- tivity of laboratory studies to detect weak effects, and may be particularly suitable to evaluate the possible interactions between RF fields and other agents in disease causation. 3. The overall database for RF fields and cancer would be strength- ened by additional studies using multi-stage model systems for cancer in tissues (such as the brain) that have been hypothesized to be targets of RF action. 4. Although genetic toxicology studies have failed to identify potential RF health effects, additional genetic toxicology studies may be warranted should evidence of oncogenicity be identified in any of the ongoing chronic toxicity/oncogenicity bioassays of RF fields in laboratory animals, or in any future studies to be performed using genetically engineered animal models. 5. A number of potentially critical cancer-related endpoints have re- ceived only very limited study and are identified in the report text. 6. In addition to cancer-related endpoints, data gaps exist in a num- ber of other areas of toxicology in which knowledge is needed to support a complete evaluation of the possible health effects of RF exposure; these gaps are identified in the body of the report. â Oncogenicity is the capacity to cause tumors.
