The increasing deployment of mobile communication base stations led to an increasing demand for epidemiologic studies on possible health effects of the radiofrequency electromagnetic field (RF-EMF) emissions of such installations.
The methodological challenges of such studies have been critically evaluated in a collaborative effort by a panel of international scientists in the field of RF engineering/dosimetry and epidemiology. Strengths and weaknesses of previous studies have been identified. Dosimetric concepts and crucial aspects in exposure assessment were evaluated in terms of epidemiologic studies on different type of outcomes.
First, we evaluated whether exposure contribution from base station RF-EMF is relevant compared with exposure from all other RF-EMF sources. Limited data on this issue were available in the literature. Relevant RF-EMF exposure contribution from base station is expected 1) for the total exposure time above a very low threshold (eg, >0.5 V/m), 2) for 24 hours whole body exposure, or 3) for the very specific downlink frequencies and/or signals. On the other hand, average contribution to the head exposure from the use of mobile phone is considerably larger than from base station.
Studies on chronic diseases such as cancer or neurodegenerative diseases require long-term exposure assessment. At present, reliable assessment of the contribution from the base station emissions to the long-term RF-EMF exposure is considered to be impossible due to the high spatial and temporal variability. For studies on physiological effects, unspecific symptoms of ill health or quality-of-life exposure during a few days to a few months is judged to be applicable. Such a short- to medium-term exposure assessment has to be developed yet, however, should be feasible. Theoretical calculations revealed that for such an exposure assessment specificity is more important than sensitivity because only a small proportion of the population is exposed to substantially increased RF-EMF levels.
In principle, base station epidemiologic studies are feasible; however, the contributions from other RF-EMF sources have to be taken into account. Short- to medium-term effects on physiology or quality of life are proposed to be investigated by cross-sectional or cohort studies. However, the applied exposure assessment method should be piloted and validated. For long-term effects, there is first a need to identify high-exposure groups in the population. For immediate effects- human laboratory studies are the most adequate approach.