Terrestrial Trunked Radio (TETRA) and Cognitive Functions in Healthy Subjects
Condition: Healthy
Study type: Interventional

Summary: 
      The purpose of this study is to analyse a possible effect of radiofrequency (RF) fields used
      for Terrestrial Trunked Radio (TETRA) of brain activity and cognitive functions in
      occupationally exposed subjects.
    

Detailed description: 
      Background

      Several international studies on the influence of electromagnetic fields from mobile
      communications on cognitive performance and brain function during waking and sleep were
      performed during the last years. No health relevant effects were found below the maximum
      exposure of 2 Watt per kilogram (W/kg), which applies for the use of mobile devices by the
      public.

      In Germany a new digital radio communication network for security authorities and
      organisations based on the TETRA standard is set up at present. TETRA (Terrestrial Trunked
      Radio) uses a frequency band around 400 MHz and has been much less investigated than public
      mobile communications. The results of the German Mobile Telecommunication Research Programme
      showed a higher temperature increase of the exposed tissue at 400 MHz than at the frequencies
      used by mobile phones. For occupational groups using mobile TETRA devices (as for example
      policemen and firemen), a local exposure up to 10 W/kg is permitted. Possible effects of
      electromagnetic fields of mobile TETRA devices will be investigated in humans to further
      reduce scientific uncertainties concerning the impact of the digital radio for security
      authorities.

      Objective

      In the present study, possible effects of an exposure with TETRA signals (sham, SAR values of
      1.5 W/kg and 6 W/kg) on the brain activity of humans are investigated. A volunteer study is
      performed on healthy young men, preferentially from the group of potential users who will be
      occupationally exposed.

      Tests are performed allowing conclusions on reaction speed and accuracy, processing of
      acoustic and visual information, ability to concentrate, memory and resilience.

      In parallel, the waking EEG (electroencephalogram, examination of brain activity) under
      different conditions (rest, processing of tests) is recorded and evaluated.

      Furthermore, the influence of TETRA exposure on sleep quality and sleep EEG, as well as
      performance and well being on the following day are investigated.

      The results will be evaluated in relation to their health relevance for occupationally
      exposed users.

      Volunteers

      For study participation, young male subjects professionally engaged with TETRA at the age of
      18 - 30 years are recruited, who are preferentially not active in night service, right handed
      and non-smokers.

        1. Scientific knowledge

           In other European countries, security authorities have been using TETRA radio networks
           for some time. Similar to Germany, other European countries are actually setting up
           their nationwide networks. Some of these countries have accompanied the introduction of
           the TETRA standard by scientific research. At the beginning of the present study, the
           scientists of Charité Berlin performed a literature review on health effects of the
           digital radio bringing together data from publications and reports on the various
           national scientific results.

           Overall there are much less data for TETRA than for mobile communications. The few
           results published previously do not prove any health effects of TETRA.In one study a
           slight influence on memory was found, which could be by chance a result of the large
           amount of tests performed. Therefore this result has to be verified.

           Literature study (PDF, in German, 398 kB, not barrier-free)

        2. Exposure setup

           In this study, volunteers are exposed in the head region to a TETRA signal at SAR values
           of 1.5 Watt per kilogram and 6 Watt per kilogram. A corresponding exposure setup was
           constructed and characterised by IMST GmbH (Kamp Lintfort). It is a flat antenna worn on
           the left side of the head which should simulate as far as possible exposures to a TETRA
           mobile device. It can be worn comfortably for up to eight hours, even during sleep. The
           true exposure of the individual brain regions was calculated in detail by Seibersdorf
           Laboratories GmbH.

           Description of the exposure setup (PDF, in German, 1,7 MB, not barrier-free)

        3. Perception of warming

      An exposure at SAR values of 6 W/kg causes a temperature increase in the head region of
      almost 1 ° C when using the exposure setup described above. Since the study is to be
      performed in a blinded way (neither the volunteer nor the directly involved scientist know
      the actual exposure situation) it is important to prove if the volunteers are able to
      perceive this warming. Therefore a pilot study was performed. It could be shown, that the
      volunteers are not able to recognize the actual temperature increase. Therefore, there is no
      risk of unblinding (the volunteers are not able to discover the specific exposure situation).

      Report of the pilot study (PDF, 1,7 MB, in German, not barrier-free)
    

Intervention name(s): low RF exposure level; sham exposure; high RF exposure
Intervention type(s): Radiation; Radiation; Radiation
Intervention description(s): Exposure with 1.5 W/kg; intervention with sham RF exposure; intervention with high RF exposure
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Basic Science
Keywords: Healthy subjects