TETRA (Terrestrial Trunked Radio)
Condition: Cognitive Performance; Well-Being
Study type: Interventional
Phase: Phase 4

Summary: 
      The purpose of this study is to investigate if electromagnetic radiation from TETRA handset
      can influence cognitive function and the well-being of healthy adults. Furthermore, the
      purpose is to provide any special information about the subjects which can cause the possible
      reactions.
    

Detailed description: 
      TETRA is the term used to describe the technology known as Terrestrial Trunked Radio. It is
      the European standard digital mobile radio communication system. TETRA has primarily been
      developed to enable the deployment of secure, digital PMR (Professional Mobile Radio)
      services required by the public safety and emergency services (police, fire and paramedics).
      The TETRA system is specified to work within the VHF and UHF bands (150 MHz to 900 MHz)
      [Chadwick, 2003], and operates most often at frequencies around 400 MHz. The lower frequency
      means that TETRA is less vulnerable to interference, which is a vital aspect of
      communications for the emergency services. The system makes it possible to offer complete
      coverage for the emergency services. One of the TETRA features is that the signal is
      transmitted in bursts that repeat. The result is a power modulation of some of the RF signal
      at a frequency of 17,6 Hz (times pr. second) [NRPB, 2001]. This pulsing has led to concerns
      about its effect on health. Since this pulsing only occurs for transmission from TETRA
      handset and not from the base stations, most concerns is related to the health effect on the
      users of TETRA handset.

      The aim is to asses whether exposure to TETRA handset can affect cognitive functions and high
      level brain functions such as learning and problem solving the volunteers will be tested by
      comparing performance with and without exposure. Sham exposure (no radiation from the
      handset) vs. TETRA signal (at the lowest carrier frequency, standard TDMA pulsing at 17,6 Hz
      and a selection of lengths of exposures at the realistic SAR value).

      56 healthy males aged 25-50 year working within public safety and emergency services (police,
      fire and paramedics), is planned to be used in this study. Subjects must be identified as
      potential users of the TETRA system.

      A climatic chamber at the Department of Environmental and Occupational Medicine, Aarhus
      University, is modified with absorbing lining to dampen reflections from the walls. The
      climatic chamber is modified to make it a screened room to prevent external RF fields, and to
      some extent low frequency fields, to enter the chamber. Except for cables to the keyboard and
      screen there are no other electromagnetic radiators in the chamber. The study will be double
      blinded as any noise (acoustic and electric) related to exposure will be the same and the
      person responsible for exposure and exposure assessment will not be able to see each other.
      The only investigator knowledgeable about the exposure will have no contact with subjects and
      staff doing measurement. This double blinding will continue until the basic statistical
      analyses have been conducted.
    

Intervention name(s): TETRA (at lowest carrier freq, std TDMA pulse at 17,6 Hz).
Intervention type(s): Device
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double
Primary purpose: Treatment
Keywords: TETRA; EMF; Human exposure study; Symptoms; Well-being; Cognitive function