title: Can exposure to a terrestrial trunked radio (TETRA)-like signal cause symptoms? A randomised double-blind provocation study.
abstract: OBJECTIVE
  Concerns have been raised about possible health effects from radiofrequency fields pulsing at around 16 Hz. A radio system used by UK police (TETRA) employs signals which pulse at 17.6 Hz. We tested whether exposure to a continuous wave signal at 385.25 MHz or a TETRA-like signal resulted in symptoms among users reporting sensitivity to TETRA compared to users not reporting sensitivity to TETRA.
  
  
  METHODS
  60 sensitive and 60 non-sensitive users were exposed to three 50 min conditions: a signal with a 16 Hz component, a continuous wave condition and a sham condition. The mean radiated power for the 16 Hz and continuous wave conditions was 250 mW. The order of conditions was randomised and testing was conducted double-blind. Participants reported the severity of eight symptoms during and after each exposure, their mood state at the end of each exposure, and whether they could tell which sessions involved active signals. The study was registered in advance with the ISRCTN register.
  
  
  RESULTS
  Exposure to the continuous wave signal increased ratings of headache in all participants, fatigue in non-sensitive participants and difficulty concentrating in sensitive participants. Paradoxically, it reduced sensations of itching in sensitive participants. These effects were not observed in the condition with 16 Hz pulsing, except for those relating to concentration. Adjusting for multiple comparisons removed most significant effects, but not those relating to itch.
  
  
  CONCLUSIONS
  The results suggested that exposure to TETRA signals is not responsible for symptoms reported by some users, although exposure to a continuous wave signal may affect symptoms. Clinical trial number ISRCTN 73321766.
authors.affiliation: Department of Psychological Medicine, Institute of Psychiatry, King’s College London, London, UK.
authors.forename: Rosa
authors.initials: R
authors.lastname: Nieto-Hernandez
authors.forename: Jonathan
authors.initials: J
authors.lastname: Williams
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Cleare
authors.forename: Sabine
authors.initials: S
authors.lastname: Landau
authors.forename: Simon
authors.initials: S
authors.lastname: Wessely
authors.forename: G James
authors.initials: GJ
authors.lastname: Rubin
mesh_terms: D000328:Adult; D004812:Epidemiologic Methods; D005221:Fatigue / Q000209:etiology; D005260:Female; D051271:Headache Disorders, Secondary / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects / Q000032:analysis; D016495:Police; D011537:Pruritus / Q000209:etiology; D011832:Radiation Injuries / Q000209:etiology*; D011846:Radio Waves / Q000009:adverse effects*; D013685:Telecommunications / Q000295:instrumentation