UK: Effecten van Tetra (C2000).

Oorspronkelijk geplaatst 27 sept. 2010 in de rubriek FAQ.
Updated en herplaatst in de rubriek onderzoeken 17 oct. 2010

Bron: Occupational Environmental Medicine. 23 sept. 2010

Can exposure to a terrestrial trunked radio (TETRA)-like signal cause symptoms? A randomised double-blind provocation study.

Nieto-Hernandez R, Williams J, Cleare AJ, Landau S, Wessely S, Rubin GJ.

King's College London, Department of Psychological Medicine, Institute of Psychiatry, London, UK.

Abstract
Objectives 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.

PMID: 20864469

Voor het originele abstract zie:
www.ncbi.nlm.nih.gov/pubmed/20864469?dopt=Abstract

Opm. Stopumts:
Aan de lopende band produceert de school van de psycholoog Rubin provocatiestudies.
Eerder werd vastgesteld dat elektrogevoelige mensen signalen niet kunnen detecteren (op aan/uit situaties) waaruit ten onrechte geconcludeerd werd (ook door de Cie. EMV van de Nederlandse Gezondheidsraad) dat een causaal verband tussen gezondheidsklachten en elektromagnetische velden niet zou kunnen bestaan. Men verzuimde o.a. om te onderzoeken of de deelnemers de effecten van EMV (een tijdvertraging in acht nemend) zouden kunnen bemerken laat staan dat men de deelnemers onderzocht op fysiologisch vast te stellen symptomen.
In bovenstaande studie zijn de uitspraken van Rubin c.s. al veel voorzichtiger, alhoewel men met een opzichtige statistische kunstgreep (adjusting for multiple comparisons) de resultaten alsnog uit de conclusies weert.



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