Autores

Eltiti S, Wallace D, Ridgewell A, Zougkou K, Russo R, Sepulveda F, Fox E. Short-term exposure to mobile phone base station signals does not affect cognitive functioning or physiological measures in individuals who report sensitivity to electromagnetic fields and controls.  Bioelectromagnetics. May 27, 2009. Ahead of print.

Background
There is concern that exposure to mobile phone technology may influence cognitive function.  Results of previous studies have shown both enhanced and reduced cognitive performance associated with exposure to electromagnetic fields (EMF).  However, few studies have been conducted among those with idiopathic environmental intolerance with attribution to electromagnetic fields (IEI-EMF).  These individuals claim to be sensitive to EMF and attribute symptoms (such as difficulties in concentration and memory) to EMF emitted by mobile phones and base stations.

Objective
The study was conducted to examine whether, under double-blind conditions, exposure to GSM and UMTS base station signals affect cognitive functioning in sensitive and control individuals.

Methods
The study sample included 44 self-reported sensitive and 115 control subjects.  One control was matched to each case based on age in some analyses.  Cognitive functioning was measured using digit symbol substitution (DSST), a measure of attention and perceptual-motor speed, forward digit span (DS), a measure of immediate memory, and mental arithmetic (MA), a cognitively demanding task.  In addition, physiological measurements of blood volume pulse (BVP), heart rate (HR), and skin conductance (SC) were taken while participants performed the cognitive tasks, as a measure of how demanding the tasks were.  Baseline measurements were taken on all participants.  In three subsequent sessions at least one week apart, participants were exposed to three conditions: GSM, UMTS, and sham (one condition per session) for 50 minutes during which time testing occurred.  All responses were made using paper and a non-metallic pen.  Physiological measurements were taken continuously using 3 small cuffs placed on the participant’s non-dominant hand.

Results
Baseline measurements of cognitive function were comparable between sensitive and control participants.  Among the 114 participating control subjects, performance on the cognitive tasks was not affected by EMF exposure.  Among the 44 matched pairs, EMF exposure did not affect cognitive functioning among either sensitive or control individuals.  In the matched analysis, sensitive individuals had a higher mean skin conductance than did controls.

Interpretation and Limitations
The finding of a higher mean skin conductance among sensitive compared to control participants while performing cognitive tasks is in accordance with previous studies and may be indicative of a general imbalance in autonomic nervous system regulation among IEI-EMF individuals.  Overall, cognitive functioning was not affected by short-term exposure to either GSM or UMTS signals among IEI-EMF or control individuals in the current study, which is consistent with previous studies.  However, this study did not investigate the role of longer-term EMF exposure on cognitive functioning.

Conclusion
The present study found no effects of either GSM or UMTS base station signals on cognitive functioning in either sensitive or control groups. 



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