ID Number		1110
Study Type		Human / Provocation
Model		900 MHz (GSM) exposure to humans and analysis of cerebral blood flow
Details		In an initial study, human volunteers were exposed to 902 MHz (GSM) RF using a mobile phone with a max output power of 0.25 watts resulting in a max average SAR of 0.993 W/kg (averaged over 10 g) and a peak SAR of 2 W/kg. The authors observed a bilateral decrease in rCBF, most pronounced on the left side (same side as exposure) of the brain in the auditory cortex, but not in the area of predicted maximum SAR. They also observed no effect in the area of the dorso-lateral prefrontal cortex. The authors concluded the change in the auditory cortex was probably a result of volunteers detecting a slight auditory signal from the mobile phone when it was on, and not due to the RF energy emitted by the phone. However in a subsequent study of volunteers (n = 12) exposed to 900 MHz (GSM) while performing a verbal working memory task, the authors report a local decrease in rCBF in the left fusiform gyrus in the posterior inferior temporal cortex (just below the phone antenna), as well as an increase in rCBF more distantly in the superior and medial frontal gyri of the prefrontal cortex. In this study, to control for potential auditory effects, the battery was removed and the phone was powered using a silent external power source positioned 3 meters away. RF exposure had no effect on reaction times or response accuracy. The authors did not think the effects were thermal, as the temperature increase immediately adjacent an active mobile phone antenna is only 0.111C, and a rise in temperature should have increased, not decreased, rCBF. They suggest the results are more consistent with changes in neuronal activity causing changed blood flow.
Findings		Effects
Status		Completed With Publication
Principal Investigator		University of Turku, Finland - christian.haarala@home.se; sargo.aalto@utu.fi
Funding Agency		Nat'l Res Prog, Finland, Nokia
Country		FINLAND
References		Aalto, S et al. Journal Cerebral Blood Flow & Metabolism, (2006) 26:885-890 Haarala , C et al. Neuroreport, (2003) 14:2019-2023
Comments		The most recent results of rCBF effects support the report by Huber, Acherman, Borbely et al (2002) [increase in rCBF in the dorso-lateral prefrontal cortex on the same side as the exposure following a 30 minute exposure to 900 MHz GSM at ~1 W/kg], although in the Huber et al study the exposure system was different and PET scans were performed after, not during, exposure. The results do not support prior reports of altered (improved) cognitive performance (Preece et al 1999; Smythe and Costall 2003; Koivisto et al 2000) but do support thier earlier report of no congnitive effects (Haarala et al, 2003b, 2004).