ID Number		491
Study Type		Human / Provocation
Model		900 MHz (GSM) exposure to humans and analysis of EEG and auditory evoked potentials (during working memory tasks)
Details		Human subjects (8 males, 8 females) were exposed for about 30 min to 900 MHz (GSM) from cellular telephones mounted on right side of head operating at full power (0.25 watts average, 2 watts peak) and analyzed for event-related desynchronization / synchronization (ERD/ERS) during verbal working memory tasks (Sternberg tasks). The subject had to decide if a single spoken verb given after a set of four spoken verbs was contained in the initial set of four verbs. There was no difference in incorrect answers during exposure compared to no exposure. In initial studies, a significant effect in the 8-10 Hz EEG frequency band (alpha band) was observed, as well as a decreased and delayed early ERS response during memory retrieval in the 4-6 Hz band. Initial studies also showed increased ERS responses during the initial stages of memory retrieval and decreased the later ERD responses in the 6-8 Hz, 8-10 Hz, 10-12 Hz bands. However in double-blind repeat studies using the same individuals as well as additional subjects, the results could not be repeated consistently. The authors conclude that RF effects on EEG and cognitive performance / memory may be variable and not easily replicable for "unknown reasons". In more recent studies (2007), the authors used the same congnitive task from previous studies that did not reproduce effects seen in the 8 Hz EEG band. Volunteers (n = 2 groups of 36) were exposed to 900 MHz (CW and GSM) and tested for working or visual memory. The authors report a slight increase in the alpha / 8 Hz EEG band with GSM exposure (vs. CW exposure) during auditory and visual tasks, although no effect on memory or performance. In related studies, children (n = 32, 10-14 yrs old) were exposed to 900 MHz (GSM) at ~2 W/kg (peak transmit power) and analyzed using a similar cognitive test battery. The authors report some effects of RF exposure on the desynchronization / synchronization (ERD/ERS) responses in the 4-8 Hz and 15 Hz frequencies. In a 2009 study, the group evaluated adult volunteers (n = 12 female, 5 male)using a similar exposure system (902 MHz GSM from a mobile phone mounted at the right side of the head, average power 250 milliwatts, reported max SAR 1.14 W/kg per 1-gram, 0.82 W/kg per 10-gram). The volunteers were administered acoustic stimuli (60 dB of sound in tones at 523 Hz, 1.049 kHz, and 1.569 kHz, with a deviant tone inserted into an otherwise consistent pattern - MMN test) and evaluated for event related potentials. The authors report no effect of the RF exposure on the latency or amplitude of event related potential measurements. In studies on children (n == 17), the authors again exposed to 900 MHz (GSM) at 1.21 W/kg (peak) and a series of auditory stimulus tones applied. The authors report no significant effects of exposure. In the review published in Bioelectromagnetics [Epub ahead of print, Dec 22, 2010] Kwon and Hamalainen concluded that: "For the last two decades, a large number of studies have investigated the effects of mobile phone radiation on the human brain and cognition using behavioral or neurophysiological measurements. This review evaluated previous findings with respect to study design and data analysis. Provocation studies found no evidence of subjective symptoms attributed to mobile phone radiation, suggesting psychological reasons for inducing such symptoms in hypersensitive people. Behavioral studies previously reported improved cognitive performance under exposure, but it was likely to have occurred by chance due to multiple comparisons. Recent behavioral studies and replication studies with more conservative statistics found no significant effects compared with original studies. Neurophysiological studies found no significant effects on cochlear and brainstem auditory processing, but only inconsistent results on spontaneous and evoked brain electrical activity. The inconsistent findings suggest possible false positives due to multiple comparisons and thus replication is needed. Other approaches such as brain hemodynamic response measurements are promising but the findings are few and not yet conclusive. Rigorous study design and data analysis considering multiple comparisons and effect size are required to reduce controversy in this important field of research."
Findings		No Effects
Status		Completed With Publication
Principal Investigator		Univ. Turku, Finland
Funding Agency		FGF, Germany, Nat'l Res Prog, Finland
Country		FINLAND
References		Kwon, MS et al. Bioelectromagnetics, (2010) 31:191-199 Kwon, MS et al. Bioelectromagnetics, (2009) 30:241-248 Krause, CM et al. Bioelectromagnetics, (2007) 28:296-308 Krause, CM et al. Int J Radiat Biol, (2006) 82:443-450 Krause, CM et al. Bioelectromagnetics, (2004) 25:33-40 Krause, CM et al. NeuroReport, (2000) 11:761-764 Krause, CM et al. Int. J. Radiat. Biol., (2000) 76:1659-1667 , , () :- Kwon, MS et al. Bioelectromagnetics., (2011) 32:253-272
Comments		In the initial study, the authors cited the report by Mann (Neurobiology 1996) as also reporting increases in power of the alpha band (8-10 Hz) with RF exposure. They also state the the findings support Preece (Int J Radiat Biol 1999) and Koivisto (NeuroReport 2000) in that the altered cortical alpha activity during information processing could have lead to accelerated mental operation. In the initial study, the phone was on for 30 minutes (either before or after a 30 minute sham exposure) - this is plenty of time for the phone (held 2cm from face) to heat up - does not appear from the text that the sham exposure used a 50 ohm load to heat up the non-transmitting phone as well. In the repeat study, however, the findings were not confirmed, and variability is probably the most plausable reason.