not understood, because these tendencies appear to oppose one another as depending upon exposure at similar SAR levels and pulse, the RF carrier component of these exposures is strongly speculated to be responsible for the amplitude modulation of this beta rhythm. Apart from investigation of RF effects on the EEG, heart function results were also noted (Table 8.1). For these results, in both consideration of statistical strength ( N = 100) and statistically improbable differences indicated between sham and exposure for both heart rate (p = 0.96) and PTT (p = 0.54), it is speculated that there are no effects of either the pulsed 900 MHz or 1800 MHz exposures on heart rate, BPV, or heart rate variability (HRV) [Atlasz et al., 2006]. This result is in accordance with Tahvanainen et al. [Tahvanainen et al., 2004] who reported no statistically significant changes due to similar exposures of 900 MHz (1.58 W/kg) and 1800 MHz (0.7 W/kg) in measures of heart rate and blood pressure (using a sphygmomanometer) in 35-minute trials ( N =
32). Aside from noted non-significant changes, in the present investigation a slight increase tendency (~2.5 ms) in the mean PTT was also observed for both exposures tested (Table 8.1), suggesting in consideration of the outlined confidence limits that a
possible decrease in blood pressure may occur in a low proportion of participants. In amongst similar studies, this outcome may be most closely interpreted in line with Atlasz et al. [Atlasz et al., 2006] who in a pilot study also indicated that a minor proportion of the population may express distinct sensitivity in HRV to RF exposures (local max. SAR: 1.3 W/kg).
There are two important points that should be raised if effects as seen in the alpha band of this investigation are to be replicated:
1. It is proposed to avoid averaging spectral power over the entire alpha band (8 – 13 Hz) during analysis, particularly because increase tendencies (8-10 Hz) and smaller decrease tendencies (10 –13 Hz) as observed will presumably cancel or possibly appear falsely as a smaller remaining increased tendency.
2. It is proposed to keep eyes closed during trials, particularly as the eyes ‘open’ condition is known to naturally diminish alpha spectral power [Fisch, 1999], which could likely scale down an already subtle effect.
SAR level, is not speculated to be the cause of the observed alpha effect however, as discussed, it may be critical in causing amplitude modulated effects over to the contralateral region to exposure. However, in consideration that the alternating median difference effect as observed across alpha can be most clearly identified at sites closest to the radiating antenna for 900 MHz exposures (i.e. at P7, P3, O1), the SAR level is speculated to be a factor which may enhance the effect. In support of this, our past
findings and other related accounts have provided evidence of more pronounced effects closer to the radiating source [D’Costa et al., 2003a][Curcio 2005][Croft et al., 2007].
- Spring '17
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