In experimental studies the person(s) conducting the research directly controls the conditions of the study. It is difficult to extrapolate results from cellular and animal studies to the human experience. Radiofrequency absorption conditions can be different in humans because energy absorption of RF radiation depends on dielectric properties, orientation, uniformity of the field, size and geometry of the exposed subject, wavelength of the radiation, near- or far-field exposure, and partial or whole body exposure (Stuchly, 1998).

There have been a number of studies of the effects of RF radiation exposure in human volunteers.

In this section human experimental studies are discussed under the following headings

Brain function includes both EEG studies and cognitive function.

Hermann and Hossmann (Journal of Neurological Sciences 1997; 152: 1- 14) have published a good review of wireless phones and their effect on brain function. They include details of in vitro and in vivo research, as well as some done in humans. They published an update of this review in 2003

Hamblin and Wood (2002) have also reviewed studies that examined the effects of mobile phone emissions on human brain activity and sleep patterns.

Cook and colleagues (2006) published a review of studies from 2001-2005 that examined physiological and cognitive effects of ELF magnetic and ELF-modulated radiofrequency fields. They discuss the different methods of measuring physiological effects. They include EEG studies that are discussed in the next section. They point out that functional and metabolic imaging of the brain can be done using several methods:
- functional magnetic resonance imaging (fMRI, measuring brain blood flow)
- magnetic resonance spectroscopy (MRS, measuring neurotransmitter concentrations)
- positron emission tomography (PET, measuring brain blood flow, metabolism and neuro-receptor occupancy)
- single photon emission tomography (SPECT, measuring blood flow and metabolism).
They caution that SPECT and PET detectors are sensitive to magnetic fields at a threshold around 100 µT. Therefore studies using these methods should use controls to ensure that the SPECT and PET detectors are themselves not affected by the exposure. This might be true also for RF exposures, particularly if associated electronics produce significant ELF components.

Cook et al. also point out that magnetic resonance systems produce fields that can have opioid-related behaviours in rodents, and on affective behaviours in both rodents and humans. Another problem with these methods is that they detect relatively late events, such as blood flow and metabolism that occur seconds to minutes after the start of brain activity.

Valentini et al. (2007) carried out a comprehensive review of the neurophysiological effects of mobile phones emissions. This review included EEG studies as well as those involving cognitive function.



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