and Key wordsEjaculated, density purified, human spermatozoa were exposed to 900 MHz GSM mobile phone radiation at two specific absorption rate levels (SAR 2.0 and 5.7 W/kg) and examined at various time points post exposure. Change in sperm mitochondrial membrane potential was analyzed using flow cytometry. Sperm motility was determined by computer assisted sperm analysis (CASA). There was no effect of 900MHz GSM radiation on mitochondrial membrane potential. This was also the case for all kinematic parameters assessed at SAR of 2.0 W/kg. However, two kinematic parameters (VSL and BCF) were statistically significantly altered after the exposure at SAR 5.7 W/kg. Effects seen cannot be ascribed to heating, as the temperature did not increase by more than 0.3ºC. A thorough investigation at lower SAR levels is required to determine the extent of the influence of RF-EMF on human sperm motility.
Recent advances in magnetic resonance imaging (MRI) have increased occupational exposure to magnetic fields. In this study, we examined the assessment of occupational exposure to gradient magnetic fields and time-varying magnetic fields generated by motion in non-homogeneous static magnetic fields of MRI scanners. These magnetic field components can be measured simultaneously with an induction coil setup that detects the time rate of change of magnetic flux density (dB/dt). The setup developed was used to measure the field components around two MRI units (1 T open and 3 T conventional). The measured values can be compared with dB/dt reference levels derived from magnetic flux density reference levels given by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The measured motion-induced dB/dt values were above the dB/dt reference levels for both MRI units. The measured values for the gradient fields (echo planar imaging (EPI) and fast field echo (FFE) sequences) also exceeded the dB/dt reference levels in positions where the medical staff may have access during interventional procedures. The highest motion-induced dB/dt values were 0.7 T s(-1) for the 1 T scanner and 3 T s(-1) for the 3 T scanner when only the static field was present. Even higher values (6.5 T s(-1)) were measured for simultaneous exposure to motion-induced and gradient fields in the vicinity of the 3 T scanner.
This paper aims to provide an overview of factors affecting the validity of epidemiological studies on health effects of mobile phone use. A qualitative review of published studies is presented, covering both risk assessment and exposure assessment. Considerable random error is likely to have occurred in studies carried out so far, primarily related to exposure assessment. Self-reported use of mobile phone appears to be imprecise. The relationship between the amount of mobile phone use and the radio-frequency field is unclear. Several factors affect the strength of the radio-frequency field emitted by the phone, and accommodating their effect has the potential to improve exposure assessment. The major opportunity to improve the quality of evidence is, however, through prospective studies. The major limitation of epidemiological studies addressing the health effects of mobile phone use is related to exposure assessment. These limitations are inherent in case-control studies. Quality of evidence can be improved by conducting prospective cohort studies.
The present study investigated the possible effects of the electromagnetic field (EMF) emitted by an ordinary GSM mobile phone (902.4 MHz pulsed at 217 Hz) on brainstem auditory processing. Auditory brainstem responses (ABR) were recorded in 17 healthy young adults, without a mobile phone at baseline, and then with a mobile phone on the ear under EMF-off and EMF-on conditions. The amplitudes, latencies, and interwave intervals of the main ABR components (waves I, III, V) were compared among the three conditions. ABR waveforms showed no significant differences due to exposure, suggesting that short-term exposure to mobile phone EMF did not affect the transmission of sensory stimuli from the cochlea up to the midbrain along the auditory nerve and brainstem auditory pathways.
The aim of this study was to design, implement and analyze a space-efficient setup for the whole-body exposure of unrestrained Wistar rats to radiofrequency (RF) electromagnetic fields at 900 MHz. The setup was used for 2 years in a cocarcinogenesis study and part of it for 5 weeks in a central nervous system (CNS) study. Up to 216 rats could be placed in separate cages in nine different exposure chambers on three racks requiring only 9 m2 of floor area (24 rats per m2). Chambers were radial transmission lines (RTL), where the rats could freely move in their cages where food and drinking water was provided ad libitum except during RF exposure periods. Dosimetrical analysis was based on FDTD computations with heterogeneous rat models and was validated with calorimetrical measurements carried out with homogeneous phantoms. The estimated whole-body average specific absorption rates (SAR) of rats were 0 (sham), 0.4, and 1.3 W/kg in the cocarcinogenesis study and 0 (sham), 0.27, and 2.7 W/kg in the CNS study with an estimated uncertainty of 3 dB (K = 2). The instantaneous and lifetime variations of whole-body average SAR due to the movement of rats were estimated to be 2.3 and 1.3 dB (K = 1), respectively.
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