10/04/2008 - Review of Recent Papers
The following is a quick summary of four papers that have come out in the last couple of months (and an older paper that we haven't previously covered) - both radiofrequency and powerfrequency related - that have an impact on the current picture of the science.
St-Pierre LS et al
, (April 2008) Altered blood chemistry and hippocampal histomorphology in adult rats following prenatal exposure to physiologically-patterned, weak (50-500 nanoTesla range) magnetic fields
, Int J Radiat Biol. 2008 Apr;84(4):325-35 [View
This study monitored the changes in blood chemistry, cerebral sizes, and hippocampal cytomorphology in adult male and female albino Wistar rats that had been exposed during their entire prenatal development to varying low level magnetic fields.
They found that adult rats that had been exposed prenatally to the physiologically-patterned magnetic fields at the low (30 - 50 nT) and medium (90 - 580 nT) intensities exhibited peak elevations of aminotransaminase, glucose, and uric acid.
It is impossible to determine exactly what implications these findings have on humans, but the prenatal exposure levels are very typical of those that would be expected living near powerlines. None of the exposure metrics quite match typical powerfrequency signals either in the UK or the US, but the field levels are sufficiently similar that it this experiment should be repeated using exposures similar to those found in "close" living distance to powerlines (approximately 200-400 nT fields).
Lerchl A et al
, (April 2008) Effects of mobile phone electromagnetic fields at nonthermal SAR values on melatonin and body weight of Djungarian hamsters (Phodopus sungorus)
, J Pineal Res. 2008 Apr;44(3):267-72 [View
In three experiments, adult male Djungarian hamsters (Phodopus sungorus) were exposed 24 hr/day for 60 days to radio frequency electromagnetic fields (RF-EMF) at 383, 900, and 1800 MHz, modulated according to the TETRA (383 MHz) and GSM standards (900 and 1800 MHz), respectively. A radial waveguide system ensured a well defined and uniform exposure at whole-body averaged specific absorption rates of 80 mW/kg.
At 383 MHz, exposure resulted in a significant transient increase in body weight up to 4%, while at 900 MHz this body weight increase was more pronounced (up to 6%) and not transient. At 1800 MHz, no effect on body weight was seen. The data support the notion that metabolic effects of RF-EMFs need to be investigated in more detail in future studies.
Again, the implications of this research for humans are not clear, but it is yet another excellent demonstration of a non-thermal effect of pulsed radiofrequency electromagnetic radiation in vivo.
Rezk AY et al
, (February 2008) Fetal and neonatal responses following maternal exposure to mobile phones
, Saudi Med J. 2008 Feb;29(2):218-23 [View
This study examined fetal and neonatal heart rate (HR) and cardiac output (COP), following acute maternal exposure to electromagnetic fields (EMF) emitted by mobile phones. The pregnant mothers were exposed to EMF emitted by mobile telephones while on telephone-dialing mode for 10 minutes during pregnancy and after birth. The main outcome were measurements of fetal and neonatal HR and COP.
A statistical significant increase in fetal and neonatal HR, and statistical significant decrease in stroke volume and COP before and after use of mobile phone were noted. All these changes are attenuated with increase in gestational age.
These are powerful findings. Whilst heart variability in itself is no evidence of harm to health, it is clear that there is a physiological response to mobile phone usage during pregnancy, both in the mother and the unborn child. It may be worth considering restriction mobile phone use when pregnant whilst the ramifications of these findings are investigated further.
Hardell L, Sage C
, (February 2008) Biological effects from electromagnetic field exposure and public exposure standards
, Biomed Pharmacother. 2008 Feb;62(2):104-9 [View
Professor Lennart Hardell and Cindy Sage (both authors of the BioInitiative report last year) have published this paper giving strong arguments for the use of public policy precautionary guidelines on occupational and residential exposure to both powerfrequency and radiofrequency electromagnetic fields.
Referring back to the BioInitiative report, they comment on the wide range of health effects reported (in the scientific literature) to be associated with exposure to ELF and/or RF EMFs, including childhood leukaemia, brain tumours, genotoxic effects, neurological effects and neurodegenerative diseases, immune system deregulation, allergic and inflammatory responses, breast cancer, miscarriage and some cardiovascular effects.
They make the following summary points:
- Regarding ELF a new lower public safety limit for habitable space adjacent to all new or upgraded power lines and for all other new constructions should be applied
- A new lower limit should also be used for existing habitable space for children and/or women who are pregnant
- A precautionary limit should be adopted for outdoor, cumulative RF exposure and for cumulative indoor RF fields with considerably lower limits than existing guidelines
- Since use of mobile phones is associated with an increased risk for brain tumour after 10 years, a new biologically based guideline is warranted
, (2006) A potential multiple resonance mechanism by which weak magnetic fields affect molecules and medical problems: the example of melatonin and experimental "multiple sclerosis"
, Med Hypotheses. 2006;66(4):811-5 [View
In this paper Michael Persinger presents a biophysical hypothesis to explain the powerful ameliorating effects of weak (nanoTesla range) magnetic fields on melatonin-related diseases.
His resonance solution also suggests that mitochondrial proton gradients may be critical to the process. The model offers an alternative explanation to the variations of Faraday's Law and the Boltzmann constant that have been employed to explain and to dismiss biological effects from weak magnetic fields.
Whilst the frequency with the greatest effect was lower than powerfrequency fields at 7 Hz, it is useful to gain further possible insights into potential mechanisms for biological effects from ELF magnetic fields, especially for those at levels below 100 nT.