Reduced ODC activity after RFR exposure in primary cell lines
A Finnish team has described reduced ornithine decarboxylase (ODC) activity in primary astrocytes after exposure to RFR at 872 MHz, and SAR of either 1.5 or 6.0 W/kg. This was seen with exposure to either a continuous wave or a GSM type of modulated signal. No consistent effect was seen when secondary cell lines were exposed. Increased ODC activity has been seen previously with RFR exposure, and has caused concern because of the possibility of the increased activity enhancing tumour development.
For more, see "Research - Laboratory studies - cancer studies".
Reference: Höytö A, Juutilainen J, Naarala
J (2007): Ornithine decarboxylase activity is affected in primary astrocytes
but not in secondary cell lines exposed to 872 MHz RF radiation. Int
J Radiat Biol 83:367-374.
Xu and colleagues examined the influence of chronic GSM-1800 microwave exposure on the expression and activity of glutamate receptor channels using whole cell patch-clamp recordings combined with immunocytochemistry in cultured hippocampal neurons of rats. The cells were exposed to the RFR for 15 minutes per day for 8 days at SAR of 2.4 W/kg. The authors found that RFR exposure reduced excitatory synaptic activity and excitatory synapse number in the cultured neurons. This might be important for better understanding of the mechanisms for cognitive performance after RFR exposure.
For more, see "Research - Laboratory studies - brain function".
Reference: Xu S, Ning W, Xu Z, Zhou S, et al. (2007): Chronic exposure
to GSM 1800-MHz microwaves reduces excitatory synaptic activity in cultured
hippocampal neurons. Neuroscience Letters 398:253-257.
These authors had previously reported that RFR exposure at 900 MHz decreased the reproductive capacity of the insect Drosophilia melanogaster. The aim of the present study was to compare the effect of exposure to 900 MHz and 1800 MHz RFR. The results showed that the reproductive capacity of the exposed groups was significantly reduced compared to a sham exposed group. The 900 MHz group tended to have less pupae than the 1800 MHz, although the results were not significantly different.
For more, see "Research - Laboratory studies - reproductive effects".
Reference: Panagopoulos DJ, Chavdoula ED, Karabarbounis A, Margaritis
LH (2007): Comparison of bioactivity between GSM 900 MHz and DCS 1800
MHz Mobile Telephony Radiation. Electromagnetic Biology and Medicine
Recent declines have been reported in the house sparrow population in the United Kingdom and in western European countries. Two papers have reported studies on the relationship between the numbers of these birds and the strength of electric fields in the area.
Balmori has previously studied the relationship between reproductive capacity of storks and electromagnetic fields (see "What's New", December '05). On this occasion he and co-author Hallberg carried out sampling at 30 points in Vallodolid, Spain. Forty visits were made between October 2002 and May 2006. They found significant declines in the mean bird density over time, and significantly lower bird density was observed in areas with high electric field strength. The authors postulate that the likeliest factor is the increase in telecommunication masts, although they mention several other potential causes of the decline in the sparrow population, and suggest that their findings should be examined in a more controlled test.
Everaert and Bauwens did a similar study in Belgium, but did all their sampling in the spring of 2006. They sampled 150 locations within 6 areas, and found that the number of male sparrows was negatively and highly significantly related to the electric field strengths. This relationship was very similar within each of the 6 study areas.
Both these studies are ecological studies, which are subject to a potential bias, in that an association observed between variables at an aggregate level does not necessarily represent the association that exists at an individual level (Last, 1988).
References: Balmori A, Hallberg Ö. The urban decline of the house sparrow (Passer domesticus): A possible link with electromagnetic radiation. Electromagnetic Biology and Medicine 2007;26:141-151.
Everaert J, Bauwens D (2007): A possible effect of electromagnetic radiation from mobile phone base stations on the number of breeding house sparrows (Passer domesticus). Electromagnetic Biology and Medicine. 26:63-72.
Last, JM. A dictionary of epidemiology. Oxford University Press, 1988.
In 1997 a paper by Repacholi and colleagues caused a stir when it was reported that mice that were genetically exposed to develop lymphoma had a higher tumour rate when exposed to GSM-like RFR than mice who were sham-exposed. However, their study was criticized on the grounds that dosimetry was uncertain, and only animals that died or were visibly ill were examined pathologically. A replication study by Utteridge and colleagues in 2002 did not find a significant effect. Both these studies exposed the mice to RFR for 1 h a day. In a previous study Sommer et al. (2005) tested the effect of chronic exposure for 24 h a day to GSM-modulated EMF on AKR/J mice, which are genetically predisposed to develop lymphoma at a high rate, and found no increased risk. In the present study they examined the effect of exposure of the same animals to a UTMS signal, and again found no increased risk to the exposed animals.
For more, see "Research - Laboratory - cancer studies".
Reference: Sommer AM, Bitz AK, Streckert J, Hansen VW, et al. Lymphoma
development in mice chronically exposed to UTMS-modulated radiofrequency
electromagnetic fields. Radiation Research 2007;168:72-80.