Wednesday, April 01, 2015

No blood-brain barrier penetration found after 30 minutes of GSM cell phone radiation exposure

Biomarkers in volunteers exposed to mobile phone radiation

Söderqvist F, Carlberg M, Hardell L. Biomarkers in volunteers exposed to mobile phone radiation.Toxicol Lett. 2015 Mar 31. pii: S0378-4274(15)00119-8. doi: 10.1016/j.toxlet.2015.03.016. [Epub ahead of print]/


For some time it has been investigated whether low-intensity non-thermal microwave radiation from mobile phones adversely affects the mammalian blood-brain barrier (BBB). All such studies except one have been either in vitro or experimental animal studies. The one carried out on humans showed a statistically significant increase in serum transthyretin (TTR) 60 min after finishing of a 30-min microwave exposure session. The aim of the present study was to follow up on the finding of the previous one using a better study design.

Using biomarkers analyzed in blood serum before and after the exposure this single blinded randomized counterbalanced study, including 24 healthy subjects aged 18-30 years that all underwent three exposure conditions (SAR10G=2W/kg, SAR10G=0.2W/kg, sham), tested whether microwaves from an 890-MHz phone-like signal give acute effects on the integrity of brain-shielding barriers.

Over time, statistically significant variations were found for two of the three biomarkers (TTR; β-trace protein); however, no such difference was found between the different exposure conditions nor was there any interaction between exposure condition and time of blood sampling.

In conclusion this study failed to show any acute clinically or statistically significant effect of short term microwave exposure on the serum levels of S100β, TTR and β-trace protein with a follow up limited to two hours. The study was hampered by the fact that all study persons were regular wireless phone users and thus not naïve as to microwave exposure.

• This single blinded randomized counterbalanced study tested whether short term exposure to an 890-MHz phone-like signal affects the integrity of brain-shielding barriers.
• The study had multiple exposure conditions and included 24 healthy subjects aged 18–30 years.
• Biomarkers analyzed in blood serum before and after the three different exposure conditions were used to evaluate potential effects.
• The study failed to show any clinically or statistically significant effect of short term microwave exposure on the serum levels of S100β, TTR and β-trace protein with a follow up limited to two hours.

The fact that results have been contradictory is not unexpected since there were large methodological differences between the studies. This being so, some studies have shown increased permeability (Eberhardt et al.,2008; Fritze et al., 1997; Neubauer et al., 1990; Nittby et al., 2009; Salford et al., 1994, 2003; Schirmacher et al., 2000; Tang et al., 2015; Töre et al., 2001) whereas others reported no effect (de Gannes et al., 2009; Finnie et al., 2009, 2002, 2001; Franke et al., 2005a,b; Grafstrom et al., 2008; Kuribayashi et al., 2005; Masuda et al., 2007a,b; Tsurita et al., 2000) ... On page 45 of the BioInitiative Report, Salford et al. write that “ . . . SAR levels below 1 or 0.1 mW/kg in the human brain were reported to cause a pathological leakage of the BBB and to neuronal damage.” (Salford et al., 2012).

There is to date an almost complete lack of human studies. Our group has published three on the matter (Soderqvist et al., 2009b,a, 65 c) but because of methodological limitations neither is conclusive as to risk assessment. Additionally in this context it should be mentioned that the BBB is not the only barrier that serves to protect the brain and maintain an optimal CNS function. Albeit, a higher permeability than the BBB the blood–cerebrospinal fluid barrier (BCSFB) has an equally important role ...

Participants underwent three trials with at least one week in between. At each trial one hour of exposure was given in a randomized counter balanced fashion at the following intensities:

(1) SAR10g 2 watt/kg; (2) SAR10g 0.2 watt/kg; (3) sham/no exposure. Each participant acted as his or her own control and blood was taken at: (a) arrival; (b) 30 min of rest; (c) 1 h of rest; (d)  immediately after 1 h of exposure/sham; (e) 1 h after finishing of the exposure; (f) 2 h after finishing of the exposure. Note that the
first two samples were taken for habituation purposes.

The radiofrequency signal was generated with a GSM-test phone (Ericsson GH 337) using an 890-MHz carrier frequency with a pulse repetition time of 4.61 ms (217 Hz) and pulse duration of 0.577 ms. No DTX was used during active exposure. The signal was fed via an amplifier 240 (Ophir 5802064) to an indoor base station antenna; hence, a larger area of the head was exposed than from use of a mobile phone ...

Two identical antennas were used, one mounted on each side of the participant’s head at a distance of 4 cm from the ear ...

Trials were carried out in a room with low-frequency electric (E), magnetic (B) and RF backgrounds low enough to be considered negligible ...

... we compared the biomarker levels of those who had used a wireless phone the day before the trial with those who had not but found no statistically significant
difference between the groups (data not in table). It might also be of relevance to the detection of possible effects that all subjects in the study reported regular (more or less daily) use of a wireless phone. Thus they had been chronically exposed to RF EMF and as such may not be the ideal group for study. Additional exposure during 1 h as in this study might not be sufficient to exert an effect in this group of young and healthy persons. A linear dose-response effect might not exist as pointed out by Salford et al. (2012) which further complicates the conclusions of our used experimental method.


This study failed to show any clinically or statistically significant effect of short term microwave exposure on the serum levels of S100b, TTR and b-trace protein. This means that the finding of higher TTR concentration 60 min after finishing of the microwave exposure in our previous study (Soderqvist et al., 2009b) most
likely was not due to microwave exposure.

There were some methodologic differences in the prior randomized trial conducted by this research team (Soderqvist et al, 2009). The prior study used a cell phone setup that exposed the temporal area of the head to  1.0W/kg, as measured over any 1 g of contiguous tissue (SAR1G). The antenna was mounted on the side of the head the subject usually held their phone while talking. The antenna was placed 8.5cm from the ear

Söderqvist F, Carlberg M, Hansson Mild K, Hardell L. Exposure to an 890-MHz mobile phone-like signal and serum levels of S100B and transthyretin in volunteers. Toxicol Lett. 2009 Aug 25;189(1):63-6. doi: 10.1016/j.toxlet.2009.04.027. Epub 2009 May 7.


Whether low-intensity non-thermal microwave radiation alters the integrity of the blood-brain barrier has been debated since the late 1970s, yet no experimental study has been carried out on humans. The aim of this study was to test, using peripheral markers, whether exposure to a mobile phone-like signal alters the integrity of the human blood-brain and blood-cerebrospinal fluid barriers. A provocation study was carried out that exposed 41 volunteers to a 30 min GSM 890 MHz signal with an average specific energy absorption rate distribution of 1.0 W/kg in the temporal area of the head as measured over any 1g of contiguous tissue. The outcome was assessed by changes in serum concentrations of two putative markers of brain barrier integrity, S100B and transthyretin. Repeated blood sampling before and after the provocation showed no statistically significant increase in the serum levels of S100B, while for transthyretin a statistically significant increase was seen in the final blood sample 60 min after the end of the provocation as compared to the prior sample taken immediately after provocation (p=0.02). The clinical significance of this finding, if any, is unknown. Further randomized studies with use of additional more brain specific markers are needed.


Joel M. Moskowitz, Ph.D., Director
Center for Family and Community Health
School of Public Health
University of California, Berkeley

Electromagnetic Radiation Safety

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