A friend on social media recently has been debating about some concerns of electromagnetic fields (in particular radiofrequencies and microwaves) on the brain function, in particular their impact on the blood-brain barrier and on brain tumors. I guess this has to also do with some comments of a hopeful presidential candidate making some dubious claims on scientific facts such as vaccines, GMOs and Wifi (!) (https://youtu.be/IGQjaSJP2Xg) with a certain sense of flip-flopping to pander to a particular fringe of the electorate. Some even found indeed a juicy business by selling overpriced cheap caps as EMF shielded caps.
I will not dive into the studies on EMFs on brain tumors becasue I want to keep this post focused on the BBB, but until now there is no evidence of increased incidence of brain tumors in rats being continously exposed to 3x the signal strength of an active call (the study in question has not been peer-reviewed but available on BioRxiv here: http://biorxiv.org/content/early/2016/06/23/055699), as well as the most recent epidemeliogical study from Japan (a country with one of the highest wireless coverage and use) that failed to find any correlation (http://www.ncbi.nlm.nih.gov/pubmed/27197787)
1. What makes a EM wave harmful?
To understand EM radiations, you have to understand the physics behind it. EM waves stands for electromagnetic waves. These are waves formed by two oscillating waves: an electrical wave and a magnetic wave. I will not enter deep into it because I am honestly lame in explaining physics but two things are important for the explanation.
First, oscillating waves have a sinusoidal pattern. Think about a roller coster pattern, in which in a succession your wagon goes up and down in a regular basis. However, this wagon always reach the same height at regular distance: this distance is refered as the wavelength (also symobilized by the Greek letter lambda). The wavelength (a distance unit), usually in the metric system) is inverse to another parameter called frequency (a time unit, expressed in Hertz), by the following formula: Wavelength=1/Frequency. Frequency is usually represented by the Greek letter “nu”
Second, the frequency is associated with energy (E in joules) by the equation of Planck as Energy (E) = Frequency x h, with h being the Planck constant.
Energy is never lost, it is only transformed. A mechanical energy can become thermal energy, that in turn can be transferred into chemical energy and so on.
This brings on the idea of non-ionizing and ionizing energy as depicted below.
If your EM wave can provide enough energy to kick out an electron from an atom, it will create an unstable ion that will do all the best to get back its missing electron, even if it means stealing from its neighbors. This is how free radicals are formed. Free radicals are fairly nasty because they are lacking an electron and will do their best to steal from its neighbor, which in turn will also become an electron thief. This is why ionizing radiations (UV, X-rays, gamma rays from certain radioactive isotopes, cosmic rays) are so dangerous and are known cause of cancer.
In the other hand, common EM waves we are constantly bombarded from our electronic devices such as the car FM radio, the satellite dish setup, the wireless signals from our phones and from the Wifi and even the microwaves from your microwave oven (that had some fearmonger at its launch) are simply too weak to ionize an atom and create the dreaded free radicals chain reaction.
2. Does EM waves make your BBB leaky?
This is some of the claims that some people use to justify their fear of EMFs, since the demonstration of EMFs to cause brain tumors failed to reach a conclusive level. To support of debunk this claim, we will use “Pubmed”, the gold-standard of scientific article database, listing every peer-reviewed studies. However one of the caveat of Pubmed is to publish studies from reputable and less reputable (aka predatory) journals making for a profane hard to distinguish the good from the bad science. However, a graduate student with a BS in Sciences (preferentially with a major in Biology) should have the knowledge to read a paper and assess the quality.
If we use the terms “blood-brain barrier AND electromagnetic field“, we are ending with 68 studies. We will also limit our search to 2005, as we in science consider obsolete any literature that is 10 years and over. We have in total 47 hits with this criteria. I am also narrowing to studies that specifically looked at the EMFs within the 900-5000Mhz, a band spectrum covering the GSM signal from wireless phones up to the Wifi signal (2400Mhz for the 802.11a/b/g norm and 5000Mhz for the 802.11n/ac norm). After removing local (non-translated studies) journals, reviews and non-related studies (one study on EMP was removed as it was not fitting the criteria defined by our analysis), we end up with 17 studies over a 10-year period (11 done in vivo and 5 done in vitro). I have summarized the finding in an easy to read graph
Two things to note.
First, the overwhelming majority (>80% of published studies) show no or even a positive effect of EMFs in drug delivery of nano-particles loaded with HIV antiviral drugs as published here here and here.
Second, the relative poor publication record on that particular niche (less than 5 studies and review published a year) that makes the argument in favor of harmful effects of EMFs either under investigated or overblown. I would stand with the latter as the odds of publishing negative results (in this case, no effects of EMFs on the BBB function) is much smaller than publishing positive results. Therefore we may indeed overblown the number of studies showing the effect of EMFs on the BBB function, as this number maybe much smaller if all studies left in a drawer were published.
Now let see these few outsiders that have shown a negative effects of EMFs on the barrier function. I have identified four studies: Zhu et al., Brain Res 2015; Kumar et al., Electromag Biol Med 2012; Demir et al., Bioelectromagnetics 2010 and Sirav et al., Electromag Biol Med 2009. With the exception of the latest study (IF2014~2.78), all the three other studies were published in journals with a very poor impact factor (IF<2), with Bioelectromagnetics and Electromagnetics Biology Medicine having a displayed IF of 1.20 and 1.5 respectively.
The second caveat is the lack of explicit definition of the intensity of exposure, especially the specific absorbance rate (or SAR) expressed in W/kg. This is the average exposure rate deemed safe. For wireless communications, the SAR in the US set by the FDA is 1.6W/kg, whereas it can go up to 3.0W/kg (with focal acute head exposure) if you are subjected to an MRI head scan. The only study that specifically provide such information is the study from Zhu and colleagues with a SAR of 2W/kg.
Now the SAR expressed a mass unit has a caveat as it does not take into account the physiological difference between a rodent brain and a human brain, both in terms of volume and surface. A rat brain has an average weight of 2g, a human brain has an average weight of 1400-1600g (source: https://faculty.washington.edu/chudler/facts.html). However, a human brain has a thickness much more important than a rat brain, especially the human cortex is twice larger than a rat cortex, so the penetration of EMF waves is twice less in humans than rats. Indeed, we should be consider the surface area that is exposed to such EMFs, in the same manner we are describing the pressure in physics as a unit of force over a surface area (Pressure (N/m2) = Force (N)/ surface area (m2)).
A rat has a surface area of 6cm2, a human has a surface area of 2500cm2.
If you apply the same force into two difference surface area, the pressure will be completely different. The force (N) is the product of the mass (kg) by the Earth gravity acceleration (9.81 m/s, for this example we will ease the calculation by rounding it to 10 m/s). If I apply one ton (1000kg) mass, it has a force of 10’000N.
Now the pressure of this one ton mass will be different if I apply to 1m2 surface (P=10’000N/m2) or if I apply it to 1000m2 surface (P=1’000N/m2). The pressure is ten-times less for the same force applied.
Now, if we replace the force by the EMF exposure limit recommended by the FDA for non-medical application (wireless communications), we have a SAR of 1.6W/kg. If we do the maths using the pressure formula, then the “EMF pressure” a rat exposed to a 2W/kg EMF has a EMF pressure of 2/6 = 0.33W/kg/cm2 or 33.3W/kg/m2. A human exposed to a 2W/kg EMF has a EMF pressure of 2/2500 = 0.0008 W/kg/cm2 or 0.08W/kg/m2.
This gives us a ratio of 33.3/0.08=41.65. So a rat in a experiment exposed to EMF radiations was exposed to a level that was over 40 times the maximal recommended dose. You have to have your head exposed to 40 wireless phones in active call next to your ear constantly to experience some of the issues reported. Or you have to stick your head next to a wireless antenna relay continuously or put your head inside a working microwave to get radiations that are at least as much as reported.
This is how bad and poorly experimental design leads to poor conclusions and fuel bad studies. You see now that not only the numbers of studies pointing to the dangers of EMFs are insufficient, but they are also so poorly designed that their translation to a real-life situation is almost impossible unless you are competing for a Darwin Award.
In conclusion, there is no evidence to support claims made by some about the dangers of the EMFs on the blood-brain barrier, the data supporting their claims are indeed so poorly designed that the only concerns someone may have are those exposed to strong EMFs as their occupational work (MRI technicians….) but this is part of OSHA regulations.
You can however play the precocious card, by limiting the time your cell phone is on your ear, if you are an avid phone person then consider using a bluetooth headset. Don’t hack your Wifi into a WiMax to send signals miles away from your router and please please please put down that tinfoil hat :p. Not only it is worthless but you just making a fool of yourself as well.